May: Slight Risk Severe Storms Thursday To End The Month

[weatherguy425]

THERE IS LOT OF UNCERTAINTY ON HOW
MUCH RAINFALL FOR THE MIDDLE TO LATE NEXT WEEK. WILL KEEP THE SLGT
CHC POPS GOING. THE BOTTOM LINE...MOST AREAS WILL PROBABLY SEE
LITTLE TO NO RAINFALL. ALSO...WEST CENTRAL TEXAS IS HEADING BACK
INTO A SHORT TERM DROUGHT AS THE PAST 60 DAYS OF RAINFALL IS ONLY 10
TO 60 PERCENT OF NORMAL ACROSS MUCH OF THE CWFA.

Quite a pre-maturely bold statement out of San Angelo NWS regarding next week, especially with them being a favored location for rain in this kind of set-up.

[srainhoutx]

The guidance is in a bit better agreement regarding the return of showers/storms in the up coming week. After a dry period for much of the last several weeks, a fairly significant rain maker appears to be ahead as a robust cut off upper low drops into California/Baja and slowly treks across Old Mexico early next week. A Pacific frontal boundary will sag S across Central/SE TX and stall setting the stage for several days of showers and storms, some possibly severe with gusty winds and hail being the primary threat.

The sub tropical jet becomes rather noisy with embedded short wave energy swinging beneath the upper low setting the stage for several rounds of storms on Tuesday into Wednesday with the SW flow aloft. The upper low should finally begin to head across Texas next Thursday into Friday and shear out as a deep trough becomes established across the Eastern half of the US. Some early indications suggest a rather widespread 2-3 inches of rainfall with isolated amounts nearing 5 inches possible for the Hill Country Lakes Region as strong storms develop near the Rio Grande and slowly march E into SE TX. Should this event pan out, cooler temps and sorely needed rainfall will be the theme of the upcoming week. Stay Tuned! Our boring weather pattern of late may well turn a bit more active.

[Belmer]

One of the most intense lightning storms just rolled through the San Marcos/Austin area. Lightning and thunder...just amazing. I was outside on a porch with a few of my friends here in San Marcos when the storms came through, talked to two different people from Austin of reports of Hail. Definitely was not expecting this. This caught a lot off guard. It sure was nice to see rain again after 3+ weeks of dry weather.
Line of storms is somewhat loosing strength, but still packing a punch heading toward Houston. Crossing my fingers it stays together long enough to reach you all.

[srainhoutx]

A dying MCS is approaching SE TX from the W this morning and showers are possible along and S of I-10 early in the day. The 06Z WRF/NMM model is suggesting a breakable cap later this afternoon if skies can clear out a bit allowing temps to reach 90F and new storms fire in a 'cold pool' aloft across areas along and N of the I-10 Corridor. Those with afternoon outdoor plans may need to keep and eye to the sky for another round of heavy storms with frequent lightening near the Houston Metro should the cap break.

Looking ahead to Tuesday-Wednesday, a Pacific boundary drops into our area suggesting increase showers/storms, some possibly severe. The slow meandering cut off upper low will near the region from the W late Thursday with an increase of moisture and a return flow from the Gulf suggesting late week strong storms once again before we clear out and cool down rather significantly. Some guidance is even suggesting night time lows in the upper 50's for next weekend bring a rather big change temp wise. We'll monitor those trends as the week ahead progresses and we enter a more active weather pattern.

[Ptarmigan]

It is dying...

If the remnant can hold together, it could re-fire up from heat of the day. However, it is cloudy, so perhaps not.

[srainhoutx]

The sun has broken through the clouds and the CU field to our W is expanding as temps rise into the upper 80's in NW Harris County. Carefully watching to our W along I-10 and further W toward the dryline where towering CU's are beginning to pop. Can we brake the cap? We will see.

[Portastorm]

One of the most intense lightning storms just rolled through the San Marcos/Austin area. Lightning and thunder...just amazing. I was outside on a porch with a few of my friends here in San Marcos when the storms came through, talked to two different people from Austin of reports of Hail. Definitely was not expecting this. This caught a lot off guard. It sure was nice to see rain again after 3+ weeks of dry weather.
Line of storms is somewhat loosing strength, but still packing a punch heading toward Houston. Crossing my fingers it stays together long enough to reach you all.

Yeah Belmer, it hit here (SW Austin) around 1 am and caught a lot of us off guard. We had very vigorous cloud-to-ground lightning for quite some time as well as more than 2 inches of rainfall. The mesoscale system was welcomed but definitely a surprise. Will be interesting to see if the I-35 corridor is affected again tonight by another MCS and if the atmosphere will de-stabilize enough today after that little post-MCS mesohigh calmed things down.

Hoping for another MCS tonight and for our SE Texas friends to "break the cap" and get some rain.

[weatherguy425]

Dry-line convection firing Northwest of the Austin area, as well as a few echoes now showing up within a growing CU field to the west of the greater Houston area.

[Ptarmigan]

Couple of teeny cells in Harris and Montgomery Counties trying to get going.

Go, little fellas, go!

Hopefully, it gets larger, so we get rain too.

[Kludge]

If it appears to you that the only thing happening in SE Texas is a "little" complex over NW Gimes County.... well that would be me.

Time to batten down the hatches... could get rough...

[srainhoutx]

Pea size hail reported up your way, Kludge. The cap broke...for you at least...a sign of things to come this week for many I'm willing to bet...

[srainhoutx]

http://www.spc.noaa.gov/products/md/md0738.html

[Katdaddy]

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
650 PM CDT SUN MAY 6 2012

TXC185-339-471-070015-
/O.CON.KHGX.SV.W.0080.000000T0000Z-120507T0015Z/
GRIMES TX-MONTGOMERY TX-WALKER TX-
650 PM CDT SUN MAY 6 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM
CDT FOR GRIMES...NORTHWESTERN MONTGOMERY AND EXTREME SOUTHWESTERN
WALKER COUNTIES...

AT 645 PM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS
STORM WAS LOCATED NEAR NAVASOTA...MOVING EAST AT 15 MPH.

LOCATIONS IMPACTED INCLUDE...
RURAL SOUTHERN GRIMES COUNTY...NAVASOTA...ANDERSON...ROANS
PRAIRIE...DACUS...AND MONTGOMERY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 60 MILES
PER HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY
RAIN. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST
FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO
DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR
LARGE HAIL AND DAMAGING WINDS. PEOPLE OUTSIDE SHOULD MOVE TO A
SHELTER...PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM
WINDOWS.

&&

LAT...LON 3073 9579 3037 9556 3032 9605 3049 9608
TIME...MOT...LOC 2345Z 256DEG 14KT 3041 9599

[Baseballdude2915]

Havent been on here in a while! I sorta need around half an inch of rain to cancel an event I will otherwise miss this weekend. I knew where to go to get the right answer. Ill be back on here for hurricane season for sure.

Anyway, looking at the GFS, I might just get my wish for a nice shower before the event this Saturday. Looks like a low spins overhead mid-day friday making it a rather wet day. What do you vets think about this set up coming to reality?

[srainhoutx]

The over night guidance is rather good agreement for the week ahead and suggests plentiful rainfall for parts of the Lone Star State and particularly for those areas that are still in a severe drought situation in W Texas. The guidance has also trended a tad further N with the slow moving upper low ejecting from Old Mexico later in the week and may bring rain chances further inland as the week progresses for Friday into Saturday morning before shearing out and heading E. We will see if that late week trend continues.

[srainhoutx]

Morning e-mail from JEff:

Chances for showers and thunderstorms will be on the increase from this afternoon through the end of the week.



Quite upper level pattern for the past several weeks dominated by high pressure aloft has been transitioning to a more active pattern since last Friday. Ridging over SE TX is losing ground with the thermal profile improving aloft as the mid level capping which has kept convection at bay for the past several weeks weakens.



At the surface a fairly chaotic pattern is in play with numerous outflow boundaries from overnight thunderstorm complexes to our northwest moving toward/into the area. Additionally, there is likely a few boundaries leftover from the late afternoon storms yesterday over the northern portions of our area and the water vapor and IR images show a series of gravity waves moving SSW to S across central and SC TX this morning. On top of all of this, there is a moderately defined meso vorticity center (MVC) located upstream of the area over N TX from the overnight storm complex and a cold front over NW TX moving SE. Air mass across the region will become very unstable by mid afternoon due to surface heating with SB CAPE pushing into the 3000-3500 J/kg range and LI’s falling into the -2 to -4 range. Convective trigger temperatures have decreased from the 89-92 degree range yesterday into the 86-89 degree range for today based on the forecasted soundings for late this afternoon at College Station and IAH. Once trigger temperatures are achieved, expect thunderstorms to begin to develop along old boundaries and ahead/near SE moving N TX MVC. Lowest trigger temperatures and best chances for storms will be along and north of I-10 although short term rapid refresh guidance is suggesting southward moving activity late this afternoon could make it into the metro area before running against slightly more unfavorable capping south of I-10.



Forecasted soundings show the potential for a few severe thunderstorms this afternoon/evening where activity develops with wind damage being the main threat. General feeling is that the threat is too isolated for a regional slight risk outlook from SPC, but a few reports of strong/severe winds or hail will be possible.



Tues-Wed:

Upstream frontal boundary over NW TX currently, will progress southward and eventually off the TX coast by late Wednesday. Expect strong heating today along this boundary coupled with upslope ESE flow off the western Gulf toward the high terrain of NE MX to set off early evening severe thunderstorms. Models are in decent agreement with activity over both the Hill Country and NE MX this evening merging and growing upscale into a large thunderstorm complex (MCS). Favorable low level inflow off the western Gulf coupled with strong moisture convergence will likely maintain this complex well into the night and into Tuesday morning. Expect activity in some form to approach our western counties by early Tuesday morning, and either the complex itself or its outflow boundaries/MVC will arrive into the area on Tuesday sparking more widespread storms. Additionally the frontal boundary itself will move into the region adding an additional focus. With such an environment driven by the meso (small scale) features, there is plenty of room for the forecast models to either under or over estimate the amount of rainfall coverage. Forecasting will be highly driven by previous day events and small scale features nearly impossible to predict more than 12 hours in advance.



Thurs:

Brief break in the active weather on Thursday as drier air seeps into the area from the NE and the frontal boundary slips into the NW Gulf. I am very wary of the active SW flow pulling up our of MX and for any potential weak impulses that models are not seeing this far out…hence rain chances could be added to Thursday as we more through the week.



Fri-Sat:

Strong upper level storm system which will dig down into the Baja region today and Tuesday will eject ENE across N MX and toward TX Fri-Sat. Frontal boundary over the NW Gulf will begin to surge back north late Thursday as strong system nears the Mexican border. Suspect returning warm front may spark a round of thunderstorms Thursday night followed by the main event Friday-Friday night as the upper low moves across central TX. Fairly slow storm motion by the main system and tremendous moisture advection ahead of the feature is raising the red flags for heavy rainfall and potential flooding, especially given the several days of “wetting” rainfall that will be possible today-Wed. Severe weather will also be possible with this system, but it is still too far out to talk about the details just yet.



Rainfall:

Widespread rainfall amounts of 1-2 inches appear likely by late Wednesday aver the region, with some areas likely seeing much higher totals up to 4 inches possible. Grounds have dried over the past several weeks with the lack of rainfall and high temperatures, and much of the rainfall will go into saturating the soil although some local run-off problems may be possible especially under the higher totals. End of the week event is more concerning as totals begin to stack up and grounds become soggy saturated with time. Not overly confident at the moment on the placement of the heavy rainfall axis Fri-Sat with both the GFS and HPC showing most offshore with the ECMWF more inland. Think the inland solution is likely on the more correct track, but this is still 4 days away!

[srainhoutx]

For our neighbors in Central Texas:

FLOOD WATCH
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
328 AM CDT MON MAY 7 2012

...A FLASH FLOOD WATCH IS IN EFFECT THIS EVENING THROUGH TUESDAY
AFTERNOON FOR THE HILL COUNTRY AND THE ADJACENT AREAS OF SOUTH
CENTRAL TEXAS...

.A SLOW MOVING COLD FRONT WILL PUSH SLOWLY SOUTHWARD INTO THE HILL
COUNTRY AND SOUTH CENTRAL TEXAS TONIGHT. THE COLD FRONT WILL
INTERACT WITH MOIST UNSTABLE GULF AIR ACROSS SOUTH TEXAS COMBINED
WITH UPPER AIR DISTURBANCES MOVING NORTHEAST ACROSS THE FRONTAL
BOUNDARY. THIS WILL RESULT IN THE POTENTIAL FOR HEAVY RAINFALL
OVERNIGHT INTO TUESDAY AS SLOW MOVING THUNDERSTORMS TRAIN ALONG
THE COLD FRONT ACROSS THE AREA.

THE FLASH FLOOD WATCH IS GENERALLY ALONG AND WEST OF INTERSTATE 35
FROM GEORGETOWN TO SAN ANTONIO...AND ALONG AND NORTH OF A LINE
FROM SAN ANTONIO TO DEL RIO. AVERAGE RAINFALL AMOUNTS ACROSS THE
WATCH AREA TONIGHT AND TUESDAY WILL BE BETWEEN 1 AND 2 INCHES.
SPOTTY ISOLATED RAINFALL TOTALS OF 3 TO 5 INCHES ARE POSSIBLE.

TXC019-029-031-053-091-137-171-209-259-265-271-299-325-385-453-
463-465-491-071600-
/O.NEW.KEWX.FF.A.0004.120507T2300Z-120508T2100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BANDERA-BEXAR-BLANCO-BURNET-COMAL-EDWARDS-GILLESPIE-HAYS-KENDALL-
KERR-KINNEY-LLANO-MEDINA-REAL-TRAVIS-UVALDE-VAL VERDE-WILLIAMSON-
INCLUDING THE CITIES OF...BANDERA...SAN ANTONIO...BLANCO...
BURNET...NEW BRAUNFELS...ROCKSPRINGS...FREDERICKSBURG...
SAN MARCOS...BOERNE...KERRVILLE...BRACKETTVILLE...LLANO...HONDO...
LEAKEY...AUSTIN...UVALDE...DEL RIO...GEORGETOWN
328 AM CDT MON MAY 7 2012

...FLASH FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH TUESDAY
AFTERNOON...

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A

* FLASH FLOOD WATCH FOR THE FOLLOWING COUNTIES IN SOUTH CENTRAL
TEXAS...BANDERA...BEXAR...BLANCO...BURNET...COMAL...EDWARDS...
GILLESPIE...HAYS...KENDALL...KERR...KINNEY...LLANO...MEDINA...
REAL...TRAVIS...UVALDE...VAL VERDE AND WILLIAMSON.

* FROM THIS EVENING THROUGH TUESDAY AFTERNOON

* AVERAGE STORM TOTAL RAINFALL AMOUNTS OF 1 TO 2 INCHES WITH
HIGHER TOTALS OF 3 TO 5 INCHES POSSIBLE.

* THESE HEAVY RAINS WILL PRODUCE FLASH FLOODING OF NORMALLY DRY
CREEK BEDS...POOR DRAINAGE AREAS...LOW WATER CROSSINGS. RAPID
RISES ON AREA RIVERS AND LARGER STREAMS WILL LIKELY MAKE SOME
ROADWAYS IMPASSABLE. THE FLASH FLOOD IMPACT WILL BE HIGHEST
OVERNIGHT TONIGHT INTO TUESDAY MORNING.

[MontgomeryCoWx]

Now we are back in business... give me 4-5 inches this week and I'll be happy.

[srainhoutx]

The SPC expands Slight Risk today a large portion of Texas from just E of the Big Bend including W TX into S Central/Central and parts of the northern areas of SE TX on NE to the ARKLATX area.

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1117 AM CDT MON MAY 07 2012

VALID 071630Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF SERN NM/SWRN
TX INTO THE LOWER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER OH
VALLEY...

...SYNOPSIS...

UPPER LOW OVER SRN MANITOBA WILL EVOLVE INTO AN OPEN WAVE AND
ELONGATE IN SW-NE FASHION FROM THE CNTRL HIGH PLAINS INTO UPPER
GREAT LAKES WHILE SWRN U.S. TROUGH FORMS A CLOSED CIRCULATION OVER
THE LOWER CO VALLEY. ELSEWHERE...A VORTICITY MAXIMUM OVER THE MID
MS VALLEY WILL PROGRESS ACROSS THE OH VALLEY TODAY WITHIN GENERALLY
WEAK WSWLY FLOW REGIME.

AT THE SURFACE...COLD FRONT FROM THE UPPER MS VALLEY THROUGH OZARKS
INTO CNTRL TX WILL ADVANCE EWD/SEWD...REACHING THE UPPER OH VALLEY
THROUGH LOWER MS VALLEY INTO LOWER RIO GRANDE VALLEY BY 08/12Z.
THIS FRONT AND PRE-EXISTING CONVECTIVE OUTFLOW BOUNDARIES WITHIN
WARM SECTOR WILL SERVE AS FOCI FOR STRONG-SEVERE TSTM DEVELOPMENT
THIS AFTERNOON AND EVENING.

...LOWER MS VALLEY INTO SWRN TX/SERN NM...

12Z OBSERVED SOUNDINGS REVEAL THAT EML AND ASSOCIATED STEEP MIDLEVEL
LAPSE RATE PLUME HAS BEEN CONFINED TO THE SLIGHT RISK AREA. WHEN
COUPLED WITH A MOIST BOUNDARY LAYER AND POTENTIAL FOR STRONG DAYTIME
HEATING...EXPECT AFTERNOON WARM SECTOR TO ONCE AGAIN BECOME
MODERATE-STRONGLY UNSTABLE WITH MLCAPE VALUES APPROACHING 2000-3500+
J/KG.

INTERACTION OF AN ACTIVE COLD POOL ASSOCIATED WITH ONGOING STORMS
OVER NRN MS WITH A MODERATELY UNSTABLE AIR MASS IS EXPECTED TO
SUPPORT THE CONTINUED SWD/SEWD MOVEMENT OF MCS TODAY ACROSS PORTIONS
OF THE LOWER MS VALLEY. VERTICAL SHEAR WILL REMAIN RATHER
WEAK...THOUGH THE STEEP LAPSE RATES AND POTENTIAL FOR UPSCALE COLD
POOL GROWTH WILL SUPPORT A FEW SEVERE STORMS CAPABLE OF DAMAGING
WINDS AND HAIL. FOR ADDITIONAL NEAR-TERM GUIDANCE ON THIS
AREA...REFERENCE MCD 742.

OVER THE ARKLATEX INTO CNTRL TX...LATEST MODEL GUIDANCE SUGGESTS
THAT TSTMS SHOULD INCREASE IN COVERAGE ALONG THE COLD FRONT THIS
AFTERNOON. HERE TOO...VERTICAL SHEAR WILL REMAIN MARGINALLY
SUPPORTIVE OF STORM ORGANIZATION. BUT...THE PRESENCE OF STRONG
INSTABILITY WILL PROMOTE INTENSE UP/DOWNDRAFTS WITH AN ATTENDANT
RISK FOR LARGE HAIL AND DAMAGING WINDS.

FARTHER W...BACKED LOW-LEVEL WIND FIELD AND GRADUALLY STRENGTHENING
SWLY MIDLEVEL FLOW DOWNSTREAM FROM SWRN U.S. UPPER LOW WILL RESULT
IN A VERTICAL WIND PROFILE SUPPORTIVE OF SUPERCELLS LATER THIS
AFTERNOON INTO TONIGHT. THE COMBINATION OF THE FRONT AND UPSLOPE
INTO THE HIGHER TERRAIN OF SERN NM/SWRN TX/NRN MEXICO WILL LIKELY
FOSTER WIDELY SCATTERED-SCATTERED TSTMS LATER TODAY. LARGE HAIL
WILL BE THE PRIMARY RISK INITIALLY...THOUGH THE POTENTIAL FOR
DAMAGING WINDS WILL INCREASE BY EVENING AS STORMS MERGE INTO
CLUSTERS OR AN MCS. A TORNADO OR TWO IS ALSO POSSIBLE LATE THIS
AFTERNOON INTO EVENING WITH ANY SUSTAINED SUPERCELL STRUCTURES.

...OH/TN VALLEYS...

DESPITE THE PRESENCE OF A MOIST BOUNDARY LAYER...12Z REGIONAL
SOUNDINGS INDICATE THAT WEAK MIDLEVEL LAPSE RATES AND VERTICAL SHEAR
ARE EXPECTED TO LIMIT THE POTENTIAL FOR ORGANIZED SEVERE TSTMS
THROUGH THIS EVENING. THE EXCEPTION MAY BE OVER PORTIONS OF THE
UPPER OH VALLEY WHERE DEEP-LAYER SHEAR MAY BE ENHANCED BY THE LOCAL
BACKING OF LOW-LEVEL WINDS AHEAD OF A MIGRATORY FRONTAL WAVE.
HERE...POTENTIAL WILL EXIST FOR MARGINAL SUPERCELL STRUCTURES WITH A
RISK FOR HAIL...DAMAGING WINDS...AND PERHAPS A BRIEF TORNADO.

..MEAD/LEITMAN.. 05/07/2012

[srainhoutx]

Storms are rapidly developing along the slow moving boundary W of San Angelo. That boundary extends across the Hill Country Lakes and on NE to Corsicana. The regions near that boundary area will be the focal point for future storm development as the afternoon/evening wears on, I suspect.