Re: Now Tropical Storm Fiona
Posted by Chris in Tampa on 8/18/2016, 1:11 am
When you have a sheared storm though, sometimes it might get further west than anticipated.

Here is the HWRF, GFDL and also DSHP:

http://hurricanecity.com/models/models.cgi?basin=al&year=2016&storm=06&display=google_map&latestrun=1&models=HWRF,GFDL,DSHP

The NHC talks about the GFDL and HWRF at 11pm Wednesday:



"TROPICAL STORM FIONA DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062016
1100 PM AST WED AUG 17 2016

For a time late this afternoon, it seemed that Fiona might lose all
its deep convection.  However, a new burst developed around 2300 UTC
and has persisted since that time.  An 0026 UTC ASCAT-B pass
revealed that the cyclone is still producing a small area of
tropical-storm-force winds, and the intensity remains 35 kt.

Fiona has a tough road ahead.  Vertical shear right now is
relatively low, but it is expected to begin increasing within the
next 24 hours and then become belligerent out of the southwest by
days 3 and 4.  In addition, the cyclone is surrounded by dry air,
and any negative impacts that the dry air is already having on the
convection is likely to be compounded once the shear increases in a
few days.  With the exception of the GFDL, which makes Fiona a
hurricane by the end of the forecast period, the rest of the
intensity models respond to the unfavorable environment by showing
relatively little strengthening.  The NHC forecast follows this same
thinking, and it shows Fiona only modestly strengthening during the
next 36 hours, with some weakening probable by day 3.  Based on the
latest intensity guidance, the new NHC forecast has been adjusted
downward from the previous forecast, but it still lies above the
consensus at most forecast times.

The recent ASCAT data helped to fix the center, and the initial
motion estimate is now west-northwestward, or 300/14 kt.  A break
in the mid-tropospheric ridge to the north of Fiona is expected to
to migrate westward during the next few days, but the cyclone's
shallow nature is expected to help maintain a west-northwestward
motion for much of the forecast period.  The bulk of the track
models are tightly clustered on such a heading.  However, the GFDL
(which makes Fiona hurricane) shows a sharp northward turn, while
the HWRF (which essentially shows no intensification) takes a much
more southern track.  Since these two scenarios appear to cancel
each other out, the NHC official forecast closely follows the
consensus models, requiring a westward adjustment to the previous
forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 15.5N  39.0W   35 KT  40 MPH
12H  18/1200Z 16.3N  40.4W   35 KT  40 MPH
24H  19/0000Z 17.1N  41.9W   40 KT  45 MPH
36H  19/1200Z 17.8N  43.5W   45 KT  50 MPH
48H  20/0000Z 18.6N  45.2W   45 KT  50 MPH
72H  21/0000Z 20.6N  49.1W   40 KT  45 MPH
96H  22/0000Z 22.5N  53.0W   40 KT  45 MPH
120H  23/0000Z 24.5N  57.0W   40 KT  45 MPH

$$
Forecaster Berg"



And here is the shear forecast following the DSHP track noted at the link above (DSHP taking land into account, although in this case it is over water for the duration):



                   * ATLANTIC     SHIPS INTENSITY FORECAST          *
                   * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                   *  FIONA       AL062016  08/18/16  00 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    35    35    37    38    39    42    42    42    43    45    45    48    50
V (KT) LAND       35    35    37    38    39    42    42    42    43    45    45    48    50
V (KT) LGEM       35    36    36    38    39    40    39    38    36    35    34    35    38
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         3     5     8    12    12    12    17    22    22    20    13    11     7
SHEAR ADJ (KT)    -1    -2    -2    -1     0     0     3     4     3     3     4     1     1
SHEAR DIR        163   172   171   185   196   227   238   250   258   269   257   275   279
SST (C)         26.8  26.8  26.7  26.7  26.8  27.0  27.3  27.6  27.8  27.8  28.1  28.4  28.7
POT. INT. (KT)   123   122   120   120   121   124   127   131   134   134   138   142   147
ADJ. POT. INT.   119   117   113   111   113   116   117   122   124   124   126   128   131
200 MB T (C)   -53.1 -53.3 -53.3 -53.2 -53.3 -53.5 -53.2 -53.6 -53.9 -54.2 -54.1 -54.2 -54.2
200 MB VXT (C)  -0.1  -0.1  -0.1  -0.1  -0.2  -0.1   0.0   0.2   0.2   0.1   0.3   0.2   0.1
TH_E DEV (C)       7     7     7     7     8     7     8     8     9     9    10    10    11
700-500 MB RH     57    58    56    55    55    47    42    40    38    39    43    47    47
MODEL VTX (KT)    13    13    13    13    13    13    12    11    10    10     8     8     7
850 MB ENV VOR    53    40    31    26    34    32    28    19    -2   -25   -37   -47   -49
200 MB DIV       -12    -4     4    16    26    23    -6     5     6    -5    13    -1    -5
700-850 TADV       0    -1     0     1     3     5     7     9    11    14     9     9     6
LAND (KM)       1865  1845  1833  1815  1799  1772  1751  1740  1706  1613  1452  1327  1208
LAT (DEG N)     15.2  15.9  16.5  16.9  17.2  18.2  19.0  19.7  20.7  21.8  23.1  24.1  24.9
LONG(DEG W)     38.5  39.4  40.3  41.0  41.7  43.4  45.1  46.8  48.8  50.7  52.7  54.5  56.4
STM SPEED (KT)    13    11     9     8     8    10     9    10    10    11    10    10     9
HEAT CONTENT       9     6     5     9    13    15     9     9     9    19    25    27    24

 FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):300/ 14      CX,CY: -11/  7
 T-12 MAX WIND:  35            PRESSURE OF STEERING LEVEL (MB):  520  (MEAN=618)
 GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  17.2 (MEAN=14.5)
 % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  13.0 (MEAN=65.0)
 PRELIM RI PROB (DV .GE. 30 KT IN 24 HR):            5.1

                       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.  11.  11.  12.  13.  13.
 SST POTENTIAL          1.   1.   1.   2.   4.   7.  10.  13.  16.  18.  19.  20.
 VERTICAL SHEAR MAG     1.   2.   3.   4.   5.   5.   4.   2.   0.  -1.  -1.   0.
 VERTICAL SHEAR ADJ     0.   0.   1.   1.   1.   1.   1.   0.   0.  -1.  -1.  -1.
 VERTICAL SHEAR DIR     0.   0.  -1.  -1.  -2.  -4.  -5.  -7.  -7.  -7.  -8.  -8.
 PERSISTENCE            0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.   0.   0.
 200/250 MB TEMP.       0.  -1.  -1.  -2.  -2.  -2.  -2.  -2.  -2.  -1.  -1.   0.
 THETA_E EXCESS         0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
 700-500 MB RH          0.   0.   0.   0.   0.   0.   1.   1.   2.   2.   2.   2.
 MODEL VTX TENDENCY     0.   0.   0.   0.  -1.  -3.  -5.  -7.  -7. -10. -12. -13.
 850 MB ENV VORTICITY   0.   0.   0.   0.   0.   0.   0.   0.   0.  -1.  -1.  -2.
 200 MB DIVERGENCE      0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.   1.   2.
 850-700 T ADVEC        0.   0.   0.   0.   0.   0.   0.   0.   0.   1.   1.   0.
 ZONAL STORM MOTION     0.   0.   0.   1.   1.   1.   2.   2.   2.   2.   3.   3.
 STEERING LEVEL PRES    0.   0.   0.   0.   1.   1.   1.   1.   1.   1.   1.   1.
 DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
 GOES PREDICTORS       -1.  -2.  -3.  -3.  -4.  -5.  -5.  -5.  -5.  -4.  -2.  -2.
 OCEAN HEAT CONTENT     0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
                       ----------------------------------------------------------
 TOTAL CHANGE           0.   2.   3.   4.   7.   7.   7.   8.  10.  10.  13.  15.

               CURRENT MAX WIND (KT):   35. LAT, LON:   15.2    38.5

     ** 2015 ATLANTIC RI INDEX AL062016 FIONA      08/18/16  00 UTC **
(SHIPS-RII PREDICTOR TABLE for 30 KT OR MORE MAXIMUM WIND INCREASE IN NEXT 24-h)

    Predictor             Value   RI Predictor Range  Scaled Value(0-1) % Contribution
12 HR PERSISTENCE (KT):     0.0     -49.5  to   33.0       0.60           3.7
850-200 MB SHEAR (KT) :     8.2      28.8  to    2.9       0.80           2.1
HEAT CONTENT (KJ/cm2) :     8.4       0.0  to  155.1       0.05           0.1
STD DEV OF IR BR TEMP :    17.2      37.5  to    2.9       0.59           1.6
2nd PC OF IR BR TEMP  :    -0.4       2.8  to   -3.1       0.54           1.4
MAXIMUM WIND (kt)     :    35.0      22.5  to  121.0       0.35           0.3
D200 (10**7s-1)       :     6.0     -23.1  to  181.5       0.14           0.2
POT = MPI-VMAX (KT)   :    79.6      28.4  to  139.1       0.46           0.7
% AREA WITH TPW <45 mm:     0.0     100.0  to    0.0       1.00           0.6
BL DRY-AIR FLUX (w/m2):   230.2     960.3  to  -67.1       0.71           0.0

SHIPS Prob RI for 20kt/ 12hr RI threshold=   6% is   1.1 times sample mean ( 5.5%)
SHIPS Prob RI for 25kt/ 24hr RI threshold=  15% is   1.3 times sample mean (11.6%)
SHIPS Prob RI for 30kt/ 24hr RI threshold=  11% is   1.5 times sample mean ( 7.2%)
SHIPS Prob RI for 35kt/ 24hr RI threshold=  10% is   2.3 times sample mean ( 4.2%)
SHIPS Prob RI for 40kt/ 24hr RI threshold=   0% is   0.0 times sample mean ( 2.8%)
SHIPS Prob RI for 45kt/ 36hr RI threshold=   9% is   1.8 times sample mean ( 4.9%)
SHIPS Prob RI for 55kt/ 48hr RI threshold=  15% is   3.0 times sample mean ( 5.1%)

Matrix of RI probabilities
---------------------------------------------------------------------
 RI (kt / h)  | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48
---------------------------------------------------------------------
  SHIPS-RII:     5.8%   15.5%   10.7%    9.8%    0.0%    9.0%   15.4%
   Logistic:     4.6%   17.1%    9.1%    4.6%    0.0%    0.9%    0.2%
   Bayesian:     0.1%    0.3%    0.1%    0.0%    0.0%    0.0%    0.0%
  Consensus:     3.5%   11.0%    6.6%    4.8%    0.0%    3.3%    5.2%

  ##         ANNULAR HURRICANE INDEX (AHI) AL062016 FIONA      08/18/16  00 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) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL062016 FIONA      08/18/2016  00 UTC **
TIME(HR)   0-12  12-24(0-24)  24-36(0-36)  36-48(0-48)
CLIMO(%)     0      0(  0)       0(  0)       0(  0)     <-- PROB BASED ON INTENSITY ONLY
PROB(%)      0      0(  0)       0(  0)       0(  0)     <-- FULL MODEL PROB (RAN NORMALLY)

** DSHIPS INTENSITY FORECAST ADJUSTED RELATIVE TO ONSET OF ERC WEAKENING PHASE **
     TIME (HR)      0     6    12    18    24    36    48    60    72    84    96   108   120
>24HR AGO (DSHIPS)  35    35    37    38    39    42    42    42    43    45    45    48    50
18HR AGO           35    34    36    37    38    41    41    41    42    44    44    47    49
12HR AGO           35    32    31    32    33    36    36    36    37    39    39    42    44
 6HR AGO           35    29    26    25    26    29    29    29    30    32    32    35    37
     NOW                              CURRENT INTENSITY < 83 KT
 IN  6HR                              INTENSITY IN  6HR < 83 KT
 IN 12HR                              INTENSITY IN 12HR < 83 KT


From: ftp://ftp.nhc.noaa.gov/atcf/stext/



You can see the shear forecast.

It seems to be what is often the case. Stronger, more north. Weaker, more west. Many days to see if Bermuda could see any impact at all, even waves.
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Invest 98L becomes Tropical Depression Six - Chris in Tampa, 8/17/2016, 12:29 am
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