ATL: ALBERTO - Post-Tropical

[Bocadude85]

Not one person is questioning the rainfall over florida... in either camp..

If that’s the case then who cares where a weather less LLC makes landfall? The rainfall is the story of this system.

Science.....

Ok and past experience has told many of us that a weak LLC will follow the convention...so what makes the GFS solution so unreasonable?

[Aric Dunn]

If that’s the case then who cares where a weather less LLC makes landfall? The rainfall is the story of this system.

Science.....

Ok and past experience has told many of us that a weak LLC will follow the convention...so what makes the GFS solution so unreasonable?

read the numerous previous pages for the multiple scenarios.. and in the discussion

[ava_ati]

Will the GFS wind up being closer to what actually takes place? Given the upper wind profile, I think it's a reasonable assumption. Could the ECM verify? Sure, it could. However, there's little doubt in my mind that BE (divergent jet forced ascent) processes will play a role in lowering surface pressures over the Gulf and this will occur east of the mid-upper level low, rather than directly beneath it. I think what most folks here (including my fellow blue-taggers) agree upon, is that this will be a sloppy, right sided system. It seems that where we differ the most is just how far east the precip shield with the highest QPF will be. To be honest, I wouldn't mind being wrong in this case. If the heavy precip swath stays out over the eastern Gulf...hey, we'll take it here on the peninsula.

The worst part for Florida is that this isn't going to get any better once this system is past us. I'm not especially worried about whatever this Low forms into but it is the rainfall we have already had, this system and the rain that is going to come after the system that has me worried.

[TheStormExpert]

Despite shear likely limiting much if any development in the GoM it’s been actually below average there as of lately.

 https://twitter.com/michaelrlowry/status/999030348934770691

[CyclonicFury]

I would not be surprised if this became a named tropical storm anyway despite the shear. Early season gyre storms have formed in strong shear before: think Andrea 2013, Colin 2016 and Cindy 2017 for some recent examples. Regardless, heavy rain is the main threat, but I think it has a decent chance to become named this weekend based on the models except for the GFS.

[AJC3]

We have two pro Mets in the GFS camp and from my experience it’s hard to go against what they say, another 10-20 inches of rainfall will cause significant flooding in South and Central Florida.

Not one person is questioning the rainfall over florida... in either camp..

If that’s the case then who cares where a weather less LLC makes landfall? The rainfall is the story of this system.

You're exactly right in that rainfall is the big story here. But even though the main global models agree on this being a sheared/sloppy right sided system, the reason (or at least one of them) why I think there's probably so much discussion/debate about this is because there's a pretty substantial difference in the QPF fields through Sunday night over a couple of land areas of note. The first is across the southern third of Florida. the GFS shows 4-7" areal average there, while the ECM shows about half that much. The second is from SELA across southern MS/AL. The ECM shows about 3-6" in this area, while the GFS shows about half of that. The difference in the fields are quite apparent over the eastern half of the GOMEX. The ECM is much wetter there. And these differences become even more pronounced early next week!

We've found that local precip maxima in tropical rainfall events is usually between 2 and 3x the forecast areal averages. This could be very significant. Some of the areas where the GFS is showing those additional rains have already received nearly a foot and half of rain.

[DestinHurricane]

Should the 5 day chances go up at the 8PM STWO

[CyclonicFury]

000
ABNT20 KNHC 222314
TWOAT

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
715 PM EDT Tue May 22 2018

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A broad surface low centered just east of Belize is producing a
large area of cloudiness and showers extending from the northwestern
Caribbean Sea across Cuba and into the Florida peninsula. Little
development is expected during the next couple of days due to strong
upper-level winds and proximity to the Yucatan Peninsula of Mexico.
However, gradual subtropical or tropical development is possible
late this week while the system moves slowly into the central or
eastern Gulf of Mexico. Regardless of development, locally heavy
rainfall is possible across western Cuba, the Cayman Islands, and
much of Florida during the next several days. For more information
on the heavy rain threat, please see products issued by your local
weather office. The next Special Tropical Weather Outlook on this
system will be issued by 800 AM EDT on Wednesday.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

$$
Forecaster Beven

[CyclonicFury]

18z GEFS is bullish on a Big Bend area TS, which fits in line with climatology.

[cycloneye]

[northjaxpro]

NHC upped the development probability over 120 hours at 50% now.

Boatload of rain in store for us in Florida for days and days to come as I am sticking with the solution.the GFS has shown us the entire time.

[gatorcane]

The GFS op continues to show significant rainfalls for SE Florida for the next 10 days partly due to 90l:

[gatorcane]

12Z UKMET a lot like the GFS:

[Aric Dunn]

12Z UKMET a lot like the GFS:

IT also does not look tropical....

[TheStormExpert]

Interesting Twitter discussion by Philippe Papin on Invest 90L and its CAG (Central American Gyre) origin and key aspects of this kind of originating TC potential.

 https://twitter.com/pppapin/status/999069322298343424




 https://twitter.com/pppapin/status/999069328237514752




 https://twitter.com/pppapin/status/999069335124504576




 https://twitter.com/pppapin/status/999069343668359168




 https://twitter.com/pppapin/status/999069346713358336

[cycloneye]

00z Best Track:

Location: 17.3°N 87.2°W
Maximum Winds: 25 kt
Minimum Central Pressure: 1008 mb

[cycloneye]

00z SHIP

Code: Select all

   * ATLANTIC     SHIPS INTENSITY FORECAST          *
                    * IR SAT DATA PROXY USED,      OHC AVAILABLE     *
                    *  INVEST      AL902018  05/23/18  00 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    25    26    27    28    29    28    30    28    33    36    36    36    35
V (KT) LAND       25    26    27    28    29    28    30    28    33    36    36    36    35
V (KT) LGEM       25    25    25    25    24    23    22    22    21    21    21    20    20
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)        21    23    22    21    22    19    23    22    26    25    21    20    21
SHEAR ADJ (KT)     0     0     2     0     1     0     4    -1     1     0     6     2     7
SHEAR DIR        266   268   269   270   263   271   242   248   240   263   228   237   227
SST (C)         28.9  28.9  28.9  28.9  28.9  28.8  28.6  28.5  28.3  28.0  26.5  25.7  23.8
POT. INT. (KT)   145   145   145   145   146   145   142   141   140   138   123   116   101
ADJ. POT. INT.   128   129   129   129   130   130   127   128   130   133   119   112    94
200 MB T (C)   -53.2 -53.5 -53.7 -53.3 -53.0 -53.5 -52.7 -53.4 -52.9 -53.5 -53.0 -54.1 -54.4
200 MB VXT (C)   0.4   0.6   0.5   0.5   0.5   0.4   0.7   0.5   0.7   0.4   0.8   0.0   0.0
TH_E DEV (C)       9     8     7     9     9     7     9     7     8     6     6     4     4
700-500 MB RH     65    67    66    66    68    68    73    70    73    72    75    76    74
MODEL VTX (KT)     8     8     7     8     8     6     8     7    11    14    13  LOST  LOST
850 MB ENV VOR    52    56    49    47    43    39    68    73    86    66    71    17    55
200 MB DIV        39    41    48    48    59    20    50    64    93    63   100    75   119
700-850 TADV       0    -3    -4     0     0    -3    -3     0     4    15    21    45    34
LAND (KM)        106    95    84    74    84   107   143   195   272   171    71   147    25
LAT (DEG N)     17.3  17.3  17.3  17.4  17.5  17.6  17.8  18.0  19.0  20.5  23.7  28.2  33.4
LONG(DEG W)     87.2  87.3  87.4  87.5  87.4  87.0  86.4  85.8  84.9  83.3  81.0  79.0  78.9
STM SPEED (KT)     0     1     1     1     2     2     3     4     9    15    22    26    25
HEAT CONTENT      40    40    40    39    38    40    47    55    58    52    10     0     0

  FORECAST TRACK FROM TABM      INITIAL HEADING/SPEED (DEG/KT):  0/  0      CX,CY:   0/  0
  T-12 MAX WIND:  25            PRESSURE OF STEERING LEVEL (MB):  561  (MEAN=618)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  19.9 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  38.0 (MEAN=65.0)
  PRELIM RI PROB (DV .GE. 55 KT IN 48 HR):            0.1

                        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.  10.  11.  12.  13.  13.
  SST POTENTIAL          1.   1.   1.   3.   6.  11.  16.  21.  25.  28.  29.  30.
  VERTICAL SHEAR MAG     1.   1.   2.   2.   1.  -1.  -4.  -7. -10. -12. -14. -16.
  VERTICAL SHEAR ADJ     0.  -0.   0.   0.   0.  -0.   0.   1.   1.   0.  -0.  -1.
  VERTICAL SHEAR DIR    -0.  -1.  -1.  -2.  -3.  -4.  -6.  -7.  -8.  -9.  -9.  -8.
  PERSISTENCE           -0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.  -0.   0.   0.   1.
  200/250 MB TEMP.      -0.  -0.  -0.  -0.  -1.  -1.  -1.  -1.  -1.  -2.  -1.  -1.
  THETA_E EXCESS         0.  -0.   0.   0.  -0.  -0.  -0.  -0.  -1.  -1.  -1.  -2.
  700-500 MB RH         -0.  -0.  -0.  -1.  -1.  -2.  -4.  -5.  -6.  -6.  -6.  -6.
  MODEL VTX TENDENCY    -0.  -1.  -0.  -0.  -3.  -2.  -4.   0.   3.   2.   1.   0.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.   1.   1.   2.   2.   2.   2.   2.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.   0.   0.   1.   1.   1.   0.  -1.
  850-700 T ADVEC        0.  -0.  -0.  -0.  -0.  -0.  -1.  -1.  -0.   0.   1.   1.
  ZONAL STORM MOTION     0.  -0.  -0.  -0.  -1.  -1.  -1.  -1.  -2.  -2.  -3.  -3.
  STEERING LEVEL PRES    0.   0.   0.   0.   0.   0.   0.   1.   1.   0.   0.   0.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.   1.   1.   1.   2.   2.   2.
  GOES PREDICTORS       -0.  -1.  -1.  -1.  -2.  -3.  -3.  -4.  -4.  -3.  -3.  -3.
  OCEAN HEAT CONTENT    -0.  -0.  -0.  -0.  -0.  -1.  -1.  -1.  -1.  -1.  -1.  -0.
                        ----------------------------------------------------------
  TOTAL CHANGE           1.   2.   3.   4.   3.   5.   3.   8.  11.  11.  11.  10.

                CURRENT MAX WIND (KT):   25. LAT, LON:   17.3    87.2

      ** 2017 ATLANTIC RI INDEX AL902018 INVEST     05/23/18  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         999.0
 850-200 MB SHEAR (KT) :    21.7      30.1  to    2.9       0.31         999.0
 HEAT CONTENT (KJ/cm2) :    39.4       0.0  to  156.2       0.25         999.0
 2nd PC OF IR BR TEMP  :  9999.0       2.4  to   -3.0     999.00         999.0
 STD DEV OF IR BR TEMP :   999.0      36.6  to    2.8     999.00         999.0
 MAXIMUM WIND (kt)     :    25.0      22.5  to  121.0       0.07         999.0
 POT = MPI-VMAX (KT)   :   104.0      28.4  to  139.6       0.68         999.0
 D200 (10**7s-1)       :    47.0     -29.7  to  181.5       0.36         999.0
 BL DRY-AIR FLUX (w/m2):    63.4     961.4  to  -67.1       0.87         999.0
 % AREA WITH TPW <45 mm:    12.6     100.0  to    0.0       0.87         999.0
 
 SHIPS Prob RI for 20kt/ 12hr RI threshold= 999% is 999.0 times sample mean ( 5.4%)
 SHIPS Prob RI for 25kt/ 24hr RI threshold= 999% is 999.0 times sample mean (11.5%)
 SHIPS Prob RI for 30kt/ 24hr RI threshold= 999% is 999.0 times sample mean ( 7.4%)
 SHIPS Prob RI for 35kt/ 24hr RI threshold= 999% is 999.0 times sample mean ( 4.3%)
 SHIPS Prob RI for 40kt/ 24hr RI threshold= 999% is 999.0 times sample mean ( 2.8%)
 SHIPS Prob RI for 45kt/ 36hr RI threshold= 999% is 999.0 times sample mean ( 5.1%)
 SHIPS Prob RI for 55kt/ 48hr RI threshold= 999% is 999.0 times sample mean ( 5.3%)
 SHIPS Prob RI for 65kt/ 72hr RI threshold= 999% is 999.0 times sample mean ( 6.0%)
   
Matrix of RI probabilities
------------------------------------------------------------------------------
  RI (kt / h)  | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48  |65/72
------------------------------------------------------------------------------
   SHIPS-RII:   999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%
    Logistic:   999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%
    Bayesian:   999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%
   Consensus:   999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%  999.0%

   ##         ANNULAR HURRICANE INDEX (AHI) AL902018 INVEST     05/23/18  00 UTC         ##
   ##         ERR=2, BOTH IR FILES BAD OR MISSING

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL902018 INVEST     05/23/2018  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)     PC4 UNAVAIL...MODEL SKILL DEGRADED

** 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)  25    26    27    28    29    28    30    28    33    36    36    36    35
 18HR AGO           25    24    25    26    27    26    28    26    31    34    34    34    33
 12HR AGO           25    22    21    22    23    22    24    22    27    30    30    30    29
  6HR AGO           25    19    16    15    16    15    17    15    20    23    23    23    22
      NOW                              CURRENT INTENSITY < 83 KT
  IN  6HR                              INTENSITY IN  6HR < 83 KT
  IN 12HR                              INTENSITY IN 12HR < 83 KT

[DestinHurricane]

All storms in this area in may, all but 1 are similar to the GFS solution

[stormreader]

Euro precip showing system approaching N Central gulf coast with a drift west and stall-meander over S Central anand SW La. Looking at precip.
https://www.facebook.com/katctv3/posts/ ... 4620441969

[Aric Dunn]

MId and upper levels are becoming less dry around the system. Could see more convection build overnight.