Extratropical Depression Lee: Inland N Gulf States

[srainhoutx]

HPC Model Diagnostics Update through the 12Z Euro:

...CENTRAL GULF OF MEXICO DISTURBANCE...
PREFERENCE: 12Z ECMWF/12Z GFS

THE NAM IS ON THE NORTHERN SIDE OF THE SPREAD WITH THIS SYSTEM.
THE UKMET AND THE NAM ARE BOTH STRONG WITH MID-LEVEL ENERGY MOVING
INTO THE GULF BUT THE 00Z UKMET KEEPS THE CENTER OF THE
DISTURBANCE SOUTH AND WEST OF THE 12Z NAM. BOTH THE 06Z GFS AND
00Z ECMWF ARE SLOW TO DEVELOP THIS DISTURBANCE AT THE UPPER
LEVELS...WITH THE FIRST DISCERNIBLE INDICATION OF THE DISTURBANCE
NOT POPPING UP UNTIL THE DAY 3 TIME PERIOD. AT THE SURFACE WEAK
LOW PRESSURE IS INDICATED BY THE GFS AND ECMWF...STAYING WELL TO
THE SOUTH AND MUCH WEAKER THAN THE NAM/UKMET. THE 12Z NAM SHOWS A
VERY DEEP AND STRONG SOLUTION ON DAY 3...MAKING ITS SOLUTION AN
OUTLIER AMONGST OTHER OPERATIONAL AND ENSEMBLE SOLUTIONS. THE 12Z
GFS HAS TRENDED NORTHWARD TOWARDS THE NORTHERN SOLUTIONS BUT IS
STILL FURTHER SOUTH THAN THE NAM AND MUCH WEAKER. THE 12Z UKMET
HAS WEAKENED THE SURFACE LOW AND HAS SHIFTED FURTHER SOUTH...MORE
IN LINE WITH THE 00Z ECMWF. IT IS STILL ONE OF THE WESTERN MOST
OPERATIONAL SOLUTIONS. THE 12Z ECMWF IS COMPARABLE TO ITS 00Z
RUN...PERHAPS SLIGHTLY WEAKER DEPTH WISE BUT THE LOW CENTER IS
STILL IN A SIMILAR LOCATION.

[srainhoutx]

A repost that I made in the Labor Day Weekend weather thread on the main page. Updated HPC extended surface charts are out: (note the stalling frontal boundary depicted to the N of our area)...

[Rip76]

Just off the coast far enough to spare us from rainfall?

[Met Tech]

In the 12Z GFS, the storm looks like it is trapped in a padded room being chased around by rabid squirrels.

It'll be a slap in the face if that front comes in strong enough to blast everything to the south before it does any good.

[am19psu]

Gah. How did this storm go from a quick spin up to a monsoon depression. What a mess. Hopefully y'all can get some better rains than currently modeled out of this.

[djjordan]

I don't think anyone is really taking into account the enormous amount of moisture that will stream in if that "weak" low actually does verify and meander around down there. The moisture combined with the front from the north will squeeze out some heavy downpours along the Texas Gulf Coast. Just my two cents.

[Met Tech]

I don't think anyone is really taking into account the enormous amount of moisture that will stream in if that "weak" low actually does verify and meander around down there. The moisture combined with the front from the north will squeeze out some heavy downpours along the Texas Gulf Coast. Just my two cents.

True enough. My hometown is between San Antonio and Del Rio, where it looks like Mars right now. I'm hoping to have some frontal lift/tropical moisture combination go to work out there, but it's not looking too promising (from this far out anyway).

[srainhoutx]

I'm already seeing some ramp up in discussions from New Orleans to Brownsville. Coastal effects are most noteable right now and the HPC is ramping up as well. Should make for an interesting long Holiday Weekend and early next week regardless...

OVER THE WRN GULF OF MEXICO... THERE IS CURRENTLY NO FEATURE FOR
WHICH THE NHC TROPICAL WEATHER OUTLOOK INDICATES CONCERN FOR
POTENTIAL DEVELOPMENT DURING THE NEXT TWO DAYS. HOWEVER BY THE
MEDIUM RANGE PERIOD THE AVERAGE OF ALL GUIDANCE OVER THE PAST 24
HRS HAS TRENDED STRONGER WITH A MID LVL WEAKNESS/POSSIBLE CLOSED
LOW AND ASSOC SFC LOW OVER THE WRN OR NRN GULF. THE 00Z AND YDAYS
12Z ECMWF RUNS WERE ON THE AGGRESSIVE SIDE OF THE ENVELOPE WITH
ITS DEVELOPMENT BUT THE NEW 12Z RUN IS MUCH WEAKER/MORE
SUPPRESSED. THE 06Z/12Z GFS ARE ON THE NERN SIDE OF THE ENVELOPE.
THE FINAL FCST INCORPORATES THE 17Z NHC/HPC COORDINATION FOR
TRACK/STRENGTH WITH AN INTERMEDIATE SOLN RECOMMENDED FOR BOTH
PARAMETERS.



THE FOCUS FOR HEAVIEST RNFL DURING THE PERIOD WILL LIKELY BE ALONG
THE GULF COAST IN ASSOC WITH THE BROAD AREA OF LOW PRESSURE FCST
TO EVOLVE OVER THE WRN HALF OF THE GULF OF MEXICO. CONFIDENCE IN
WHERE THE GREATEST IMPACT WILL BE IS FAIRLY LOW DUE TO THE CURRENT
SPREAD AMONG MODEL/ENSEMBLE SOLNS. MEANWHILE A SERIES OF FRONTS
WILL PROGRESS ACROSS THE CNTRL-ERN STATES... ACCOMPANIED BY
SHWRS/TSTMS OF VARYING INTENSITY.

[jeff]

something is likely to develop in the Friday-Sunday period. Where is goes and how strong is up for much debate. HPC progs are really pushing the heavy rainfall well east of the coordinated NHC/HPC points. I think they may be too far east/north. Watch out for a coastal flooding event with a slow moving/stalled system for several days leading to a gradual increase in tides and seas over several tide cycles (TS Frances 98). Leaving anything over the NW Gulf this time of year is cause for at least some concern.

[Ptarmigan]

If this storm was like Frances of 1998, it would be a huge rainmaker and large storm. As for where it goes, too early to tell until it develops.

[tireman4]

Patience my dear Ed, patience.....

[ticka1]

Ed can be on the side for the half empty glass of optimism
while others like me will be on the other side of glass half full with optimism

WE JUST NEED RAIN.

[skidog38]

Allison is back

[Ptarmigan]

The computer models all agree something will develop. They don't agree on where it will go is the issue. When you average them out, it puts it around Southeast Texas.

[srainhoutx]

00Z recap: GFS has TCG (tropical cyclone genesis) further E near New Orleans which is picked up by a diving East Coast Trough and swept NE along a colf front. The Canadian, on the other hand dvelops a cyclone, albeit weak, near SW LA and keeps it hugging the Coast moving WSW into the Middle TX Coast over a 3 day period. We'll see what the Euro and UKMET offer tonight in the model world 'wheel of fortune'...

[Andrew]

00Z recap: GFS has TCG (tropical cyclone genesis) further E near New Orleans which is picked up by a diving East Coast Trough and swept NE along a colf front. The Canadian, on the other hand dvelops a cyclone, albeit weak, near SW LA and keeps it hugging the Coast moving WSW into the Middle TX Coast over a 3 day period. We'll see what the Euro and UKMET offer tonight in the model world 'wheel of fortune'...

Canadian shows a scary run as you have an intensifying storm running up the Middle to uppper Texas coast. On the other hand though the canadian is known for "over doing" the intensity of storms. Tonight should be a LARGE lesson for many. When you don't have an established system or low the models will be all over the place. The GFS shows a possible east coast event while the canadian shows a Texas event. Where this develops, how fast it develops, and how strong it develops will tell us where it goes. The euro is coming up next. Lets see what is shows.

[Andrew]

Euro is looking real good:

http://raleighwx.americanwx.com/models/ ... _loop.html

[djjordan]

Even though we don't even have an invest yet, I'm tending to lean with the Euro more than any other models as it seems to have the right idea in slowly developing this system in the WGOM over the weekend into labor day. WIth all that moisture and a very slow moving system .... this could equal alot of rain for our parched selves. Still need to be on guard this weekend though.

[Andrew]

Euro goes pretty crazy by letting it sit out there.

[djjordan]

Yep it does but if it sits out there as a weaker system, IMO that gives us a much better shot at sustainable rain for our drought stricken selves. That coupled with some weak steering currents, not a 0 Shear environment, I would think that would inhibit rapid intensification which if it is far enough south would turn our faucet off.