Tropical Storm Bertha Model Runs

[Recurve]

I was about to ask if shear got it in that UKM run, because it seemed to stay farther south, possibly out of the stronger shear.

[cycloneye]

907
WHXX01 KWBC 041824
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1824 UTC FRI JUL 4 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) 20080704 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
080704 1800 080705 0600 080705 1800 080706 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 15.3N 30.8W 16.7N 34.1W 18.0N 37.7W 18.5N 41.7W
BAMD 15.3N 30.8W 16.4N 33.6W 17.5N 36.6W 18.5N 39.4W
BAMM 15.3N 30.8W 16.5N 33.8W 17.6N 37.0W 18.4N 40.1W
LBAR 15.3N 30.8W 16.4N 33.8W 17.9N 37.2W 19.1N 40.6W
SHIP 45KTS 49KTS 53KTS 57KTS
DSHP 45KTS 49KTS 53KTS 57KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
080706 1800 080707 1800 080708 1800 080709 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 19.0N 46.0W 19.5N 53.8W 20.0N 60.2W 20.9N 65.1W
BAMD 19.4N 42.2W 21.4N 46.2W 23.4N 47.3W 24.1N 44.2W
BAMM 19.1N 43.4W 20.8N 48.7W 22.4N 52.6W 24.0N 55.6W
LBAR 20.1N 43.9W 22.6N 47.9W 25.3N 46.9W 26.1N 43.4W
SHIP 60KTS 63KTS 61KTS 55KTS
DSHP 60KTS 63KTS 61KTS 55KTS

...INITIAL CONDITIONS...
LATCUR = 15.3N LONCUR = 30.8W DIRCUR = 290DEG SPDCUR = 16KT
LATM12 = 14.0N LONM12 = 27.6W DIRM12 = 296DEG SPDM12 = 14KT
LATM24 = 13.2N LONM24 = 25.2W
WNDCUR = 45KT RMAXWD = 30NM WNDM12 = 40KT
CENPRS = 1000MB OUTPRS = 1012MB OUTRAD = 180NM SDEPTH = D
RD34NE = 75NM RD34SE = 30NM RD34SW = 0NM RD34NW = 75NM

['CaneFreak]

Hurricane models such as the GFDL, HWRF, and others like it have a finer resolution and we can predict intensity a little better with these models because that is what they were designed for. Also, these hurricane models actually can predict what a storm will do relative to intensity better because these models interpolate SST data, OHC data, and other very important thermodynamic data from many different sources into its data algorithm.

[cycloneye]

The 18 UTC SHIP Forecast.After 36 hours it will enter above 26c ssts but shear will increase.

Code: Select all

                    *   ATLANTIC SHIPS INTENSITY FORECAST       *
                    *        GOES/OHC INPUT INCLUDED            *
                    *      BERTHA  AL022008  07/04/08  18 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    45    47    49    51    53    57    60    62    63    62    61    58    55
V (KT) LAND       45    47    49    51    53    57    60    62    63    62    61    58    55
V (KT) LGE mod    45    47    49    51    53    57    61    64    66    66    63    60    57

SHEAR (KTS)        7    12    12     9     6    12     9    19    19    26    26    29    24
SHEAR DIR        196   234   242   243   182   225   218   232   226   243   248   232   239
SST (C)         25.0  24.7  24.8  25.0  25.2  25.7  26.0  26.5  27.1  27.5  27.9  28.0  27.9
POT. INT. (KT)   107   105   106   108   109   114   116   121   127   131   136   138   136
ADJ. POT. INT.   105   102   103   105   107   111   113   115   120   123   126   127   123
200 MB T (C)   -53.5 -53.7 -54.1 -54.2 -53.9 -54.4 -54.3 -54.5 -54.3 -54.4 -54.7 -54.9 -55.0
TH_E DEV (C)       5     5     5     5     5     6     7     7     9     9     9     9     9
700-500 MB RH     62    61    60    57    56    51    48    50    46    43    45    45    48
GFS VTEX (KT)     15    15    15    15    14    14    13    13    13    13    15    13    11
850 MB ENV VOR    96    99   100   102   105    92    63    59    44     7    -1   -24   -43
200 MB DIV        48    61    56    29     9    21    40    17    30    17    19    28    -2
LAND (KM)       1428  1605  1783  1977  2057  1861  1689  1612  1473  1301  1105   971   897
LAT (DEG N)     15.3  15.7  16.1  16.5  16.9  17.6  18.3  19.1  20.0  21.0  22.1  23.4  24.7
LONG(DEG W)     30.8  32.5  34.1  35.9  37.7  41.3  45.0  48.3  51.1  53.6  55.9  58.1  60.4
STM SPEED (KT)    17    16    17    18    18    18    17    15    13    12    12    12    12
HEAT CONTENT       0     0     0     0     0     0     0    10    19    26    34    28    27

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):290/ 16      CX,CY: -14/  5
  T-12 MAX WIND:  40            PRESSURE OF STEERING LEVEL (MB):  576  (MEAN=625)
  GOES IR BRIGHTNESS TEMP. STD DEV. 100-300 KM RAD:  26.6 (MEAN=20.0)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  64.0 (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.   7.   8.   9.
  VERTICAL SHEAR         1.   1.   2.   3.   4.   5.   4.   2.  -1.  -3.  -5.  -7.
  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.   3.   3.   4.
  THETA_E EXCESS         0.  -1.  -2.  -2.  -3.  -4.  -5.  -6.  -7.  -8.  -8.  -8.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  GFS VORTEX TENDENCY    0.   0.   0.  -1.  -2.  -3.  -3.  -3.  -3.  -2.  -4.  -5.
  850 MB ENV VORTICITY   1.   1.   2.   2.   3.   4.   4.   4.   4.   4.   3.   2.
  200 MB DIVERGENCE      0.   1.   1.   1.   1.   1.   1.   1.   1.   1.   1.   1.
  ZONAL STORM MOTION     0.   0.   1.   1.   2.   3.   3.   4.   4.   5.   6.   6.
  STEERING LEVEL PRES    0.   0.   0.   0.   1.   1.   1.   1.   1.   1.   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.  13.  16.  18.  20.  18.  17.  15.  12.

  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.   0.   0.   0.   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.  -2.  -2.  -2.  -2.  -2.
                        ----------------------------------------------------------
  TOTAL CHANGE (KT)      2.   4.   6.   8.  12.  15.  17.  18.  17.  16.  13.  10.

   ** 2008 ATLANTIC RI INDEX AL022008     BERTHA 07/04/08  18 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) :   9.1 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.8/  1.3
 D200 (10**7s-1)       :  40.6 Range:-20.0 to 149.0 Scaled/Wgted Val:  0.4/  0.5
 POT = MPI-VMAX (KT)   :  59.7 Range: 25.1 to 130.7 Scaled/Wgted Val:  0.3/  0.4
 850-700 MB REL HUM (%):  74.6 Range: 56.0 to  88.0 Scaled/Wgted Val:  0.6/  0.2
 % area w/pixels <-30 C:  51.0 Range: 17.0 to 100.0 Scaled/Wgted Val:  0.4/  0.1
 STD DEV OF IR BR TEMP :  22.1 Range: 35.1 to   3.2 Scaled/Wgted Val:  0.4/  0.5
 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 07/04/08  18 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   

[cycloneye]

12z GFDL continues to be in hurricane mode.

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

[Tampa Bay Hurricane]

Latest GFS means the Bahamas and SE should watch closely.

GFDL starts to take it further north earlier as a category 2.

We will see what happens.

[cheezyWXguy]

12z GFDL continues to be in hurricane mode.

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

wow...almost at cat 3 it looks like

[Blown Away]

12z GFDL continues to be in hurricane mode.
http://moe.met.fsu.edu/cgi-bin/gfdltc2. ... =Animation

It seems there is a small window for Bertha to turn more NW. Maybe I'm reading to much into the GFDL run, but as Bertha deepens into a cane she starts to find the weakness near 50W and start the turn, but at the end Bertha seems bend back more WNW which may indicate the ridge is building back in and blocking the recurve. I'm curious to see what is happening at the end of the GFS and GFDL runs, the GFDL starts to bend Bertha back WNW and the GFS has a SW hook at the end.

[cycloneye]

The 12z EURO tracks it towards Bermuda and as a weak system.

12z EURO

['CaneFreak]

12Z Model Guidance from Hurricane Alley:

http://www.hurricanealley.net/images/02LSPAG.gif

[Blown Away]

12Z Model Guidance from Hurricane Alley:
http://www.hurricanealley.net/images/02LSPAG.gif

What's interesting is some of the models have a flat WNW movement and many of them have that SW hook at the end of the run, is that an indication of the ridge building back in?

[gatorcane]

Something to note. NWS Miami is forecasting the mid-atlantic ridge to build not only at the mid-levels but at the upper levels starting late this coming week (Thurs-Fri) timeframe.

.TUESDAY THROUGH FRIDAY...MID/UPPER LVL ATLANTIC RIDGE WILL BUILD
WEST ACROSS THE PENINSULA AND INTO CENTRAL GULF OF MEX. THIS WILL
BRING A SHIFT IN THE WEATHER PATTERN WITH AFTERNOON CONVECTION
CONCENTRATING MAINLY OVER INTERIOR AND WEST SECTIONS OF MAINLAND
SOUTH FLORIDA

The SW bend in some of those models maybe reflecting this ridge building. Just a thought and something we will definitely be paying close attention to since Bertha will be in the vicinity of where the ridge should build by then. It's looking possible that if she misses the weakness created by the Upper-level low at around 60W, she could make it farther west but still as a weaker system at least that is my current thinking.

[Aric Dunn]

12z nogaps

pretty far west slight turn at the end but the ridge still looks to be holding down

http://moe.met.fsu.edu/cgi-bin/ngptc2.c ... =Animation

[Aric Dunn]

gfs



ukmet

[Derek Ortt]

nearly all of the models are now showing weakening beyond 72 hours, except for GFDL. It may be the odd model out so to speak

[Aric Dunn]

nearly all of the models are now showing weakening beyond 72 hours, except for GFDL. It may be the odd model out so to speak

and your point?

[Derek Ortt]

the point is the track wont matter if this degerates into a wave or weakens to a remnant low!

[Aric Dunn]

the point is the track wont matter if this degerates into a wave or weakens to a remnant low!

and your faith in the models and their intensity forecast is coming from where?

[Aric Dunn]

i mean the gfs had felix as a open wave in the carribean when it was a cat 5 lol ...

[Squarethecircle]

the point is the track wont matter if this degerates into a wave or weakens to a remnant low!

and your faith in the models and their intensity forecast is coming from where?

One could say that this cynicism is putting your support more in favor of the GFDL, which presents the opposing option and is the lone one out. I think it's agreed that the GFDL does not have such a position of power over every single other model.