ATL: DON - Remnant - Discussion

[cycloneye]

12z Tropical Model tracks

The BAMS have shifted south.

[plasticup]

One thing that seems to be the consensus this year. So far. Is most of the reliable models have not done a good job in showing organization of storms. I don't know why. But it sure looks like this will be a depression/storm when recon gets there today. Hopefully it will give some much needed rain to Texas.

That's because Bret and Cindy were very atypical storms. They pinched off the end of a front, which is a fairly unpredictable process. And they may not have been entirely tropical in origin. The models are excellent with Cape Verde-type systems like 90L. Not perfect, but very very good.

[thetruesms]

As an aside, the 0% from Monday morning's TWO has verified.

Now, as for those 0%s from the afternoon or evening TWOs verifying? Ehhhhh . . . . The afternoon one might just because recon might not have arrived yet when the product is due.

[Tireman4]

Morning e-mail from Jeff:

Potential tropical cyclone threat to the state of Texas later this week/weekend.

Significant forecast changes likely over the next 48 hours.
Discussion:
The strong tropical wave over the NW Caribbean Sea continues to become better organized with deep convection frequent near/over the wave axis. Radar out of Cancun and surface observations suggest that the strong mid level center may be working its way to the surface and developing a surface circulation, at this time it is weak and barely noted in the surface data and deep convection while persistent remains scattered.

Track:
Massive high pressure ridge holding over TX for months will be moving ENE toward the Carolinas over the next 48 hours allowing a weakness to develop over the NW Gulf of Mexico and the TX coast. The Caribbean system will track along the SW side of the ridge into this weakness or in the general direction of the TX coast. Global guidance is still not “seeing” what is happening in the Caribbean Sea and shows little development, so will toss it out as it is clear that a tropical system is forming. Will follow the expected ridge position and split the difference between the 2 hurricane forecasting models (GFDL and HWRF) and the multi model consensus package and indicate a potential threat from Galveston to Brownsville with highest threat right now from about Corpus Christi to Port O Connor. GFDL takes the system as a cat 1 hurricane into Galveston Bay while the HWRF takes the system as a strong cat 1 into the area near Corpus Christi. The multi model consensus is pegged just west of Port O Connor taking into account the GFS and GFDL upper coast and the HWRF and EURO southern coast.

Will get a better handle on the spreading track solutions by this evening as data from a USAF mission midday today is ingested into the models.

Intensity:
Overall size of the system is small which means it is vulnerable to surrounding atmospheric conditions moreso than a large system. The system is over very warm waters with temperatures in the mid to upper 80’s across much of the Gulf of Mexico and the NW Caribbean Sea. Upper level shear while strong over the northern Gulf of Mexico is light over the southern Gulf and forecast to gradually weekend as the southern plains high shifts eastward. The air mass over the southern Gulf does have a bit of dry air and this may be one reason as to why the convection has been fairly meager with this system and this could impact the system down the road as it moves across the Gulf. Overall conditions in the Gulf appear favorable for development and small system can spin up/down very quickly due to surrounding atmospheric changes (dry air intrusion, weak shear, ect). SHIPS guidance brings the system to a hurricane in the Gulf along with the GFDL and HWRF hurricane models, while the GFS, EURO, and CMC show very little development at all. Feel the big global models (GFS, EURO, and CMC) are missing this small system altogether and will not put much faith in their current forecast, while the hurricane models do seem high. For now will go with a blend of the two camps and lean toward the stronger solutions with a strong tropical storm or possibly a weak hurricane approaching the TX coast late Friday.

Impacts:
Feel it is best to await data from the aircraft this afternoon before going full force on coastal impacts. Forecast will no doubt need some significant changes with respect to seas, tides, rain changes, and rainfall amounts, along with wind forecast for Friday into Saturday. Will at least bump rain chances to 50% for Friday for areas south of I-10 and this could go much higher and hit those same areas with widespread 1-2 inches of rainfall. Coastal winds will begin to back from the SSW to ESE and then E Thursday night into Friday and increase. For now will hold winds below TS force over all areas awaiting NHC wind guidance if/once the system is declared. Based on current track guidance feel, TS force winds (40mph or greater) will be needed by Friday evening over parts of the middle and upper TX coast waters and coastal counties and spreading inland Friday night.

Preparations:
Residents along the TX coast should review hurricane preparation plans and be prepared to put these plans into effect over the next 48 hours. Closely monitor weather forecast for potential rapid changes and increasing impacts to the Texas coast.

[plasticup]

:?: When is landfall expected?

Landfall is only a meaningful term if the system develops into a tropical storm and maintains that status until it reaches the coast. But, assuming 90L does those things (and it may not!), we are looking at about 3 days to the Mexico/Texas/Louisiana coast.

Again, I'm just an amateur looking at a couple of models. This isn't an official forecast - the NHC hasn't released any products specifying track forecasts yet.

[thequeenamom]

Landfall is only a meaningful term if the system develops into a tropical storm and maintains that status until it reaches the coast. But, assuming 90L does those things (and it may not!), we are looking at about 3 days to the Mexico/Texas/Louisiana coast.

Again, I'm just an amateur looking at a couple of models. This isn't an official forecast - the NHC hasn't released any products specifying track forecasts yet.

Thank you- Just curious because my daughter has a ball in Galveston this Sat. evening...........

[NDG]

The circulation is beginning to poke out the northern side of the convection from the northerly shear.. pretty apparent we have a closed surface circ. and it seems as though its trying to get pulled north... at the moment..

Initially I thought the same but as vis sat pics keep coming in it appears that the possible LLC is staying under the covers.
But yeah, Cancun and Cuban radar shows that the deep convection is to the south of the COC, it might be already feeling the NE shear.

[HURAKAN]

Latest visible

[Aric Dunn]

The circulation is beginning to poke out the northern side of the convection from the northerly shear.. pretty apparent we have a closed surface circ. and it seems as though its trying to get pulled north... at the moment..

Initially I thought the same but as vis sat pics keep coming in it appears that the possible LLC is staying under the covers.
But yeah, Cancun and Cuban radar shows that the deep convection is to the south of the COC, it might be already feeling the NE shear.

well half is exposed. convection keeps trying to refire. the shear should relax though today.

[plasticup]

Landfall is only a meaningful term if the system develops into a tropical storm and maintains that status until it reaches the coast. But, assuming 90L does those things (and it may not!), we are looking at about 3 days to the Mexico/Texas/Louisiana coast.

Again, I'm just an amateur looking at a couple of models. This isn't an official forecast - the NHC hasn't released any products specifying track forecasts yet.

Thank you- Just curious because my daughter has a ball in Galveston this Sat. evening...........

I wouldn't cancel any plans yet. This system may not end up anywhere near Galveston. And even if it does, it may only be a bit of rain on Saturday. There is so much uncertainty at this point. This is a hurricane forum, so people here (myself included) tend to focus on the outcomes that result in hurricanes. Often we diminish the possibility that these things can splutter and fizzle.

[Air Force Met]

:?: When is landfall expected?

Landfall is only a meaningful term if the system develops into a tropical storm and maintains that status until it reaches the coast. But, assuming 90L does those things (and it may not!), we are looking at about 3 days to the Mexico/Texas/Louisiana coast.

Again, I'm just an amateur looking at a couple of models. This isn't an official forecast - the NHC hasn't released any products specifying track forecasts yet.

Actually we're not that far out now. Probably more like 2 1/2 now. Late Friday evening maybe...

[Stormcenter]

As I stated yesterday this looks like a SE Texas maybe SW LA. event.
The only issue now is whether or not it will be a sheared system or formidable tropical storm or hurricane. JMHO

[cycloneye]

The shear forecast at 12z by SHIP shows light shear during the GOM track.

Code: Select all

           *   ATLANTIC SHIPS INTENSITY FORECAST       *
                    * GOES AVAILABLE,       OHC AVAILABLE       *
                    *      INVEST  AL902011  07/27/11  12 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    30    32    35    38    41    48    53    61    66    72    75    77    76
V (KT) LAND       30    32    35    38    41    48    53    61    40    31    28    27    27
V (KT) LGE mod    30    32    35    38    41    47    55    63    42    31    28    27    27
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         8     8     0     6    11     3    11     5     4     1     8     3     8
SHEAR ADJ (KT)     1    -3    -3    -2    -2    -2    -1    -3    -3     0    -3    -4    -3
SHEAR DIR        351    27   242   293     4    99    26    80    44   265    31    20    41
SST (C)         28.8  28.4  28.3  28.5  28.8  29.3  28.8  27.9  28.4  29.0  29.1  28.8  28.3
POT. INT. (KT)   148   142   141   144   149   157   149   136   143   151   152   146   137
ADJ. POT. INT.   136   128   128   132   135   142   134   121   125   130   129   121   111
200 MB T (C)   -52.9 -52.6 -52.4 -52.6 -52.8 -52.2 -52.3 -51.8 -52.2 -52.0 -52.4 -52.1 -52.2
TH_E DEV (C)      10    11    11    12    11    13    11    14    11    14    10    12    10
700-500 MB RH     63    64    65    61    63    58    57    52    52    55    53    52    49
GFS VTEX (KT)      4     4     5     3     3     3     1  LOST  LOST  LOST  LOST  LOST  LOST
850 MB ENV VOR   -28   -16    -4    -1    -8   -11   -21   -13   -16   -18   -13   -30   -25
200 MB DIV        -3     9    12    24    16    17   -16   -15    -6    -4     1    -4     1
700-850 TADV       0    -3     0     0    -9     1   -10    -1    -7    -3    -7    -2   -10
LAND (KM)         68    79   113   200   288   479   291    76  -179  -393  -554  -661  -689
LAT (DEG N)     21.9  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x  xx.x
LONG(DEG W)     86.5 xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x xxx.x
STM SPEED (KT)    10     9    10    11    11    11    12    12    11     8     7     4     2
HEAT CONTENT       3     5     7    20    34    44    50    10     0  9999  9999  9999  9999

  FORECAST TRACK FROM OFPI      INITIAL HEADING/SPEED (DEG/KT):290/ 11      CX,CY:  -9/  4
  T-12 MAX WIND:  25            PRESSURE OF STEERING LEVEL (MB):  619  (MEAN=623)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  31.0 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  37.0 (MEAN=65.0)

                        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.  12.  12.  13.  13.
  SST POTENTIAL          1.   1.   2.   3.   6.  11.  16.  20.  24.  26.  27.  28.
  VERTICAL SHEAR MAG     1.   3.   4.   6.   9.  11.  12.  14.  15.  16.  16.  16.
  VERTICAL SHEAR ADJ     0.   0.   0.   1.   1.   1.   2.   2.   2.   3.   2.   2.
  VERTICAL SHEAR DIR     0.   0.   0.   0.   1.   1.   1.   1.   1.   0.   0.  -1.
  PERSISTENCE            1.   1.   2.   2.   2.   2.   2.   1.   1.   1.   0.   0.
  200/250 MB TEMP.       0.   0.  -1.  -1.  -1.  -2.  -2.  -3.  -3.  -4.  -4.  -4.
  THETA_E EXCESS         0.   0.   0.   0.   1.   1.   2.   2.   3.   3.   3.   3.
  700-500 MB RH          0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.   0.
  GFS VORTEX TENDENCY    0.   0.   0.  -1.  -1.  -3.  -2.  -2.  -3.  -3.  -3.  -4.
  850 MB ENV VORTICITY   0.  -1.  -1.  -1.  -1.  -2.  -3.  -3.  -4.  -4.  -5.  -5.
  200 MB DIVERGENCE      0.   0.   0.  -1.  -1.  -1.  -2.  -2.  -2.  -2.  -2.  -2.
  850-700 T ADVEC        0.   0.   0.   0.   0.   0.   0.   0.   0.   1.   1.   1.
  ZONAL STORM MOTION     0.   0.   0.   1.   1.   1.   1.   2.   2.   2.   2.   2.
  STEERING LEVEL PRES    0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.  -1.
  GOES PREDICTORS       -1.  -2.  -2.  -3.  -4.  -4.  -4.  -3.  -3.  -3.  -2.  -2.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE           2.   5.   8.  11.  18.  23.  31.  36.  42.  45.  47.  46.

   ** 2011 ATLANTIC RI INDEX AL902011     INVEST 07/27/11  12 UTC **
 
 12 HR PERSISTENCE (KT):   5.0 Range:-45.0 to  30.0 Scaled/Wgted Val:  0.7/  2.2
 850-200 MB SHEAR (KT) :   6.7 Range: 26.2 to   3.2 Scaled/Wgted Val:  0.8/  1.6
 STD DEV OF IR BR TEMP :  31.0 Range: 34.1 to   3.2 Scaled/Wgted Val:  0.1/  0.2
 D200 (10**7s-1)       :  11.6 Range:-21.0 to 165.0 Scaled/Wgted Val:  0.2/  0.4
 POT = MPI-VMAX (KT)   : 102.0 Range: 33.8 to 126.5 Scaled/Wgted Val:  0.7/  0.8
 850-700 MB REL HUM (%):  64.4 Range: 56.0 to  85.0 Scaled/Wgted Val:  0.3/  0.2
 Heat content (KJ/cm2) :  13.8 Range:  0.0 to 130.0 Scaled/Wgted Val:  0.1/  0.0
 % area w/pixels <-30 C:  34.0 Range: 17.0 to 100.0 Scaled/Wgted Val:  0.2/  0.1
 
 Prob of RI for 25 kt RI threshold=    19% is   1.5 times the sample mean(12.8%)
 Prob of RI for 30 kt RI threshold=    12% is   1.4 times the sample mean( 8.4%)
 Prob of RI for 35 kt RI threshold=     2% is   0.3 times the sample mean( 5.0%)
 Prob of RI for 40 kt RI threshold=     1% is   0.3 times the sample mean( 3.4%)

   ##         ANNULAR HURRICANE INDEX (AHI) AL902011     INVEST 07/27/11  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) ##

** PROBLTY OF AT LEAST 1 SCNDRY EYEWL FORMTN EVENT AL902011     INVEST 07/27/2011  12 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)


[RL3AO]

As I stated yesterday this looks like a SE Texas maybe SW LA. event.
The only issue now is whether or not it will be a sheared system or formidable tropical storm or hurricane. JMHO

Disagree. The track isn't locked it. This could just as well hit South Texas.

[HouTXmetro]

I think we can discount the BAM(S) suite at this point being that we are no longer in the DEEP Tropics...

[ronjon]

There appears to be some N-NW shear impacting 90L from the ULL off the east coast of FL. The easterly shear screaming across the north half of the GOM has relaxed some and moved north along the coast. As 90L moves NW, it should encounter fairly benign shear conditions. I believe the system is starting to get tugged N-NW by troughing in the NE GOM and the weakening of the mid-level ridge along he northern gulf coast.

http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

[NDG]

So how many of you think that the NHC may go ahead in upgrading 90L to TD 4 at 15z?
A closed surface circulation is now very evident based on radar, satellite and surface observations with 1.5 sat classification.

[Stormcenter]

Oh I agree the track is not locked in at all but based on where it's at now I just don't see making landfall that far south in TX. Of course I say that and watch it make landfall on the Mexican coastline south of Brownsville. JMHO

As I stated yesterday this looks like a SE Texas maybe SW LA. event.
The only issue now is whether or not it will be a sheared system or formidable tropical storm or hurricane. JMHO

Disagree. The track isn't locked it. This could just as well hit South Texas.

[cycloneye]

So how many of you think that the NHC may go ahead in upgrading 90L to TD 4 at 15z?
A closed surface circulation is now very evident based on radar, satellite and surface observations with 1.5 sat classification.

They will wait for recon.

[ronjon]

So how many of you think that the NHC may go ahead in upgrading 90L to TD 4 at 15z?
A closed surface circulation is now very evident based on radar, satellite and surface observations with 1.5 sat classification.

NDG I think they'll wait for RECON just a few hours later. You know how conservative NHC is.