INVEST 91L -Discussions,Analysis and Imagery

[cheezyWXguy]

I really hope this makes landfall on the upper texas coast, as a huge, weak tropical storm, and moves north into DFW. Although rainfall surpluses are still here in texas, we all need a break from the heat. Its 1pm and were already at 103 here in Dallas.

[Lowpressure]

Does this mean something bad for me?[/quote]

It means a system is trying to form and looks to become something you will need to monitor. If you live on the Gulf coast- you should know the drill. If you are new to the coast, check on your preparations. Either case- listen to local authorities if the storm approaches your area.

Chuck

[Extremeweatherguy]

.PREV DISCUSSION... /ISSUED 1101 AM CDT MON AUG 13 2007/

DISCUSSION...
FIRST THE BAD NEWS. THE HEAT ADVISORY REMAINS IN EFFECT UNTIL 5 AM.
15Z OBS SHOW TEMPERATURES ALREADY IN THE LOWER 90S ALMOST AREAWIDE.
HEAT INDEX VALUES ARE ON THEIR WAY UP...AND EXPECT CRITERIA LEVEL
READINGS (AOA 108) TO BE REACHED IN THE NEW COUPLE OF HOURS. WENT
AHEAD AND ADDED NEAR RECORD HIGH TEMPERATURES FOR THE COASTAL COUNTIES
WHERE GLS`S RECORD HIGH WILL LIKELY BE REACHED. CANNOT RULE OUT
ISOLATED SHOWER/THUNDERSTORM DEVELOPMENT THIS AFTERNOON ACROSS SE TX.

NOW THE GOOD NEWS. SOME OF THE 12Z MODELS ARRIVING THIS MORNING ARE
POINTING TOWARD A MUCH WETTER WEDNESDAY/THURSDAY FORECAST AS WESTERN
CUBA AND NORTHERN YUCATAN DEEP TROPICAL MOISTURE MOVES INTO OUR AREA.
THIS PATTERN WOULD BRING AN END TO OUR NEAR RECORD HIGH TEMPERATURES
AND WOULD BRING RAIN TO MUCH OF THE AREA.

FINALLY...THE OTHER NEWS. PER THE TPC/NHC MORNING TROPICAL WEATHER
OUTLOOK...THAT WESTERN CUBA AND YUCATAN AREA MOISTURE IS NOW A BROAD
SURFACE LOW CENTERED ABOUT 90 MILES NNE OF CANCUN. THEIR OUTLOOK
SAYS A TROPICAL DEPRESSION MAY FORM LATER TODAY OR TOMORROW AS IT
MOVES WNW AT 10 TO 15 MPH.

EXPECT SOME FORECAST CHANGES TO BE MADE WITH THE AFTERNOON
PACKAGE.

Looks like the Houston NWS thinks this will get close enough to bring us some clouds and rain. Thank god! A break from the heat!

[Lowpressure]

Well I hope that is not the case stratosphere. We need to get some clouds and may be some light rain to get us out of this heat for a day or two!

Please do not ring all the moisture out of this system- send some to the Carolinas when you are done.

[Sanibel]

The ULL still looks strong to me. I'm with Frank2.

The storm is pulsing down right now in preparation for another organization burst. However, the SST's just north of Yucatan where the LLC is are cool. Don't expect much until it clears this cool upwelling area and hits warmer water to the west. Right now the system is half exposed on the west by ULL shear.

[Stratosphere747]

Well I hope that is not the case stratosphere. We need to get some clouds and may be some light rain to get us out of this heat for a day or two!

Well I know your enthusiasm EWG.... But many of these systems have little effect to those in Houston proper and points north. I'll get some good swells and decent gusts, but that's about it. Of course dependant on this staying weak.

[Steve]

>>Might just be one of those systems that those on the Upper coast will not even realize it's out there. No rain or wind. Seen quite a few of these were any tropical conditions are relegated to the immediate coastline.

Hard to say. I ran the "rainfall" on most of the models and there was disagreement as to where they had the moisture rolling in. Some of them had it north, others right through where the system went ashore.

>>...1999 Bret

Yeah, I'm thinking +/- 75 miles in either direction and obviously not as strong. I don't mean to downplay the water temperatures, but there isn't enough time in my opinion for a Cat 4 (wasn't that what it became???). At the same time, everyone knows that systems hitting Texas from the east can strengthen/tighten up quite a bit close to landfall based on the interaction with the landmass. That goes without saying, so I don't want to downplay that so much that it's not out of the realm of possibility that if a 50-60mph storm is heading the way I think it's going to, and it gets within 12-20 hours of landfall, it could tighten up (ala Claudette a few years ago or Cindy 2005 Louisiana).

Steve

[Ptarmigan]

QPF forecast for the next 5 days.

QPF 5 Day Forecast

PW=6.4 inches of rain.

[clevelandindians]

i EXPECT this to be TD 5 in the next 12-24 hours

[Stratosphere747]

>>Might just be one of those systems that those on the Upper coast will not even realize it's out there. No rain or wind. Seen quite a few of these were any tropical conditions are relegated to the immediate coastline.

Hard to say. I ran the "rainfall" on most of the models and there was disagreement as to where they had the moisture rolling in. Some of them had it north, others right through where the system went ashore.

>>...1999 Bret

Yeah, I'm thinking +/- 75 miles in either direction and obviously not as strong. I don't mean to downplay the water temperatures, but there isn't enough time in my opinion for a Cat 4 (wasn't that what it became???). At the same time, everyone knows that systems hitting Texas from the east can strengthen/tighten up quite a bit close to landfall based on the interaction with the landmass. That goes without saying, so I don't want to downplay that so much that it's not out of the realm of possibility that if a 50-60mph storm is heading the way I think it's going to, and it gets within 12-20 hours of landfall, it could tighten up (ala Claudette a few years ago or Cindy 2005 Louisiana).

Steve

Yeah Steve. The models were quite divergent with respect to the rainfall. If this was coming up from the BOC I would say that the Upper Coast would be more susceptible to a decent soaking. Not sure about a due west track which seems to be the probability.

Very possible about this having the potential to tighten up as it nears shore. Will be interesting to see where the High is. Might see some decent coastal flooding with the gradient.

[EyELeSs1]

13/1745 UTC 22.3N 87.0W T1.0/1.0 91L -- Atlantic Ocean

[CrazyC83]

i EXPECT this to be TD 5 in the next 12-24 hours

Maybe within 3 hours.

[PTrackerLA]

Hopefully we can get at least some clouds and showers from this system. The heat is just unbearable and things are drying up quickly. I don't hold out much hope for relief until next week unfortunately.

[clfenwi]

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 13 2007

...SPECIAL FEATURE..

A 1011 MB SURFACE LOW PRESSURE CENTER FORMED AT 13/1500 UTC
NEAR 22N86.5W IN THE YUCATAN CHANNEL. UPPER LEVEL WINDS ARE
BECOMING MORE FAVORABLE FOR DEVELOPMENT OF THIS SYSTEM...AND
IT IS POSSIBLE THAT A TROPICAL DEPRESSION MAY FORM LATER TODAY
OR TOMORROW AS THE LOW MOVES TO THE WEST-NORTHWEST AT 10 TO
15 MPH. RESIDENTS IN THE WESTERN GULF OF MEXICO SHOULD MONITOR
THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE RECONNAISSANCE
PLANE IS SCHEDULED TO INVESTIGATE THIS SYSTEM TOMORROW IF
NECESSARY. THIS LOW CENTER FORMED ALONG A TROPICAL WAVE ALONG
86W/87W SOUTH OF 26N. ISOLATED TO WIDELY SCATTERED MODERATE
SHOWERS AND POSSIBLE THUNDERSTORMS ARE SOUTH OF 27N BETWEEN
82W AND 88W. UPPER LEVEL DIFFLUENT WIND FLOW HAS BEEN CREATED
IN THE WESTERN CARIBBEAN SEA DUE TO THE CYCLONIC FLOW AROUND
THE CENTRAL GULF OF MEXICO MIDDLE TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER...AND THE NORTHEAST-TO-SOUTHWEST ORIENTED
CARIBBEAN SEA MIDDLE TO UPPER LEVEL TROUGH. ISOLATED TO WIDELY
SCATTERED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ALSO ARE
NORTH OF 14N WEST OF 78W. THE SCATTERED MODERATE TO ISOLATED
STRONG SHOWERS AND THUNDERSTORMS SOUTH OF 12N BETWEEN 78W AND
79W ARE PROBABLY MORE RELATED TO THE MIDDLE TO UPPER LEVEL
TROUGH THAT STRETCHES FROM THE NORTHEASTERN CARIBBEAN SEA
TO THE SOUTHWESTERN CARIBBEAN SEA.

[Sanibel]

So you are ignoring the fact that it is travelling over cool SST's?

[clfenwi]

Code: Select all

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1827 UTC MON AUG 13 2007
 
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
 
DISTURBANCE INVEST (AL912007) 20070813 1800 UTC
 
        ...00 HRS...   ...12 HRS...   ...24 HRS. ..   ...36 HRS...
        070813  1800   070814  0600   070814  1800   070815  0600
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    22.1N  86.9W   22.5N  89.2W   23.3N  91.4W   23.9N  93.7W
BAMD    22.1N  86.9W   23.1N  89.2W   24.2N  91.7W   25.3N  94.1W
BAMM    22.1N  86.9W   22.9N  89.2W   24.0N  91.7W   25.0N  94.2W
LBAR    22.1N  86.9W   22.7N  89.2W   23.5N  92.2W   24.4N  95.2W
SHIP        25KTS          30KTS          36KTS          43KTS
DSHP        25KTS          30KTS          36KTS          43KTS
 
        ...48 HRS...   ...72 HRS...   ...96 HRS. ..   ..120 HRS...
        070815  1800   070816  1800   070817  1800   070818  1800
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    24.9N  96.1W   26.8N 100.1W   28.1N 103.9W   29.1N 106.7W
BAMD    26.6N  96.7W   29.5N 100.4W   31.7N 102.4W   34.0N 101.0W
BAMM    26.3N  96.9W   29.1N 100.4W   31.0N 102.8W   32.6N 102.9W
LBAR    25.7N  98.2W   28.8N 102.8W   31.6N 104.4W   32.7N 103.4W
SHIP        50KTS          60KTS          68KTS          66KTS
DSHP        50KTS          29KTS          27KTS          27KTS
 
         ...INITIAL CONDITIONS...
LATCUR =  22.1N LONCUR =  86.9W DIRCUR = 290DEG SPDCUR =  11KT
LATM12 =  21.2N LONM12 =  84.9W DIRM12 = 297DEG SPDM12 =  11KT
LATM24 =  20.1N LONM24 =  83.0W
WNDCUR =   25KT RMAXWD =   50NM WNDM12 =   25KT
CENPRS = 1008MB OUTPRS = 1011MB OUTRAD =  130NM SDEPTH =   M
RD34NE =    0NM RD34SE =    0NM RD34SW =    0NM RD34NW =   0NM

[Steve]

>>Yeah Steve. The models were quite divergent with respect to the rainfall. If this was coming up from the BOC I would say that the Upper Coast would be more susceptible to a decent soaking. Not sure about a due west track which seems to be the probability.

That special statement has it going a little WNW (didn't say at what heading), but if it follows the retrograding ULL a little to the south, it's still hard to say. Run the Goes East WV at 30 frames (link below) and speed it up a little:

http://weather.msfc.nasa.gov/GOES/goeseasthurrwv.html

Looks to me that the ULL does have a northerly component to its westward movement though it's sometimes hard to tell with upper level lows that are a little oblong as this one is.

What do you think strat?

Steve

[Stormcenter]

It looks like it's tracking WNW per visible satellite image.

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

[Steve]

>>So you are ignoring the fact that it is travelling over cool SST's?

Cool being what, low-mid 80's? It won't matter with something weak IMHO. Here's the latest (8/13 no time given) high res:

https://128.160.23.54/products/OFA/gsscofa.gif

I don't see much to hinder anything. It's not going to be an IH or anything, but there's ample water out there for this to moderately strengthen if it wants to (IMHO of course).

Steve

[sevenleft]

So you are ignoring the fact that it is travelling over cool SST's?

It is August in the GOM. It's not cool. Heat potential is lower in the shallower water but the water is not cold and is not going to inhibit development.