May: Isolated Showers To End The Month

[srainhoutx]

E-mail update from Jeff:

SPC has issued a Severe Thunderstorm Watch until 1000pm for the NE ½ of SE TX of roughly NE of a line from College Station to Sugar Land to Galveston.

At 330pm a line of severe thunderstorms was located from SE of Waco to NW of College Station moving ESE at 25mph. These storms will be moving into our NW set of counties over the next 1 hour and into much of our northern tier of counties this evening. Low level inflow off the Gulf of Mexico is increasing feeding this line and expect the segment nearing College Station to begin to bow toward the ESE/SE over the next few hours increasing the threat for wind damage along the leading edge of the line.

South of this line capping continues to hold strong and expect this complex to push SE toward the Galveston Bay/Liberty Co area by 800-900pm this evening with a trailing outflow boundary WNW back toward Austin. This boundary will become very slow moving over the next 12 hours and may focus additional severe storms and heavy rainfall as the next disturbance moves out of MX on Friday. This thinking is supported by latest short term models.

It should be noted that the potential is there for a few wind gust to 70-75mph this afternoon/evening with this bowing line of storms. This will be capable of downing trees and causing power outages.

[ticka1]

will houston or the east side see these storms?

[srainhoutx]

Flash Flood Warning issued for Byran/College Station

[srainhoutx]

E-mail update from Jeff:

Complex of severe thunderstorms producing rainfall amounts of 1-2 inches per hour over Brazos, Madison, and Walker Counties.

Visible and IR images/loops show a classic “V” signature to the cloud pattern with this complex of storms suggesting low level jet inflow from the SSW of 25-35kts is favorably feeding moist Gulf air NNE into the backside of this complex of storms. Law enforcement and media report flooding ongoing across Bryan/College Station as cell training is in progress. Main vort associated with this complex of storms is lifting ENE south of Dallas with trailing outflow boundary from Bastrop County to N Grimes County. Visible images suggest cumulus field on SW flank of this boundary is becoming agitated and additional storms may blow up shortly if capping can be overcome. Additional development on this boundary would pose a flash flooding risk across Burleson, Brazos, Madison, Grimes, and Walker Counties as cell training continued.

Storm totals of 1-2” are likely with this complex and if additional storms fire on the western flank of the outflow boundary totals of 3-4 inches would be possible.

In addition to the heavy rainfall, storm damaging winds are progressing eastward with the northern bowing segment over Madison and Walker Counties into Houston and Trinity Counties shortly. Widespread wind damage has been reported over Madison Counties and leading edge winds of 60-70mph can be expected shortly across much of Walker and Houston Counties.

Current thinking is that the southern extent of the line will develop into Washington, northern Waller and Montgomery Counties or along the northern edge of stronger capping to the south. Additional storms over NW TX may travel ESE/SE overnight and affect the area early Friday.

[srainhoutx]

NWS Houston/Galveston issues Tornado Warning for Houston & Trinity Counties

[srainhoutx]

Flash Flood Warning issued for Grimes, Montgomery and Walker Counties

[Kludge]

3.1" here so far, with new development on the train noted west of CLL

[jasons2k]

Nice final shot of the day - you can really see the cloud tops contrast:

[Kludge]

Just crossing over the 4" line. Seems WXMAN57 was willing to share a bit this time around.

[Paul Robison]

To whom it may concern:

Anybody besides me got a creepy feeling Houston's going to get even STRONGER storms, Friday? Strong enough that Governor Perry might be looking down at a lot of wrecked homes from a helicopter the next day?

[djjordan]

Watching the small but intense complex moving along IH 10 heading eastward/southeastward. With all the boundaries in place and the next disturbance heading out of Mexico, looks to be an active morning in our CWA. Intense lightning and Large/Very Large Hail has been reported with the complex out near San Marcos/NE San Antonio, etc...

[Paul Robison]

Watching the small but intense complex moving along IH 10 heading eastward/southeastward. With all the boundaries in place and the next disturbance heading out of Mexico, looks to be an active morning in our CWA. Intense lightning and Large/Very Large Hail has been reported with the complex out near San Marcos/NE San Antonio, etc...

Current NOAA thinking is that there COULD be an isolated severe storm or two, but the MAIN threat is heavy rains. Watch it, OK?

[srainhoutx]

weather.gov     
National Weather Service

Watches, Warnings & Advisories


Local weather forecast by "City, St" or zip code

Flood Advisory
FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
244 AM CDT FRI MAY 10 2013

TXC039-071-157-201-291-100945-
/O.NEW.KHGX.FA.Y.0026.130510T0744Z-130510T0945Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LIBERTY TX-FORT BEND TX-CHAMBERS TX-BRAZORIA TX-HARRIS TX-
244 AM CDT FRI MAY 10 2013

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
SOUTHEASTERN LIBERTY COUNTY IN SOUTHEAST TEXAS...
EAST CENTRAL FORT BEND COUNTY IN SOUTHEAST TEXAS...
NORTHWESTERN CHAMBERS COUNTY IN SOUTHEAST TEXAS...
EXTREME NORTH CENTRAL BRAZORIA COUNTY IN SOUTHEAST TEXAS...
HARRIS COUNTY IN SOUTHEAST TEXAS...

* UNTIL 445 AM CDT

* AT 240 AM CDT...DOPPLER RADAR AND AUTOMATED RAIN GAUGES INDICATED
HEAVY RAIN DUE TO THUNDERSTORMS. THIS WILL CAUSE URBAN AND SMALL
STREAM FLOODING IN THE ADVISORY AREA. UP TO 1.5 INCHES OF RAIN HAS
FALLEN IN THE PAST HOUR.

* SOME LOCATIONS THAT WILL EXPERIENCE MINOR FLOODING INCLUDE
PASADENA...BAYTOWN...MISSOURI CITY...CHANNELVIEW...DEER PARK...
CLOVERLEAF...FIRST COLONY...BELLAIRE...SOUTH HOUSTON...WEST
UNIVERSITY PLACE...GALENA PARK...JACINTO CITY...STAFFORD...
HIGHLANDS...FRESNO...BARRETT...MONT BELVIEU...BROOKSIDE VILLAGE...
CROSBY...SHELDON...SOUTHSIDE PLACE...OLD RIVER-WINFREE...AMES...
ARCOLA...DEVERS...COVE AND THOMPSONS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE PONDING OF WATER IN
URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER
POOR DRAINAGE AREAS AND LOW LYING SPOTS. DO NOT ATTEMPT TO TRAVEL
ACROSS FLOODED ROADS. FIND ALTERNATE ROUTES. IT TAKES ONLY A FEW
INCHES OF SWIFTLY FLOWING WATER TO CARRY VEHICLES AWAY.

&&

LAT...LON 2970 9498 2978 9504 2978 9505 2975 9506
2971 9506 2973 9503 2970 9503 2970 9500
2938 9571 2948 9578 2980 9533 3011 9463
2991 9449

$$

40
FLOOD ADVISORY
NATIONAL WEATHER SERVICE LAKE CHARLES LA
250 AM CDT FRI MAY 10 2013

TXC199-241-245-351-361-100945-
/O.NEW.KLCH.FA.Y.0026.130510T0750Z-130510T0945Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
HARDIN TX-JASPER TX-NEWTON TX-JEFFERSON TX-ORANGE TX-
250 AM CDT FRI MAY 10 2013

THE NATIONAL WEATHER SERVICE IN LAKE CHARLES HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR MINOR FLOODING OF POOR
DRAINAGE AREAS IN...
HARDIN COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITIES OF...SOUR LAKE...SILSBEE...SARATOGA...
LUMBERTON...KOUNTZE...
SOUTHEASTERN JASPER COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITIES OF...EVADALE...BUNA...
NORTHERN JEFFERSON COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITIES OF...PORT NECHES...PORT ARTHUR...NOME...
NEDERLAND...GROVES...CENTRAL GARDENS...BEAUMONT...
SOUTHWESTERN NEWTON COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITY OF CALL...
WESTERN ORANGE COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITIES OF...VIDOR...MAURICEVILLE...

* UNTIL 445 AM CDT

* AT 248 AM CDT LINES OF HEAVY SHOWERS AND THUNDERSTORMS CONTINUE TO
PASS REPEATEDLY...IN SUCCESSION...OVER THE SAME LOCATIONS. NUISANCE
FLOODING IS THE RESULT. HEAVY RAINFALL...WITH RATES AROUND 2 INCHES
PER HOUR...WILL OVERWHELM SOME DRAINAGE AREAS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND...DON`T DROWN... MOST FLOOD DEATHS OCCUR IN AUTOMOBILES.
NEVER DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR. JUST ONE
FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP VEHICLES OFF THE
ROAD. WHEN ENCOUNTERING FLOODED ROADS MAKE THE SMART CHOICE...TURN
AROUND...DONT DROWN.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

&&

LAT...LON 3070 9373 2989 9389 2987 9391 2984 9390
2983 9393 2984 9393 2983 9394 2988 9445
3011 9445 3011 9459 3022 9464 3025 9464

$$

JT
FLOOD ADVISORY
NATIONAL WEATHER SERVICE LAKE CHARLES LA
130 AM CDT FRI MAY 10 2013

LAC001-003-011-019-039-053-097-113-TXC351-361-100830-
/O.NEW.KLCH.FA.Y.0025.130510T0630Z-130510T0830Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NEWTON TX-ST. LANDRY LA-EVANGELINE LA-BEAUREGARD LA-ALLEN LA-
ACADIA LA-CALCASIEU LA-ORANGE TX-JEFFERSON DAVIS LA-VERMILION LA-
130 AM CDT FRI MAY 10 2013

THE NATIONAL WEATHER SERVICE IN LAKE CHARLES HAS ISSUED A

* FLOOD ADVISORY FOR...
EXTREME SOUTHWESTERN EVANGELINE PARISH IN CENTRAL LOUISIANA...
THIS INCLUDES THE CITY OF BASILE...
EXTREME WEST CENTRAL ST. LANDRY PARISH IN CENTRAL LOUISIANA...
THIS INCLUDES THE CITY OF EUNICE...
SOUTH CENTRAL NEWTON COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITY OF DEWEYVILLE...
EASTERN ORANGE COUNTY IN SOUTHEAST TEXAS...
THIS INCLUDES THE CITIES OF...WEST ORANGE...ORANGE...
ACADIA PARISH IN SOUTHWEST LOUISIANA...
THIS INCLUDES THE CITIES OF...RAYNE...MERMENTAU...IOTA...CROWLEY...
SOUTHERN ALLEN PARISH IN SOUTHWEST LOUISIANA...
THIS INCLUDES THE CITIES OF...REEVES...KINDER...
SOUTHERN BEAUREGARD PARISH IN SOUTHWEST LOUISIANA...
THIS INCLUDES THE CITIES OF...RAGLEY...FIELDS...
CALCASIEU PARISH IN SOUTHWEST LOUISIANA...
THIS INCLUDES THE CITIES OF...LAKE CHARLES REGIONAL AIRPORT...
WESTLAKE...VINTON...SULPHUR...STARKS...MOSS BLUFF...LAKE CHARLES...
IOWA...HAYES...DE QUINCY...
JEFFERSON DAVIS PARISH IN SOUTHWEST LOUISIANA...
THIS INCLUDES THE CITIES OF...WELSH...LAKE ARTHUR...JENNINGS...
FENTON...ELTON...
NORTHWESTERN VERMILION PARISH IN SOUTHWEST LOUISIANA...

* UNTIL 330 AM CDT

* AT 128 AM CDT LINES OF HEAVY SHOWERS AND THUNDERSTORMS ARE FORMING
AND PASSING REPEATEDLY...IN SUCCESSION...OVER THE SAME LOCATIONS.
NUISANCE FLOODING IS THE RESULT. HEAVY RAINFALL...WITH RATES FROM 2
TO 3 INCHES PER HOUR...WILL OVERWHELM SOME POOR DRAINAGE AREAS.!

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND...DON`T DROWN... MOST FLOOD DEATHS OCCUR IN AUTOMOBILES.
NEVER DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR. JUST ONE
FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP VEHICLES OFF THE
ROAD. WHEN ENCOUNTERING FLOODED ROADS MAKE THE SMART CHOICE...TURN
AROUND...DONT DROWN.

&&

LAT...LON 3005 9387 3053 9378 3053 9228 3007 9225

$$

JT
U.S. Dept. of Commerce
NOAA National Weather Service
1325 East West Highway
Silver Spring, MD 20910
E-mail: w-nws.webmaster@noaa.gov
Page last modified: June 2, 2009
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NATIONAL WEATHER SERVICE: for Safety, for Work, for Fun - FOR LIFE

[djjordan]

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
313 AM CDT FRI MAY 10 2013

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
HARRIS COUNTY IN SOUTHEAST TEXAS...

* UNTIL 515 AM CDT

* AT 308 AM CDT...DOPPLER RADAR AND AUTOMATED RAIN GAUGES INDICATED
THUNDERSTORMS PRODUCING HEAVY RAIN OVER THE AREA. BETWEEN 2 AND
3.3 INCHES OF RAIN HAVE FALLEN SINCE 2 AM CDT. FLASH FLOODING IS
EXPECTED.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CHANNELVIEW...CLOVERLEAF...GALENA PARK...JACINTO CITY...AND
HIGHLANDS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

[srainhoutx]

E-mail update from Jeff:
A band of intense…at times…severe thunderstorms have developed over Fort Bend, southern Harris, and southern Liberty Counties as a result of overnight outflow boundary settling southward. Extensive thunderstorm complex to our N and E overnight has produced a large area of 2-5 inches of rainfall. In the last 1.5 hours HCFCD Flood Warning gages and radar indicates 2-3 inches of rainfall over SE Harris County from The Medical Center to Baytown. Significant street flooding is likely under the band of slow moving thunderstorms with several gages reporting over 1.0 inch in 15-minutes.

 Favorable low level inflow off the western Gulf of Mexico continues to supply a rich feed of moisture into the southern and western flank of this complex as it has all night long allowing the continued development of cells on the SW flank which then train ENE. An additional 1-3 inches of rainfall will be possible in the next hour along this band of storms with storm totals nearing 3-4 inches.

 Be aware of high water on streets for the morning commute.

[srainhoutx]

Busy night for Jeff. Another update:
NWS has issued a Flash Flood Watch for the following counties in SE TX: Grimes, Polk, San Jacinto, and Walker through this afternoon.

 Overnight complex of training and slow moving storms from Huntsville to Lake Livingston has produced 4-6 inches of rainfall. Next well defined disturbance over SW TX has already fired off a complex of thunderstorms and this complex will be moving toward SE TX today. Short term models have been under-estimating to amount of development and rainfall amounts thus far and appear to be off on the slower timing of the next round of weather coming in from the west. With grounds saturated over our northern counties and run-off still in progress from the overnight rains, additional heavy rainfall will quickly lead to flooding and rises on area watersheds.

 Guidance and HPC progs appear way too low on the forecasted rainfall amounts as this air mass is very capable of 2-4” per hour if not more. With numerous low level boundaries in place and a frontal boundary sinking in from the north corridors of cell training and excessive rainfall seem likely this afternoon into tonight. Easily 2-3 inches of rainfall under these bands with isolated amounts up to 5-6 inches and possibly locally higher.

 This watch may be extend and expanded to include more of the area later this morning or this afternoon.

[ticka1]

looks like another round devloping in the hill country moving this direction!

[jasons2k]

The outflow skipped over me last night without doing much, other than hearing lots of thunder to my south. I hope I see some more rain today.

[srainhoutx]

A bit worrisome seeing development over Grimes County with the approaching disturbance near San Antonio.



DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT FRI MAY 10 2013

VALID 101300Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF CNTRL AND SRN TX
TO THE CNTRL GULF COAST...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER OH VALLEY INTO
MID ATLANTIC STATES...

...SYNOPSIS...

A SPLIT FLOW REGIME WILL PERSIST THROUGH THE D1 PERIOD...FEATURING
AN EVOLVING LARGE-SCALE TROUGH OVER THE CNTRL AND ERN CONUS INTO NRN
MEXICO...AND AN AMPLIFIED RIDGE FROM THE FAR ERN PACIFIC THROUGH THE
PACIFIC NW INTO WRN CANADA. WITHIN THIS BROAD-SCALE PATTERN...MID
AND UPPER-LEVEL JET STREAKS DEVELOPING EQUATORWARD FROM THE CANADIAN
PRAIRIE PROVINCES INTO THE NRN PLAINS AND UPPER MS VALLEY WILL
CONTRIBUTE TO SIGNIFICANT INTENSIFICATION OF A POLAR-BRANCH TROUGH
OVER ONTARIO INTO THE UPPER GREAT LAKES. THIS SYSTEM WILL BE
PRECEDED BY A WEAKER SHORT-WAVE TROUGH WHICH WILL PROGRESS EWD
ACROSS THE GREAT LAKES AND OH VALLEY. MEANWHILE...A SUBTROPICAL JET
STREAK WILL BE MAINTAINED FROM THE DOWNSTREAM SIDE OF A POSITIVELY
TILTED TROUGH OVER THE SRN ROCKIES INTO NWRN MEXICO EWD ACROSS THE
S-CNTRL AND SERN CONUS. A SERIES OF VORTICITY MAXIMA ARE FORECAST
TO EMERGE FROM THIS TROUGH AND TRANSLATE EWD WITHIN THIS
HIGH-MOMENTUM AIR STREAM...AFFECTING TX AND THE GULF COAST STATES.

IN THE LOW LEVELS...A COLD FRONT ASSOCIATED WITH THE
LEAD...POLAR-BRANCH SHORT-WAVE TROUGH WILL ADVANCE EWD THROUGH THE
OH VALLEY AND LOWER GREAT LAKES REGION...TRAILING A DEEPENING
SURFACE LOW WHICH WILL TRACK FROM SRN LOWER MI NEWD INTO SRN QUEBEC
BY 11/12Z. THE SWRN EXTENSION OF THE COLD FRONT WILL PROGRESS SEWD
THROUGH THE OZARK PLATEAU...AND ACROSS MUCH OF THE SRN PLAINS...AND
INTO THE LOWER MS VALLEY. THIS COLD FRONT AND PRE-EXISTING OUTFLOW
BOUNDARIES WILL SERVE AS THE PRIMARY FOCI FOR STRONG TO SEVERE
STORMS TODAY INTO TONIGHT.

...TX TODAY INTO TONIGHT...

A SMALL CLUSTER OF STORMS WHICH EVOLVED EARLY THIS MORNING WAS
LOCATED JUST W/SW OF SAT AS OF 12Z. BASED ON 12Z OBSERVED
SOUNDINGS...THIS ACTIVITY IS LIKELY SLIGHTLY ELEVATED AND ROOTED
WITHIN A STEEP LAPSE RATE ENVIRONMENT ABOVE THE CAP. DAYTIME
HEATING COUPLED WITH A MOISTENING PBL ALONG AND SOUTH OF A
RETREATING OUTFLOW BOUNDARY WILL RESULT IN THESE STORMS BECOMING
PROGRESSIVELY SURFACE-BASED BY MID TO LATE MORNING AS THEY APPROACH
THE MIDDLE AND UPPER TX COAST. HERE...THE 12Z OBSERVED SOUNDING
DATA INDICATE THE POTENTIAL FOR MODERATE AFTERNOON INSTABILITY WITH
MLCAPE VALUES APPROACHING 1500-2500 J/KG. GIVEN AROUND 50 KT OF
DEEP-LAYER SHEAR...THE POTENTIAL WILL EXIST FOR SUPERCELLS AND
BOWING STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

ADDITIONAL STORM DEVELOPMENT WILL BE POSSIBLE THIS AFTERNOON INTO
EVENING FROM THE VICINITY OF THE COLD FRONT OVER WRN PARTS OF THE
EDWARDS PLATEAU SEWD ALONG AN OUTFLOW BOUNDARY INTO THE TX BRUSH
COUNTRY. HERE TOO...THE ENVIRONMENT WILL BE SUPPORTIVE OF ORGANIZED
STORM MODES /INCLUDING SUPERCELLS/ CAPABLE OF LARGE HAIL AND
DAMAGING WINDS.

...LOWER MS VALLEY TODAY...

A LONG-LIVED QLCS WILL CONTINUE ESEWD THROUGH THE REMAINING PARTS OF
SERN LA/MS WHERE A VERY MOIST PBL WITH DEWPOINTS OF AROUND 70 F ARE
YIELDING MLCAPE VALUES OF 500-1000 J/KG. GIVEN 60 KT OF EFFECTIVE
BULK SHEAR AND EFFECTIVE SRH VALUES OF AROUND 200 M2/S2 --PER 12Z
LIX SOUNDING...THE SETUP WILL REMAIN SUPPORTIVE OF EMBEDDED LEWP
STRUCTURES CAPABLE OF DAMAGING WINDS...HAIL...AND PERHAPS A TORNADO.
THIS THREAT MAY DEVELOP INTO SWRN AL /AND PERHAPS THE WRN FL PNHDL/
LATER THIS MORNING BEFORE DIMINISHING AS THE CONVECTIVE SYSTEM
ENCOUNTERS AN INCREASINGLY DRY AND MORE STABLE AIR MASS.

FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE WW 154 AND MCD 620.

...UPPER OH VALLEY INTO THE MID ATLANTIC STATES THIS AFTERNOON AND
EVENING...

LATEST MODEL GUIDANCE SUGGESTS THAT A VORTICITY MAXIMUM CURRENTLY
OVER WRN TN WILL ACCELERATE NEWD INTO THE REGION TODAY...AHEAD OF
THE LEAD...POLAR-BRANCH SHORT-WAVE TROUGH. A CORRESPONDING
ENHANCEMENT IN FORCING FOR ASCENT AND VERTICAL SHEAR WILL GIVE RISE
TO WIDELY SCATTERED STRONG TO SEVERE TSTMS ALONG AND AHEAD OF THE
COLD FRONT WITHIN A MODERATELY UNSTABLE ENVIRONMENT WITH MLCAPE
APPROACHING 1000-1500 J/KG. UPSCALE GROWTH OF STORMS INTO BOWING
LINE SEGMENTS IS POSSIBLE WITH THE PRIMARY HAZARDS BEING DAMAGING
WINDS AND SOME HAIL.

...FL THIS AFTERNOON...

LATEST CONVECTION-ALLOWING MODEL GUIDANCE IS IN GOOD AGREEMENT IN
SUGGESTING THE DEVELOPMENT OF TSTMS THIS AFTERNOON OVER THE CNTRL
PENINSULA WITH STORMS SUBSEQUENTLY MOVING OFF THE E-CNTRL AND SERN
COAST LATE THIS AFTERNOON INTO EVENING. THE COMBINATION OF MODERATE
INSTABILITY...RELATIVELY COOL MIDLEVEL TEMPERATURES...AND MODEST
DEEP-LAYER SHEAR WILL BE SUPPORTIVE OF ISOLATED SEVERE STORMS
CAPABLE OF MARGINALLY SEVERE HAIL AND LOCALLY DAMAGING WIND GUSTS.

..MEAD/DEAN.. 05/10/2013

[srainhoutx]

Update from Jeff:

Next disturbance is quickly approaching the area this morning.

 Thunderstorm complex currently crossing I-35 moving E at 40mph along and ahead of the next disturbance ejecting out of the upper level low stalled over the SW US. Recently thunderstorms have begun to once again develop from Brazos County and the College Station area SW toward this complex possibly along an old outflow boundary from the overnight activity. These newly developing storms are showing slow storm motions and this is over an area that was hit hard yesterday…so it is not going to take much rainfall to cause problems.

Southward the complex along I-35 will continue east into a moist and unstable air mass over the western sections of SE TX where dewpoints are in the lower 70’s and PWS in the 1.5-1.7 inch range. Two large supercells on the southern flank of this line continue to have a large hail and wind damage threat and radar and satellite images show rotation within the main rain shield suggesting a meso low has developed with this system and is helping in the downstream lifting of the air mass. Appears our local air mass is still primed and ready to go given recent development across an area that was heavily worked over last night. This is likely due to the fact that the feed of moisture off the Gulf has yet to be disrupted by storm complexes that have remained north of I-10 and not affected the coast counties much. Feel that this complex will maintain its intensity and possibly intensify some over the next 1-3 hours as it enters our western counties. This may enhance the severe weather threat across the region late this morning.

As far as the heavy rainfall threat goes…there has been little to no change in the air mass and the concern continues to be cell training with excessive rainfall rates. Next few hours will favor areas north of a Navasota to Conroe to Livingston line and then the entire area late this morning as the next complex arrives. Forward motion with this approaching complex is 30-40mph and there does not appear to be a significant amount of cell regeneration on its SW flank so the complex is progressively passing a location and not training over the same areas. Moisture levels continue to pool highly over the region along both outflow boundaries and later today and approaching frontal boundary. Similar rainfall rates to what has been experienced seems likely with the next few rounds of storms, but it is impossible to determine where the training may set up.

Meso models have become of little use as they nor the global systems are handling the ejecting disturbances well. Models really hammer the area again tonight, but this current complex approaching may in fact finally stabilize things some and hold back development this evening/overnight. With that said, the incoming next short wave does look potent and I suspect the current complex will move more ESE and not SE allowing the persistent Gulf feed to be maintained and a quick recharging of the air mass.