Tropical Storm Bertha Model Runs

[cycloneye]

The 12:00 SHIP forecast:

Code: Select all

            *   ATLANTIC SHIPS INTENSITY FORECAST       *
                    *        GOES/OHC INPUT INCLUDED            *
                    *      BERTHA  AL022008  07/04/08  12 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    45    47    49    52    54    56    59    62    65    67    64    61    57
V (KT) LAND       45    47    49    52    54    56    59    62    65    67    64    61    57
V (KT) LGE mod    45    47    49    51    53    57    61    65    68    71    73    71    65

SHEAR (KTS)        8     7    10     9     6     8    13    12    11    13    25    29    33
SHEAR DIR        239   182   229   243   232   195   231   207   247   207   255   246   256
SST (C)         25.4  25.0  24.7  24.8  25.0  25.4  25.8  26.2  26.8  27.3  27.5  27.6  27.5
POT. INT. (KT)   110   107   105   106   108   111   114   118   124   129   131   132   131
ADJ. POT. INT.   108   105   103   104   106   108   111   113   118   120   121   120   117
200 MB T (C)   -54.1 -53.6 -53.8 -54.2 -54.3 -54.1 -54.5 -54.1 -54.5 -54.2 -54.4 -54.3 -54.9
TH_E DEV (C)       5     5     5     5     5     6     6     7     8     9     9     9     8
700-500 MB RH     69    64    65    64    60    53    52    51    47    46    48    50    52
GFS VTEX (KT)     15    15    15    15    15    13    13    12    12    12    12    11    11
850 MB ENV VOR    77    85    92   100    97    88    73    59    39    16   -12   -19   -44
200 MB DIV        10    29    46    43    20     7    21    46    35    19    12     8     4
LAND (KM)       1235  1406  1579  1773  1967  1939  1765  1659  1588  1474  1314  1234  1238
LAT (DEG N)     14.7  15.2  15.7  16.1  16.5  17.1  17.9  18.7  19.7  21.0  22.5  24.2  26.1
LONG(DEG W)     29.0  30.6  32.2  34.0  35.8  39.5  43.1  46.4  49.4  51.9  53.9  55.6  57.1
STM SPEED (KT)    15    16    17    18    18    18    17    15    14    12    12    12    11
HEAT CONTENT       0     0     0     0     0     0     0     3    16    20    20    31    24

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):290/ 14      CX,CY: -12/  5
  T-12 MAX WIND:  40            PRESSURE OF STEERING LEVEL (MB):  541  (MEAN=625)
  GOES IR BRIGHTNESS TEMP. STD DEV. 100-300 KM RAD:  24.1 (MEAN=20.0)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  60.0 (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.  -1.  -1.  -1.   0.   2.   4.   6.   6.   7.   7.
  VERTICAL SHEAR         1.   1.   2.   3.   5.   6.   6.   7.   7.   5.   3.   0.
  PERSISTENCE            1.   1.   2.   2.   2.   2.   2.   2.   1.   1.   0.   0.
  200/250 MB TEMP.       0.   0.   0.   0.   0.   1.   1.   2.   2.   2.   3.   4.
  THETA_E EXCESS         0.  -1.  -2.  -2.  -3.  -4.  -5.  -6.  -7.  -8.  -9.  -9.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   0.   0.   0.   0.  -1.  -1.
  GFS VORTEX TENDENCY    0.   0.   0.  -1.  -2.  -2.  -4.  -4.  -4.  -4.  -5.  -5.
  850 MB ENV VORTICITY   0.   1.   1.   2.   3.   3.   4.   4.   4.   3.   3.   2.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.   0.   1.   1.   1.   1.   1.   0.
  ZONAL STORM MOTION     0.   0.   1.   1.   2.   2.   3.   3.   3.   4.   5.   5.
  STEERING LEVEL PRES    0.   0.   1.   1.   1.   1.   1.   2.   2.   2.   1.   1.
  DAYS FROM CLIM. PEAK   0.   0.   0.  -1.  -1.  -2.  -2.  -2.  -3.  -3.  -3.  -4.
                        ----------------------------------------------------------
  SUB-TOTAL CHANGE       2.   5.   7.   9.  12.  16.  18.  22.  23.  21.  18.  14.

  SATELLITE ADJUSTMENTS ----------------------------------------------------------
  MEAN ADJUSTMENT        0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -2.
  GOES IR STD DEV        0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  GOES IR PIXEL COUNT    0.   0.   0.   0.   0.   0.   0.   0.   1.   1.   1.   0.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.
                        ----------------------------------------------------------
  TOTAL ADJUSTMENT       0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -2.  -2.  -2.  -2.
                        ----------------------------------------------------------
  TOTAL CHANGE (KT)      2.   4.   7.   9.  12.  14.  17.  20.  22.  19.  16.  12.

   ** 2008 ATLANTIC RI INDEX AL022008     BERTHA 07/04/08  12 UTC **
           ( 25 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   5.0 Range:-45.0 to  30.0 Scaled/Wgted Val:  0.7/  1.2
 850-200 MB SHEAR (KT) :   8.2 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.8/  1.3
 D200 (10**7s-1)       :  29.6 Range:-20.0 to 149.0 Scaled/Wgted Val:  0.3/  0.4
 POT = MPI-VMAX (KT)   :  60.1 Range: 25.1 to 130.7 Scaled/Wgted Val:  0.3/  0.4
 850-700 MB REL HUM (%):  75.0 Range: 56.0 to  88.0 Scaled/Wgted Val:  0.6/  0.2
 % area w/pixels <-30 C:  53.0 Range: 17.0 to 100.0 Scaled/Wgted Val:  0.4/  0.1
 STD DEV OF IR BR TEMP :  17.0 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.6/  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=    21% is   1.7 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 07/04/08  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]

Hmm thats interesting because they have the system at 26N by 120hrs which is about in line with the BAMM guidence as well. Also shows shear steadily increasing as it gets further north and towards that upper low, eventually reaching 33kts which would be make it very hard for the system to survive I'd have thought.

[Thunder44]

What!! A cat 3 from GFDL,101 kts? Are you kidding me? I am not snarking,look at the animation.

http://moe.met.fsu.edu/cgi-bin/gfdltc2. ... =Animation

Remember 101 kts is 10 meters above the surface.

[Steve]

>>Latest from JB this morning = He thinks the storm will get to at least 70W before crossing 25N, meaning it could potentially be a threat to the east coast of the U.S. or the Canadian Maritimes.

It has been clear for a couple of days that the 45W or 60W solutions did not jibe with the progged high pressure across most of the Atlantic. I'm not making a call on anything, just an observation.

Steve

[gatorcane]

well models have shifted to about where I thought they should be. I can't see them going too much more left unless the Bermuda High decides to build in beyond 6+ days out. It's possible considering we are in early July where we expect strong Bermuda Highs to exist but the TUTT trough hopefully will hold strong.

[NDG]

I would not be surprised if models keep shifting west and coming more in line with the Euro and UKMET.
Interesting that euro places decent UL conditions as the system tracks WNW, very close to the Bahamas by day 7.
I am giving some trust to the Euro since it did so well in sypnotic set up last year, we will see how well it does with Bertha.

[Frank2]

Interesting how everyone is giving up on the NW motion so quickly - especially since it's still moving in that direction (now nearing 16N 29W):

http://www.ssd.noaa.gov/goes/flt/t1/loop-avn.html

actually, this might be something for the folks in the Azores to monitor...

[KWT]

Surely though if UL were that good on the ECM then the ECM would make the system stronger then what it does?

Anyway current movement is 290 degree which is about where most of the models are as well.

[Derek Ortt]

I think you're tracking the system wrong, Frank. The center is somewhat exposed south of the convective envelope and is moving WNW

[Frank2]

Yes, I see what you mean Derek (serves me right for tracking it with the IR only)...

Still, as KWT said, it seems the track is about where it was thought to be at this point - if it's that far north already (and it's not even at 30W), that pretty much says it all...

[NDG]

Surely though if UL were that good on the ECM then the ECM would make the system stronger then what it does?

Anyway current movement is 290 degree which is about where most of the models are as well.

The ECM does strengthens it back up at 72hrs, but by that time the central Atlantic trough starts lifting and starts getting influenced by the ridge over Bermuda.

[Ivanhater]

GFS Ensembles

[Frank2]

But, trough or no, the further it moves away from the equator, especially at this early stage, the higher the chance of it turning to the right when it encounters any weakness to the west:

http://en.wikipedia.org/wiki/Coriolis_force

[NDG]

But, trough or no, the further it moves away from the equator, especially at this early stage, the higher the chance of it turning to the right when it encounters any weakness to the west:

http://en.wikipedia.org/wiki/Coriolis_force

Correct, the next question is going to be after the central Atlantic lifts when and where will it encounter the next trough or weakness, SE of Bermuda or SW of Bermuda.

[Extremeweatherguy]

Anyone know why the SFWMD model page is not updating? It is still showing model runs from last night...

https://my.sfwmd.gov/portal/page?_pagei ... ema=PORTAL

[gatorcane]

oh boy have these models been shifting...wow. Lesson learned: the tropics are highly unpredictable.

[Ivanhater]

It looks like the Bermuda high builds back in strong as most the models move it back due west later in the forecast...

[KWT]

Hmmm the ensembles keep this on a constant WNW trac, indeed it gets past 50W before reaching 20N which is impressive given a few days ago the GFS didn't even have the system reaching 50W at all, certainly a shift to the west.

I think AP07 would cause a scare!

[Tampa Bay Hurricane]

The strength of that high is going to be very important...the current
model trends are a bit more concerning, especially with the
westward trend.

[KWT]

The thing with the ensembles is that they will show a weaker storm as they have a lower resolution, therefore are less likely to get a grip on a systems strength. They are a good indication of a possible track if it remains weak which is looking increasingly possible.