Reanalysis questions

This is the general tropical discussion area. Anyone can take their shot at predicting a storms path.

Moderator: S2k Moderators

Forum rules

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

Help Support Storm2K
Message
Author
User avatar
Shell Mound
S2K Supporter
S2K Supporter
Posts: 209
Age: 25
Joined: Thu Sep 07, 2017 3:39 pm
Location: Forever Island, FL ↔︎ Scandinavia

Re: Reanalysis questions

#301 Postby Shell Mound » Thu Mar 08, 2018 6:41 pm

1900hurricane wrote:Regarding Joan '88, I created a plot from the 20th Century Reanalysis v2 dataset to estimate OCI and ROCI to use with KZC. For OCI, I have 1008 mb, and for ROCI, I have 285 nm. For storm speed, I took the distance between the 00Z and 06Z best track points and divided by six for the six hour average speed, which ended up being 6.83 kt. L is 11.9ºN from best track, and P is 932 mb also from best track. When all plugged into KZC, expected Vmax is a cool 130 kt even.

>>> from KZCeq import KZC, KZCroci
>>> p = 932
>>> c = 41 / 6
>>> c
6.833333333333333
>>> 9.5 * 30
285.0
>>> roci = 285
>>> l = 11.9
>>> oci = 1008
>>> p0 = 1000
>>> v = 100
>>> while p0 >= p:
v = v + 0.1
p0 = KZC(KZCroci(v, c, roci, l), oci)


>>> print('%3.0f' % v)
130


I've been playing with the ROCI version of KZC a little bit, and for the most part it appears to match up very well with the TS wind radius version that is operationally used. It does diverge a little bit towards the 'windier' out beyond 155 kt or so, but not exceptionally so, and I actually prefer the ROCI version when it comes to weaker storms that sometimes have inconsistent wind radii. Naturally, I then pulled up some old surface charts of past storms and computed away. Here's a few that I did.

1900hurricane: p = 936, c = 13.8, roci = 250, l = 29.1, oci = 1009, v = 121 kt
(p = 931) v = 127 kt
Andrew '92: p = 922, c = 17.3, roci = 113, l = 25.5, oci = 1013, v = 148 kt
Celia '70: p = 945, c = 13.3, roci = 120, l = 27.6, oci = 1009, v = 114 kt
Camille '69: p = 900, c = 14.0, roci = 120, l = 30.3, oci = 1003, v = 156 kt
Carla '61: p = 931, c = 4.33, roci = 375, l = 28.0, oci = 1004, v = 114 kt

Interestingly, your V-max estimates come very close to the official ones in HURDAT, but with a reasonable difference of ± 10 knots in some cases. The surface analysis of Andrew (OCI over South Florida: 1013 mb!) makes strikingly clear how such a small, intense storm, making landfall in the same area, would have easily gone undetected prior to 1900, as South Florida was virtually unsettled before the arrival of the railroads and associated growth. An Andrew-type storm in the 1800s or earlier would have been assessed as a weak low that passed over South Florida, entered the Gulf, and brought breezy, rainy conditions to parts of FL and rural LA. The very high environmental pressures and compact RMW would have greatly skewed official estimates on how strong the storm was.
0 likes   
From the Land of Allapattah to the Shore of Caloosahatchee

User avatar
Ptarmigan
Category 5
Category 5
Posts: 5029
Joined: Wed Aug 16, 2006 9:06 pm

Re: Reanalysis questions

#302 Postby Ptarmigan » Sun Mar 11, 2018 9:36 pm

CrazyC83 wrote:The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

As for Gilbert, if I reanalyzed it based on data I have seen, here's what it would look like:

AL081988, GILBERT, 49,
19880908, 1800, , TD, 12.0N, 54.0W, 25, 1008, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880909, 0000, , TD, 12.7N, 55.6W, 25, 1007, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880909, 0600, , TD, 13.3N, 57.1W, 30, 1006, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880909, 1200, , TS, 14.0N, 58.6W, 35, 1004, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880909, 1800, , TS, 14.5N, 60.1W, 40, 1001, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880910, 0000, , TS, 14.8N, 61.5W, 45, 998, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880910, 0600, , TS, 15.0N, 62.8W, 55, 994, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880910, 1200, , TS, 15.3N, 64.1W, 60, 992, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880910, 1800, , HU, 15.7N, 65.4W, 70, 987, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880911, 0000, , HU, 15.9N, 66.8W, 85, 979, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880911, 0600, , HU, 16.2N, 68.0W, 90, 976, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880911, 1200, , HU, 16.1N, 69.5W, 100, 975, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880911, 1800, , HU, 16.2N, 70.7W, 100, 970, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880912, 0000, , HU, 16.8N, 72.0W, 105, 964, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880912, 0600, , HU, 17.3N, 73.7W, 110, 962, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880912, 1200, , HU, 17.6N, 75.3W, 115, 959, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880912, 1700, L, HU, 17.8N, 76.8W, 120, 957, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880912, 1800, , HU, 17.9N, 76.9W, 115, 958, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880913, 0000, , HU, 18.2N, 78.5W, 110, 962, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880913, 0600, , HU, 18.5N, 79.7W, 120, 952, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880913, 1200, , HU, 18.8N, 81.1W, 140, 934, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880913, 1800, , HU, 19.4N, 82.5W, 165, 905, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880914, 0000, , HU, 19.7N, 83.8W, 170, 884, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880914, 0600, , HU, 19.9N, 85.3W, 160, 889, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880914, 1200, , HU, 20.4N, 86.5W, 155, 892, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880914, 1500, L, HU, 20.7N, 87.0W, 150, 900, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880914, 1800, , HU, 20.9N, 87.8W, 120, 925, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880915, 0000, , HU, 21.3N, 89.5W, 85, 944, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880915, 0600, , HU, 21.6N, 90.7W, 85, 949, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880915, 1200, , HU, 21.9N, 91.7W, 85, 950, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880915, 1800, , HU, 22.1N, 92.8W, 90, 950, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880916, 0000, , HU, 22.5N, 93.8W, 95, 948, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880916, 0600, , HU, 22.9N, 94.8W, 100, 944, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880916, 1200, , HU, 23.7N, 95.9W, 105, 943, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880916, 1800, , HU, 23.9N, 97.0W, 100, 947, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880916, 2200, L, HU, 24.2N, 97.8W, 90, 955, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880917, 0000, , HU, 24.4N, 98.2W, 75, 964, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880917, 0600, , TS, 24.8N, 99.3W, 50, 988, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880917, 1200, , TS, 25.0N, 100.5W, 35, 996, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880917, 1800, , TD, 25.4N, 101.9W, 30, 1000, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880918, 0000, , TD, 26.0N, 103.2W, 30, 1002, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880918, 0600, , TD, 27.6N, 103.7W, 30, 1004, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880918, 1200, , TD, 29.3N, 102.6W, 25, 1003, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880918, 1800, , TD, 31.5N, 101.3W, 25, 1003, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880919, 0000, , TD, 33.2N, 99.7W, 25, 1002, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880919, 0600, , TD, 35.8N, 97.7W, 25, 1001, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880919, 1200, , TD, 37.7N, 93.2W, 25, 999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880919, 1800, , EX, 40.2N, 89.9W, 25, 998, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19880920, 0000, , EX, 43.4N, 86.5W, 25, 995, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,

Some reasoning:

* Limited Recon data suggests that Gilbert intensified a bit more earlier in its life due to lower pressure measurements. Hence the intensities on the 10th and 11th were largely increased.
* The intensity at Jamaican landfall is estimated at 120 kt. That is based on surface data of 100-105 kt sustained winds, which may have very well been 10-min winds, and the limited spatial observations. That is despite a fairly high pressure (analyzed at 957 mb). Slight weakening occurred thereafter, probably due to an ERC, as the pressure filled a bit per Recon.
* The lowest pressure was 888 mb at 2130Z on September 13. The next Recon penetration was not until about 0500Z on September 14, when 894 mb was measured, and then the following pass measured 890 mb. Due to the difficulty of measuring low pressures in extreme conditions, 889 was maintained at 0600Z. The minimum pressure was hence analyzed at 884 mb at 0000Z, assuming additional deepening after the 888 report.
* There is also uncertainty in the peak intensity - I went with 170 kt, although a case for an even higher intensity could be made. That is based on the extremely low pressure and the 173 kt measured at 700 mb, which in a rapidly deepening storm the 90% rule may be very conservative. Those winds were also not particularly reliable in 1988. I could have gone with 175 or even 180 kt, knowing that Dvorak was an easy T8.0, which is unique in the record.
* At Yucatan landfall, I analyzed an intensity of 150 kt. That is higher than HURDAT, based on flight level winds around 155 kt and the 900 mb pressure.
* In the Gulf, uncertainty is quite high. Flight level winds were all over the place - ranging from 85 kt to 115 kt. Yet the pressure only dropped a bit to about 943 at its minimum, and then rose to 955 at landfall. Dvorak largely ran at T5.0 or T5.5. There is nothing to suggest it was a cat 4 (as with the BT), hence the intensities come down. I have it emerging from the Yucatan with 85 kt winds, increasing to a final peak of 105 kt, then down to 90 kt at final landfall. Those are very uncertain estimates though.


1900hurricane wrote:Did you know the 888 mb in Gilbert wasn't actually measured? It's actually an estimate based on the 700 mb extrapolated pressure which was then bias corrected. The paper by Willoughby, Masters, and Landsea goes into detail how the value was derived. It's quite an interesting read.


I always thought Gilbert had a central pressure lower than 888 millibars. I read the Hurricane Hunters measured as low as 882 millibars.
0 likes   

User avatar
Chris90
Tropical Storm
Tropical Storm
Posts: 108
Age: 28
Joined: Thu Jun 01, 2017 9:36 pm

Re: Reanalysis questions

#303 Postby Chris90 » Tue Mar 20, 2018 8:15 pm

I'm curious, does anyone have good recon data from the flight into Allen that measured the 899mb on August 7th?

I did a Google search this evening because I was wondering how they came to the 165kt peak intensity, but all I found was a journal article that covered the 1980 hurricane season. The article said that they measured a 155kts 10 second average at 500m altitude on August 5th, when Allen was a Cat 5 for the first time with a minimum central pressure of 911mb. Based off the article on eyewall wind profiles, 155kts at 500m would translate to at most 140kts surface, correct? I'm kind of guesstimating that. If we go with that estimate though, 140kts and 911mb, does 899mb really translate to 165kts?

If anyone has more data from when they measured 899mb, I would greatly appreciate it. Also interested to hear opinions and analysis from others on Allen too. I'm just not sure it peaked at 165kts, when other storms have had more impressive presentation in my opinion.
0 likes   
I can't stand the rain..

User avatar
1900hurricane
Category 5
Category 5
Posts: 3689
Age: 27
Joined: Fri Feb 06, 2015 12:04 pm
Location: College Station, TX
Contact:

Re: Reanalysis questions

#304 Postby 1900hurricane » Tue Mar 20, 2018 9:25 pm

From the NHC report, peak flight level winds were measured at 165 kt on the 899 mb pass, and surface winds estimated from the sea state were said to actually be as high as 170 kt (which I believe was actually the operational intensity estimate). Estimating surface winds from sea state can be very subjective though (which is why SFMR was developed to objectively measure it).

Image

165 kt was probably settled on for a couple of reasons. The wind/pressure relationship used at the time had winds between 160 and 165 kt for a pressure of 899 mb. When blending this with the operational estimate, 165 kt is a good compromise. This also matched the flight level winds in a time before standard wind reductions from flight level were established.

Going back to the 165 kt flight level wind, assuming this occurred at ~700 mb, the standard 0.9 reduction factor would yield a surface estimate of about 149 kt. If a 0.95 reduction factor is used, the surface estimate rises up to about 157 kt. A hypothesis of mine is that more intense systems often have a 700 mb reduction closer to 0.95 than 0.9, but there is unfortunately not much data to go off. The only two particularly intense systems I know that had reliable SFMR data were Megi '10 and Patricia '15. SFMR data from Patricia '15 seemed to run at about the 0.95 ratio near peak intensity while Megi '10 appeared to run closer to the more standard 0.9.

>>> 165 * 0.9
148.5
>>> 165 * 0.95
156.75


KZC can also be used to estimate intensity. Pressure is known at 899 mb, latitude at 21.8ºN, and speed is derived from the coordinates. I got a forward speed of about 16.8 kt using the 12Z and 18Z coordinates from August 7th. Additionally, I derived an outermost closed isobar of 1009 mb at an average radius of 270 nm from 20th Century Reanalysis v2 data (below).

Image

Putting it all together and running it through KZC, I get an expected Vmax of about 162 kt.

>>> from TCeq import KZC, KZCroci
>>> 25 - 16
9
>>> 9 * 30
270
>>> roci = 270
>>> oci = 1009
>>> l = 21.8
>>> p = 899
>>> c = 16.8
>>> v = 100
>>> p0 = 1000
>>> while p0 > p:
... v = v + 0.1
... p0 = KZC(KZCroci(v, c, roci, l), oci)
...
>>> print('%3.0f' % v)
162


Satellite imagery for Allen near peak intensity is actually only that of a T7.0, but a pretty strong one. In fact, the satellite appearance is fairly similar to that of Rita '05 and Flo '90, which also both had sub 900 mb pressures. It is suspected that the Dvorak Technique can underestimate systems T6.5 and above at times.

Image

Just based on all this, I'd probably estimate Allen '80 to have a peak intensity of about 160 kt concurrent with the 899 mb pressure, although a 155 kt intensity might also be appropriate.
2 likes   
Wayward meteorology student on a journey back to the promised land.

Follow me on Twitter at @1900hurricane : Read blogs at https://1900hurricane.wordpress.com/

User avatar
Chris90
Tropical Storm
Tropical Storm
Posts: 108
Age: 28
Joined: Thu Jun 01, 2017 9:36 pm

Re: Reanalysis questions

#305 Postby Chris90 » Tue Mar 20, 2018 10:35 pm

Thank you for the response. Your analysis is always so insightful.
It's interesting that they estimated 170kt surface winds. I'm wondering if this was from the first experimental SFMR. I read that the first experimental SFMR was used for the first time in Allen to make measurements, but then they never used it again. I had been wondering if maybe this was how they derived the 165kt and if it was possibly inflated. Now that you've posted the 165kts flight level wind as well as the KZC analysis, 165kts definitely seems reasonable.
0 likes   
I can't stand the rain..

CrazyC83
Professional-Met
Professional-Met
Posts: 26984
Joined: Tue Mar 07, 2006 11:57 pm
Location: Deep South, for the first time!

Re: Reanalysis questions

#306 Postby CrazyC83 » Thu Mar 22, 2018 7:07 pm

I'm not sure how reliable that 170 kt intensity would be. If the 90% rule was used for 165 kt FL winds, that would translate to an intensity around 150 kt. Dvorak would also support 150 kt. There are definitely conflicting signs in Allen. Given the KZC analysis, I would leave it at 165 kt.

However, I wonder if winds were also up there when it was in the eastern Caribbean? I believe the pressure was 910 at the time.
0 likes   

User avatar
1900hurricane
Category 5
Category 5
Posts: 3689
Age: 27
Joined: Fri Feb 06, 2015 12:04 pm
Location: College Station, TX
Contact:

Re: Reanalysis questions

#307 Postby 1900hurricane » Fri Mar 23, 2018 9:21 pm

I get 154 kt for the 00Z August 5th best track point, which had a pressure of 911 mb.

Image

>>> oci = 1007
>>> roci = 210
>>> 107 / 6
17.833333333333332
>>> c = 17.8
>>> l = 14.8
>>> p = 911
>>> p0 = 1000
>>> v = 100
>>> while p0 > p:
v = v + 0.1
p0 = KZC(KZCroci(v, c, roci, l), oci)


>>> print('%3.0f' % v)
154


Image

Additionally, I get 148 kt for the 909 mb Gulf of Mexico peak at 06Z August 9th.

Image

>>> roci = 330
>>> oci = 1009
>>> c = 12
>>> l = 25
>>> p = 909
>>> v = 100
>>> p0 = 1000
>>> while p0 > p:
v = v + 0.1
p0 = KZC(KZCroci(v, c, roci, l), oci)


>>> print('%3.0f' % v)
148


Image
1 likes   
Wayward meteorology student on a journey back to the promised land.

Follow me on Twitter at @1900hurricane : Read blogs at https://1900hurricane.wordpress.com/

User avatar
Shell Mound
S2K Supporter
S2K Supporter
Posts: 209
Age: 25
Joined: Thu Sep 07, 2017 3:39 pm
Location: Forever Island, FL ↔︎ Scandinavia

Re: Reanalysis questions

#308 Postby Shell Mound » Sat Apr 14, 2018 12:18 pm

Does anyone know when the 1961-65 reanalysis will be released? I wonder why there's been a holdup since 2016...
0 likes   
From the Land of Allapattah to the Shore of Caloosahatchee

User avatar
galaxy401
Category 5
Category 5
Posts: 1252
Age: 23
Joined: Sat Aug 25, 2012 9:04 pm
Location: Casa Grande, Arizona

Re: Reanalysis questions

#309 Postby galaxy401 » Sat Apr 14, 2018 5:25 pm

Shell Mound wrote:Does anyone know when the 1961-65 reanalysis will be released? I wonder why there's been a holdup since 2016...


Looks like the next analysis will be 1961-1970. Looks like it might be revealed in two days in a presentation though I don't know when it will be released for everyone else.
0 likes   
I don't get hurricanes here but I do get their remnants.

User avatar
Iune
Category 1
Category 1
Posts: 270
Joined: Mon Aug 04, 2008 12:23 pm
Location: Urbana, Illinois

Re: Reanalysis questions

#310 Postby Iune » Sat Apr 14, 2018 6:47 pm

galaxy401 wrote:
Shell Mound wrote:Does anyone know when the 1961-65 reanalysis will be released? I wonder why there's been a holdup since 2016...


Looks like the next analysis will be 1961-1970. Looks like it might be revealed in two days in a presentation though I don't know when it will be released for everyone else.


In only two more days? I've been looking forward to this update since the winter. :D I think I heard rumors that Inez (1966) would be upgraded to a Category 5 storm following reanalysis.
1 likes   
Floyd 1999 · Irene 2011 · Sandy 2012

User avatar
Shell Mound
S2K Supporter
S2K Supporter
Posts: 209
Age: 25
Joined: Thu Sep 07, 2017 3:39 pm
Location: Forever Island, FL ↔︎ Scandinavia

Re: Reanalysis questions

#311 Postby Shell Mound » Sat Apr 14, 2018 8:34 pm

galaxy401 wrote:
Shell Mound wrote:Does anyone know when the 1961-65 reanalysis will be released? I wonder why there's been a holdup since 2016...


Looks like the next analysis will be 1961-1970. Looks like it might be revealed in two days in a presentation though I don't know when it will be released for everyone else.

As far as I know, the reanalysis is typically released in five-year segments. Perhaps the Best Track Committee is looking to expedite the process by releasing more at a time...
0 likes   
From the Land of Allapattah to the Shore of Caloosahatchee

User avatar
Hammy
Category 5
Category 5
Posts: 3496
Age: 35
Joined: Fri May 25, 2012 5:25 pm
Contact:

Re: Reanalysis questions

#312 Postby Hammy » Sat Apr 21, 2018 1:36 pm

Has there been any new information on this? I know there was a hurricane conference this week but don't know what all was presented.
0 likes   
The above post is not official and should not be used as such. It is the opinion of the poster and may or may not be backed by sound meteorological data. It is not endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
---
My comics.
http://tba.cfw.me/
http://tbakids.cfw.me/

CrazyC83
Professional-Met
Professional-Met
Posts: 26984
Joined: Tue Mar 07, 2006 11:57 pm
Location: Deep South, for the first time!

Re: Reanalysis questions

#313 Postby CrazyC83 » Sat Apr 21, 2018 4:00 pm

Another of the great storms of that era I'm going to look at: Allen from 1980. Here's how I would change HURDAT2:

AL041980, ALLEN, 48,
19800731, 0600, , DB, 11.1N, 27.8W, 25, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800731, 1200, , TD, 11.0N, 30.0W, 30, 1010, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800731, 1800, , TD, 10.9N, 32.2W, 30, 1010, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800801, 0000, , TD, 10.8N, 34.3W, 30, 1010, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800801, 0600, , TD, 10.7N, 36.4W, 30, 1010, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800801, 1200, , TD, 10.7N, 38.6W, 25, 1012, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800801, 1800, , TD, 10.7N, 40.7W, 25, 1013, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800802, 0000, , TD, 11.0N, 42.8W, 30, 1008, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800802, 0600, , TS, 11.4N, 44.8W, 40, 1004, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800802, 1200, , TS, 11.9N, 46.9W, 45, 1001, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800802, 1800, , TS, 12.3N, 49.1W, 50, 998, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800803, 0000, , TS, 12.4N, 51.4W, 55, 995, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800803, 0600, , TS, 12.6N, 53.6W, 60, 991, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800803, 1200, , HU, 12.8N, 55.6W, 65, 986, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800803, 1800, , HU, 12.9N, 57.5W, 85, 972, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800804, 0000, , HU, 13.3N, 59.1W, 110, 950, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800804, 0600, , HU, 13.6N, 61.0W, 120, 946, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800804, 1200, , HU, 14.0N, 63.0W, 110, 944, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800804, 1800, , HU, 14.4N, 64.9W, 135, 930, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800805, 0000, , HU, 14.8N, 66.7W, 155, 911, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800805, 0600, , HU, 15.4N, 68.6W, 150, 916, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800805, 1200, , HU, 15.9N, 70.5W, 140, 932, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800805, 1800, , HU, 16.5N, 72.3W, 135, 937, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800806, 0000, , HU, 17.8N, 73.8W, 125, 942, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800806, 0600, , HU, 18.3N, 75.9W, 110, 950, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800806, 1200, , HU, 19.2N, 78.0W, 100, 956, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800806, 1800, , HU, 20.0N, 80.1W, 105, 951, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800807, 0000, , HU, 20.1N, 81.9W, 110, 945, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800807, 0600, , HU, 20.4N, 83.6W, 135, 931, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800807, 1200, , HU, 21.0N, 84.8W, 155, 910, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800807, 1800, , HU, 21.8N, 86.4W, 165, 899, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800808, 0000, , HU, 22.2N, 87.9W, 140, 924, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800808, 0600, , HU, 22.8N, 89.2W, 105, 946, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800808, 1200, , HU, 23.4N, 90.5W, 100, 956, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800808, 1800, , HU, 23.9N, 91.8W, 115, 940, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800809, 0000, , HU, 24.5N, 93.0W, 135, 915, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800809, 0600, , HU, 25.0N, 94.2W, 145, 909, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800809, 1200, , HU, 25.2N, 95.4W, 130, 917, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800809, 1800, , HU, 25.4N, 96.1W, 120, 921, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800810, 0000, , HU, 25.8N, 96.8W, 105, 931, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800810, 0600, , HU, 26.1N, 97.2W, 90, 946, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800810, 0700, L, HU, 26.2N, 97.4W, 90, 948, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800810, 1200, , HU, 26.7N, 98.1W, 65, 966, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800810, 1800, , TS, 27.3N, 99.0W, 50, 985, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800811, 0000, , TS, 27.7N, 99.8W, 40, 992, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800811, 0600, , TS, 28.0N, 100.9W, 35, 1000, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800811, 1200, , TD, 28.5N, 101.9W, 30, 1005, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19800811, 1800, , TD, 28.9N, 102.9W, 30, 1008, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,

There are many changes I make. Some highlights:

* Satellite data suggests genesis was 12 hours earlier at 1200Z July 31, although I could have gone earlier still. However, it actually loses organization on August 1 (Igor redux?) and its classification as a tropical storm is delayed.
* Pre-Recon intensities are mostly lowered. That is due to satellite data suggesting it was not as strong as HURDAT - in fact, an open eye was not visible until Recon arrived. Hurricane status is delayed 12 hours.
* Once Recon arrived at 1800Z August 3, Allen was in a clear, rapid intensification trend. In just 18 hours, it went from 65 kt to 120 kt, based on Recon plus Dvorak changes from T4.0 to T6.5.
* The initial eastern Caribbean peak remains 155 kt, but moves up to the same time as the 911 mb pressure. That was after a brief weakening due to an ERC (confirmed by satellite). The only reliable winds were 155 kt at 925 mb around 1800Z August 5, at that point with the storm having weakened. Since that is just above the surface (pressure 937), the intensity at that time was kept a possibly generous 135-140 kt.
* Another weakening trend, due to an ERC and shear, occurred in the central Caribbean. HURDAT only lowered it to 115 kt in that time, but the pressure bottomed out at 956 and Dvorak dropped to T5.0, The NOAA plane (reliable then) had winds of 116 kt followed by 123 kt at 1800Z and 0000Z on August 6-7. Those suggest intensities of 105-110 kt in that period (no other wind data was reliable). Given the higher pressure earlier on August 6, the relative lull in winds I estimate at 100 kt.
* The next rapid deepening led Allen to the minimum pressure of 899 mb. The NOAA plane had 165 kt winds at 700 but a surface estimate (likely unreliable) of 170 kt. Dvorak looked to be around T7.5. Given that bombing storms often have SFMR readings near the FL winds (obviously not available in 1980!), the 165 kt peak intensity in HURDAT I maintained.
* Right after the peak, a rapid filling occurred. The pressure filled from 899 to 961 in about 16 hours (before returning to 956 by synoptic time), and Dvorak went from T7.5 to T5.0. No reliable wind data was available. HURDAT never lowers the intensity below 115 kt, but given the rapid fluctuations and pressure relationships, I bottomed it out again at 100 kt (with considerable uncertainty).
* Now a large storm in the Gulf, the pressure tumbled again to 909. However, the highest winds by the NOAA plane (measured about 6 hours before that peak) were 145 kt at 850, but that was in the middle of the rapid deepening. At that point, I went with 135 kt for the intensity (again due to the underestimation during RI) and 145 kt at its Gulf peak.
* Slow movement and land interaction resulted in clear filling before landfall. The NOAA plane never recorded winds higher than 90 kt at 700 mb in the hours leading up to landfall. Dvorak had dropped to about T4.5, but the pressure was still in the 940s. The highest winds on land were gusts to 120 kt at Port Mansfield, and an elevated sustained wind of 120 kt on an oil rig (which would likely translate to about 100-105 kt at the surface, but I doubt that was reliable). A blend of all the data would support a 90 kt landfall intensity, leaning towards the lower data but still respecting the oil rig data and pressure.
2 likes   

User avatar
Shell Mound
S2K Supporter
S2K Supporter
Posts: 209
Age: 25
Joined: Thu Sep 07, 2017 3:39 pm
Location: Forever Island, FL ↔︎ Scandinavia

Re: Reanalysis questions

#314 Postby Shell Mound » Fri May 04, 2018 2:29 pm

https://ams.confex.com/ams/33HURRICANE/webprogram/Paper339830.html

The recorded presentation of the 1961–70 reanalysis is now available online. At 11:40, the presentation adds some previously unknown information: that Esther (1961) has been upgraded to 140 knots at its peak, meaning two new Cat 5s rather than just Inez (1966); that Celia (1970) has been preliminarily upgraded to 120 knots (Cat 4) at its landfall in Texas; and that two new hurricanes have been discovered in 1962 and 1970, respectively. (Interestingly, the slide at 11:40 does not mention any other notable changes to the status of U.S. hurricanes, so there may not be any new and/or dramatic changes to storms such as Cleo [1964], but I'm just speculating.) At 13:06, the presentation mentions that the 1961-65 reanalysis has already "been effected," implying that it is already officially finalised by the Best Track Committee, so I would expect the changes to be made public within the next several weeks. Preliminary reanalysis has already been completed for 1966-71.
1 likes   
From the Land of Allapattah to the Shore of Caloosahatchee

User avatar
Hammy
Category 5
Category 5
Posts: 3496
Age: 35
Joined: Fri May 25, 2012 5:25 pm
Contact:

Re: Reanalysis questions

#315 Postby Hammy » Sun May 06, 2018 5:09 pm

:uarrow: Any word on when (or if) the preliminary 1966-71 will be published, or when 61-65 will be out, or if the preliminary seasonal maps are available anywhere?
0 likes   
The above post is not official and should not be used as such. It is the opinion of the poster and may or may not be backed by sound meteorological data. It is not endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
---
My comics.
http://tba.cfw.me/
http://tbakids.cfw.me/

CrazyC83
Professional-Met
Professional-Met
Posts: 26984
Joined: Tue Mar 07, 2006 11:57 pm
Location: Deep South, for the first time!

Re: Reanalysis questions

#316 Postby CrazyC83 » Wed May 09, 2018 1:10 pm

Hammy wrote::uarrow: Any word on when (or if) the preliminary 1966-71 will be published, or when 61-65 will be out, or if the preliminary seasonal maps are available anywhere?


That presentation said 1961-65 is coming soon, likely this summer. I am not sure when the thesis/results will be published, probably in the next year or so.
0 likes   

CrazyC83
Professional-Met
Professional-Met
Posts: 26984
Joined: Tue Mar 07, 2006 11:57 pm
Location: Deep South, for the first time!

Re: Reanalysis questions

#317 Postby CrazyC83 » Wed May 09, 2018 1:21 pm

Shell Mound wrote:https://ams.confex.com/ams/33HURRICANE/webprogram/Paper339830.html

The recorded presentation of the 1961–70 reanalysis is now available online. At 11:40, the presentation adds some previously unknown information: that Esther (1961) has been upgraded to 140 knots at its peak, meaning two new Cat 5s rather than just Inez (1966); that Celia (1970) has been preliminarily upgraded to 120 knots (Cat 4) at its landfall in Texas; and that two new hurricanes have been discovered in 1962 and 1970, respectively. (Interestingly, the slide at 11:40 does not mention any other notable changes to the status of U.S. hurricanes, so there may not be any new and/or dramatic changes to storms such as Cleo [1964], but I'm just speculating.) At 13:06, the presentation mentions that the 1961-65 reanalysis has already "been effected," implying that it is already officially finalised by the Best Track Committee, so I would expect the changes to be made public within the next several weeks. Preliminary reanalysis has already been completed for 1966-71.


Regarding Celia, I agree with the upgrade, but I might have even been able to make a case for 125 kt given its size and ferocity. Interesting re: Esther, maybe they found a Recon flight with an even lower pressure (in the low 920s)?
0 likes   

User avatar
Hammy
Category 5
Category 5
Posts: 3496
Age: 35
Joined: Fri May 25, 2012 5:25 pm
Contact:

Re: Reanalysis questions

#318 Postby Hammy » Wed May 09, 2018 2:45 pm

Strange as it may be the two most interesting things for me are Kendra's track and intensity (now that I know for sure they're adding it back) as well as the additional storm in 1970 east of the Caribbean--likely a very long-lived depression that for years I've suspected was stronger.

Image
1 likes   
The above post is not official and should not be used as such. It is the opinion of the poster and may or may not be backed by sound meteorological data. It is not endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
---
My comics.
http://tba.cfw.me/
http://tbakids.cfw.me/

CrazyC83
Professional-Met
Professional-Met
Posts: 26984
Joined: Tue Mar 07, 2006 11:57 pm
Location: Deep South, for the first time!

Re: Reanalysis questions

#319 Postby CrazyC83 » Sun Jul 22, 2018 9:57 pm

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

Another older storm I'm going to look at is Hurricane David of 1979:

(Red - stronger, Green - weaker, Blue - new point)

AL091979, DAVID, 61,
19790825, 0000, , TD, 11.8N, 32.0W, 25, 1010, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790825, 0600, , TD, 11.8N, 34.1W, 30, 1008, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,

19790825, 1200, , TS, 11.7N, 36.1W, 35, 1006, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790825, 1800, , TS, 11.7N, 38.2W, 45, 1003, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790826, 0000, , TS, 11.7N, 40.3W, 45, 1003, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790826, 0600, , TS, 11.6N, 42.2W, 50, 1001, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790826, 1200, , TS, 11.6N, 44.0W, 55, 998, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790826, 1800, , TS, 11.6N, 45.5W, 60, 995, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790827, 0000, , HU, 11.7N, 47.0W, 65, 992, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790827, 0600, , HU, 11.8N, 48.5W, 75, 983, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790827, 1200, , HU, 11.8N, 50.0W, 90, 968, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790827, 1800, , HU, 11.9N, 51.5W, 105, 954, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790828, 0000, , HU, 12.2N, 52.9W, 120, 944, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790828, 0600, , HU, 12.5N, 54.4W, 125, 941, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790828, 1200, , HU, 12.8N, 55.7W, 130, 937, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790828, 1800, , HU, 13.2N, 56.9W, 120, 943, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790829, 0000, , HU, 13.7N, 58.0W, 105, 952, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790829, 0600, , HU, 14.2N, 59.2W, 115, 945, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790829, 1200, , HU, 14.8N, 60.3W, 125, 938, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790829, 1645, L, HU, 15.2N, 61.3W, 130, 936, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790829, 1800, , HU, 15.3N, 61.6W, 130, 935, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790830, 0000, , HU, 15.6N, 62.8W, 140, 927, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790830, 0600, , HU, 16.0N, 64.2W, 140, 924, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790830, 1200, , HU, 16.3N, 65.2W, 135, 924, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790830, 1800, , HU, 16.6N, 66.2W, 125, 931, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790831, 0000, , HU, 16.8N, 67.3W, 130, 931, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790831, 0600, , HU, 17.0N, 68.3W, 135, 928, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790831, 1200, , HU, 17.2N, 69.1W, 140, 926, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790831, 1800, , HU, 17.9N, 69.7W, 145, 921, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790831, 2030, L, HU, 18.3N, 70.0W, 150, 918, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790901, 0000, , HU, 18.8N, 70.4W, 95, 945, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790901, 0600, , HU, 19.3N, 72.0W, 65, 985, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790901, 1200, , TS, 19.7N, 73.7W, 50, 1002, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790901, 1800, , TS, 20.6N, 74.6W, 45, 997, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790902, 0000, , TS, 21.3N, 75.2W, 50, 992, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790902, 0600, , TS, 21.9N, 75.5W, 55, 990, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790902, 1200, , HU, 23.0N, 76.3W, 65, 981, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790902, 1800, , HU, 23.9N, 77.4W, 70, 979, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790902, 1930, L, HU, 24.1N, 77.6W, 75, 975, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790903, 0000, , HU, 24.6N, 78.2W, 80, 968, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790903, 0600, , HU, 25.3N, 79.1W, 80, 972, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790903, 1200, , HU, 26.3N, 79.6W, 85, 967, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790903, 1600, L, HU, 26.7N, 80.1W, 90, 960, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790903, 1800, , HU, 27.2N, 80.2W, 90, 960, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790904, 0000, , HU, 28.0N, 80.5W, 85, 965, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790904, 0230, L, HU, 28.4N, 80.6W, 85, 968, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790904, 0600, , HU, 29.1N, 80.8W, 85, 968, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790904, 1200, , HU, 30.2N, 80.9W, 85, 969, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790904, 1800, L, HU, 31.5N, 81.2W, 85, 966, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790905, 0000, , HU, 32.5N, 81.1W, 65, 972, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790905, 0600, , TS, 33.5N, 80.9W, 50, 976, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790905, 1200, , TS, 34.9N, 80.6W, 45, 980, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790905, 1800, , TS, 36.2N, 80.1W, 40, 982, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790906, 0000, , TS, 37.6N, 79.5W, 40, 987, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790906, 0600, , TS, 39.2N, 78.5W, 40, 989, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790906, 1200, , TS, 41.5N, 76.3W, 40, 991, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790906, 1800, , EX, 43.3N, 73.7W, 40, 992, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790907, 0000, , EX, 45.0N, 70.0W, 40, 991, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790907, 0600, , EX, 46.5N, 66.0W, 45, 988, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790907, 1200, , EX, 47.5N, 61.5W, 45, 987, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790907, 1800, , EX, 50.0N, 57.0W, 45, 986, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,
19790908, 0000, , EX, 52.5N, 52.5W, 45, 985, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999, -999,

* Genesis, with uncertainty, is moved up 12 hours. The first images I find, a few hours after the time of HURDAT genesis (at 25 kt) suggests around T3.0-3.5 already. I conservatively went with 45 kt at that point and backed it up to 0000Z.
* Pre-Recon intensities are increased based on satellite images, and at the first Recon flight (952 mb) I went with 105 kt.
* Little change is made in the rapid intensification on August 27-28, but around midday on the 28th, it appears David underwent an ERC and the pressure rose quite a bit, hence a brief lowering to 105 kt (after a peak of 130 kt) early on the 29th.
* The long period as a cat 5 in the eastern Caribbean is broken up. David crossed Dominica (south of where Maria did) as a cat 4, then peaked soon after at 140 kt. Thereafter, an ERC occurred again and the intensity is brought down as low as 125 kt (instead of 145-150 kt).
* After the ERC, it was clear that David was deepening. Pressure fell from 931 to 924 in the morning of the 31st. Unfortunately, there were no more Recon flights before landfall. Satellite images suggested even further deepening occurred and it may have been rapid. As a result, a possibly conservative pressure of 918 mb was estimated - the new minimum - and the original intensity of 150 kt was maintained.
* Very rapid weakening occurred early on September 1st over Hispaniola. By the time David emerged, pressure was 1002! Satellite didn't suggest a well organized storm either. Intensity is brought down to 50 kt, and then 45 kt shortly thereafter despite the lower pressure - the signature was even worse then.
* Steady re-strengthening began thereafter. However, surface obs over Florida (at multiple locations) suggest much lower pressures than Recon, which bottomed out in the low 970s. The lowest pressure was 960 mb in Vero Beach. Based on that data, it is estimated that David actually made landfall (not a near miss) in SE Florida at 90 kt with the 960 pressure. Due to the parallel track, another landfall is added at Cape Canaveral.
* The intensity largely held steady until final landfall in the middle Georgia coast. The lowest pressure in GA was 970 mb at the Savannah airport (west of town). Based on slight weakening in the few hours before that time (it was over marshland), the landfall intensity is set at 966 mb and 85 kt.
* No significant changes are made to the post-landfall track.
1 likes   


Return to “Talkin' Tropics”

Who is online

Users browsing this forum: AtlanticWind, JPmia, Ntxw and 21 guests