June: Onshore Flow Returns With Increasing Gulf Moisture

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
358 PM CDT SUN JUN 10 2012

TXZ163-164-176>179-195>200-210>214-226-227-235>238-102300-
HOUSTON-TRINITY-MADISON-WALKER-SAN JACINTO-POLK-BURLESON-BRAZOS-
WASHINGTON-GRIMES-MONTGOMERY-LIBERTY-COLORADO-AUSTIN-WALLER-
HARRIS-CHAMBERS-WHARTON-FORT BEND-JACKSON-MATAGORDA-BRAZORIA-
GALVESTON-
INCLUDING THE CITIES OF...CROCKETT...TRINITY...GROVETON...
MADISONVILLE...HUNTSVILLE...SHEPHERD...COLDSPRING...LIVINGSTON...
CORRIGAN...ONALASKA...CALDWELL...LAKE SOMERVILLE...
COLLEGE STATION...BRYAN...BRENHAM...NAVASOTA...THE WOODLANDS...
CONROE...WILLIS...LIBERTY...CLEVELAND...DAYTON...COLUMBUS...
EAGLE LAKE...WEIMAR...SEALY...BELLVILLE...HEMPSTEAD...
PRAIRIE VIEW...BROOKSHIRE...HOUSTON...PASADENA...KATY...TOMBALL...
HUMBLE...WINNIE...MONT BELVIEU...ANAHUAC...EL CAMPO...WHARTON...
PIERCE...SUGAR LAND...MISSOURI CITY...RICHMOND...ROSENBERG...
EDNA...BAY CITY...PALACIOS...PEARLAND...LAKE JACKSON...ALVIN...
ANGLETON...FREEPORT...LEAGUE CITY...TEXAS CITY...FRIENDSWOOD...
GALVESTON
358 PM CDT SUN JUN 10 2012

...VERY HIGH HEAT INDEX VALUES EXPECTED ON MONDAY...

A STRENGTHENING UPPER LEVEL RIDGE ACROSS TEXAS WILL ALLOW
AFTERNOON HIGH TEMPERATURES TO REACH THE MID TO UPPER 90S ACROSS
ALL OF SOUTHEAST TEXAS ON MONDAY. THESE TEMPERATURES...COMBINED
WITH HIGH DEWPOINTS AT THE SURFACE WILL ALLOW AFTERNOON HEAT INDEX
VALUES TO REACH 105 DEGREES ACROSS MUCH OF THE REGION. A FEW
LOCATIONS MAY SEE HEAT INDEX VALUES AS HIGH AS 107 DEGREES. HEAT
INDEX VALUES WILL DECREASE SLIGHTLY BY TUESDAY BUT ARE EXPECTED TO
REMAIN ABOVE 100 DEGREES EACH AFTERNOON THIS WEEK.

[Ptarmigan]

Hope we see rain this week. Otherwise it will be a doldrum week.

[weatherguy425]

Waiting on the ECMWF, but the 0Z GFS has come in wetter for Tuesday, and keeps the possibility of precipitation for at least the northeastern zones through the weekend, then hints at the possibility that daily seabreeze storms will be possible into the following week with a moist flow off of the Gulf sets up.

[srainhoutx]

Guidance is advertising a couple of potent short wave crossing the region late Tuesday and again on Wednesday. While storms appear to be likely N of the I-10 Corridor, all will depend on just how far S the MCS pushes SE. A stalling frontal boundary to our N with storm complexes developing during the afternoon hours to our NW seem likely. The SPC has introduce a rather large area of Slight Risk extending from NE New Mexico and on SE very near our northern zones for Tuesday. The short term meso models are suggesting a rather robust MCS will approach the area Tuesday night. We'll need to monitor these trends today as see if the threat continues. Additional storm chances may be likely Wednesday as a second upper air disturbance swings by.

Meanwhile it will be very warm today with temps in the middle to upper 90's and very high heat index near or just above 100F. Those with outdoor plans need to drink plenty of water. Very high dew points will make 'feel' extremely hot. Stay safe out there today.

Looking ahead to next weekend in the longer range, a broad area of low pressure is suggested across the W Caribbean and possibly the Bay of Campeche as heights fall and lowering pressures increase from the EPAC on E into the Western North Atlantic Basin. The monsoonal trough looks to start lifting N from Central America and these features were noted by Forecaster Roth of the HPC this morning.

ACROSS THE TROPICS...MID-LEVEL HEIGHTS BECOME LOW ENOUGH BETWEEN
BERMUDA AND THE SOUTHEAST COAST TO INDUCE A BROAD SURFACE LOW/AREA
OF DISTURBED WEATHER IN THE WESTERN CARIBBEAN FROM THIS WEEKEND
ONWARD. RIDGING ACROSS NORTHERN MEXICO BRINGS THE PROMISE OF
RENEWED TROPICAL ACTIVITY SOUTH OF MEXICO ACROSS THE TROPICAL
PACIFIC OVER THE NEXT WEEK...WITH THE 12Z GLOBAL ENSEMBLE MEMBERS
INDICATING THREE PROSPECTS FOR DEVELOPMENT. SEE NATIONAL
HURRICANE CENTER /NHC/ TROPICAL WEATHER OUTLOOKS CONCERNING THE
FIRST OF THESE AREAS CURRENTLY WELL SOUTH OF BAJA CALIFORNIA.

ROTH

06112012 SPC Day 2 day2otlk_0600.gif

06112012 00Z Euro Ensembles 00zECMWF6-10day500mbHeightAnomalyNA.gif

06112012 00Z GFS Ensembles 00zENS6-10day500mbHeightAnomalyNA.gif

[srainhoutx]

Morning e-mail from Jeff:

SE TX will lie in the divide between an active/wet pattern over extreme east TX and LA and a hot and dry pattern over central and south TX.



Upper level trough that was over the area last week has moved well east of the area with high pressure having built overhead on Sunday. Smoke from a wildfire in Chambers County (sparked by lightening Friday evening) has plagued the areas around Galveston Bay over the weekend. High altitude smoke arrived in the area from the WNW last evening from the big wildfires burning in New Mexico and Arizona…so there will be a hazy/smokey look to the sky today.



Strong ridge of high pressure is over the area today, but the air mass just north of the area will become extremely unstable by late afternoon and expect a large complex of thunderstorms to develop over NE TX, SE OK at that time and move SSE to S overnight. Position of the eastern flank of the ridge over SW TX will guide this storm complex, and the current thinking is that the high pressure will be strong enough to shunt move of the activity into east TX and LA although would not rule out our NE and E counties from getting a storm (along and east of a line from Livingston to Liberty to High Island). What happens tonight will have at least some affect on the forecast for Tuesday, but boundaries likely pushing into the area from thunderstorm complexes just to our NE and E. Feel the ridge will remain strong for areas west of I-45, but eastern areas will at least stand a shot at some late day strong storms…and this area does need additional rainfall.



Ridging then builds slightly for the rest of the week, but active weather/unsettled pattern will remain just to our east over LA and will have to watch for any outflow boundaries or activity that may try and sneak westward in the late afternoon and early evening hours…especially if the ridge gives just a little ground.



Other item will be heat index values pushing into the 105-107 range during peak heating with highs topping out in the 94-98 range…may even see a couple of 100’s in the College Station to Huntsville corridor. We are just below advisory criteria of two days with heat index at or above 108 and/or overnight lows above 80. We will be close for much of the early to mid part of the week, but likely not fully meet the required criteria for a heat advisory.



Fire Weather:

While many locations did get wetting rainfall late last week, the areas that needed it the most were largely missed. Severe drought conditions have re-developed over San Jacinto, Polk, and Trinity counties. KBDI values range from 500-600+ over Liberty, San Jacinto, Polk, Trinity, and Houston counties indicating that vegetation health is drying and the formation and spread of wildfires is increasing. As noted with the lightening induced wildfire over Chambers County this weekend. Southerly winds today will range from 15-20mph by the afternoon, but surface RH will remain in the 30-40% range during the afternoon hours. This is not an overly high wildfire threat, but with a lot of dead fuel from the drought of 2011 and gusty winds, along with drying of fine fuels the threat is there for fire development and spread.

[srainhoutx]

The 12Z WRF/NMM remain hopeful for some relief from the hot temps for Tuesday evening into Wednesday. We will see.

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1015 AM CDT MON JUN 11 2012

TXZ163-164-176>179-195>200-210>214-226-227-235>238-120000-
HOUSTON-TRINITY-MADISON-WALKER-SAN JACINTO-POLK-BURLESON-BRAZOS-
WASHINGTON-GRIMES-MONTGOMERY-LIBERTY-COLORADO-AUSTIN-WALLER-
HARRIS-CHAMBERS-WHARTON-FORT BEND-JACKSON-MATAGORDA-BRAZORIA-
GALVESTON-
INCLUDING THE CITIES OF...CROCKETT...TRINITY...GROVETON...
MADISONVILLE...HUNTSVILLE...SHEPHERD...COLDSPRING...LIVINGSTON...
CORRIGAN...ONALASKA...CALDWELL...LAKE SOMERVILLE...
COLLEGE STATION...BRYAN...BRENHAM...NAVASOTA...THE WOODLANDS...
CONROE...WILLIS...LIBERTY...CLEVELAND...DAYTON...COLUMBUS...
EAGLE LAKE...WEIMAR...SEALY...BELLVILLE...HEMPSTEAD...
PRAIRIE VIEW...BROOKSHIRE...HOUSTON...PASADENA...KATY...TOMBALL...
HUMBLE...WINNIE...MONT BELVIEU...ANAHUAC...EL CAMPO...WHARTON...
PIERCE...SUGAR LAND...MISSOURI CITY...RICHMOND...ROSENBERG...
EDNA...BAY CITY...PALACIOS...PEARLAND...LAKE JACKSON...ALVIN...
ANGLETON...FREEPORT...LEAGUE CITY...TEXAS CITY...FRIENDSWOOD...
GALVESTON
1015 AM CDT MON JUN 11 2012

...VERY HIGH HEAT INDEX VALUES EXPECTED THIS AFTERNOON...

AN UPPER LEVEL RIDGE CENTERED ACROSS THE STATE OF TEXAS WILL ALLOW
AFTERNOON HIGH TEMPERATURES TO REACH THE MID TO UPPER 90S TODAY
ACROSS SOUTHEAST TEXAS. THESE TEMPERATURES...COMBINED WITH HIGH
SURFACE DEWPOINTS WILL ALLOW AFTERNOON HEAT INDEX VALUES TO REACH
103-105 DEGREES ACROSS AREAS NORTH OF INTERSTATE 10 AND 105-107
DEGREES BETWEEN INTERSTATE 10 AND THE COAST. HEAT INDEX VALUES
WILL DECREASE SLIGHTLY FOR TUESDAY BUT ARE EXPECTED TO RISE ABOVE
100 DEGREES EACH AFTERNOON THIS WEEK.

[srainhoutx]

MESOSCALE DISCUSSION 1125
NWS STORM PREDICTION CENTER NORMAN OK
0332 PM CDT MON JUN 11 2012

AREAS AFFECTED...W-CNTRL AND NW TX

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 112032Z - 112130Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THE THREAT FOR LARGE HAIL AND DMGG WIND GUSTS IS
INCREASING OVER PARTS OF W-CNTRL AND NW TX. A WW WILL LIKELY BE
NEEDED WITHIN THE NEXT HR.

DISCUSSION...SFC ANALYSIS FROM 20Z PLACES A DEEPENING SFC LOW NEAR
SPS...WITH A SLOW-MOVING COLD FRONT ORIENTED SW-NE ACROSS N TX.
RECENT VISIBLE SATELLITE IMAGES SHOW INDICATIONS OF A DEVELOPING
SFC-BASED CU FIELD 40 NW MWL OCCURRING ALONG WIND SHIFT...AND
ADDITIONAL TOWERING CU DEVELOPING APPROXIMATELY 30 N SJT. VERY
STRONG BOUNDARY LAYER HEATING...WITH TEMPERATURES REACHING NEAR 100
F...HAS BEEN SUFFICIENT TO OVERCOME A WARM LAYER NEAR 850 MB
OBSERVED IN 12Z SOUNDINGS. FORCING FOR ASCENT IS EXPECTED TO BE
WEAK...BUT GIVEN THE STRONG HEATING AND CONTINUED WEAK CONVERGENCE
ALONG/NEAR WIND SHIFT AND ATTENDANT DRYLINE...INITIATION OF AT LEAST
ISOLATED STORMS APPEARS INCREASINGLY LIKELY. WITH MLCAPE VALUES NOW
EXCEEDING 4000 J/KG IN SOME AREAS...STORMS WILL LIKELY BE CAPABLE OF
PRODUCING VERY LARGE HAIL AND ISOLATED DMGG WIND GUSTS...BUT STORM
ORGANIZATION SHOULD BE SOMEWHAT LIMITED BY WEAK EFFECTIVE SHEAR
/NEAR 20 KTS/.

..ROGERS/MEAD.. 06/11/2012


ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

[Portastorm]

Like our neighbors in SE Texas ... rather unpleasant heat indices here in south central Texas. Late this Monday afternoon, we're sitting at 99 degrees with a heat index of 107. (sweat)

[srainhoutx]

06112012 ww0374_overview_wou.gif

06112012 2030Z TX VIS latest.jpg

[Kludge]

I think today's West Texas storms are forming a bit more south than expected...and I like the current trajectory they're on. With the current heat and dewpoints I think that they may hold together late into the evening, and the odds of us on the northern portions of the CWA may be decent for a shower later. Fingers crossed... we didn't see much out of last week's rains.

[Edit] Okay...maybe not.

[srainhoutx]

A stalled frontal boundary from Abilene to the Dallas Area are the features on the charts this morning. Short wave energy and left over boundaries from the line of storms that moved offshore of the Northern Gulf over night will provide isolated shower chances along the Coastal areas this morning. Guidance develop additinal storms this afternoon to our NW and those storm look to flirt with our Northern zones late afternoon and into tonight. Additional storm chances across our Northern areas for Wednesday as another piece of short wave energy passes.

The ridge will build back late week into the weekend before relaxing early next week as a Tropical Wave approaches the Western Gulf. We'll need to monitor the Western Caribbean/Bay of Campeche for thunderstorm development. Should storms fire across those areas, guidance has been 'sniffing' a broad low forming, but without thunderstorms, there would be no development. The monsoonal trough does lift N from Central America and pressures are expected to lower next week. We will continue to monitor any possible tropical troubles in our Hurricane Central area of our Forum.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT TUE JUN 12 2012

VALID 121300Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE WRN GULF CST AND SRN
PLNS NWD THROUGH THE CNTRL HI PLNS...

...SYNOPSIS...
CONTINUED EWD MOTION OF UPR GRT LKS TROUGH INTO QUE WILL LEAVE
LARGELY ZONAL FLOW ACROSS MOST OF THE CONUS AS FLAT RIDGE PERSISTS
OVER THE SRN PLNS/WRN GULF OF MEXICO. TWO BANDS OF ENHANCED FLOW IN
THE ZONAL CURRENT SHOULD REMAIN MORE OR LESS STNRY THROUGH THE
PERIOD...A NRN ONE EXTENDING FROM ID/WY INTO NEB/IA...AND A SRN
BRANCH EXTENDING FROM NM INTO THE SRN PLNS/SRN OZARKS.

AT LWR LVLS...COLD FRONT ASSOCIATED WITH THE GRT LKS TROUGH WILL
MOVE E ACROSS THE UPR OH VLY/APPALACHIANS THIS AFTN/EVE...WHILE ITS
WRN EXTENSION BECOMES QSTNRY/DIFFUSE OVER THE LWR MS VLY/SRN PLNS
AND LEE TROUGH STRENGTHENS OVER THE HIGH PLNS. NUMEROUS STRONG TO
SVR TSTMS ARE EXPECTED THIS PERIOD NOT ONLY ALONG/NEAR QSTNRY FRONT
OVER THE SRN PLNS/LWR MS VLY...BUT ALSO ALONG LEE TROUGH OVER THE
SRN AND CNTRL HIGH PLNS.

...SE TX/SRN LA TODAY...
OVERNIGHT ARKLATEX MCS HAS LEFT AN ELONGATED /W-E/ COLD POOL OVER
CNTRL LA THAT MAY SERVE AS THE FOCUS FOR RENEWED STORM DEVELOPMENT
THROUGH AT LEAST MIDDAY AS MODEST WSW LOW LVL FLOW AND DEEP EML
PERSIST TO ITS SOUTH. THIS SETUP COULD YIELD ADDITIONAL PERIODIC
EPISODES OF ENHANCED FORWARD PROPAGATION/BOWING...WITH AN ATTENDANT
RISK FOR SVR WIND VIA HIGH PW/WATER LOADING.

...SRN PLNS/SRN HIGH PLNS THIS AFTN THROUGH TNGT...
WIDELY SCTD TSTMS NOW OVER W TX/ERN NM ARE ELEVATED ATOP SHALLOW
POST-FRONTAL COOL DOME. THEY MAY PERSIST FOR AWHILE THIS
MORNING...AND MAY POSE A LOW RISK FOR SVR WIND/HAIL.

MEANWHILE...LOW LVL MOISTURE /MID 50S-MID 60S/ WILL CONTINUE TO
SPREAD WNW INTO THE SRN HIGH PLNS TODAY AS STALLING FRONT LOSES
DEFINITION AND LEE TROUGH STRENGTHENS E OF THE RCKYS.
COUPLED WITH SFC HEATING...MOISTURE INFLOW SHOULD YIELD VERY STRONG
INSTABILITY...WITH SBCAPE RANGING FROM AROUND 2000 J/KG IN ERN NM TO
NEAR 4000 J/KG IN NW TX.

DEEP/STRONG EML LIKELY WILL DELAY STORM DEVELOPMENT UNTIL AFTN WHEN
COMBINATION OF STRONG HEATING AND UPSLOPE FLOW BREACH THE CAP.
25-30 KT WNWLY 500 MB FLOW ATOP ESELY LOW LVL FLOW SHOULD PROVIDE
AMPLE /30-40 KT/ WNWLY DEEP SHEAR FOR SUPERCELLS. THESE STORMS WILL
BE CAPABLE OF VERY LARGE HAIL IN ADDITION TO LOCALLY DMGG WIND. THE
THREAT FOR TORNADOES MAY INCREASE BY EARLY EVE AS TEMP-DEWPOINT
SPREADS AND LCLS DECREASE.

THE STORMS LIKELY WILL MERGE INTO A LARGE CLUSTER TOWARD DARK AS THE
STORMS MOVE/DEVELOP INTO INCREASINGLY MOIST SELY NEAR-SFC FLOW...SLY
LLJ NOCTURNALLY STRENGTHENS...AND SRN BRANCH JET PERSISTS ALOFT.
THIS SYSTEM MAY EVOLVE INTO A LARGER SCALE WIND-PRODUCING
EVENT/POSSIBLE DERECHO. IF SUCH A SYSTEM DEVELOPS...IT SHOULD MOVE
SE ALONG THE MOISTURE AXIS THROUGH LATE TNGT. PARTS OF WRN AND
CNTRL TX MAY REQUITE UPGRADE TO MDT RISK IN LATER OUTLOOKS.

...CNTRL HI PLNS...
A SEPARATE AREA OF ENHANCED SVR THREAT MAY EVOLVE OVER FAR ERN WY
AND WRN PORTIONS OF NEB/SD...WHERE UPLIFT WILL BE ENHANCED BY A
DISTURBANCE IN NRN STREAM JET. WHILE MOISTURE WILL REMAIN LIMITED
RELATIVE TO POINTS FARTHER S...IT SHOULD BE SUFFICIENT FOR WIDELY
SCTD TSTMS /INCLUDING SUPERCELLS/ WITH A RISK FOR SVR HAIL/WIND.
THESE MAY EVOLVE INTO A SMALL E OR SE-MOVING CLUSTER TNGT.

...UPR OH/TN VLYS AND WRN APPALACHIANS THIS AFTN...
ALONG AND AHEAD OF COLD FRONT...MODERATE INSTABILITY /1000-1500
J PER KG MLCAPE/ WILL DEVELOP IN A RELATIVELY NARROW CORRIDOR WHERE
STRONGER HEATING WILL OCCUR IN PRESENCE OF 20-30 KT WLY DEEP SHEAR.
ISOLD STRONG TO SVR MULTICELLS COULD YIELD LOCALLY SVR HAIL/WIND.

...SERN STATES THIS AFTN...
SCTD MAINLY DIURNAL TSTMS EXPECTED WHERE POCKETS OF HEATING OCCUR
AHEAD OF STALLING COLD FRONT AND ALONG RESIDUAL OUTFLOW BOUNDARIES
FROM YESTERDAYS STORMS. ISOLD STRONGER STORMS MAY YIELD BRIEF/
LOCALLY DMGG WIND.

..CORFIDI/LEITMAN.. 06/12/2012

06122012 SPC day1otlk_1300.gif

[srainhoutx]

Morning e-mail from Jeff:

What to do…Oh…what to do with the chances for thunderstorms today.



Large convective complex is currently roaring through central and western LA this morning with a westward moving gravity wave having kicked off local showers and thunderstorms in the favored streamer belts this morning from Galveston Bay to Chambers and Liberty Counties…this activity has weakened. Upstream outflow boundary along/ahead of the LA complex with no doubt get into the region from the NE/E at some point late this morning or early afternoon. Meso scale short term models are showing any number of solutions from a full blown line of thunderstorms moving across the entire area (WRF-NNM) to isolated storms along an outflow boundary (HRRR) to a new line of storms developing over NE TX and moving into the area this evening (TT WRF). Likely that none of the models are fully correct or incorrect and will side mostly with the less aggressive HRRR and blend in some of the TT WRF with the feeling that the WRF-NNM is way too aggressive with activity.



Air mass over the region will be hot, humid and very unstable by early to mid afternoon, but capped especially south of I-10 where the influences of high pressure over MX and S TX is in place. Forecast soundings north of I-10 suggest that when inputted with the forecast high temperatures the mid level inversion is weakened and is breakable. Additionally suspect there will be any number of outflow boundaries moving into the region from late morning through early afternoon which will/could help in forcing surface parcels through any remaining capping aloft. Boundaries will likely initiate storms and with good low level instability expect that some storms will be strong to locally severe with large hail and damaging winds the main threats. Best location for thunderstorms will be along and NE of a line from College Station to Conroe to High Island…in the region where capping is weakest and low level boundaries will reach during peak heating. Storms will then track S to SW into the region, but how far they make it is the big question. Suspect a few will make it to I-10 and possibly deeper into the area driven by strong outflow boundaries and a very unstable and super-heated late day air mass. It is not out of the possibility that storms could make it into the metro Houston area and even as far S and W as Waller, Fort Bend, and Galveston Counties. If the HRRR model is correct then the entire area will see activity…but this seems excessive given the capping south of I-10.



Wet pattern will continue just to our east into Wednesday and once again large storm complexes rolling down the eastern flank of the S TX ridge will just clip our area and sending their outflow boundaries into the region. Could once again see isolated to scattered storms on Wednesday north of I-10. Central US ridge builds a little into the late week and weekend while the S TX high pressure cell moves westward into Mexico. This dries out east TX and LA and allows a surge of tropical moisture to arrive into coastal south and central TX by Sunday. Models are showing the potential for some seabreeze thunderstorms this weekend especially from about Galveston Bay SW along the TX coast.



Early to mid next week a weakness develops in the ridge over the central US Gulf coast and moves westward along the southern flank of the central US high. This should increase tropical moisture transport northward into the area and provide a better shot at daily seabreeze thunderstorms.



Tropics:

Lots of uncertainty going into next week as several global models have been bouncing around with the idea of some sort of tropical cyclone formation anywhere from the western Caribbean to the southern Gulf of Mexico to the eastern Pacific. There is nothing there now, but models are showing a significant increase in moisture over the western Caribbean and southern Gulf likely in response to the lifting northward of the monsoon trough over central America and Mexico. Favorable global teleconnection patterns also appear to be aligning at the same time with a favorable wet phase of the MJO affecting the E PAC and Gulf of Mexico by mid to late next week. For now will need to watch the period from Friday-Monday for an increase in the moisture in this area (if this does occur) then it is likely that the models may be on to something and at some point next week a tropical system could attempt to spin up in the highlighted region.

[weatherguy425]

If only it was a little later in the day. Lin ear system in Louisiana has an attached (somewhat strong) outflow boundary currently tracking south into our northern counties. Some showers are beginning to develop and I can see a few TCU's to my north and east. Though, it is only 10AM and surface instability would be much greater if this was moving through later in the day.

[srainhoutx]

The 12Z GFS has come in a bit wetter across the area this afternoon. We will see.

[srainhoutx]

HGX is suggesting the HIRES guidance is not doing a good job with the ongoing activity to our NE. Scattered showers/storms a developing across Montgomery County on E with some additional development in Grimes/Austin/Waller Counties. A new Severe Thunderstorm Watch has been issued across N/N Central TX. We may see a bit more active day than was originally expected. We will see.

Edit to add: The 12Z GFS continues to advertise increasing disturbed weather across the EPAC/Bay of Campeche/Western Caribbean as we head into early next week. While there remains multiple areas of vorticity suggested with the monsoonal trough, a slow and steady increase in tropical moisture is suggested along the Texas/Mexico Gulf Coastal Region.

Code: Select all

BULLETIN - IMMEDIATE BROADCAST REQUESTED
     SEVERE THUNDERSTORM WATCH OUTLINE UPDATE FOR WS 381
     NWS STORM PREDICTION CENTER NORMAN OK
     1100 AM CDT TUE JUN 12 2012
     
     SEVERE THUNDERSTORM WATCH 381 IS IN EFFECT UNTIL 500 PM CDT
     FOR THE FOLLOWING LOCATIONS
     
     TXC001-035-059-085-093-113-121-133-139-143-161-193-213-217-221-
     231-237-251-257-293-309-349-363-367-379-397-417-425-429-439-467-
     497-503-122200-
     /O.NEW.KWNS.SV.A.0381.120612T1600Z-120612T2200Z/
     
     TX 
     .    TEXAS COUNTIES INCLUDED ARE
     
     ANDERSON             BOSQUE              CALLAHAN            
     COLLIN               COMANCHE            DALLAS              
     DENTON               EASTLAND            ELLIS               
     ERATH                FREESTONE           HAMILTON            
     HENDERSON            HILL                HOOD                
     HUNT                 JACK                JOHNSON             
     KAUFMAN              LIMESTONE           MCLENNAN            
     NAVARRO              PALO PINTO          PARKER              
     RAINS                ROCKWALL            SHACKELFORD         
     SOMERVELL            STEPHENS            TARRANT             
     VAN ZANDT            WISE                YOUNG               
     
     
     ATTN...WFO...FWD...SJT...

[Portastorm]

And your neighbors to your west-northwest may get in on the action as well, per EWX:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
955 AM CDT TUE JUN 12 2012

.UPDATE...
UPDATED FORECAST REFLECTS CHANGES TO LOCAL AND SPC THINKING IN
REGARD TO POTENTIAL DEVELOPMENT ALONG OUTFLOWS ACROSS CENTRAL...
WEST CENTRAL TEXAS LATER THIS AFTERNOON. MAINTENANCE OF HIGH
DEWPOINTS INTO EASTERN HILL COUNTRY HEIGHTENS CONCERN FOR
DEVELOPMENTS FURTHER WEST WHICH MAY PROPAGATE THEIR WAY SOUTH
INTO THE SLIGHT RISK AREA. IF THERMALS CAN BREAK A PERSISTENT EML
(EQUILIBRIUM MIXED LAYER) ALOFT...AND PUSH INTO SBCAPES ABOVE 3000
J/KG...WE COULD UNDOUBTEDLY SEE SOME SEVERE CONVECTION WITH MOSTLY
DAMAGING WINDS. UPDATED FORECAST ADDS SEVERE TO THE SLIGHT CHANCE
AND MOVES SLIGHT RISK AREA A LITTLE FURTHER TO THE SOUTH AND WEST
AS SPC SUGGESTS.

[srainhoutx]

Good luck, Portastorm. I know you folks have been dry in the Austin Area. The N Central Texas storm complex does look to have a more SSE component. The SPC has made some adjustments with their latest update...

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1125 AM CDT TUE JUN 12 2012

VALID 121630Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE HIGH PLAINS TO
CNTRL GULF COAST...

...SYNOPSIS...

LARGE-SCALE PATTERN WILL UNDERGO SLIGHT DE-AMPLIFICATION DURING THE
D1 PERIOD AS PRIMARY UPPER TROUGH MOVES FROM ONTARIO INTO QUEBEC.
12Z UPPER-AIR ANALYSIS DEPICTS A COUPLE OF HIGHER MOMENTUM FLOW
CHANNELS IN THE MID TO UPPER-TROPOSPHERE...ONE FROM THE PACIFIC NW
THROUGH CNTRL PLAINS INTO GREAT LAKES...AND THE OTHER FROM SRN CA
INTO SRN HIGH PLAINS AND S TX. WITHIN THIS BROADER-SCALE
PATTERN...WATER VAPOR IMAGERY SHOWS A NUMBER OF WEAK
PERTURBATIONS...TWO OF WHICH MAY BE INSTRUMENTAL IN SEVERE TSTM
DEVELOPMENT LATER TODAY INTO TONIGHT. THE FIRST IS EMBEDDED WITHIN
POLAR BRANCH OF WESTERLIES OVER N-CNTRL WY WHICH WILL TRANSLATE EWD
INTO WRN SD BY AFTERNOON. THE OTHER IS A BIT WEAKER AND LOCATED IN
SUB-TROPICAL AIR STREAM NEAR THE FOUR CORNERS...WITH THIS FEATURE
MOVING INTO THE SRN HIGH PLAINS BY LATE AFTERNOON INTO EVENING.

AT THE SURFACE...SEGMENT OF COLD FRONT FROM CENTRAL OH TO MS-OH
RIVER CONFLUENCE WILL ADVANCE THROUGH THE LOWER GREAT LAKES AND INTO
THE CNTRL APPALACHIANS AND TN VALLEY. THE WRN EXTENSION OF SYNOPTIC
FRONT HAS BEEN MASKED BY A NUMBER OF CONVECTIVE OUTFLOW BOUNDARIES
RESIDING ACROSS THE SRN PLAINS WITH A BROAD CONFLUENCE AXIS
STRETCHING FROM THE RED RIVER INTO PERMIAN BASIN OF TX.
ELSEWHERE...A LEE CYCLONE DEVELOPING ALONG THE CHEYENNE RIDGE WILL
MOVE SLOWLY EWD TODAY WITH A LEE TROUGH BECOMING BETTER-DEFINED WITH
TIME ACROSS THE CO FRONT RANGE.

...SRN PLAINS...

TSTMS WHICH INITIATED LATE MONDAY NIGHT OVER NERN NM ARE ONGOING
OVER NWRN TX...FORCED BY A WEAK MIDLEVEL IMPULSE AND LOW-LEVEL
WAA/ISENTROPIC ASCENT ABOVE SHALLOW OUTFLOW BOUNDARY/FRONT. AIR
MASS AHEAD OF THESE STORMS ACROSS N-CNTRL/CNTRL TX SHOULD UNDERGO
RAPID DESTABILIZATION TODAY OWING TO THE PRESENCE OF STEEP MIDLEVEL
LAPSE RATES AND AN INCREASINGLY MOIST BOUNDARY LAYER WITH SWD EXTENT
INTO CNTRL TX WHERE AFTERNOON MLCAPE WILL APPROACH 2500-3500 J/KG.
IN FACT...THERE IS SOME INDICATION IN CONVECTION-ALLOWING AND
DETERMINISTIC MESOSCALE MODEL GUIDANCE THAT THESE STORMS COULD GROW
UPSCALE INTO A FORWARD-PROPAGATING MCS WITH A DAMAGING WIND AND HAIL
THREAT SPREADING SEWD TOWARD THE SABINE RIVER VALLEY AND UPPER TX
COAST.

OVER THE HIGH PLAINS...OUTFLOW IN THE WAKE OF NWRN TX TSTMS WILL
ENHANCE LOW-LEVEL UPSLOPE FLOW COMPONENT...WHICH WHEN COUPLED WITH
THE POTENTIAL INFLUENCE OF WEAK FOUR CORNERS IMPULSE...WILL FOSTER
WIDELY SCATTERED TSTMS ACROSS PORTIONS OF NERN/E-CNTRL NM INTO WRN
TX BY MID-LATE AFTERNOON. AMBIENT ENVIRONMENT WILL BE CHARACTERIZED
BY MLCAPE OF 1500-2500 J/KG AND 40-50 KT OF DEEP WLY SHEAR WHICH
WILL FAVOR SUPERCELLS AS THE INITIAL STORM MODE WITH AN ASSOCIATED
RISK FOR A FEW TORNADOES...DAMAGING WINDS AND VERY LARGE HAIL.
THEREAFTER...THERE IS REASONABLY GOOD AGREEMENT IN THE
CONVECTION-ALLOWING AND MESOSCALE MODELS THAT STORMS WILL MERGE INTO
ONE OR MULTIPLE MCSS WHICH WOULD PROGRESS SEWD INTO LOWER ELEVATIONS
OF THE SRN PLAINS WITH THE POTENTIAL FOR SWATHS OF DAMAGING WINDS
AND LARGE HAIL ALONG SYSTEM TRACK/S/.

...NRN/CNTRL HIGH PLAINS...

FORCING ASSOCIATED WITH WY IMPULSE WILL AUGMENT LOW-LEVEL
CONVERGENCE ASCENT INVOF LEE CYCLONE AND TROUGH TO GIVE RISE TO
WIDELY SCATTERED TSTMS BY MID AFTERNOON FROM WRN SD INTO ERN CO.
WHILE THE BOUNDARY LAYER WILL BE LESS MOIST THAN POINTS TO THE
SOUTH...STEEP LOW TO MIDLEVEL LAPSE RATES WILL YIELD MLCAPE VALUES
OF 1000-1500 J/KG IN THE PRESENCE OF 40-50 KT DEEP WNWLY SHEAR.
HERE TOO...SUPERCELLS APPEAR LIKELY WITH THE POTENTIAL FOR LARGE
HAIL...DAMAGING WINDS...AND PERHAPS A TORNADO.

...SRN LA...

THE INFLUX OF A MODERATELY UNSTABLE AND VERY MOIST AIR MASS INTO
SWD-PROPAGATING MCS WILL MAINTAIN ROBUST UPDRAFT DEVELOPMENT ALONG
LEADING EDGE OF SYSTEM COLD POOL. WHILE SOME LARGE HAIL IS
POSSIBLE...DAMAGING WINDS WILL BE THE PRIMARY HAZARD.

...UPPER OH VALLEY/LOWER GREAT LAKES SWD INTO THE CNTRL
APPALACHIANS...

UPLIFT ALONG COLD FRONT AND DEEPER-LAYER FORCING ASSOCIATED WITH A
VORTICITY MAXIMUM MOVING ACROSS THE REGION WILL SUPPORT AN INCREASE
IN TSTM ACTIVITY THIS AFTERNOON INTO EVENING. WHILE VERTICAL SHEAR
WILL REMAIN SUB-OPTIMAL FOR STORM ORGANIZATION/SUSTENANCE...THE
PRESENCE OF A MOIST...MODERATELY UNSTABLE AIR MASS /I.E. MLCAPE
VALUES OF 1000-2000 J PER KG/ WILL SUPPORT A FEW VIGOROUS STORMS
CAPABLE OF MARGINALLY SEVERE HAIL AND LOCALLY STRONG WIND GUSTS INTO
THIS EVENING.

...MID ATLANTIC AND SERN STATES...

12Z SOUNDINGS AND SATELLITE-DERIVED PW IMAGERY INDICATE THE PRESENCE
OF A VERY MOIST AIR MASS /I.E. PW VALUES OF 1.75-2.00 INCHES/ WHICH
WILL CONTRIBUTE TO POCKETS OF MODERATE INSTABILITY BY AFTERNOON.
THIS IS ESPECIALLY THE CASE ACROSS PORTIONS OF GA/NRN FL INTO SC
WHERE VISIBLE SATELLITE SUGGESTS THE POTENTIAL FOR STRONGER DAYTIME
HEATING. A DEVELOPING LEE TROUGH WILL COMBINE WITH EXISTING
CONVECTIVE OUTFLOW BOUNDARIES AND AN MCV OVER THE SAVANNAH RIVER
VALLEY TO PROMOTE SCATTERED TSTMS THIS AFTERNOON. VERTICAL SHEAR
WILL REMAIN WEAK...BUT THE HIGH MOISTURE CONTENT WILL BE FAVORABLE
FOR WET MICROBURST FORMATION OWING TO WATER LOADING EFFECTS.

..MEAD/ROGERS.. 06/12/2012

[sleetstorm]

So, if all of the elements in the atmosphere are ripe a Derecho will be feasible?