Possible NW Gulf Development Late This Week?

[bayoubebe]

Two of NOLA's TV METs were saying this morning there is a good possibility that SE LA and coastal MS could receive heavy rains from the system currently in the BOC later this week. Could the METs in NOLA be right or is the system in the BOC primarily heading for SC TX, SE TX, or SW LA?

TWC is only indicating a 30 to 40% chance of "Isolated Thunderstorms" at this point in our area(SE LA).

[vbhoutex]

This is what Jeff Lindner is saying about it this morning. This is more specialized towards SE TX/SW LA, but it does give an idea of the possibilities.

....
Late Week-Weekend:

Forecast models continue to show a trough/surface low developing along the TX coast. Upper pattern with SW flow aloft does favor the formation of a coastal trough. GFS tries to close the feature off into a tropical system near KBRO and move it NNE toward K LCH over the weekend. Given 25-40kts of WSW shear forecasted across the TX coastal waters this weekend I see a better chance of the coastal trough remaining just a trough and not developing into a closed low. With that said…it is possible a surface center could spin up in all the convection off the coast. Still we are far better off than one year ago as Ike was leaving Cuba and entering the SE Gulf.

The impacts will be nearly the same as extremely moist air mass with PWS forecasted upwards of 2.3-2.5 inches streams into the area. Chance for heavy to excessive rainfall will be increasing especially along and S of I-10 where most favorable pattern of lift and moisture lie. Latest run of the GFS keeps the heaviest rainfall off the coast Friday and Saturday and this may be possible depending on the position of the trough and any surface low formation.

Early Next Week:

No change in the upper air pattern as we slide toward a very wet period. Gulf of Mexico remains wide open with PWS forecasted to remain above the magical 2.0 inches. GFS tries to spin up another surface feature early next week along the W Gulf surface trough. Wind shear may be slightly lighter for this period and it is possible that something could develop.

Point being the next 4-6 days look very wet with periods of tropical rains moving inland off the Gulf. For now will discard the threat of anything tropical and maintain just modest coastal winds and a building easterly swell under a longer fetch.

While the area continues in drought conditions…the amount of moisture available, warm air column, and light steering winds all point to excessive rainfall. Would not be surprised to see some areas erase their drought over the next 5 days and a few locations near the coast could see an easy 5-10 inches of rainfall through early next week.

[Air Force Met]

Two of NOLA's TV METs were saying this morning there is a good possibility that SE LA and coastal MS could receive heavy rains from the system currently in the BOC later this week. Could the METs in NOLA be right or is the system in the BOC primarily heading for SC TX, SE TX, or SW LA?

TWC is only indicating a 30 to 40% chance of "Isolated Thunderstorms" at this point in our area(SE LA).

Please remember that TWC isn't really doing much "independent" forecasting. They are using the NWS forecast.

[srainhoutx]

12Z NAM (yes I know the NAM ) wants to form a surface low along the Lower/Middle TX Coast over the next couple of days. HGX has mentioned the interesting nature of this as well. We shall see.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[Air Force Met]

12Z NAM (yes I know the NAM ) wants to form a surface low along the Lower/Middle TX Coast over the next couple of days. HGX has mentioned the interesting nature of this as well. We shall see.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

Saw that. Just sits it there too. It also wants to put 9" of rain just offshore.

Might be a little wet around here. We need it (hopefully not flooding...).

[Portastorm]

12Z NAM (yes I know the NAM ) wants to form a surface low along the Lower/Middle TX Coast over the next couple of days. HGX has mentioned the interesting nature of this as well. We shall see.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

Saw that. Just sits it there too. It also wants to put 9" of rain just offshore.

Might be a little wet around here. We need it (hopefully not flooding...).

That would be terrible for us in south central Texas. Gulf inflow would be cut off ... we'd get little if any rain. Boooo!

Let's keep that trough open so that all of us can enjoy the ample rainfall.

[Air Force Met]

That would be terrible for us in south central Texas. Gulf inflow would be cut off ... we'd get little if any rain. Boooo!

Let's keep that trough open so that all of us can enjoy the ample rainfall.

Sounds like a conference call in our future...lol...

[srainhoutx]

That would be terrible for us in south central Texas. Gulf inflow would be cut off ... we'd get little if any rain. Boooo!

Let's keep that trough open so that all of us can enjoy the ample rainfall.

Sounds like a conference call in our future...lol...

Portastorm, I hope you folks will benefit some from this setup. Shortwaves do appear to be in play for those in Central TX. Thanks for the heads up AFM.

[Portastorm]

Not funny AFM ... not funny at all! (well, it is kinda funny).

srain, hope so buddy. Multiple short waves going west to east across us with that upper level trough pumping Gulf moisture our way would be a nice set up for a few days.

[IvanSurvivor]

On one of the "other weather forums" I noticed someone was talking about the possibility of something also developing in the central GOM as well as the western GOM. Any thoughts on that? Oh and Storm2K is the best!

[deltadog03]

GFS and nam trying to show something in the W gom pushing east. GFS tries to build a weak upper-anticyclone over the gom.

[lrak]

Hallelujah...we have rain in Corpus Christi! The tropical event has commenced IMO....WOOT.

[bayoubebe]

Two of NOLA's TV METs were saying this morning there is a good possibility that SE LA and coastal MS could receive heavy rains from the system currently in the BOC later this week. Could the METs in NOLA be right or is the system in the BOC primarily heading for SC TX, SE TX, or SW LA?

TWC is only indicating a 30 to 40% chance of "Isolated Thunderstorms" at this point in our area(SE LA).

Please remember that TWC isn't really doing much "independent" forecasting. They are using the NWS forecast.

Thanks for pointing that out AFM and for remembering some of us are not pros or any sort of weather experts.

[HURAKAN]

Latest

[Tireman4]

Thanks AFM. We do appreciate your input.

[Ptarmigan]

Hallelujah...we have rain in Corpus Christi! The tropical event has commenced IMO....WOOT.

I am glad you guys in Corpus Christi got rain. We have rain too here.

[srainhoutx]

Brownsville is now officially interested...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
144 PM CDT WED SEP 9 2009

.DISCUSSION...
DEEP MOISTURE SFC AND ALOFT REMAINS FIRMLY ENSCONCED ACROSS THE
WHOLE OF TEXAS TODAY. MIDLEVEL LOW ROUGHLY CENTERED JUST NORTH OF
SAN ANGELO CONTINUES TO PROVIDE MIDLEVEL INSTABILITY. INITIAL
SHOWER ACTIVITY TODAY HAS BEEN TRIGGERED BY STREAMER SHOWERS
MOVING IN FROM THE SOUTHWEST...BUT IS NOW BECOMING MORE OUTFLOW
ORIENTED AS ACTIVITY BECOMES MORE WIDESPREAD. CONTINUED WITH
LIKELY CHANCES TODAY...FALLING TO SLIGHT CHANCE OVERNIGHT MAINLY
ALONG THE COAST DUE TO LOSS OF DAYTIME HEATING. ANOTHER ROUND OF
SHOWER AND THUNDERSTORM ACTIVITY WILL COMMENCE AGAIN TOMORROW
MORNING WITH LITTLE CHANGE TO ATMOSPHERIC CONDITIONS FROM TODAY.

FRIDAY THINGS GET MORE MURKY. MODELS ARE ALL SIMILAR IN BRINGING A
FRONTAL BOUNDARY INTO THE FAR NORTHWEST GULF BY FRIDAY MORNING.
WHAT THE MODELS ARE DISSIMILAR ON IS SFC LOW PRESSURE DEVELOPING
ON THAT LOW DURING THE DAY FRIDAY. ALL MODELS DO INDICATE A CLOSED
SFC LOW WRAPPING UP...BUT ARE DIFFERING ON WHERE THIS
HAPPENS...FROM AS FAR WEST AS COTULLA TO AS FAR EAST AS 100 MILES
EAST OF CRP OVER THE NW GULF. NEEDLESS TO SAY...THE MODELS OVER
WATER ARE TAPPING THE WARM GULF WATERS AND WRAPPING THIS INTO A
SEMI-TROPICAL SYSTEM EJECTING BACK TO THE NORTH OVER THE WEEKEND.
ANY OF THESE SCENARIOS WILL STILL BRING CONTINUED RAINFALL ACROSS
THE REGION THROUGH THE WEEKEND...AND LIKELY INTO NEXT WEEK. THE
BEST TIME FOR WIDESPREAD RAIN WILL BE FRIDAY AS THE LOW DEEPENS TO
THE NORTH. WILL KEEP A SHARP EYE ON THIS FEATURE FOR MODEL
AGREEMENT.

[N2FSU]

From the Tallahassee NWS discussion:

THROUGH THE FIRST 48 HOURS...IT LOOKS LIKE THE NAM MIGHT HAVE A GOOD
HANDLE ON OUR LOCAL WEATHER...IF NOT THE OVERALL EVOLUTION OF THE
SYSTEM IN THE GULF OF MEXICO. THEREAFTER...A BLEND BETWEEN THE
GFS...EURO AND SREF WAS USED. THE NAM SOLUTION JUST DOESN`T LOOK
RIGHT WITH TWO SURFACE LOWS IN THE GULF...AND THE EASTERN ONE
ATTEMPTING TO FUJIWHARA AROUND THE WESTERN ONE. WHILE THE UPPER
LEVEL PATTERN WOULD BE SOMEWHAT SUPPORTIVE OF THAT SOLUTION...THE
OVERALL TREND IN THE GUIDANCE HAS BEEN FOR A WEAKER EASTERN SIDE TO
THE SYSTEM AND A STRONGER WESTERN SIDE...AND THAT IS GENERALLY
REFLECTED IN THE GFS AND EURO SOLUTIONS.


.LONG TERM (SATURDAY THROUGH WEDNESDAY)...A VERY COMPLEX AND
DIFFICULT FCST IS SETTING UP FOR THE EXTENDED PERIOD...AND
UNFORTUNATELY...AFTER A COUPLE OF DAYS OF FAIRLY CONSISTENT LONG
RANGE MODEL OUTPUT...BOTH THE GFS AND ECMWF ARE BEGINNING TO KEY ON
SOME POTENTIALLY SIGNIFICANT CHANGES TO THE UPPER LEVEL SYNOPTIC
PATTERN ACROSS THE SE U.S.. DURING THE THE PAST 2 DAYS...THE MODELS
WERE INDICATING THAT THE SUBTROPICAL RIDGE (WHICH IS NOW STILL FAR
TO THE EAST OF THE BAHAMAS) WOULD NOT BE MUCH OF A FACTOR...BUT NOW
THE MODELS ARE INDICATING THAT IT MAY ATTEMPT TO BUILD RAPIDLY
WESTWARD...POSSIBLY REACHING THE SE GULF OF MEXICO SOMETIME OVER THE
WEEKEND. IF THIS RIDGE WERE NOT TO BE A MUCH OF A FACTOR...IT HAD
APPEARED THAT THE FLOODGATES OF THE GULF OF MEXICO WOULD BE WIDE
OPEN ACROSS THE CWA FOR SEVERAL DAYS AS A NEW UPPER LOW DROPPED SE
OUT OF CANADA INTO THE GREAT PLAINS...WHICH WOULD ALLOW AMPLE GULF
MOISTURE TO POUR INTO THE REGION WITH STRENGTHENING MID-UPPER LEVEL
SW FLOW...POSSIBLY LEADING TO A NEAR WASHOUT OVER THE WEEKEND AND A
DECENT CHANCE FOR A SIGNIFICANT RAINFALL EVENT OVER THE CWA. NOW...
MUCH OF THE FCST WILL BE DEPENDANT ON THE NW EXTENT OF THE
SUBTROPICAL RIDGE AND IF IT WILL BE ABLE OR STRONG ENOUGH TO PUSH
BACK SOME OF THIS DEEP LAYER MOISTURE BACK OFF TO OUR NORTH AND
WEST. THE EARLIER 12 UTC RUN OF THE ECMWF IS CLEARLY THE WETTER OF
THE 2 SOLUTIONS...BUT WILL BE VERY INTERESTED TO SEE THE IF THE NEW
00 UTC RUN OF THE EURO TRENDS FURTHER TOWARDS THE GFS. IN ANY
EVENT...POPS SHOULD STILL BE ABOVE CLIMO THROUGHOUT MUCH OF THE
PERIOD...WITH THE TROF AXIS EXPECTED TO SWING THROUGH WITH DRIER AIR
BY NEXT WEDNESDAY. THEREFORE...POPS...TEMPS...AND QPF WILL BE VERY
TOUGH CALLS FOR THIS FCST PACKAGE...AND AM CLEARLY NOT AS CONFIDENT
IN RAISING POPS TOO HIGH FOR THIS PERIOD AS WE WERE BEGINNING TO
THINK OF DOING LAST NIGHT.

[southerngale]

NWS Houston's take on the situation...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
258 PM CDT WED SEP 9 2009

.DISCUSSION...
VERY MOIST ATMOS IN PLACE ACROSS THE REGION...WITH VALUES RANGING
FROM AROUND 2" WELL INLAND TO 2.4" ALONG THE COAST ACCORDING TO GPS
MET PLOT. THIS DEEP MOISTURE SHOULD REMAIN IN PLACE THRU AT LEAST
SAT (ASSUMING NAM12 SOLN DOESN`T VERIFY - MORE ON THAT LATER).
COASTAL TROF...WHICH SHOULD BECOME BETTER PRONOUNCED CLOSER TO THE
IMMEDIATE COAST WITH TIME...WILL CONTINUE TO BE A FOCUS FOR
SHRA/TSTM DEVELOPMENT THRU AT LEAST SAT. GENERAL TREND HAS BEEN FOR
PRECIP TO TAPER OFF INLAND TOWARD MID EVENING WITH ADDITIONAL
NIGHTTIME DEVELOPMENT OFFSHORE EVENTUALLY SPREADING INLAND IN THE
MORNING AND AFTERNOON HOURS. NOT TO SAY THIS WILL BE THE CASE EVERY
DAY AS A NUMBER OF FACTORS COULD AFFECT TIMING, ETC. BUT FOR THE
MOST PART...EXPECT PERIODS OF RAIN FOR THE NEXT 72 HOURS OR
SO...WITH LOCATIONS CLOSER TO THE COAST SEEING THE HIGHER
ACCUMULATIONS ALONG WITH LOCALLY HEAVY RAINS AT TIMES ESP FRI/SAT.

REGARDING THE NAM12 SOLN...THE LAST SEVERAL RUNS HAVE SHOWN A SFC
LOW DEVELOPING AND DEEPENING OUT NEAR BUOY 42002 BEGINNING TOMORROW
AFTN/EVNG. IT`S NOT TOTALLY OUT OF THE RANGE OF POSSIBILITY CONSIDERING
ALL THE MODELS ARE SHOWING A TEMPORARY WEAKENING OF THE SHEAR ALOFT
AT THAT TIME OFF THE TX COAST. BUT THEY ALSO INCREASE IT AGAIN
EARLY FRI. MAJORITY OF THE MODELS DO SHOW VARIOUS CIRCULATIONS
BETWEEN NOW AND THE WEEKEND...MOST OF WHICH ARE USUALLY SPURIOUS
OR SHORT LIVED CONVECTIVELY INDUCED IN SUCH A PATTERN WE ARE
UNDER. THAT BEING SAID THIS IS TYPICALLY THE PEAK WEEK OF
HURRICANE SEASON SO WILL NEVER RULE ANYTHING COMPLETELY OUT...BUT
HAVE A FEELING THE NAM12 IS OVER DEVELOPING THAT FEATURE BUT HAVE
SEEN WEIRDER THINGS OCCUR. WILL JUST HAVE TO WATCH. IF FOR SOME REASON
SOMETHING DOES DEVELOP...WE`LL PROBABLY NEED TO PARE POPS DOWN IN
THE SHORT TERM AS MOST PRECIP WILL BECOME FOCUSED OFFSHORE.

ECMWF/GFS KEEPS UPPER TROFFINESS IN PLACE (WITH ECMWF DEEPER AND
FURTHER W) THRU THE 2ND HALF OF THE FCST PERIOD BUT BEST MOISTURE
SHOULD HAVE SHIFTED OFF TO THE EAST. WILL MAINTAIN THE 20-30% POPS
IN PLACE MON-WED. 47

[cycloneye]

NWS Corpus Christi discussion of situation.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
321 PM CDT WED SEP 9 2009

.LONG TERM (FRIDAY THROUGH WEDNESDAY)...SOME MUCH NEEDED DROUGHT
RELIEF WL PERSIST EARLY IN THE FCST PD. HOWEVER...GIVEN THAT
RAINFALL DEFICITS STILL AVERAGE MORE THAN 16 INCHES IN MANY
LOCATIONS...THIS RAINFALL WL NOT EVEN BE CLOSE TO ENDING THE LONG
TERM DROUGHT THAT HAS PLAGUED SOUTH TX FOR MORE THAN A YEAR. THE
VERY ACTIVE WX PATTERN WL CONTINUE ON FRI AS THE MEAN MID/UPR TROUGH
AXIS REMAINS ACROSS THE CWA WITH A LOW LVL TROUGH AXIS ANCHORED
ACROSS THE ERN ONE-THIRD OF THE CWA. AN UNCAPPED AND VERY MOIST
AIRMASS (PWS 2-2.3 INCHES) AIDED BY THE PREVIOUSLY MENTIONED
SYNOPTIC FEATURES...SUFFICIENT BOUNDARY LAYER HEATING AND
OUTFLOWS/SEABREEZE INTERACTION WL BE THE FUEL THAT WL AID IN THE
DEVELOPMENT OF WIDESPREAD CONVECTIVE ACTIVITY ON FRI. HEAVY RAIN
AND LOCALIZED FLOODING WL REMAIN A CONCERN FOR FRI...ESPECIALLY THE
ERN AREAS. BY SAT...THE WET PATTERN WL BEGIN TO BREAK DOWN. THE
MID/UPR TROUGH AXIS WL HAVE SHIFTED TO THE EAST OF THE CWA WHILE THE
SFC TROUGH AXIS AND ATTENDANT WK SFC LOW WL HAVE SHIFTED INTO THE
OFFSHORE WATERS BY SAT EVE. NO TROPICAL CYCLONE DEVELOPMENT IS
EXPECTED GIVEN THE CONSENSUS MODEL SOLNS AND AMOUNT OF WESTERLY
SHEAR PRESENT. THE OUTLIER NAM SOLN OF DEVELOPING A TROPICAL
CYCLONE IN THE NORTHWEST GULF ALONG THE SFC TROUGH AXIS WL BE
DISCARDED GIVEN ITS VERY POOR PERFORMANCE IN GENERAL AND ALSO DURING
TROPICAL SITUATIONS. THE NET EFFECT FROM THIS EWD SHIFT OF BOTH THE
UPR AND SFC TROUGH AXIS WL BE TO DIMINISH THE OVERALL PCPN COVERAGE
AS THE BEST SLUG OF MOISTURE AND LIFT ADVECTS TWDS SE TX AND
LOUISIANA. DRIER AND MORE SUBSIDENT AIR WL IMPACT THE CWA BEGINNING
ON SAT...ESPECIALLY ACROSS THE WRN AND CENTRAL AREAS. THIS GRADUAL
DRYING TREND WL THEN CONTINUE THROUGH NEXT WEEK AS DRIER AND MORE
STABLE AIR CONTINUES TO ADVECT INTO THE CWA FROM THE NORTH AND
WEST. AS A RESULT...WL KEEP THE HIGHEST POPS ON FRI AND THEN
GRADUALLY LOWER POPS THEREAFTER. TEMPS WL INITIALLY REMAIN BELOW
NORMAL GIVEN THE THICK CLOUDS AND WIDESPREAD PCPN. THEREAFTER...A
SLOW WARMUP IS EXPECTED BUT IT WL BE TEMPERED SOMEWHAT BY THE WET
SOILS.

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