Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 4

[Srain]

Morning e-mail from Jeff:

Wet period expected for the region today-Sunday

Gulf moisture is making a return to the region with overnight dewpoints rising into the 60’s and 70’s and scattered showers developing on radar south of I-10 this morning. This increase in moisture is in response to the washing out of the frontal boundary offshore and low pressure developing over the central plains encouraging southerly winds to bring the deep tropical moisture over the western Gulf northward. Feel the wetter guidance is on the right track for today given the amount of development noted on the radar at this time. Most favorable are for showers/thunderstorms will be along the coast where moisture values are greatest this morning and then spreading inland today as the seabreeze and moisture surge northward.

Expect scattered rains today and Thursday with better coverage and chances on Friday and Saturday as a weak diffuse frontal boundary sags into the area and stalls near the coast/just offshore. More organized thunderstorms will be possible during this period as the front provides lift along with the slow progression of an upper level low over the SW US. Front should limp off the coast before stalling while the main upper level trough/low remains west of the area into the weekend. This will produce an overrunning pattern and additionally force surface low pressure to form along the frontal boundary. Could see a break in the more organized rainfall Saturday afternoon, before the coastal low moves NE up the frontal slope providing another good shot at rainfall Saturday evening/night. Best rain chances over the weekend may focus closer to the coast or even offshore depending on where the frontal boundary pulls up stationary.

With PWS forecast to reach 2.0 inches heavy rainfall will be likely. Fast storm motions today and Thursday along with very dry grounds should mitigate any flooding threat. Friday-Saturday more widespread and organized heavy rainfall could present some problems in the urban areas, but forecasted QPF totals remain below the thresholds that would cause widespread problems. Widespread amounts of 1-2 inches with isolated totals of 3-4 inches appear possible from today-Sunday. Best chances of rainfall and highest QPF should be south of I-10.

Fire Weather:

KBDI values a starting to reach critical levels across the region as vegetation had dried under weeks of hot weather and lack of rainfall…especially north of I-10. 500 acre wildfire in Walker/Houston County yesterday suggest the fire potential is high in those areas mainly north of HWY 105. Luckily, RH will be much higher today and winds weaker and this should preclude any rapid fire growth. Wetting rains appear likely over the next several days and this should greatly reduce the wildfire threat.

[Ed Lizard]

I'm not watching the tropics anymore as a source of sensible weather - except for nice low to mid level moisture return, with an HGX SWS for tropical funnels possible mainly South of I-10 with any stronger showers or storms.

LCH sounidng rather dry above 600 mb w/ WSW to W winds above, but almost saturated below, with convective temps in the mid 80s. West winds aloft aren't going away anytime soon per GFS, but again, who needs the tropics (well, other than as a source of low/mid level moisture).

[Srain]

A very complex and complicated forecast is unfolding across the Southern half of the Lone Star State for the next 4-6 days. A frontal boundary will push S and stall while an upper trough meanders over New Mexico to our W and lingers. Add to the mix TS Kristy along the offshore Pacific Waters of Mexico and you have a recipe for a potential heavy rainfall event over Texas.

Showers and storms will increase in aerial coverage today as deep tropical moisture surges inland from the Gulf. PW's of 2.0+ will sweep inland as the frontal boundary sags S and stalls. The upper level support then collapses and brings S Cetral/SE TX into a very favorable region for a heavy rainfall potential. Several waves of low pressure look to develop along the Coastal Waters of the Gulf and move slowly ENE over the weekend. The fly in the ointment will be the meandering upper trough to our W. The overnight Euro and the 06Z GFS now suggest this feature will be with us until another cold front and mid latitude trough drops S from Canada late next Tuesday or Wednesday. Kristy moisture from the EPAC continues to be entrained over NE Mexico and Texas throughout the period to further complicate things. I wouldn’t be too surprised to see 3-5 inches of rainfall throughout this wet pattern with some isolated 6-8+ amounts possible.

[Srain]

Morning e-mail from Jeff:

Showers and thunderstorms already ongoing this morning over the region.

Moisture has increased over the past 24 hours leading to scattered showers and thunderstorms moving northward off the western Gulf of Mexico. Storms have been prodigious lightening producers which is somewhat unusual given the very tropical air mass in place. Little change is expected for the next 24 hours as moisture continues to stream northward and showers/thunderstorms will become most numerous with a little bit of morning heating and then weaken toward the late afternoon hours only to re-develop again early Friday morning.

On Friday, the frontal boundary over NW TX currently will move slowly southward and into our region toward the afternoon hours. This boundary will interact with the abundant tropical moisture in place and weak upper air disturbances associated with a deep layer trough over the SW US to produce a good chance of widespread showers/thunderstorms. Unlike the current scattered activity, the period from Friday afternoon-Saturday will feature more organized storms with greater potential for sustained heavy rainfall.

Forecast for the weekend is difficult as competing weather factors will be in place. The slow moving front looks to cross into the near shore Gulf waters at some point late Saturday into Sunday morning and expect this to act as the main focus for rainfall on Saturday. NAM attempts to bring in drier air from the east this weekend shutting down rain chances, but with the main upper trough axis still west of the area and the GFS showing more moisture hanging in behind the front think the wetter solutions is what will likely pan out. Feel the GFS is heading in the right direction keeping high rain chances on Saturday and only slowly lowering chances into early next week. Models really diverge by early next week with some indicating ridging building into the area and others keeping the trough located across the region.

Rainfall amounts of the next 2-3 days will average 1-3 inches with isolated totals of 4-5 inches possible. This tropical air mass is very capable of producing some very heavy short term rainfall rates of 1-2 inches in an hour or less. While grounds are generally dry, multiple rounds of rainfall along with the potential for more organized rains on Friday/Saturday do raise some red flags especially with PWS at or above 2 inches.

[Srain]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 09/13/12 1543Z

SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404

LATEST DATA USED: GOES-13 1515Z JBN

.

LOCATION...TEXAS...

.

ATTN WFOS...LCH...HGX...FWD...CRP...EWX...

ATTN RFCS...WGRFC...

.

EVENT...DEVELOPING CONVECTION OVER SERN TX/NWRN GULF OF MEXICO

.

SATELLITE ANALYSIS AND TRENDS...LATEST GOES IR/VIS IMAGERY SHOWS A GROWING

CLUSTER OF CONVECTION OVER THE NWRN GULF OF MEXICO/SERN TX. CONVECTION

APPEARS TO BE MIGRATING NWWD WITHIN CORRIDOR OF DEEPER MOISTURE VALUES

NOSING NWWD INTO CNTRL TX. WITH ADDITIONAL DAYTIME HEATING TAKING PLACE

AND SOME WEAK UL DIVERGENCE IN PLACE, WOULD EXPECT CONVECTION TO CONTINUE

TO DEVELOP AND PERHAPS FORM EITHER SOME MORE ORGANIZED BANDS THAT COULD

TRAIN OR A LARGER CLUSTER THAT WORKS NWWD FROM THE COAST. MANUAL SATELLITE

ESTIMATE TECHNIQUES SUGGEST RAIN RATES OF 1-1.5"/30 MIN MAY BE OCCURRING

WITH THE CONVECTION. COULD SEE 1-3" AMTS OF RAIN THE NEXT FEW HRS WHERE

CONVECTION PERSISTS THE LONGEST/CAN TRAIN OVER SERN TX.

.

SHORT TERM OUTLOOK VALID 1545Z-1945Z...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...MAY SEE A FEW MORE ORGANIZED NW TO SE ORIENTED BANDS

TAKE SHAPE ACROSS SE TX THE ENXT FEW HRS THAT SHOULD WORK NWWD ACROSS

THE DISCUSSION AREA. THIS COULD LEAD TO SOME TRAINING/ISOLATED HIGHER

RAIN FALL AMTS THE NEXT COUPLE OF HRS MAY PRODUCE SOME MAINLY POOR

DRAINAGE/URBAN TYPE FLOODING PROBLEMS ACROSS THE DISCUSSION AREA. GREATER

THREAT FOR SOME FLOODING WOULD OCCUR IF BANDS CONTINUE TO ORGANIZE AND

EXTEND INTO GULF OF MEXICO AND FEED NWWD FOR SEVERAL HRS. COULD SEE

A SLIGHT CHANCE OF THIS HAPPENING IN A FEW SPOTS AS IT LOOKS LIKE THE

CONVERGENCE ZONE INITIALLY RESPONSIBLE FOR THE CONVECTION EXTENDS PRETTY

FAR SEWD INTO THE GULF IN VIS IMAGERY. THIS ZONE REMAINS PRETTY ACTIVE

WITH CONVECTION STILL DEVELOPING OVER THE WATER IN ATTM.

.

[DoctorMu]

Holy *****...is that radar real?

[Ed Lizard]

Holy *****...is that radar real?

My lawn rejoices, and the thunder is loud at the Galleria.

[Srain]

From Nesdis...

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 09/13/12 2217Z

SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404

LATEST DATA USED: GOES:2202Z JS

.

LOCATION...W LOUISIANA/S CENT AND E TEXAS...

.

ATTN WFOS...LCH...SHV...HGX...FWD...CRP...EWX...SJT...MAF...

ATTN RFCS...LMRFC...WGRFC...

.

EVENT...CURRENTLY WATCHING AREA OF S CENT AND SW TX FROM N OF SAN ANTONIO

TO THE RIO GRANDE AND AREA OF E TX FOR LOCALIZED HEAVY RAINFALL.

.

SATELLITE ANALYSIS AND TRENDS...THE MERGER BETWEEN THE SFC FRONT/OUTFLOW

MOVING TO THE SE AND THE CELLS/OUTFLOW SPREADING NORTHWARD FROM THE

GULF HAS OCCURRED FOR A LARGE PORTION OF CENT TX RESULTING IN LOCALIZED

INTENSE RAINFALL RATES FOR A RELATIVELY SHORT PERIOD OF TIME. MUCH OF

THE ACTIVITY OVER CENT TX HAS BEGUN TO SLOWLY DIMINISH LEAVING BEHIND A

SHIELD OF MOSTLY MODERATE RAIN. HOWEVER, THERE ARE STILL SOME ADDITIONAL

CELL/OUTFLOW INTERACTIONS UPCOMING FOR S CENT TO SW TX AND FOR E TX

SPREADING INTO W LA DURING THE NEXT COUPLE OF HOURS. CURRENTLY WATCHING

ACTIVITY CONVERGING FROM MULTIPLE DIRECTIONS ON THE AREA STRETCHING

FROM JUST N OF SAN ANTONIO TO NEAR DEL RIO TX. HAVE ALREADY SEEN

SOME SIGNIFICANT CELL MERGERS AND OVERSHOOTING TOPS WITH SOME OF THE

ACTIVITY IN THIS REGION WHICH HAS YIELDED SATELLITE ESTIMATED RATES TO

NEAR 3"/HR. LOCALIZED ESTIMATED TOTALS OF AT LEAST 2-3" HAVE ALSO LIKELY

OCCURRED ESPECIALLY IN THE REGION FROM WILLIAMSON TO KENDALL COUNTIES

PER AUTOMATED SATELLITE ESTIMATES. FARTHER TO THE NE, THE OTHER LOCATION

FOR MERGING CELLS/OUTFLOW IS AFFECTING E TX WITH SIMILAR ESTIMATED RATES

BRIEFLY TO NEAR 3"/HR AND 2-3" TOTALS PARTICULARLY FROM VAN ZANDT TO

HARRISON/PANOLA COUNTIES.

.

AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION THREAT AREA

SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED BELOW IN APPROXIMATELY

10-15 MINUTES.

.

SHORT TERM OUTLOOK VALID 2215-0115Z...MEDIUM TO HIGH CONFIDENCE FACTOR

IN SHORT

TERM OUTLOOK...FOR S CENT/SW TX...LATEST OBJECTIVELY DERIVED SFC MOISTURE

CONVERGENCE SHOWS MAX LOCATED BETWEEN SAN ANTONIO AND DEL RIO WHICH

IS WHERE THE CELLS/BOUNDARIES ARE SET TO INTERSECT OVER THE NEXT HOUR

OR SO. BELIEVE THE MOST INTENSE ACTIVITY WILL CONTINUE TO SHIFT SLOWLY

TO THE S AND SW DURING THE NEXT SEVERAL HOURS. FOR E TX/W LA...ADDITIONAL

CELL/OUTFLOW INTERACTIONS ARE ALSO LIKELY IN THIS AREA. SOME ERRATIC

CELL MOVEMENT MAY OCCUR FOR A TIME AS THESE INTERACTION OCCUR OVER E TX,

BUT AN OVERALL GRADUAL EASTWARD SHIFT FOR THE STRONGER/NEWER CELLS INTO

W LA SHOULD OCCUR OVER THE NEXT SEVERAL HOURS. THIS IS WHERE BETTER SE

LOW LEVEL INFLOW IS ORIGINATING AND IT IS ALSO A REGION WHICH HASN'T

BEEN WORKED OVER AS OF YET.

[Quixotic1]

We were supposed to get 1" - 3". We got nada. It was probably the worst radar loop I've ever seen. Nothing but a solid mass of rain out west of here and then nothing. 2 hours later, another solid mass out east develops.

[Srain]

The slow moving frontal boundary remains to our N and W from near San Antonio to The Ft Worth area with a weakening MCS to our W near San Antonio/Austin area moving ENE along the boundary. PW's have increased to the 2.2 range across SE Texas and shower/storms are moving inland while rains to the W shift slowly E. Daytime heating and increased Gulf moisture heading inland should produce heavy rainfall W of I-45 this afternoon and tonight as the boundary sags S into our area and stalls. Areas along the 290 corridor in NW Harris County received 3+ inches yesterday from a training storm complex and we may we see a repeat of that today with storm totals in the 2-4 inch range with isolated higher amounts nearing 5-6 inches.

The upper air disturbance is further W just entering New Mexico and should continue to provide high precip chances on Saturday. A Coastal low may develop and ride the stalled boundary during late Saturday into Sunday as the upper air disturbance slowly heads E across TX. Some guidance ( the Euro ) deepen the 500mb low and drop it SE into Central/SE TX on Sunday and slowly shift it E into Louisiana on Monday. Dry air may push into the area Monday, but another short wave and Pacific front heads SE Tuesday that may bring additional showers before we finally dry out later next week.

[Srain]

Morning e-mail from Jeff:

Slow moving cool front currently depicted in the surface observations along a line from NW LA to just north of College Station to south of San Antonio this morning. Meso low noted in radar images over C TX moving ENE at the present time while showers and thunderstorms are spreading northward into the coastal plains from the NW Gulf of Mexico. Moisture has increased over the region compared to yesterday with PWS in the 1.9-2.2 inch range and soundings nearly saturated. Water vapor images reveal mid and high level moisture tap spreading NE from TS Kristy in the EPAC off the western coast of Mexico. Storms yesterday were once again prodigious lightning producers and also produced some very heavy rainfall. Several locations picked up 1 inch of rainfall in 15 minutes or less and a few locations totaled nearly 4 inches. This proves this air mass is capable of some excessive rainfall in a short period of time especially if storm motions slow.

Set up over the area is starting to resemble some similarities to past fall flooding events with a stalling surface front, deep tropical Gulf moisture, upper trough slowly moving in from the west, and the EPAC tropical system tap. Thus far rains have remained fairly scattered, but with the frontal boundary entering the region today expect more organized rainfall. Additionally storm motions will be slowing as steering currents weaken. Frontal boundary should progress very slowly toward the coast tonight into Saturday and may limp offshore. Moisture levels will remain high as the upper trough remains west of the area. This trough begins to move eastward Saturday night/Sunday with increasing jet stream dynamics aloft. Still some timing differences in the models on when the main trough moves across the state and provides good lift and good chance of rainfall…currently looking like Sunday into Sunday night. Some sort of coastal low looks to develop along the boundary over the Gulf waters and this will help to spread rainfall along the coast and inland ahead of the upper trough.

Should start to clear and dry things out on Monday, but a secondary trough drops into the region by Tuesday with a potentially decent frontal passage. Not overly confident on the timing and moisture may linger into Monday producing scattered showers/thunderstorms.

Rainfall:

Some areas really were nailed yesterday with excessive rainfall, but most of these locations were localized and thus far widespread heavy rainfall has not occurred in our region. With that said, the current air mass is capable for some quick 2-3 inches in an hour or less and with the potential for storm motions to slow and become more organized along/near the frontal boundary does raise some red flags in the flooding department. Feel the best chances of excessive rainfall today will be west of I-45 and then toward the coast over the weekend (S of I-10). An additional 1-3 inches can be expected with isolated amounts up to 5 inches possible.

[Ed Lizard]

Not quite sure about "eyes on the tropics" in the thread subtitle anymore, but I believe in keeping hope alive for those who still believe. Despite the fact that exclusing a couple of tropical equivalents of the 2004 Christmas snow miracle systems in October, and yes, nothing is near the horizon before the Equinox, which is the unofficial end of TC season for the NW Gulf, the 2 week GFS, while not showing anything tropical nearby, has the STR in about as favorable a position it has been in all year to deliver some unexpected miracle to Texas, and while 250 mb Westerlies are 30 knots in the extreme Northern Gulf, they are much lighter over the rest of the Gulf. Plus the 1949 storm I've referenced before.

. 3/512th glass full optimistic on a TC for Texas yet this year

And really, what most people secretly root for, a daytime landfall in Florida captured by a plethora of people and uploaded to U-Tube, if we use Kate as inspiration, we have two full months of meaningful season left.

In the more down to earth world of sensible weather and my lawn, I can't complain.

[Srain]

The short term rapid refresh meso models including the HRRR and RAP are beginning to suggest heavy rains and storm developing around 21Z across the area and continuing overnight into tomorrow. The 16Z RAP is suggesting the Coastal low will be near the Upper Texas Coast in about 18 hour and the 4km HIRES NAM is very suggestive that the upper low near the Big Bend will pass directly over SE Texas with showers/storms wrapping around the eastern half of that feature tomorrow. It appears we are nearing convection temps and the morning daytime heat along with high PW’s near the 2.2 range will provide for a heavy rainfall potential with rainfall rates in the 1-2 inch per range as all the features move closer to the Upper Texas Coast.

[wxmx]

Almost 5" in the last 72 hrs after being around 1" since early July. Looks like 93L will be the last gasp for the region this tropical season.

[Ed Lizard]

Almost 5" in the last 72 hrs after being around 1" since early July. Looks like 93L will be the last gasp for the region this tropical season.

That part (tropics winding down locally) is to be expected, more concerning is the Euro ensembles at Day 10 and GFS ensemble means throughout showing Texas (and NL) winding up on the West/dry side of the 500 mb trough.

16 day GFS MOS around here is very dry after tomorrow.

Silver lining watch - Seeing signs in the models of an increasingly happy Southern branch of the 250 mb jet with the main jet splitting coming towards the West Coast of North America, perhaps a sign of happy a happy warm ENSO Autumn. Maybe it is just rose colored glasses, but 1992 had a warm ENSO and an awesome Autumn in November.

[DoctorMu]

0.79 in in CLL. A little disappointing for Sept, but we'll take it. The low is overhead and hoping for some scattered action late this am or early pm.

[patrick7032]

Well not everyone in west central Texas received a large amount of rainfall....but some of areas in our CWA did pretty decent.

[Ed Lizard]

Fudge- the storms with the short wave along the front over the Big Country early this morning are fizzling, as much of Texas looks at an incredibly boring and dry 2 weeks. Silver lining- good outdoor activity weather. A tenth in 2 weeks doesn't trip my trigger...

[Ed Lizard]

I'm looking at the EastPac tropics as a source of fun...

[DoctorMu]

This fantasy is 8 days away...I hate watering anytime, but there's the tightrope between brown grass and brown patch this time of the year that is particularly dicey.

[patrick7032]

Interesting graphic....click on the map under "Water Supply" halfway down the page in the center.

http://watrnews.com/...ke-levels-down/

[Srain]

As we head toward the last week of September, another complicated and complex pattern is developing as rain chances once again enter the picture beginning Wednesday along our Coastal Counties. PW’s appear to increase to near the 1.8 range as a return flow becomes established and tropical moisture begins to pool across the Western Gulf.

Along the West Coast of Mexico, Hurricane Miriam will begin to turn N to NNE as an advancing trough and 500mb upper low develops off the California Coast. A series of short waves (upper air disturbances) begin to enter the picture on Thursday and tap into that mid/upper level moisture associated with Miriam and the 500mb low begins to slowly meander E across the Four Corners Regions on Thursday/Friday and the onshore flow across Texas increases with PW’s nearing the 2.2 range by Friday. Showers/storms appear rather likely in the 50%+ range at this time. The fly in the ointment will be just how quickly all these feature move along to our E. The GFS appears to be too aggressive and ends rain chances Saturday evening, while the ensembles and the operational Euro and Canadian are slower suggesting rain chances continue into Sunday and even Monday.

While it is too far out to know with any certainty, all and all it does appear that some remnants of Miriam and a myriad of upper air disturbances will enter the picture as an active period weather wise replaces the pleasant pattern of the past week and ½.

[Ed Lizard]

Upcoming week looks darn dull. But comfortably warm. Upper 80s is perfect, IMHO.

I'll accept cooler GFS long range forecast for October if we can get a chance of strong storms out of it.

Not giving up on Miriam yet for mid level happiness, and NHC forecasts trending South and East.

[DoctorMu]

AM HOU NOAA Discussion

recipe for some wetness this weekend...

DISCUSSION...

PATCHY FOG HAS DEVELOPED ONCE AGAIN WITH A FEW SPOTS SOUTH AND

SOUTHWEST OF HOUSTON REPORTING VSBYS BELOW A HALF MILE. THE FOG IS

SHALLOW AND SHOULD BURN OFF SHORTLY AFTER SUNRISE. TODAY LOOKS

SIMILAR WILL UPPER LEVEL RIDGING CENTERED OVER THE STATE AND SFC

HIGH PRESSURE OFF TO THE NORTHEAST. MAX TEMPS WILL AGAIN WARM

INTO THE LOWER AND MIDDLE 90S INLAND...UPPER 80S COAST. THE UPPER

RIDGE WILL BEGIN TO GET DISPLACED TO THE EAST ON TUESDAY BUT 850

TEMPS STILL LOOK PLENTY WARM AND PW VALUES DROP SO FEEL ANOTHER

WARM DAY IS ON TAP. 850 TEMPS BEGIN TO COOL ON WEDNESDAY AS A WEAK

S/WV MOVES ACROSS THE CENTRAL PLAINS. MOISTURE LEVELS ALSO BEGIN

TO SLOWLY CLIMB AND CLOUD COVER IS EXPECTED TO INCREASE. WILL

TREND TEMPS COOLER FOR WEDNESDAY. FCST SOUNDINGS OVER THE NORTH

HALF OF THE REGION SHOW PW VALUES AROUND 1.2 INCHES BUT CONVECTIVE

TEMPS ARE IN THE LOWER 80S (REACHABLE) AND CAPPING IS NIL. WAS

TEMPTED TO ADD POPS FOR WEDNESDAY BUT MODEL MASS FIELDS LOOK

RATHER MEAGER.

PW VALUES CLIMB TO 1.7 INCHES ON THURSDAY WITH ADDITIONAL COOLING

NOTED AT 850 MB. CAPPING IS WEAK AND FCST SOUNDINGS SHOW A

SATURATED PROFILE BETWEEN 18-00Z. WILL CONTINUE TO CARRY 20 POPS

FOR NOW AND FEEL HIGHER POPS MIGHT BE IN ORDER. ANOTHER S/WV ON

FRIDAY COUPLED WITH PW VALUES BETWEEN 2.00 AND 2.20 INCHES WILL

YIELD DECENT RAIN CHANCES. THE ECMWF...GFS AND CANADIAN ALL

PRODUCE QPF ON FRIDAY SO WILL RAISE RAIN CHANCES TO 40/50. LONG

RANGE MODELS DIVERGE SATURDAY AND BEYOND. WAS WAITING FOR A

CONSENSUS BETWEEN THE MODELS AND THIS DID NOT OCCUR. THE ECMWF

WITH SOME SUPPORT FROM THE LONG RANGE CANADIAN CARVES OUT A DEEP

UPPER TROUGH OVER THE SOUTHERN ROCKIES AS ENERGY FROM PACIFIC

STORM MIRIAM IS PULLED NORTHWARD. THE ECMWF DEVELOPS A SURFACE LOW

OVER NORTH TEXAS ON SATURDAY AND DRAGS A WEAK FRONT ACROSS SE

TEXAS ON SUNDAY. THE CANADIAN AND ECMWF LOOK RATHER SIMILAR WITH

THEIR RESPECTIVE UPPER LEVEL FEATURES BUT DIFFER WITH REGARD TO

THE SURFACE LOW AND FRONT. THE ECMWF HAS BEEN CONSISTENT WITH THIS

SOLUTION FOR THE LAST 3 DAYS. THE GFS KEEPS MIRIAM OVER THE BAJA

AND ENERGY FROM THIS SYSTEM DOES NOT GET PULLED NORTH UNTIL

SUNDAY. THE UPPER TROUGH HANGS OUT WEST AND DOES NOT APPROACH SE

TX UNTIL DAY 10 (NEXT WEDNESDAY). CAN`T SAY FOR SURE WHICH

SCENARIO WILL PLAY OUT SO WILL COMPROMISE FOR NOW AND BLEND THE

EC/GFS WITH A SLIGHT NOD TOWARD THE ECMWF AND MENTION RAIN CHANCES

THROUGH THE WEEKEND. 43

[wxmx]

This should keep Ed warm (time sensitive)

[Ed Lizard]

This should keep Ed warm (time sensitive)

Warm is good. IN the meantime, although GFS MOS is only a couple of tenths over a couple of days, it can be directly tied to Miriam, or I can claim 2012 Texas tropics season wasn't 100% fail.

[DoctorMu]

The soup thickens:

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

312 PM CDT MON SEP 24 2012

.DISCUSSION...

EXPECTING A COUPLE MORE WARM LATE SEPTEMBER DAYS ACROSS SOUTHEAST TEXAS

BEFORE RISING MOISTURE LEVELS BRING INCREASING CLOUDS AND RISING RAIN

CHANCES BACK INTO OUR FORECAST. WILL KEEP THE AREA DRY AND WARM THROUGH

WEDNESDAY. BY THURSDAY...PRECIPITABLE WATER VALUES BEGIN TO RISE AND

ENOUGH MOISTURE AND LIFT MIGHT BE CAPABLE OF PRODUCING ISOLATED SHOWERS/

THUNDERSTORMS. IF MODEL TIMING IS RIGHT...BEST RAIN CHANCES DUE TO A

SERIES OF MID/UPPER LEVEL DISTURBANCES MOVING ACROSS THE AREA IN COMBINATION

WITH PRECIPITABLE WATER VALUES AROUND TWO INCHES WILL END UP BEING SOME

TIME BETWEEN FRIDAY AFTERNOON THROUGH SUNDAY MORNING. ANTICIPATE DECREASING

CLOUDS...SLIGHTLY COOLER TEMPERATURES...AND LOWER HUMIDITY LEVELS BY

THIS TIME NEXT WEEK AS WE BEGIN THE NEW MONTH. 42

&&

[Srain]

HGX is beginning to ramp up the chatter regarding the late week/weekend pattern. I would expect the HPC to slowly increase the QPF forecast over the next couple of days as well. The upcoming pattern is not all that different from what we experienced a week and 1/2 ago where some folks saw some much needed rainfall while others received little.

AREA FORECAST DISCUSSION...CORRECTED

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

448 AM CDT TUE SEP 25 2012

.DISCUSSION...

ONE MORE FAIR WEATHER AND UNSEASONABLY WARM DAY CAN BE EXPECTED

ACROSS SE TX AS A HIGH PRESSURE RIDGE CONTINUES OVERHEAD. OVER THE

NEXT FEW DAYS THE MODELS ARE CONSISTENT IN PUSHING THE RIDGE EAST

AND SOUTH WHILE AN UPPER LEVEL LOW PRESSURE AREA DEEPENS OVER THE

ROCKIES AND BEGINS TO MOVE EASTWARD. MOISTURE ALONG AND AHEAD OF

THE TROUGH WILL BE ENHANCED FROM TROPICAL MOISTURE STREAMING

NORTHEASTWARD FROM MARIAM OFFSHORE OF THE BAJA CA COAST. ALTHOUGH

THE MODELS ARE CONSISTENT IN THE DEVELOPMENT AND MOVEMENT OF THE

UPCOMING SYSTEM...THEY ARE NOT IN AGREEMENT WITH THE TIMING. THE

GFS IS A BIT FASTER THAN THE ECMWF. THIS FORECAST TAKES IN ACCOUNT

A SLOWER SOLUTION LATE IN THE WEEKEND BUT LEANS HEAVILY TOWARD

THE GFS.

AS FOR DETAILS...MOISTURE ADVECTION WILL HELP TEMPER THE

TEMPERATURES AND PROVIDE A SLOW INCREASE IN THE CLOUD COVER TODAY

AND WEDNESDAY. THE RIDGE ALOFT HANGS AROUND LONG ENOUGH TO KEEP

THE DEEPER LAYER MOISTURE OUT OF THE AREA UNTIL FRIDAY. THE

CURRENT MODEL ACTUALLY AGREES FAIRLY WELL WITH THE CURRENT

FORECAST EXCEPT FOR A BIT LESS COVERAGE ON FRIDAY. THE ARRIVAL OF

THE TROPICAL MOISTURE ALOFT WILL COINCIDE WITH THE GULF MOISTURE

TO BRING THE BEST CHANCES AND MOST COVERAGE LATE FRIDAY INTO

SATURDAY. THE GFS ACTUALLY RAISES PW/S INTO THE 2 TO 2.5 INCH

RANGE OVER THE CENTRAL AND SOUTHERN COUNTIES FRIDAY NIGHT INTO

SATURDAY EVENING. IF THIS TREND CONTINUES...THE POTENTIAL FOR

LOCALLY HEAVY RAINFALL MAY DEVELOP AND WILL ADDRESS THIS CONCERN

OVER THE NEXT DAY OR SO IF NEEDED. THE MODELS END THE RAINFALL

CHANCES BY LATE SUNDAY.

[Srain]

Morning e-mail from Jeff:

After over a week of nice fall weather, changes are on the way.

High pressure aloft over the region and ridging SW from the eastern US has kept a fairly dry and warm air mass in place for the past several days. However high pressure at the surface is moving eastward and low pressure is developing in the lee of the Rockies ahead of a slow moving upper level trough over the SW US. This is resulting in an increase in the southerly flow and slight increase in surface moisture. At the same time powerful Hurricane Miriam is moving NW off the western coast of MX under the influence of ridging over N MX and the developing trough over the SW US. High level moisture plume is clearly noted extending NE from the circulation of Miriam spreading ENE to NE into central MX and toward the TX border.

Parameters are slowly coming together for a period of very wet weather Fri-Sun as the upper trough over the SW US interacts with eastern Pacific hurricane Miriam. The overall setup will likely produce an excessive rainfall event for some location across the state of TX late this week/this weekend. Current upper level trough will slow with lift reaching TX by late this week, while both Gulf and mid/high level moisture increase across the area as Miriam sheds moisture and energy NE. PWS increase toward 1.5 inches on Thursday and 2.0 inches by late Friday and then into the 2.0-2.4 inch range on Saturday with soundings becoming increasingly saturated. Upper level jet dynamics come into play by Friday as a 250mb jet streak is progged over NC TX increasing large scale lift over C and SE TX. Expect to see scattered showers and thunderstorms develop and move inland along the TX coast with more organized rainfall over C and N TX on Friday. With moisture levels running very high expect areas of very heavy rainfall.

Upper trough and moisture plume from Miriam sag eastward over the weekend with SE TX coming increasingly under the influence of both the lifting by the trough aloft and high level moisture/energy from the tropical system. Expect more widespread and organized rainfall potential Saturday into Sunday. With moisture levels in the “excessive” range heavy rainfall is likely, but at this time there is no well defined surface boundary to focus/anchor convection at least not at the present time. One would think that with upstream convection some sort of outflow boundary could/would be present on the following days and this potential will need to be watched.

Since we are still over 48 hours from the onset of any event, there is plenty of time to fine tune and nail down the location that looks most favorable for heavy rainfall. Only recently have model guidance come into decent agreement on the phasing of the moisture of Miriam and the upper level trough so some additional changes are likely.

[Ed Lizard]

HGX AFD offers some hope for the weekend. Euro w/ ~3 inches is much happier than GFS.