Tropical Storm Bertha Model Runs

[KWT]

Yep indeed Derek comprasions between the GFS runs here in the UK have found that the 12z and the 0z are the best as well with the 12z being marginally better over the period of 3 years.

[Blown Away]

The thing that we need to be aware is the GFS and models similar to it were dead keen on recurving the system into the first weakness but it just hasn't happened as they over-estimated the weakness, I think we have got to be aware that the exact same thing could happen with the 06z solution this time round as well.

If the NHC does not shift the track a little right at the 11am, then they have discounted the 06z run.

[ronjon]

Well, this mornings model suite hasn't really shed any light on the long term track. Seems the global models are struggling with the upper air pattern next weekend. The GFS, GFDL, CMC, and HWRF want to find a weakness in the ridge and turn Bertha N or NW into the Atlantic. On the other hand, the NOGAPs, UKMET, and Euro somewhat want to keep the storm on a more southerly route. It all boils down to the strength of the trough over the NE US next weekend which we probably won't know for a couple of more days. Here's the most ominous run - the 00Z NOGAPS which shows the ridge holding tough next weekend.

http://moe.met.fsu.edu/cgi-bin/ngptc2.cgi?time=2008070500&field=Sea+Level+Pressure&hour=Animation

At the end run, is the ridge building back in or weakening?

Looks to me that the ridge may be building back west on the last day of the NOGAPS run. On the other hand, the UKMET has consistently kept a strong Atlantic ridge pretty much throughout its 6 day run.

[Thunder44]

6Z and 18Z runs are also the least reliable

at 0 and 12 the best input data is available

I don't know if this should be applied to the tropics. But with the winter storms up here, I've noticed a change in the 6z run, was sometimes a precursor to more changes in the following 12z run. Although it was more the case, with being it more closer with the 0z ECMWF solution before that too. The 18z run is worst out of all them, in my opinion.

[Bane]

canefreak and aric are right... right into the carolinas!!! almost 12 years to the day... about 3 days late to 96's version... gonna be very interesting next week...






Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

well, we do need the rain. maybe a weak slow moving storm would be alright.

[KWT]

Yeah though over favorable UL conditions and warm gulf waters a weak storm can quickly become a larger problem Bane thats a risk you take on wanting a system to make landfall even if its for the right reasons.

[Bane]

Yeah though over favorable UL conditions and warm gulf waters a weak storm can quickly become a larger problem Bane thats a risk you take on wanting a system to make landfall even if its for the right reasons.

been through 11 canes. i never said i wanted it to make landfall. if it does come this way, hopefully it will stay weak.

[cycloneye]

No change in intensity=45kts.

WHXX01 KWBC 051240
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1240 UTC SAT JUL 5 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) 20080705 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
080705 1200 080706 0000 080706 1200 080707 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 16.4N 36.4W 17.4N 39.7W 18.3N 43.4W 19.4N 47.0W
BAMD 16.4N 36.4W 17.6N 39.6W 18.7N 42.9W 20.0N 46.0W
BAMM 16.4N 36.4W 17.6N 39.7W 18.5N 43.4W 19.6N 46.9W
LBAR 16.4N 36.4W 17.4N 39.9W 18.5N 43.6W 19.6N 47.2W
SHIP 45KTS 48KTS 52KTS 56KTS
DSHP 45KTS 48KTS 52KTS 56KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
080707 1200 080708 1200 080709 1200 080710 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 20.3N 50.6W 22.2N 57.0W 24.3N 62.3W 26.5N 66.3W
BAMD 21.3N 48.3W 23.4N 50.6W 24.8N 51.6W 24.6N 52.5W
BAMM 20.7N 49.8W 22.9N 53.9W 25.5N 57.0W 27.4N 58.9W
LBAR 20.5N 50.4W 22.9N 54.8W 25.8N 56.6W 25.9N 56.4W
SHIP 63KTS 72KTS 71KTS 69KTS
DSHP 63KTS 72KTS 71KTS 69KTS

...INITIAL CONDITIONS...
LATCUR = 16.4N LONCUR = 36.4W DIRCUR = 280DEG SPDCUR = 18KT
LATM12 = 15.8N LONM12 = 32.6W DIRM12 = 285DEG SPDM12 = 18KT
LATM24 = 14.7N LONM24 = 29.0W
WNDCUR = 45KT RMAXWD = 30NM WNDM12 = 45KT
CENPRS = 1000MB OUTPRS = 1012MB OUTRAD = 180NM SDEPTH = D
RD34NE = 75NM RD34SE = 30NM RD34SW = 0NM RD34NW = 75NM

$$
NNNN

[storms in NC]

Last night on the news here they put in the cone up to 120 hours I think. I have never seen they do this brfore. They said by next weekend we may have to be watching the storm. It just blew my mine when they did the track like that so far down the road. Times are changing

Deb

[cycloneye]

SHIP 12:00 UTC Forecast=Shear is not prohibitive thru the period.

Code: Select all

         *   ATLANTIC SHIPS INTENSITY FORECAST       *
                    *        GOES/OHC INPUT INCLUDED            *
                    *      BERTHA  AL022008  07/05/08  12 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    45    46    48    50    52    56    63    69    72    72    71    72    69
V (KT) LAND       45    46    48    50    52    56    63    69    72    72    71    72    69
V (KT) LGE mod    45    46    47    49    51    56    61    68    73    75    76    77    77

SHEAR (KTS)        8     6    11     9     6    11     9    10    17    14    16    12    15
SHEAR DIR        213   183   187   202   209   214   289   232   264   239   259   238   264
SST (C)         25.1  25.2  25.5  25.7  25.9  26.3  27.1  27.7  27.9  27.8  27.9  28.0  28.1
POT. INT. (KT)   109   110   112   114   116   120   128   135   137   135   136   138   139
ADJ. POT. INT.   107   107   110   112   114   117   125   130   129   125   125   127   128
200 MB T (C)   -54.3 -53.9 -54.2 -54.6 -54.7 -54.1 -54.6 -54.5 -54.9 -54.9 -55.2 -55.1 -55.5
TH_E DEV (C)       6     6     6     6     6     8     8    10     9     9     9    10    10
700-500 MB RH     57    58    55    54    50    45    43    43    46    49    53    45    48
GFS VTEX (KT)     14    14    14    14    14    12    13    14    14    12    11     8     6
850 MB ENV VOR   107   107   107   100    81    60    56    31    20     1   -17   -33   -53
200 MB DIV        24    23    22    30    62    71    46    11    19     4    -1    -1    19
LAND (KM)       2030  1999  1889  1788  1687  1563  1391  1168   886   690   618   601   593
LAT (DEG N)     16.4  16.7  17.0  17.3  17.6  18.3  19.1  19.9  20.6  21.6  22.8  23.8  24.6
LONG(DEG W)     36.4  38.3  40.1  42.0  43.9  47.6  51.3  54.7  57.6  60.1  62.2  64.8  67.6
STM SPEED (KT)    18    18    18    18    18    18    17    16    13    12    12    13    13
HEAT CONTENT       0     0     0     0     0     6    21    34    44    30    28    29    28

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):280/ 18      CX,CY: -17/  3
  T-12 MAX WIND:  45            PRESSURE OF STEERING LEVEL (MB):  625  (MEAN=625)
  GOES IR BRIGHTNESS TEMP. STD DEV. 100-300 KM RAD:  21.9 (MEAN=20.0)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  47.0 (MEAN=68.6)

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     1.   2.   3.   4.   6.   8.   9.  10.  11.  12.  12.  13.
  SST POTENTIAL          0.   0.   0.   0.   1.   3.   6.   8.  10.  11.  11.  12.
  VERTICAL SHEAR         1.   1.   2.   3.   5.   6.   8.   6.   6.   5.   6.   5.
  PERSISTENCE            0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.
  200/250 MB TEMP.       0.   0.   0.   1.   1.   1.   2.   2.   3.   4.   5.   6.
  THETA_E EXCESS         0.  -1.  -1.  -2.  -2.  -3.  -3.  -4.  -5.  -5.  -6.  -6.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  GFS VORTEX TENDENCY    0.   0.   0.  -1.  -2.  -2.  -2.  -2.  -3.  -5.  -7.  -8.
  850 MB ENV VORTICITY   1.   1.   2.   2.   3.   3.   3.   3.   3.   2.   2.   1.
  200 MB DIVERGENCE      0.   0.   0.   0.   1.   2.   2.   2.   2.   1.   1.   1.
  ZONAL STORM MOTION     0.   0.   1.   1.   3.   3.   4.   5.   5.   6.   7.   8.
  STEERING LEVEL PRES    0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  DAYS FROM CLIM. PEAK   0.   0.   0.  -1.  -1.  -2.  -2.  -2.  -2.  -3.  -3.  -4.
                        ----------------------------------------------------------
  SUB-TOTAL CHANGE       1.   3.   6.   8.  12.  19.  26.  28.  28.  28.  28.  27.

  SATELLITE ADJUSTMENTS ----------------------------------------------------------
  MEAN ADJUSTMENT        0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -2.
  GOES IR STD DEV        0.   0.   1.   1.   1.   1.   0.   0.   0.   0.   0.   0.
  GOES IR PIXEL COUNT    0.  -1.  -1.  -1.  -1.  -1.   0.   1.   1.   1.   1.   0.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.
                        ----------------------------------------------------------
  TOTAL ADJUSTMENT       0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -2.
                        ----------------------------------------------------------
  TOTAL CHANGE (KT)      1.   3.   5.   7.  12.  18.  24.  27.  27.  26.  27.  24.

   ** 2008 ATLANTIC RI INDEX AL022008     BERTHA 07/05/08  12 UTC **
           ( 25 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   0.0 Range:-45.0 to  30.0 Scaled/Wgted Val:  0.6/  1.1
 850-200 MB SHEAR (KT) :   8.3 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.8/  1.3
 D200 (10**7s-1)       :  32.2 Range:-20.0 to 149.0 Scaled/Wgted Val:  0.3/  0.5
 POT = MPI-VMAX (KT)   :  65.0 Range: 25.1 to 130.7 Scaled/Wgted Val:  0.4/  0.4
 850-700 MB REL HUM (%):  73.2 Range: 56.0 to  88.0 Scaled/Wgted Val:  0.5/  0.2
 % area w/pixels <-30 C:  36.0 Range: 17.0 to 100.0 Scaled/Wgted Val:  0.2/  0.0
 STD DEV OF IR BR TEMP :  18.9 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.5/  0.7
 Heat content (KJ/cm2) :   0.0 Range:  0.0 to 132.0 Scaled/Wgted Val:  0.0/  0.0
 
 Prob of RI for 25 kt RI threshold=    19% is   1.6 times the sample mean(12.3%)
 Prob of RI for 30 kt RI threshold=     3% is   0.3 times the sample mean( 7.8%)
 Prob of RI for 35 kt RI threshold=     1% is   0.3 times the sample mean( 4.5%)

   ##         ANNULAR HURRICANE INDEX (AHI) AL022008     BERTHA 07/05/08  12 UTC         ##
   ## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3                          ##
   ## AHI=  0   (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
   ##     ANNULAR INDEX RAN NORMALLY   

[KWT]

Hmmm SHIPS isn't showing that pretty major weakening that it did a few days ago when it reached 50W, I think there may be less shear out there at that time in the central Atlantic then was estimated before.

[cycloneye]

Here is the spaggetti:

[HURAKAN]

That's a significant reduction in shear from days 3 to 5. That could mean that Bertha may become a hurricane in that time period.

[Recurve]

My goodness. What happened to the high shear this was supposed to encounter?

What are the synoptics showing as far as the chance for it to get completely trapped under the ridge?

I looked at the Andrew track last night, it crossed 20N around 60w I believe. It completed the westward bend and then was pretty much due west. Is there a similar setup for steering in the offing?

If it hasn't started recurve by 66W Florida and everywhere else on the EC is going to get nervous. At 120 hours on the latest forecast I have it 785 miles from SFL, less than 3 days away moving 12.5 knots.

[Recurve]

Historical tracks for July within 150 miles of the 120 hr. forecast position (24.5N 66.0W):

[Tampa Bay Hurricane]

Recurve, I think everyone from the Bahamas and from SE Florida
to North Carolina will need to watch this closely. The ridge
is likely to be pretty strong, based on the intense
SE flow we will have here across the FL peninsula.

[hurricanefloyd5]

My goodness. What happened to the high shear this was supposed to encounter?

What are the synoptics showing as far as the chance for it to get completely trapped under the ridge?

I looked at the Andrew track last night, it crossed 20N around 60w I believe. It completed the westward bend and then was pretty much due west. Is there a similar setup for steering in the offing?

If it hasn't started recurve by 66W Florida and everywhere else on the EC is going to get nervous. At 120 hours on the latest forecast I have it 785 miles from SFL, less than 3 days away moving 12.5 knots.

Well my local weather guy tom terry sayd bertha would I mean should come within 700miles from the florida coast and then recurve but let's wait and see shall we!!!!

[CrazyC83]

Recurve, I think everyone from the Bahamas and from SE Florida
to North Carolina will need to watch this closely. The ridge
is likely to be pretty strong, based on the intense
SE flow we will have here across the FL peninsula.

I would think the greater danger if Bertha is sitting at the 120hr position would be from the Carolinas northward to New England.

[gatorcane]

NHC now forecasting a hurricane moving WNW towards the CONUS. Still not specifying if CONUS will be impacted.....

wow have things changed. I think Bertha has really shown models just aren't there any predicting these systems yet especially out in the middle of the Atlantic where there are little observations available.

[CrazyC83]

NHC now forecasting a hurricane moving WNW towards the CONUS. Still not specifying if CONUS will be impacted.....

wow have things changed. I think Bertha has really shown models just aren't there any predicting these systems yet especially out in the middle of the Atlantic where there are little observations available.

Yep, and Bermuda will REALLY have to watch this one. Although it might just go for the hole in the Gulf Stream between Bermuda and the US East Coast.