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

[Srain]

Morning e-mail from Jeff:

Widespread rainfall event increasingly likely this weekend

Ingredients continue to come together for a period of wet weather from Friday-Sunday. Moisture is returning to SE TX this morning as noted by the isolated inland moving showers on radar over the coastal waters into the coastal and inland first tier counties. These showers appear to be in response to a sliver of higher moisture being transported northward on increased southerly flow of the past 48 hours. With a little heating this morning expected a continuation of these showers today.

Of more importance is the late week period into the weekend as parameters are coming together to produce a potential widespread rainfall event. Low pressure formation ahead of a deepening SW US trough will help transports low level tropical moisture over the southern Gulf of Mexico northward into the region starting Thursday. May see slightly better rain chances on Thursday than currently being indicated, but the better chances should hold off until Friday when the tropical moisture reaches the area. Expect numerous showers and thunderstorms on Friday pulling northward off the western Gulf of Mexico. At the same time, mid and high level moisture is already spreading NE across MX into TX from EPAC tropical system Miriam. This moisture along with the increasing Gulf moisture will become entrained in the slow moving trough producing widespread rainfall from SW TX into E TX over the weekend.

Surface frontal boundary currently over NW TX will only slowly drag SE over the next 2 days and gradually enter the area early Saturday…more importantly this boundary adds a focus for deep convection that was largely absent yesterday in the model guidance. This change does raise some concern for more significant rainfall over the weekend as the slow moving trough, a slow moving surface boundary, saturated air column, and extremely high moisture levels (PWS 2.2-2.4 inches) all combine to produce some very heavy rainfall. Still not overly confident on where the heavy rains will set up although the southern half of TX appears to be in the best location south of the 250mb jet streak and near/south of the surface boundary. The “tropical like” air column will support some very heavy rainfall rates in a short period of time and this will need to be watched especially if any cell training or slow storm motions are noted. Would not at all be surprised to see some 2-3 inch per hour rainfall rates with this set up. Models are really keying in on Saturday afternoon-Sunday morning as the best time for organized heavy rainfall spreading from SW to NE across the region.

[Srain]

This is looking more and more like the event we experience during mid September where areas of Central Texas saw some isolated 8 inch amounts and NW Harris County receive 6+ inches while areas down S in Galveston/Brazoria Counties saw little if any rainfall. Perhaps the areas that have been lacking will benefit this time around. The fly in the ointment is the lack of a stronger frontal boundary as a focal point close to our part of the world and as always, any meso features that cannot be forecast at this range.

[DoctorMu]

Moderate rain event this weekend coming together.

A Colorado Rocky Mountain Low...looks a bit like that late winter pattern

http://www.goes.noaa.gov/GSSLOOPS/ecwv.html

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

319 PM CDT WED SEP 26 2012

.DISCUSSION...

LATEST MODEL RUNS HAVE MOISTURE THAT IS CURRENTLY BUILDING IN THE CENTRAL

GULF WATERS HEADING THIS WAY OVER THE NEXT SEVERAL DAYS...AND SATELLITE

IMAGERY SHOWS TROPICAL PACIFIC MOISTURE FROM MARIAM BEGINNING TO WORK

ITS WAY INTO TEXAS. THE COMBINATION OF THESE INCREASING MOISTURE FIELDS

ALONG WITH RIDGING BREAKING DOWN ACROSS OUR AREA WILL LEAD TO GRADUALLY

INCREASING RAIN CHANCES THROUGH THE END OF THE WEEK AND ESPECIALLY DURING

THE FIRST PART OF THE UPCOMING WEEKEND. OUR AREA`S BEST CHANCE OF RAIN

LOOKS LIKE IT IS SETTING UP FOR FRIDAY NIGHT THROUGH SUNDAY MORNING

WHEN A MID/UPPER LEVEL TROUGH MOVES ACROSS THE STATE AND A SURFACE LOW

FORMS SOMEWHERE OFF THE TEXAS COAST. WHERE THIS LOW FORMS AND WHERE

IT HEADS COULD BECOME A SIGNIFICANT PLAYER ON WHERE OUR HIGHEST RAINFALL

TOTALS END UP. FOR NOW...CURRENT THINKING HAS MUCH OF SOUTHEAST TEXAS

SEEING EVENT TOTALS OF 1/2 TO 1 INCH WITH ISOLATED SPOTS NEAR THE COAST

AND OFFSHORE POSSIBLY RECEIVING 1 TO 3 INCH TOTALS. ONCE WE GET THE

TROUGH AND SURFACE LOW TO MOVE OFF TO OUR EAST BEGINNING ON SUNDAY...EXPECT

DECREASING RAIN CHANCES FROM WEST TO EAST WITH THE MAJORITY OF THE AREA

RAIN FREE BY SUNDAY AFTERNOON. COOLER AND DRIER WEATHER IS EXPECTED

FOR THE FIRST HALF OF NEXT WEEK AS WE KICK OFF THE NEW MONTH. 42

&&

[Srain]

Morning e-mail from Jeff:

Active weather period expected Friday-Sunday.

Upper level storm system over the western US will move slowly eastward into TX over the next 48-72 hours. High pressure aloft will be pushed southward and at the surface eastward allowing a more favorable influx of both Gulf and Pacific moisture and lowering heights aloft. General subsidence will be replaced with general lift as the upper trough and impulses rotating around the trough move into the state. Increasing moisture today will likely cause a few streamer showers west of I-45 and south of I-10 similar to yesterday. Rain chances begin to creep upward on Friday as surface high shifts eastward allowing the pool of deep tropical moisture over the southern Gulf of Mexico to surge northward. At the same time mid and high level moisture from weakening tropical system Miriam will move across TX from the SW. With the air column becoming increasingly saturated and hard to time or ill defined disturbances approaching from the SW by midday Friday expect showers and thunderstorms to begin to develop and overspread the region from the Gulf waters. Coverage should be on the lower side for most of Friday, but where it rains it will be heavy.

Main event looks to be Saturday into Saturday night as the main upper trough ejects into SW TX and forces surface low pressure formation over SW TX. GFS/ECMWF/NAM model all generally agree on the development of thunderstorms over SW TX late Friday night/early Saturday in a region of strong lift ahead of the upper trough which then moves eastward across SC TX on Saturday. GFS and NAM QPF bullseyes suggest some sort of MCS feature may develop and track ESE toward the middle TX coastal plain by Saturday evening. Air mass ahead of the upper trough and surface low completely saturates with PWS pushing 2.3 inches and favorable low level inflow. The extreme moisture levels (pushing 2 std above early October normals) combined with slow moving organized thunderstorms raises flash flooding red flags. Given the saturated air column warm rainfall production will be likely with little dry air entrainment leading to excessive short term rainfall rates. Tropical like MCS systems tend to slow in the overnight hours some especially as they near the TX coastal plains where the low level inflow increases after dark and this raises the threat for extended heavy rainfall into Sunday morning.

Both models agree that the best lift and rainfall will be focused south of I-10 and west of I-45 or toward the coastal bend into our SW counties where the models are showing the greatest QPF. While the models are in agreement on this placement, that does not mean that is where the threat will be greatest and it is possible that more of the area could be under the gun Saturday night for excessive rainfall. Will likely not be able to firm the threat area up any more than broadly prior to Saturday morning. Widespread rainfall amounts of 2-3 inches are likely with isolated amounts of 4-5 inches especially over those SW counties. Given the moisture profiles I would not be surprised to see a few locations pick up a quick 6-8 inches but these should be fairly small is spatial coverage…hopefully. Grounds are generally dry over much of the area and will be able to handle much of this rainfall, but urban areas will respond quickly to the high short term rates and some flooding or ponding is likely where rainfall rates exceed 1.5 inches in less than 30 minutes. While widespread rains are likely, most rivers are at or below base flow levels, so there is plenty of capacity to handle the expected amounts of run-off.

[Ed Lizard]

Couple of sweet looking svr warned storms over the Panhandles, Northwest Texas and Oklahoma last night.

[DoctorMu]

Hoping for an ejection and even small training right over CLL this weekend. The GFS long range is parched after this until a strong front in mid Oct.

[Srain]

Flood Watches hoisted for a large area of Texas this morning with more likely later today as a complicated forecast develops with a combination of EPAC moisture from Miriam/94E, a slow moving Coastal Low and a slow moving frontal boundary interact to bring some impressive rainfall rates and totals to the Lone Star State and Louisiana.

SHORT RANGE FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

452 AM EDT FRI SEP 28 2012

VALID 12Z FRI SEP 28 2012 - 12Z SUN SEP 30 2012

...TROPICAL MOISTURE STREAMING IN FROM THE EASTERN PACIFIC IS

EXPECTED TO BRING A THREAT OF FLASH FLOODING FROM TEXAS EASTWARD

INTO THE CENTRAL GULF COAST DURING THE NEXT FEW DAYS...

...A SLOW-MOVING FRONT WILL KEEP A GOOD CHANCE OF SCATTERED

SHOWERS AND THUNDERSTORMS FROM ACROSS THE SOUTHEAST INTO THE

MID-ATLANTIC...

PLENTY OF TROPICAL MOISTURE FROM THE EASTERN PACIFIC IS SPREADING

NORTHEASTWARD INTO NORTHERN MEXICO. THE INVASION OF MOISTURE

COMBINED WITH AN UPPER-LEVEL WAVE OF LOW PRESSURE IS EXPECTED TO

BRING HEAVY RAIN EASTWARD ACROSS SOUTHERN TEXAS TONIGHT AND INTO

SATURDAY...REACHING THE LOUISIANA COAST LATER ON SUNDAY. IN THE

MEANTIME...A LOW PRESSURE SYSTEM IS EXPECTED TO FORM IN SOUTHERN

TEXAS ON SATURDAY...MOVING OFF THE TEXAS COAST ON SUNDAY. THIS

WILL BRING A PERIOD OF WET...COOL AND WINDY WEATHER ACROSS THE

NORTHWESTERN GULF COAST WITH A THREAT OF FLASH FLOODING DURING THE

WEEKEND.

A FRONTAL BOUNDARY FROM ACROSS THE SOUTHERN PLAINS INTO THE

MID-ATLANTIC STATES HAS BEEN MOVING RATHER SLOWLY. SHOWERS AND

THUNDERSTORMS...MAINLY SCATTERED IN THE NATURE...ARE RIDING FROM

WEST TO EAST ACROSS THE CENTRAL PLAINS AND INTO SOUTHERN NEW

ENGLAND. TWO WAVES OF LOW PRESSURE ARE EXPECTED TO FORM ON THE

FRONT AND THE FRONT WILL BE SLOW TO MOVE OUT OF THE MID-ATLANTIC

OVER THE NEXT FEW DAYS.

ELSEWHERE...A DRY FRONT IS EXPECTED TO BRING LITTLE IF ANY

PRECIPITATION ACROSS THE PACIFIC NORTHWEST AND THE NORTHERN

ROCKIES. MAINLY FINE WEATHER SHOULD PREVAIL ACROSS MUCH OF THE

NORTHERN U.S. DURING THE NEXT FEW DAYS. HOWEVER...AN UPPER-LEVEL

LOW AND ITS ASSOCIATED COLD CORE IS EXPECTED TO DIP INTO THE GREAT

LAKES DURING THE WEEKEND. THE ASSOCIATED INSTABILITY IS EXPECTED

TRIGGER SCATTERED THUNDERSTORMS OVER EASTERN GREAT LAKES DURING

THE WEEKEND.

KONG

[Srain]

Morning e-mail from Jeff:

Widespread heavy rainfall becoming increasingly likely.

Parameters continue to come together from midday Friday-Sunday to produce widespread heavy rainfall across the region. Slow moving upper level trough over the SW US will begin to spread large scale lift into TX over the next 6-12 hours with surface low pressure forming over the SW Rio Grande plains near/around Laredo. Tremendous tropical moisture advection off the western Gulf of Mexico will surge PWS into the 2.0-2.4 in range by late today with mid and high level moisture arriving from the west from the remains of EPAC hurricane Miriam. Surface low will move ENE across the area on Saturday/early Sunday with widespread thunderstorms.

Flash Flood Threat:

With the air column becoming increasingly saturated over the next 12 hours rainfall production will become more tropical like with excessive short term rainfall rates likely. Moisture levels rise to near 2 standard deviations above late September averages and this combined with the potential for cell training and organized slow moving storms really raises the threat for flash flooding. While grounds are fairly dry and flash flood guidance is high, short term rainfall rates of 2-4 inches per hour will be possible given the setup and air mass capabilities and the threat for training or slowing storm motions could extend such a rainfall rate over a period of time. Urban areas will be at greatest risk from the short term excessive rainfall rates likely leading to street flooding and ponding. While most rivers are at base flow or below total rainfall amounts over the weekend will likely produce significant rises.

Widespread amounts of 2-4 inches appear likely with isolated totals of 3-6 inches and I would not at all be surprises to see some locations with totals in the 8-10 inch range (these bigger totals) should be fairly isolated. Similar set ups in the past (October 1998) and (October 2002) have produce some incredible short term rainfall amounts especially over SC TX. Still too early to attempt to determine where the greatest risk area will be, but areas along and south of I-10 will have the best moisture.

A Flash Flood Watch will likely be require for portions or all of SE TX later today.

[Srain]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 09/28/12 1326Z

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

LATEST DATA USED: GOES-14 1315Z HANNA

.

LOCATION...TEXAS...

.

ATTN WFOS...EWX...SJT...LUB...MAF...

ATTN RFCS...WGRFC...

.

EVENT...HEAVY RAIN

.

SATELLITE ANALYSIS AND TRENDS...LATEST SURFACE ANALYSIS SHOWS WEAK

SYNOPTIC FRONTAL BOUNDARY EXTENDING FROM NEAR THE ARKLATEX AND EXTENDING

SW TOWARDS THE BIG BEND AREA. RETURN FLOW OF MOISTURE AHEAD OF TROFFING

OVER THE E PAC HAS BEEN RAPIDLY INCREASING THIS MORNING OVER THE LOWER

RIO GRANDE VALLEY ACCORDING TO LATEST BLENDED PW ANALYSIS. THIS RETURN

FLOW HAS BEEN OVERRUNNING SYNOPTIC BOUNDARY AND HAS RESULTED IN A SMALL

QUASI-STATIONARY MCS TYPE FEATURE THAT EXTENDS FROM ANDREWS AND ECTOR

COUNTY E TO FISHER AND NOLAN COUNTY. THE MOST ACTIVE AREA OF CONVECTION

AND PERIODIC CLOUD TOP COOLING WITHIN THIS AREA APPEARS TO HAVE MOVED OVER

MITCHELL COUNTY AND ALSO MOST RECENTLY OVER MARTIN COUNTY. BELIEVE THAT

RAINFALL RATES WITHIN THIS AREA ARE LIKELY RUNNING OVER 1.0"/HR.

.

SHORT TERM OUTLOOK VALID 1240-1540Z...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...IT APPEARS AS THOUGH LOCAL AREA VWPS HAVE SHOWN SOME

MODEST WEAKENING AND BACKING OF LLJ OVER THE LAST HOUR. BELIEVE THAT THE

WEAKENING OF LLJ SHOULD ONLY BE TEMPORARY THOUGH AS UPSTREAM SHORTWAVE

TROF OVER N MEXICO SHOULD ALLOW FOR A CONTINUED BACKING AND EVENTUAL

STRENGTHENING OF LLJ. SO BELIEVE THAT ALTHOUGH THERE MAY BE AN EVENTUAL

TEMPORARY WEAKENING OF ONGOING SYSTEM THAT FOCUS WILL SHIFT FURTHER W

INTO W CNTRL AND SW TX. FOR THE MEANTIME THOUGH, WOULD EXPECT ADDITIONAL

RAINFALL TOTALS OF 1.0-2.0" FROM MITCHELL COUNTY AND THEN SLOWLY SPREADING

ENE INTO POSSIBLY PORTIONS OF NOLAN AND TAYLOR COUNTY.

[DoctorMu]

Ponchos are mandatory for the A&M-Arkansas game.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

1016 AM CDT FRI SEP 28 2012

...LOCALLY HEAVY RAINFALL EXPECTED ACROSS A LARGE PART OF SOUTHEAST

TEXAS OVER THE WEEKEND AS A STORM SYSTEM SLOWLY MOVES THROUGH THE AREA...

.DISCUSSION...

SCATTERED SHOWERS AND THUNDERSTORMS NEAR THE COAST AND OFFSHORE THIS

MORNING WILL WORK THEIR WAY INLAND TODAY. SIMILAR TO YESTERDAY AFTERNOON/

EVENING...SOME SPOTS COULD SEE SOME LOCALLY HEAVY RAINFALL IN THE SLOWER

MOVING ACTIVITY. GREATER RISK FOR HEAVY RAINFALL COMES SATURDAY THROUGH

SUNDAY MORNING WHEN A STORM SYSTEM DEVELOPS AND MOVES ACROSS OUR AREA.

VERY HIGH PRECIPITABLE WATER VALUES (>2 INCHES) COUPLED WITH DECENT

CONVERGENCE AHEAD OF A STRENGTHENING SURFACE LOW IS EXPECTED TO HELP

TO PRODUCE EVENT RAINFALL TOTALS AVERAGING 1 TO 2 INCHES WITH ISOLATED

AMOUNTS EASILY REACHING 2 TO 4 INCHES. EVEN HIGHER AMOUNTS CANNOT BE

RULED OUT! WITH AREA GROUNDS POSSIBLY BECOMING WET AHEAD OF THE MAIN

STORM SYSTEM...A FLASH FLOOD WATCH IS PROBABLY GOING TO BE ISSUED WITH

THIS AFTERNOON`S PACKAGE. EXACTLY WHERE THE HIGHEST RAINFALL TOTALS

AND GREATEST FLASH FLOOD RISK ENDS UP IS STILL HARD TO PINPOINT DUE

TO DIFFERENT MODEL SOLUTIONS CONCERNING THE LOCATION AND STRENGTH OF

THIS SYSTEM...BUT CONFIDENCE CONTINUES TO INCREASE THAT LARGE PORTIONS

OF SOUTHEAST TEXAS WILL RECEIVE HEAVY RAINFALL WITH THIS EVENT.

HERE ARE SOME AREA RECORD RAINFALL TOTALS (AND YEAR SET) FOR THIS WEEKEND.

SATURDAY (9/29) SUNDAY (9/30)

CLL - 1.84" (1921) 1.85" (1927)

IAH - 2.51" (1985) 2.55" (1913)

HOU - 1.70" (1985) 1.15" (1934)

GLS - 2.12" (1921) 4.33" (1945)

[Srain]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 09/28/12 1621Z

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

LATEST DATA USED: GOES-14 1602Z HANNA

.

LOCATION...TEXAS...NEW MEXICO...

.

ATTN WFOS...FWD...OUN...EWX...SJT...LUB...MAF...ABQ...

ATTN RFCS...ABRFC...WGRFC...

.

EVENT...HEAVY RAIN

.

SATELLITE ANALYSIS AND TRENDS...LATEST SATELLITE IMAGERY CONTINUES TO SHOW

THE THREAT FOR HEAVY SHOULD CONTINUE ON THE SHORT TERM OVER PORTIONS OF

W CNTRL TX AND SW TX. OVER THE LAST HOUR THE MOST SIGNIFICANT CLOUD TOP

COOLING HAS SHIFTED INTO PORTIONS OF SW TX, PARTICULARLY OVER PRESIDIO AND

BREWSTER COUNTIES. THIS INCREASE IN CONVECTION APPEARS TO BE PARTIALLY

IN RESPONSE TO SUBTLE SHORTWAVE TROF THAT WAS LIFTING NE OUT OF PORTIONS

OF N MEXICO AND ALSO DUE TO ENTRANCE REGION FROM STRENGTHENING JET STREAK

OVER THE S PLAINS.

.

LATEST BLENDED PW ANALYSIS SHOWS THAT STRONG MOISTURE FLUX CONTINUES UP

THE LOWER RIO GRANDE RIVER VALLEY THIS MORNING WHILE LATEST PROFILER DATA

SHOWS THAT WINDS HAVE BACKED TO A MORE EASTERLY COMPONENT OVER PORTIONS

OF E AND SE TX. THIS HAS AND WILL HELP TO FOCUS THE BEST MOISTURE FLUX

FURTHER SW THIS AFTERNOON OVER PORTIONS OF SW TX AND BELIEVE AN INCREASE

IN CONVECTION SHOULD CONTINUE OVER THIS AREA THROUGH THE MORNING AND

AFTERNOON.

.

SHORT TERM OUTLOOK VALID 1630-2230Z...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...BELIEVE LOCALIZED HEAVY RAIN THREAT WILL CONTINUE AND

EXPAND INTO PORTIONS OF SW TX THROUGH THE MORNING AND INTO THE AFTERNOON.

WOULD EXPECT LOCALIZED RAINFALL RATES OF 1.0-2.0"/HR IN THE MOST INTENSE

CONVECTION AND LOCALIZED TOTALS OF 2.0-3.0" ARE POSSIBLE THROUGH THE

AFTERNOON.

[Ed Lizard]

Near saturated sounding/low lapse rates means sub-500 J/Kg CAPE tomorrow afternoon, BUT, glass half full, very low cloud bases and almost 300 J/Kg helicity, an isolated tornado or three, isn't impossible.

Somewhat different situation, last January, but good helicity and low cloud bases can partially offset "meh" CAPE for tornadoes.

[Srain]

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

229 PM EDT FRI SEP 28 2012

PRELIM DAY 1 QPF DISCUSSION

VALID SEP 29/0000 UTC THRU SEP 30/0000 UTC

REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR

DAY 1...

CNTRL TO SRN TX INTO SRN LA...

WIDESPREAD HVY TO LOCALLY EXCESSIVE PCPN AMTS LIKELY DAY 1 ACRS

PORTIONS OF CNTRL TO SRN TX IN AN AXIS OF MUCH ABOVE AVG PW

VALUES...2-2.5+ STD ABOVE THE MEAN...THAT ARE EXPECTED TO PERSIST

DAY 1 FROM NRN MEXICO ACRS CNTRL TO SRN TX AND INTO LA. SEVERAL

PIECES OF SHRTWV ENERGY EXPECTED TO PUSH EWD AND ENEWD IN THIS HI

PW AXIS...STRENGTHENING THE SELY TO SLY LOW LEVEL FLOW AND

ENHANCING UPR DIFFLUENCE ACRS THE SRN PLAINS. CONFIDENCE IN

SHRTWV DETAILS IS NOT GREAT...BUT CONFIDENCE IS HIGH FOR

WIDESPREAD HVY TO LOCALLY EXCESSIVE PCPN AMTS GIVEN THE HI

PWS...STRONG UPR DIFFLUENCE AND FAIRLY GOOD MODEL AGRMNT. THERE

ARE SOME DIFFS WITH RESPECT TO THE QPF AXES AMONG THE LATEST

OPERATIONAL AND HI RES GUIDANCE. THE HI RES ARW...NMM AND SPCWRF

ALONG WITH MANY OF THE LATEST SREF MEMBERS ARE SHOWING A FARTHER

SWD AXIS THAN THE GFS...NAM AND NAM CONEST. DAY 1 QPF LEANED

HEAVILY TOWARD THE FARTHER SWD HI RES GUIDANCE AND ALSO TOWARD

THEIR MORE PROGRESSIVE ESEWD PUSH OF HEAVY PCPN THIS PERIOD GIVEN

THEIR GENERAL BETTER PERFORMANCE WITH AREAS OF ORGANIZED

CONVECTION. WIDESPREAD 1-3" AREAL AVG AMTS DEPICTED THIS PERIOD

ACRS CNTRL TO SRN TX...WITH ISOLATED TOTALS IN EXCESS OF 5"

POSSIBLE.

[Ed Lizard]

2.4 inch PW. That'd be an impressive value even in the beginning of September.

[Srain]

It appears the Canadian may well be the winner of the various model solutions over the past 24 hours regarding how events will unfold today across Central/SE Texas as EPAC Miriam and Norman remnants spread NE from Mexico. The Canadian has been more correct in suggesting S Central TX would be the area to watch and now the 00Z UKMet has joined that solution. Areas S of San Antonio has seen rounds of stronger storms and Flash Flood Warnings as well as a Severe Thunderstorm Warning since 1AM. It appears a meso low will move NE along the HWY 59 Corridor and pass directly over the Houston Metro tonight/early Sunday morning. Heavy showers/storms continue to develop near and to the W of Victoria heading N while the meso low and developing surface low pressure moves NE. The HPC 1-2 Day QPF Forecast just issued now places along and N of HWY 59 in the 'favored' area with some 5+ inch isolated rainfall totals. The latest SPC Updated also suggests that stronger storms with gusty winds are not out of the question as well. Some rainfall rates in the 1-3 inch per hour range may not be out of the question and we'll need to monitor for training cells as the flow off the Gulf increases this morning ahead of the advancing surface low to our S and W. It does appear as if everyone in SE TX will see rainfall from this event before the surface low and upper low over W Texas passes us off to the E tomorrow ending our rain chances as we end September.

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

546 AM EDT SAT SEP 29 2012

FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION

VALID SEP 29/1200 UTC THRU OCT 02/1200 UTC

REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR

DAY 1...

UPDATED...OPTED TO GIVE THE FINAL DAY1 QPF OVR A LITTLE MORE

'AMPLIFIED' LOOK UPPING AMTS ALONG THE DEFORMATION ZONE ASOCTD

WITH THE H7 LO. THE GEM REGIONAL CONTINUES TO BE THE MODEL OF

CHOICE WITH THIS SYSTEM WITH THE 00Z ECMWF APPEARING TO HAVE

FEEDBACK ISSUES. OTHERWISE..ADJUSTED FCST BASED ON CURRENT

OBSERVATIONAL DATA.

...TX TO THE LOWER MS VLY...

THE VRY IMPRESSIVE TROPICAL MSTR PLUME OBSERVED IN CURRENT STLT

IMAGERY..AND SHRTWV ENERGY EMBEDDED IN IT WORKING NEWD INTO TX IS

SETTING THE STAGE FOR A VRY SGFNT RNFL EVENT ACROSS THE AREA.

PROBLEM HOWEVER IS AT WHAT LATITUDE TO PLACE THE MAXIMA PCPN

TOTALS WITH THERE BEING DIFFERENT FCST CAMPS IN THIS REGARD. THE

UKMET AND CANADIAN MODELS ARE ON THE SIDE OF A MORE SRN SOLUTION

CLOSER TO COAST AND THE BETTER PWS AND INSTABILITY WHILE THE NCEP

MODELS AND YDAS ECMWF ARE FARTHER TO THE NORTH CLOSER TO THE

DEFORMATION AXIS ASOCTD WITH THE MID LVL CNTR. AT THIS TIME FEEL

THE FORCING ASOCTD WITH THE FORMATION OF THE SFC LO INVOF THE TX

COAST AROUND MID PD AND THE LACK OF STG MID LVL CNTR SUGGESTS

BUYING INTO THE MORE SRN SOLUTION. IN ADDITION..LAST NIGHTS GEM

REGIONAL DID A BANG UP JOB PARTICULARLY ON THE IDEA OF HVY CNVCTN

RAINS DVLPNG OVR S CNTRL TX TNGT AS COMPARED TO THE NCEP GLOBAL

MODELS AND THE ECMWF. THE FACT THAT THE UKMET NOW SUPPORTS TNGTS

GEM REGIONAL SCENARIO AT LEAST IN REGARDS TO THE MAXIMA LENDS MORE

CREDENCE TO THE GEMS FCST. FINALLY..IF THE MORE SRN SOLUTION

WHICH WILL BE CLOSER TO THE SFC BNDRY OCCURS..IT SHOULD LIMIT THE

MSTR FLUX NWWD TO THE DEFORMATION ZONE/ISENTROPIC LIFT CLOSER TO

THE TRACK OF THE H7 CNTR.

[Ed Lizard]

...WRN GULF COAST REGION...

DISORGANIZED MCS HAS BEEN MOVING EWD ACROSS SRN TX DURING THE EARLY

MORNING HOURS...WITH WARM ADVECTION SHOWERS/THUNDERSTORMS SPREADING

NWD OVER THE TX/LA GULF COAST AHEAD OF THE MCS. THESE STORMS ARE

EMBEDDED WITHIN A VERY MOIST AIRMASS...CHARACTERIZED BY SURFACE

DEWPOINTS IN THE LOW 70S AND PW VALUES FROM 2.0-2.25 INCHES.

HOWEVER...LOW AND MIDLEVEL LAPSE RATES ARE VERY WEAK...WHICH WILL

LIMIT MUCAPE VALUES TO LESS THAN 1000 J/KG THROUGHOUT THE FORECAST

PERIOD.

DURING THE DAY TIME HOURS...AN ISOLATED STRONG TO SVR DOWNBURST WILL

BE POSSIBLE WITH STRONGER UPDRAFT CORES...GIVEN THE VERY MOIST

AIRMASS. BY EVENING/NIGHT...AN UPPER TROUGH WILL BECOME BETTER

DEFINED OVER TX...AND SURFACE LOW PRESSURE WILL PROGRESS E-NEWD

ACROSS SRN INTO ERN TX. THIS MAY LEAD TO THE DEVELOPMENT OF ANOTHER

NOCTURNAL MCS MOVING ACROSS THE TX GULF COAST REGION. IN ADDITION TO

AN ISOLATED DAMAGING WIND GUST THREAT...THE POTENTIAL FOR A BRIEF

TORNADO WILL ALSO EXIST AS LOW-LEVEL WINDS AND VERTICAL SHEAR

STRENGTHEN SLIGHTLY TONIGHT.

That time has arrived, when one checks the SPC page before/instead of the NHC page. Will try to watch the battle of two former SWC teams I never liked very much, just because the only thing better than football in a monsoon is football in a blizzard, and well, in September, one has to be realistic.

[Ed Lizard]

I'm hoping out evening line of strong storms is just starting to develop between Uvalde and the Rio Grande now. Not sure of that, but I am a naturally silver lining optimist guy.

HRRR still suggests biggest fun may be Southwest counties HGX CWA and into CRP area... Would be area that gets best insolation today...

[andyhb]

SEVERE WEATHER STATEMENT

NATIONAL WEATHER SERVICE CORPUS CHRISTI TX

421 PM CDT SAT SEP 29 2012

TXC057-292200-

/O.CON.KCRP.TO.W.0056.000000T0000Z-120929T2200Z/

CALHOUN-

421 PM CDT SAT SEP 29 2012

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CDT FOR NORTHERN

CALHOUN COUNTY...

AT 418 PM CDT...WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE A

SEVERE THUNDERSTORM WITH STRONG ROTATION. THIS TORNADO WAS LOCATED

NEAR KAMAY...OR 8 MILES WEST OF PORT LAVACA...MOVING EAST AT 10 MPH.

* LOCATIONS IMPACTED INCLUDE...

KAMAY...

PORT LAVACA...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO MAY ALREADY BE ON THE GROUND...OR IS EXPECTED TO DEVELOP

SHORTLY. IF YOU ARE IN THE PATH OF THIS DANGEROUS STORM...MOVE

INDOORS AND TO THE LOWEST LEVEL OF THE BUILDING. STAY AWAY FROM

WINDOWS. IF DRIVING...DO NOT SEEK SHELTER UNDER A HIGHWAY OVERPASS.

THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A

WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS

AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN

INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO

COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.

IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A

SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE

NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

[Srain]

As nice cool morning on tap for the first day of October with upper 50's/low 60's across the Northern half of the region. It appears a short wave will drop SE tomorrow in the NW flow aloft and bring a chances of showers/storms to the area. Those looking for that first strong fall cold front may not have to wait too much longer. The first snow of the season may be ahead later in the week for Colorado and that front should arrive during the weekend into Central/SE Texas. There are hints of a stronger front next week, but that is still too far out to know with any certainty just how it will play out. That said the pattern does suggest that a transition to more active cold fronts are ahead as we transition from a summer pattern to that of a fall like pattern when those fronts dive S from Canada and increase in frequency. Tis that time of the year after all...

[wxmx]

As nice cool morning on tap for the first day of October with upper 50's/low 60's across the Northern half of the region. It appears a short wave will drop SE tomorrow in the NW flow aloft and bring a chances of showers/storms to the area. Those looking for that first strong fall cold front may not have to wait too much longer. The first snow of the season may be ahead later in the week for Colorado and that front should arrive during the weekend into Central/SE Texas. There are hints of a stronger front next week, but that is still too far out to know with any certainty just how it will play out. That said the pattern does suggest that a transition to more active cold fronts are ahead as we transition from a summer pattern to that of a fall like pattern when those fronts dive S from Canada and increase in frequency. Tis that time of the year after all...

Could be, although if the energy stays near the west coast, only a glancing blow, with a couple of days slightly below normal and very warm after that could ensue. 0z Euro has a very strong SE ridge at the end of the run.

[Srain]

Morning e-mail from Jeff:

Active upper level pattern remains in place over the US with deep troughing over the eastern US. Western edge of this deep trough lies across much of the central and southern plains with a strong short wave noted over NC TX this morning between Dallas and Wichita Falls. While the air mass over the region is fairly dry, especially in the low levels, the strong ascent that will be yielding by the approaching short wave today along with its associated cold pool aloft may generate a few showers and thunderstorms. Best chances will be west of I-45 where surface temperatures will rise into the mid to upper 80’s making the air mass increasingly unstable. Dry sub cloud layer will support strong gusty winds near the thunderstorms.

After today the eastern US trough begins to push eastward allowing onshore winds to return to the area and a gradual warming trend. Not overly impressive with the degree of moisture return behind this latest system and suspect that pleasant weather will continue into Thursday with only a slow increase in afternoon highs and morning lows. A weak frontal boundary will advance southward toward the end of the week, but stall well north of SE TX on Friday. Compressional heating ahead of this boundary could result in highs pushing or exceeding 90 on Friday.

Big changes heading into the weekend as fairly strong surface high pressure for this time of year plunges southward out of Canada and down the plains bringing a strong cold front through TX over the weekend. Stalled frontal boundary near the Red River Friday afternoon will begin to surge southward on Friday night and should reach our northern counties by early Saturday and then blast off the coast by Saturday afternoon/evening. Decent cold air advection and gusty NW winds will follow the front with temperatures falling from the mid and upper 80’s into the 70’s behind the front and into the mid to lower 50’s by Sunday morning. GFS shows moisture becoming trapped in a fairly deep layer between 900 and 700mb in the post frontal air mass suggesting and cloudy and chilly day on Sunday. While model forecast high temperatures are in the mid 70’s, if the clouds pan out as expect, highs will not get out of the 60’s on Sunday with gusty NW winds. Moisture looks fairly meager with this front, maybe a thin line of showers right along the boundary or behind it Saturday afternoon. Post frontal lift appears weak with more clouds than precipitation. Plenty of time to fine tune the weekend temperature forecast as we are still several days out from the event.

Weekend Rainfall Totals (Friday-Sunday)

Houston County (Grapeland area): 10.55

La Pryor: 8.39

Hallettsville: 5.69

San Marcos: 4.81

San Antonio: 3.71

Port Lavaca: 4.13

Palacios: 3.64

Sugar Land: 1.77

Huntsville: 2.32

College Station: 2.69

[Srain]

A brief warm up is ahead through Friday before fairly stout cold fronts drops into Central/SE Texas during the day on Saturday. Over running clouds and light drizzle/light rain along with gusty N to NW winds should make for good home cooked chili weather overnight Saturday into Sunday as temps struggle to reach the low 60's and even some upper 50's for highs on Sunday in the Hill Country and Northern Areas. The Panhandle/Permian Basin may well see temps dip into the 30’s, so this in fact is a strong front for this time of year as Lubbock usually doesn’t see its first freeze until the 31^st. Temps may well fall into the upper 40's Sunday night/early Monday if we can clear out and get some radiational cooling as the winds relax. It appears a return flow will re establish next Tuesday as a deep upper low to our W in California begins to meander E and possibly bring a return of plentiful moisture to the Lone Star State later next week. We will see how that longer range forecast plays out. Meanwhile, enjoy the warmth while it lasts. The weekend is looking cool and dreary.

[Srain]

Morning e-mail from Jeff:

Decent cold front for early October will arrive on Saturday with much colder conditions in place for Sunday.

Cold air mass has dropped out of Canada into the northern Rockies this morning with temperatures in the 20’s and 30’s across much of Wyoming and Colorado. This front has made it southward into the TX panhandle and western Oklahoma where strong north winds gusting to 40mph and temperatures in the 40’s and 50’s can be found. The first short wave will be passing into the Great Lakes today with the frontal push slowing. A very warm day is expected both today and Friday with highs pushing into the low 90’s with humid conditions. Secondary short wave will drop through the developing trough over the eastern US and plow the frontal boundary southward starting Friday. Front should clear north TX and enter our northern counties early Saturday morning and then cross the area and move offshore by early evening. Some timing differences with respect to frontal movement on Saturday yield great differences in high temperatures. Think northern counties will see highs prior to the front moving through with temperatures possibly reaching the upper 70’s before falling into the 60’s under gusty NW winds. Central and southern counties will likely warm into the mid and possibly upper 80’s prior to the frontal passage and then fall quickly into the lower 70’s or 60’s behind the front. Exactly when the front passes a location will determine how warm the afternoon temperatures will get. Those with any kind of outdoor activities on Saturday and especially Saturday evening should be prepared for the onset of much cooler and windy conditions.

Rain chances do not look very good with this front as the best upper level support will be well NE of the region and moisture profiles are fairly limited. Could see a thin line of showers right along or behind the boundary especially over the southern counties where temperatures will be warmest prior to the frontal passage and moisture the deepest. Post frontal lift will be general allowing a deck of low clouds to become trapped under the shallow frontal inversion. This low deck will hang tough into Sunday keeping high temperatures well below average for this time of year. Suspect many locations will struggle to reach 70 degrees with clouds and cloud air advection in place. Should the clouds clear sooner than expected high will be warmer (mid to upper 70’s). Lows on Sunday morning will be in the low to mid 50’s under gusty NW winds making it feel chilly. Clearing skies and calming winds on Sunday night/Monday morning will allow good radiational cooling conditions with lows possibly into the lower 50’s in the urban areas and upper 40’s in the rural areas.

Fairly quick warming trend will be in progress by Tuesday of next week with increasing Gulf moisture possibly brining a chance of rain.

[Ed Lizard]

I hate the first cold front of Autumn, and in six weeks, I'll be leaving for work before dawn and getting home after sunset.

Not even in a categorial t-storm risk area, I'd accept upper 40s this early in the season if preceded by a stout squall line.

[DoctorMu]

Mid October through mid-November is actually my favorite time of year in southeast central Texas. There's usually some rain then sun and mild temps. A/C and water down or off saving on that Utility bill.

A booster shot of coolish weather and clouds are on the way. Limited chance of precip unfortunately tomorrow..

[Ed Lizard]

Record low maxima today, San Angelo, Wichita Falls, DFW, Waco, Abilene.

Climate change?

[Ed Lizard]

Changing climate slams Texas, 35ºF in Ft Worth-Alliance, 32ºF in Graham, Texas. That is ZERO Canadian in parts of North Texas!!!

[Srain]

After a couple of cool days, a warming trend is set to begin as a return flow off the Gulf becomes established. A potent fall storm system will begin to meander E across California/Great Basin and slowly trek E toward the Southern Plains. While best the dynamics appear to be further N into the Texas Panhandle/N Texas/Oklahoma area during the mid to late week time frame, the guidance is suggesting some potential for strong to severe storms as a Pacific cool front drops S into Central Texas on Friday into Saturday and the robust upper low ejects into the Southern Plains. The SPC has a ‘see text’ area outline for portions of N Texas/Oklahoma in the day 3 time frame for potential super cell development. After several days of a strong return flow off the Gulf and increasing moisture and developing low level jet as well as a rather impressive tap of EPAC moisture along with a developing split flow, conditions may develop for a fall severe weather episode as we head toward the end of the week. We will see.

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0217 AM CDT MON OCT 08 2012

VALID 101200Z - 111200Z

...SYNOPSIS...

EASTERN PACIFIC BLOCKING APPEARS LIKELY TO CONTINUE SLOWLY BREAKING

DOWN DURING THIS FORECAST PERIOD. WHILE THE CLOSED LOW NEAR THE

CALIFORNIA COAST IS EXPECTED TO REMAIN CUT-OFF FROM THE STRONGER

WESTERLIES...MODELS DO SUGGEST IT WILL TURN EASTWARD AND BEGIN TO

SLOWLY ADVANCE INLAND. DOWNSTREAM...CONFLUENT BELTS OF WESTERLIES

ACROSS THE ROCKIES INTO THE ATLANTIC SEABOARD ARE FORECAST TO BECOME

MORE ZONAL...AS A VIGOROUS IMPULSE WITHIN THE SOUTHERN PORTION OF A

NORTHERN STREAM SHORT WAVE TROUGH ACCELERATES EAST NORTHEAST OF THE

GREAT LAKES REGION...AND THROUGH THE NEW ENGLAND. AN ASSOCIATED

SURFACE FRONT IS EXPECTED TO SURGE OFF THE NORTH ATLANTIC

COAST...WHILE STALLING/WEAKENING ACROSS THE SOUTHEAST INTO THE

SOUTHERN PLAINS...BEFORE BEGINNING TO LIFT NORTHWARD ACROSS THE

PLAINS/OZARK PLATEAU WEDNESDAY NIGHT. AT THE SAME

TIME...THOUGH...IT APPEARS ANOTHER MORE SIGNIFICANT COLD SURFACE

RIDGE WILL BEGIN NOSING SOUTHWARD TO THE LEE OF THE NORTHERN

ROCKIES.

...PARTS OF SRN PLAINS INTO LWR/MID MS VALLEY...

AN INFLUX OF MOISTURE SHOULD CONTINUE ON SOUTHERLY LOW-LEVEL FLOW

OFF THE GULF OF MEXICO. SUBSTANTIVE BOUNDARY LAYER DESTABILIZATION

APPEARS POSSIBLE NEAR THE SURFACE FRONT ACROSS NORTHERN TEXAS AND

PARTS OF THE ARKLATEX BY LATE WEDNESDAY AFTERNOON...BENEATH REMNANT

ELEVATED MIXED LAYER. NAM FORECAST SOUNDINGS INDICATE MIXED LAYER

CAPE EXCEEDING 2000 J/KG...IN THE PRESENCE OF WIND PROFILES

GENERALLY CHARACTERIZED BY VEERING WITH HEIGHT BENEATH MODEST

WESTERLY MID/UPPER FLOW. CONDITIONS MAY BECOME SUFFICIENT FOR

SUPERCELL DEVELOPMENT...BUT FORCING FOR UPWARD VERTICAL MOTION

BENEATH SOUTHERN STREAM RIDGING REMAINS UNCLEAR.

STORM DEVELOPMENT APPEARS A BIT MORE PROBABLE NORTH OF THE SURFACE

FRONT DURING THE EVENING/OVERNIGHT HOURS...SUPPORTED BY AREAS OF

STRENGTHENING LOWER/MID TROPOSPHERIC WARM ADVECTION...ACROSS

PORTIONS OF THE SOUTHERN HIGH PLAINS...AND THE RED RIVER VALLEY

NORTHWARD INTO PARTS OF THE CENTRAL PLAINS AND MIDDLE MISSISSIPPI

VALLEY. SOME OF THIS ACTIVITY...IN CLOSER PROXIMITY TO THE BETTER

LOW-LEVEL MOISTURE ACROSS THE SOUTHERN PAINS...MAY BE ACCOMPANIED BY

THE RISK FOR SEVERE HAIL...BUT COVERAGE IS STILL TOO UNCERTAIN FOR

SLIGHT RISK PROBABILITIES AT THE PRESENT TIME.

..KERR.. 10/08/2012

[Srain]

Morning e-mail from Jeff:

Cool surface dome of high pressure is over the area this morning with weak overrunning cloudiness starting to erode from the north. Should see clouds continue to break and scatter out over the next 2-4 hours with sun eventually for most areas by late afternoon. Decreasing clouds should result in a nice warm up into the mid to upper 70’s by this afternoon.

Surface high pressure moves off to the east ending our brief cool spell. Onshore winds return to the area starting early Tuesday and will be in place for several days. Morning lows will creep into the 60’s while afternoon highs warm into the upper 80’s under increasingly humid conditions. The chance of rain will remain on the low side through the end of the week. Toward next weekend the next trough from the west will move into the region, but the main impacts look to be north of our area over the central plains. Deepening moisture profiles may support at least a 20-30% rain chance by Saturday or Sunday.

[patrick7032]

Another cold morning here in West Central Texas.

RECORD EVENT REPORT

NATIONAL WEATHER SERVICE SAN ANGELO TX

745 AM CDT MON OCT 8 2012

...RECORD DAILY LOW TEMPERATURES SET AT ABILENE AND SAN ANGELO...

A RECORD LOW TEMPERATURE OF 34 DEGREES WAS SET THIS MORNING AT THE

ABILENE REGIONAL AIRPORT. THIS TEMPERATURE TIES THE OLD RECORD OF 34

DEGREES WHICH WAS SET IN 1921.

A RECORD LOW TEMPERATURE OF 36 DEGREES WAS SET AT MATHIS FIELD THIS

MORNING. THIS TEMPERATURE BREAKS THE OLD RECORD OF 37 DEGREES WHICH

WAS SET IN 1952.

$$

DOLL