TC Bertha

[wxmann_91]

One thing I didn't address in my post was intensity and I will say that the structure has improved markedly today with shear decreasing significantly. Still unsure about the evolution of the TUTT to the west (I'll call this TUTT 2) and how strong/deep it will be. As miamiensiswx eluded to the current TUTT (TUTT 1) over the ctrl ATL could provide a nice outflow channel and good upper diffluence for Bertha as it lifts out to the NE. In fact if Bertha manages to strengthen enough and can tap into TUTT 1 to the NE the interaction could amplify TUTT 1 enough so that upstream a stronger (relative to what is progged) upper anticyclone can build (and thus precluding the formation of a strong, shearing TUTT 2). This scenario is favored by yesterday's 0Z GFS.

Of course, the alternate scenario is that TUTT 2 amplifies more and shears Bertha to death. This scenario is favored by today's 12Z GFS & UKMET.

[Aric Dunn]

Looking nice.

yep. strengthening will probably occur tonight. NHC will mention it at 11..

[wxmann_91]

Ok so you are saying that there's a trough of low pressure that is going to push the bh east again or break it down and allow an opening for bertha to ride of the coast possibly brushing the coast and boomerang ne? Can you post a map showing the upcoming trough please? I am sorry I don't quite know where to get these maps myself.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_120m.gif

Assuming that Bertha smack dab in the middle between the Bahamas and Bermuda, that is a clear recurve.

Of course, this is a 120 hr GFS model map. But you get the picture. Negative height anomalies in ern Canada = very likely recurve into Maritimes/out to sea.

Ok please don't laugh but is there an ukmet model map supporting it's forecast? I realize that it is an outlier right now but you never know.

Compare (they only give vorticity maps w/o height contours so these are slightly harder to read, but positive vort is associated with troughiness):

UK at 72 (strong Bermuda High at 500mb): http://moe.met.fsu.edu/tcgengifs/ukm/20 ... vort13.png

UK at 120 (substantial weakness invof Bermuda): http://moe.met.fsu.edu/tcgengifs/ukm/20 ... vort21.png

However, it keeps Bermuda weak and down far south and in fact I am willing to bet that extrapolation of the UK's progged environment lends to an eventual GOM setting for Ms. Bertha.

[Matt-hurricanewatcher]

Yeah, that kind of looks like a "eye" like feature trying to wrap. It will have a 24-36 hour window I believe before hitting "tutt" or whats lefted of it that is still there. I expect the ridge to be stronger to the north.

[hurricanefloyd5]

Yeah, that kind of looks like a "eye" like feature trying to wrap. It will have a 24-36 hour window I believe before hitting "tutt" or whats lefted of it that is still there. I expect the ridge to be stronger to the north.

that trought your talked about holding strong ddose that mean it would stay on a more westward movement or ride the coast????

[Matt-hurricanewatcher]

I've got strong doubts that the ridge will weaken as fast as the Gfs, GFDL says it will. The last few days we thought that the weakness would of recurved it before 40 west then 50. This ridge could easly be strong enough to hold it more to the south, I say if it don't get past 20 north at 50 west. Then chances are fair to good that a NC, SC landfall could happen. Now we do have to watch the trend very carefully because something unexpected could always happen. That is what is enjoyable with tracking tropical cyclones. It maybe worth watching a few more runs of the models before leaving the westward thinking.

[Blown Away]

Bertha was 90 miles west at 5pm from the 24 hour forecast from 5pm yesterday. Bertha has been running away to the west from the NHC's forecast.

[wxman57]

A lot of discussion here about where Bertha might go. I was curious as to how many storms have hit the U.S. from Bertha's 5-day forecast position so I went back to the Coastal Services Center web page and put in the lat/lon of the 5-day forecast point and searched within 50nm of that point from June-November 1851 through 2007. The result is below. Only 4 storms since 1851 have reached the U.S. from Bertha's 5-day forecast point. Two hit Florida (Dora 1964 was one) and 2 hit the Carolinas. Pretty low percentage.

While you can't use climatology to make a forecast, you can't ignore climatology. It's rare that a storm on Bertha's current track reaches the U.S. for a good reason - there are usually weaknesses in the Bermuda high that allow for recurvature east of the U.S. We can see two such weaknesses in Bertha's path. There's nothing to indicate that the Bermuda high is so strong, or will be so strong as to push Bertha straight west to Florida. A Florida miss is not a 100% certainty, but landfall in Florida is a very low probability at this point. I think there's a fair chance that Bertha will recurve east of the U.S. and head out to sea. But there's a shot it may stall or slow down significantly around day 6-7. If that happens, then the chance of a Carolinas hit increases.

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

[deltadog03]

I agree matt.....GFS is MORE than known to break down ridges too quickly....Look how much the models have been off in the short term....

[z1z2]

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

Interesting...what 00z model runs do you speak of? I have not seen any other than the BAM runs.

[robbielyn]

A lot of discussion here about where Bertha might go. I was curious as to how many storms have hit the U.S. from Bertha's 5-day forecast position so I went back to the Coastal Services Center web page and put in the lat/lon of the 5-day forecast point and searched within 50nm of that point from June-November 1851 through 2007. The result is below. Only 4 storms since 1851 have reached the U.S. from Bertha's 5-day forecast point. Two hit Florida (Dora 1964 was one) and 2 hit the Carolinas. Pretty low percentage.

While you can't use climatology to make a forecast, you can't ignore climatology. It's rare that a storm on Bertha's current track reaches the U.S. for a good reason - there are usually weaknesses in the Bermuda high that allow for recurvature east of the U.S. We can see two such weaknesses in Bertha's path. There's nothing to indicate that the Bermuda high is so strong, or will be so strong as to push Bertha straight west to Florida. A Florida miss is not a 100% certainty, but landfall in Florida is a very low probability at this point. I think there's a fair chance that Bertha will recurve east of the U.S. and head out to sea. But there's a shot it may stall or slow down significantly around day 6-7. If that happens, then the chance of a Carolinas hit increases.

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

what two such weaknesses are you talking about? Are they current or future?

[Aric Dunn]

A lot of discussion here about where Bertha might go. I was curious as to how many storms have hit the U.S. from Bertha's 5-day forecast position so I went back to the Coastal Services Center web page and put in the lat/lon of the 5-day forecast point and searched within 50nm of that point from June-November 1851 through 2007. The result is below. Only 4 storms since 1851 have reached the U.S. from Bertha's 5-day forecast point. Two hit Florida (Dora 1964 was one) and 2 hit the Carolinas. Pretty low percentage.

While you can't use climatology to make a forecast, you can't ignore climatology. It's rare that a storm on Bertha's current track reaches the U.S. for a good reason - there are usually weaknesses in the Bermuda high that allow for recurvature east of the U.S. We can see two such weaknesses in Bertha's path. There's nothing to indicate that the Bermuda high is so strong, or will be so strong as to push Bertha straight west to Florida. A Florida miss is not a 100% certainty, but landfall in Florida is a very low probability at this point. I think there's a fair chance that Bertha will recurve east of the U.S. and head out to sea. But there's a shot it may stall or slow down significantly around day 6-7. If that happens, then the chance of a Carolinas hit increases.

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

well instead of doing that from a uncertain future point it makes more sense to use its current position and see what path storms took from there..

and this is what you get.

[soonertwister]

A lot of discussion here about where Bertha might go. I was curious as to how many storms have hit the U.S. from Bertha's 5-day forecast position so I went back to the Coastal Services Center web page and put in the lat/lon of the 5-day forecast point and searched within 50nm of that point from June-November 1851 through 2007. The result is below. Only 4 storms since 1851 have reached the U.S. from Bertha's 5-day forecast point. Two hit Florida (Dora 1964 was one) and 2 hit the Carolinas. Pretty low percentage.

While you can't use climatology to make a forecast, you can't ignore climatology. It's rare that a storm on Bertha's current track reaches the U.S. for a good reason - there are usually weaknesses in the Bermuda high that allow for recurvature east of the U.S. We can see two such weaknesses in Bertha's path. There's nothing to indicate that the Bermuda high is so strong, or will be so strong as to push Bertha straight west to Florida. A Florida miss is not a 100% certainty, but landfall in Florida is a very low probability at this point. I think there's a fair chance that Bertha will recurve east of the U.S. and head out to sea. But there's a shot it may stall or slow down significantly around day 6-7. If that happens, then the chance of a Carolinas hit increases.

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

well instead of doing that from a uncertain future point it makes more sense to use its current position and see what path storms took from there..

and this is what you get.

Why not just storms in July? Once again, this is climatological and the database of storm for July in this region is obviously too small to make any meaningful predictions of future trends.

[dixiebreeze]

Looks like Bertha is getting her groove back tonight:

http://www.ssd.noaa.gov/goes/flt/t1/rb-l.jpg

[Aric Dunn]

Looks like Bertha is getting her groove back tonight:

http://www.ssd.noaa.gov/goes/flt/t1/rb-l.jpg

yep.. and at this rate it may reach hurricane strength sooner rather than later.. and we will probably see a annular hurricane do yo the relatively stable air surround bertha. which would be interesting.

[RL3AO]

New guidance message out. But no change from the one released an hour ago.

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0139 UTC SUN JUL 6 2008

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BERTHA (AL022008) 20080706 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
080706 0000 080706 1200 080707 0000 080707 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 16.8N 40.3W 17.7N 43.5W 18.9N 46.6W 19.8N 49.4W
BAMD 16.8N 40.3W 17.9N 43.5W 19.1N 46.5W 20.3N 48.7W
BAMM 16.8N 40.3W 17.6N 43.8W 18.7N 47.1W 19.6N 49.5W
LBAR 16.8N 40.3W 17.7N 43.9W 18.9N 47.4W 19.9N 50.7W
SHIP 45KTS 49KTS 54KTS 61KTS
DSHP 45KTS 49KTS 54KTS 61KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
080708 0000 080709 0000 080710 0000 080711 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 20.7N 51.9W 22.0N 56.0W 23.7N 59.4W 25.5N 61.7W
BAMD 21.5N 49.8W 23.4N 50.2W 25.2N 49.9W 25.5N 49.1W
BAMM 20.4N 51.1W 21.8N 53.2W 23.7N 54.8W 25.4N 56.2W
LBAR 20.9N 53.3W 23.2N 56.6W 25.7N 58.0W 26.4N 58.4W
SHIP 67KTS 71KTS 67KTS 70KTS
DSHP 67KTS 71KTS 67KTS 70KTS

...INITIAL CONDITIONS...
LATCUR = 16.8N LONCUR = 40.3W DIRCUR = 280DEG SPDCUR = 18KT
LATM12 = 16.4N LONM12 = 36.4W DIRM12 = 275DEG SPDM12 = 19KT
LATM24 = 15.8N LONM24 = 32.6W
WNDCUR = 45KT RMAXWD = 30NM WNDM12 = 45KT
CENPRS = 1000MB OUTPRS = 1012MB OUTRAD = 180NM SDEPTH = D
RD34NE = 75NM RD34SE = 30NM RD34SW = 0NM RD34NW = 75NM

$$
NNNN

[robbielyn]

A lot of discussion here about where Bertha might go. I was curious as to how many storms have hit the U.S. from Bertha's 5-day forecast position so I went back to the Coastal Services Center web page and put in the lat/lon of the 5-day forecast point and searched within 50nm of that point from June-November 1851 through 2007. The result is below. Only 4 storms since 1851 have reached the U.S. from Bertha's 5-day forecast point. Two hit Florida (Dora 1964 was one) and 2 hit the Carolinas. Pretty low percentage.

While you can't use climatology to make a forecast, you can't ignore climatology. It's rare that a storm on Bertha's current track reaches the U.S. for a good reason - there are usually weaknesses in the Bermuda high that allow for recurvature east of the U.S. We can see two such weaknesses in Bertha's path. There's nothing to indicate that the Bermuda high is so strong, or will be so strong as to push Bertha straight west to Florida. A Florida miss is not a 100% certainty, but landfall in Florida is a very low probability at this point. I think there's a fair chance that Bertha will recurve east of the U.S. and head out to sea. But there's a shot it may stall or slow down significantly around day 6-7. If that happens, then the chance of a Carolinas hit increases.

One thing I note is that the 00Z model guidance has shifted right a bit, and I don't mean the BAMs (ignore them now). They're seeing a little deeper trof along the east U.S. Coast late next week. We shall see...

well instead of doing that from a uncertain future point it makes more sense to use its current position and see what path storms took from there..

and this is what you get.

Why not just storms in July? Once again, this is climatological and the database of storm for July in this region is obviously too small to make any meaningful predictions of future trends.

How about the fact there is no known storm that started that far east as a ts this early in the season and is getting stronger right now. All bets are off to rely solely on climatology this may defy climatology. It might be rare for this to continue straight west and head towards fl but so is the fact this storm started this far east this early in the season. I think this storm will really be fun to track.

[Aric Dunn]

of course we were just looking at it.. climatology is just a history lesson. i just checked and none of those were in july

[MiamiensisWx]

Based on decreasing upper level shear and organization trends, we may see a 50-55 kt TS very shortly by tomorrow morning. In fact, it could attain 50 kt surface winds (1-min) tonight.

http://www.ssd.noaa.gov/goes/east/tatl/loop-ir2.html

[soonertwister]

Looks like Bertha is getting her groove back tonight:

http://www.ssd.noaa.gov/goes/flt/t1/rb-l.jpg

yep.. and at this rate it may reach hurricane strength sooner rather than later.. and we will probably see a annular hurricane do yo the relatively stable air surround bertha. which would be interesting.

Annular canes are one of the most fascinating things I've seen, but they are pretty rare. Maybe not as rare as we used to think they were due to observational tool improvements, but not at all common.