April 2015: Pleasant Weather To End April

[srainhoutx]

A quick update this afternoon regarding what we are seeing for Sunday afternoon and especially Monday across the Region. The 12Z guidance continues to paint a very impressive storm system slowly ejecting out of the Great Basin and meandering across Texas into Louisiana. The upper air feature at 500mb and 700mb are very cold with its origin in the Gulf of Alaska. This disturbance is bringing snow to the higher elevations of the Sierra Mountains in California today which will spread E in the higher elevations of Arizona, Northern New Mexico and Colorado tomorrow as well as much of the Rockies into early Tuesday. A brief look at the GFS and European computer schemes suggest a very dynamic storm system will evolve particularly on Monday. The fly in the ointment will be just how fast this storm system moves East across Texas near the Red River. Lee side cyclogenesis seems certain across the Southern Rockies into the Southern Plains, but there are growing indications that a surface low may form near Brownsville complicating the forecast. Below are the various computer charts at many levels and you can notice a kink, or a meso low depicted near SE Texas on Monday. That feature if correct, raises a red flag for the potential of all modes of severe weather. We will be providing additional in depth analysis over the next 24 to 36 hours, so get out and enjoy the Beautiful Weather!

Euro:

The attachment 04252015 12Z Euro 48 ecmwf_mslp_uv850_us_3.png is no longer available

GFS:

[TexasBreeze]

Anybody know why HGX took away the hourly obs table at the bottom of the homepage?

[Paul Robison]

A quick update this afternoon regarding what we are seeing for Sunday afternoon and especially Monday across the Region. The 12Z guidance continues to paint a very impressive storm system slowly ejecting out of the Great Basin and meandering across Texas into Louisiana. The upper air feature at 500mb and 700mb are very cold with its origin in the Gulf of Alaska. This disturbance is bringing snow to the higher elevations of the Sierra Mountains in California today which will spread E in the higher elevations of Arizona, Northern New Mexico and Colorado tomorrow as well as much of the Rockies into early Tuesday. A brief look at the GFS and European computer schemes suggest a very dynamic storm system will evolve particularly on Monday. The fly in the ointment will be just how fast this storm system moves East across Texas near the Red River. Lee side cyclogenesis seems certain across the Southern Rockies into the Southern Plains, but there are growing indications that a surface low may form near Brownsville complicating the forecast. Below are the various computer charts at many levels and you can notice a kink, or a meso low depicted near SE Texas on Monday. That feature if correct, raises a red flag for the potential of all modes of severe weather. We will be providing additional in depth analysis over the next 24 to 36 hours, so get out and enjoy the Beautiful Weather!

Euro:

04252015 12Z Euro 48 ecmwf_mslp_uv850_us_3.png

04252015 12Z Euro 48 ecmwf_z500a_sd_us_3.png

GFS:

04252015 12Z GFS 48 gfs_uv250_us_9.png

04252015 12Z GFS gfs_z500_vort_us_10.png

04252015 12Z GFS 54 gfs_mslp_pcpn_us_9.png

04252015 12Z GFS gfs_mslp_wind_us_9.png

04252015 12Z GFS 54 gfs_mslp_pwata_us_10.png

04252015 12Z GFS 60 vgfs_mslp_pcpn_us_10.png

No drama intended, but--will this be a hugely damaging wx event for Houston?

[Andrew]

Looking ahead to Sunday and Monday a rather potent upper level low will cross through the area, bringing back the potential for severe weather across the area. Currently, models indicate that this neutrally tilted low could provide plenty of shear across the area with some pretty good CAPE indices. Looking at Sunday specifically, both the NAM and GFS indicate that an EHI of 6-7 (at least) could be present across the dry line from south central Tx up north into northern Tx. Lower level shear looks rather impressive and mid/low level lapse rates should be steep enough to provide strong updrafts, but the potential trigger causes an issue. Models indicate that northern Texas will be under the gun tomorrow, but if surface temperatures can increase enough I wouldn't be surprised to see some isolated showers around the region. Come Monday though, models are having a lot of difficult resolving the lows ejection. While the indices from global models aren't particularly impressive, the presence of a MSC look rather impressive (especially from the Corpus area to the Houston area). Shear still looks really impressive but cloud cover will be the main issue. If we can get large amounts of clearing, discrete cells could initially be a possibility. A lot of quesitons and answers to come tomorrow. A complicated setup to say the least.

[srainhoutx]

How quickly things can and often do change regarding the sensible weather across our Region. The Storm Prediction Center has outlined an Enhanced Risk for Severe Storms today into tonight with some mention of needing to Upgrade to a Moderate Risk across portions of Texas later today. Showers and elevated storms developed along and ENE of Matagorda Bay and continue to move inland. A very moist maritime airmass has moved inland to around Del Rio to Tyler and continues advancing slowly North. Daytime heating and the presence of a dryline across West Central Texas in advance of a deepening cold core upper low pressure that should close off today and its attending upper trough should set the stage for a very active 24 to 36 hour across our Region with ALL modes of severe weather possible. Stay Tuned!

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0803 AM CDT SUN APR 26 2015

VALID 261300Z - 271200Z

...THERE IS AN ENH RISK OF SVR TSTMS OVER LARGE PART OF TX...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ENHD RISK AREA
FROM THE RIO GRANDE NWD INTO SRN/CNTRL OK...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE ABOVE AREAS
FROM DEEP S TX INTO THE SRN PLNS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER CNTRL FL...

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF SC...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED OVER PARTS OF THE
SOUTHERN PLAINS THIS AFTERNOON THROUGH TONIGHT...WITH THE STORMS
SPREADING SOUTH AND EAST TOWARD THE TEXAS GULF COAST EARLY MONDAY.
ISOLATED STRONG TO POTENTIALLY SEVERE STORMS ALSO MAY OCCUR THIS
AFTERNOON OVER PARTS OF SOUTH CAROLINA AND FLORIDA.

...SYNOPSIS...
FOUR CORNERS TROUGH EXPECTED TO TURN EWD AND EVOLVE INTO A CLOSED
LOW OVER THE SRN HIGH PLNS TNGT/EARLY MON AS 80 KT NLY JET STREAK
NOW OVER THE LWR CO VLY REFORMS E ACROSS FAR W TX...AND UPSTREAM
RIDGE BUILDS N ACROSS THE PAC NW.

AT LWR LVLS...STRENGTHENING SLY FLOW/LEE TROUGHING WILL ALLOW
MARITIME TROPICAL AIR TO SURGE NNW ACROSS CNTRL AND E TX
TODAY...WHILE WEAK NRN STREAM COLD FRONT SETTLE FARTHER S ACROSS OK
AND AR.

...SRN PLNS TODAY THROUGH TNGT...
COMPLEX CONVECTIVE SCENARIO EXPECTED TO UNFOLD OVER THE SRN PLNS
THIS PERIOD AS FORCING ASSOCIATED WITH APPROACHING UPR TROUGH
INTERACTS WITH RAPIDLY MOISTENING LOW-LVL ENVIRONMENT AND
STRENGTHENING SHEAR OVER MUCH OF TX AND SRN OK. SETUP APPEARS
FAVORABLE FOR MULTIPLE ROUNDS OF STRONG TO SVR STORMS/STORM CLUSTERS
OVER MUCH OF THE REGION...WITH VARIABLE STORM MODES AND INTENSITIES
EXPECTED TO SEVERAL FACTORS.

IR SATELLITE IMAGERY AND SFC DATA SHOW LEADING EDGE OF RETURNING
MARITIME AIR ATTM EXTENDS FROM NEAR DRT ENE NEAR TYR. SATELLITE ALSO
SUGGEST PRESENCE OF A LEAD UPR IMPULSE NOW OVER CNTRL NM THAT
PRECEDES THE AZ TROUGH. THIS FEATURE...AND PERHAPS ANOTHER FARTHER
S IN NRN CHIHUAHUA...IN CONJUNCTION WITH SFC HEATING...MAY SUPPORT
SCTD TSTM DEVELOPMENT BY EARLY AFTN OVER PARTS OF W TX. OTHER SCTD
STORMS...ELEVATED ABOVE THE EML...ALSO MAY PERSIST ACROSS S TX AND
ALONG THE MIDDLE TX GULF CST. THESE STORMS ARE NOT EXPECTED TO
BECOME SVR.

LATER THIS AFTN AND EVE...HOWEVER...COMBINATION OF SFC
HEATING...RETURNING LOW-LVL MOISTURE...AND INCREASING HEIGHT
FALLS/DCVA EXPECTED TO FOSTER INTENSE STORM DEVELOPMENT INVOF LEE
TROUGH/WARM FRONT/COOL FRONT INTERSECTION OVER NW TX AND SW OK.
GIVEN STRENGTH AND VERTICALLY-VEERING NATURE OF WIND FIELD...THIS
ACTIVITY COULD YIELD SEVERAL SUPERCELLS WITH VERY LARGE
HAIL...TORNADOES...AND LOCALLY DMGG WIND AS SBCAPE INCREASES TO
BETWEEN 1500 AND 3000 J/KG. A CONDITIONAL RISK ALSO WILL EXIST FOR
MORE ISOLD SVR STORMS TO ARISE FARTHER S ACROSS THE TX HILL COUNTRY
INVOF LOW-LVL MOISTURE GRADIENT...AND OVER N CNTRL TX...AS HEATING
AND STRENGTHENING LOW-LVL CONFLUENCE LOCALLY BREACH EML CAP. THESE
STORMS ALSO WILL POTENTIALLY INCLUDE SUPERCELLS WITH VERY LARGE
HAIL...LOCALLY DMGG WIND...AND A COUPLE TORNADOES GIVEN 40-50 KT
WSWLY DEEP SHEAR.

BY EARLY EVE...THE CNTRL AND N TX STORMS LIKELY WILL MERGE INTO ONE
OR MORE LOOSELY-ORGANIZED CLUSTERS. EMBEDDED SUPERCELLS WITHIN THE
STORM SYSTEMS WILL CONTINUE TO POSE A RISK FOR VERY LARGE
HAIL...ISOLD TORNADOES...AND A SOMEWHAT ENHANCED RISK FOR MORE
WIDESPREAD DMGG WIND. LATER TNGT AND EARLY MON...ARRIVAL OF STRONGER
HEIGHT FALLS WITH MAIN UPR TROUGH...AND THE CONTINUED INFLOW OF VERY
RICH GULF AIR...SUGGEST THAT A SEPARATE MCS OR TWO MAY FORM OVER S
CNTRL TX. THIS ACTIVITY COULD EVOLVE INTO A
LARGER-SCALE...FORWARD-PROPAGATING CONVECTIVE SYSTEM...EXTENDING THE
RISK FOR DMGG WIND AND HAIL FROM EMBEDDED BOWS E/ESE ACROSS THE TX
CSTL PLN THROUGH THE END OF THE PERIOD.

PARTS OF TX ULTIMATELY MAY REQUIRE UPGRADE TO MDT RISK IN LATER
OTLKS AS MESOSCALE CORRIDORS OF ENHANCED BUOYANCY AND LOW-LVL
FORCING FOR ASCENT BECOME MORE FOCUSED THAN THEY APPEAR ATTM.

...SERN STATES...
SCTD DIURNAL STORMS ARE EXPECTED OVER CNTRL FL TODAY...WHERE SFC
HEATING SHOULD BOOST AFTN SBCAPE TO AROUND 2000 J/JG. COUPLED WITH
SEASONABLY STRONG /40-50 KT/...UNIDIRECTIONAL WLY FLOW IN THE
700-500 MB LAYER...POTENTIAL WILL EXIST FOR A FEW SUSTAINED
MULTICELLS WITH A RISK FOR LOCALLY DMGG WIND AND SVR HAIL. THIS RISK
APPEARS GREATEST OVER E CNTRL FL...WHERE CONVERGENCE SHOULD MAXIMIZE
ALONG THE SEA BREEZE FRONT.

A SEPARATE AREA OF SCTD AFTN STORMS MAY FORM ALONG STALLING
BACK-DOOR FRONT IN SC...WHERE SOMEWHAT MORE MODEST WLY FLOW WILL
PERSIST IN WAKE OF DEPARTING UPR TROUGH....AND MOISTURE WILL BE
SUFFICIENT FOR DEVELOPMENT.

..CORFIDI/DEAN.. 04/26/2015

[srainhoutx]

Storm reports from yesterday morning from Jeff:

Another day of storm reports over SE TX.

Morning thunderstorm complex brought mainly wind damage and a few large hail reports to the region. Most impressive wind damage occurred in a corridor from southern Austin County across extreme southern Waller/N Fort Bend County and then across western and northern Harris County. Initial supercell thunderstorm grew upscale into a forward moving bow echo over western Harris County and finally weakened over Lake Houston/Humble. Widespread wind damage occurred along the track of both the supercell and bow echo from Sealy to Katy to Cypress to Spring. Several of the areas impacted in Cypress were hit hard last Sunday evening with damaging hail.

Listed below is also a summary of an incredible bow echo which moved out of Mexico late yesterday evening and decimated portions of S TX with powerful winds.

Madisonville, Madison: Trees blown down on Mary St and Shady Creek

El Campo, Wharton: Dime size hail reported by law enforcement

18 ESE Palacios: Marine thunderstorm wind gust of 46mph

San Felipe, Austin: 58mph wind gust with tree damage.

Pattison, Waller: trees down, fences blown over from straight line winds

Katy, Harris: spotter recorded sustained 58mph g 69mph at SH 99/Franz Rd. At the same time KIAH tower terminal velocity was showing 70kts over western Harris County.

Katy, Fort Bend: Large billboard in front of Gallery Furniture building blown over on top of fireworks stand. Est winds to 85mph, fences down, trees uprooted.

Weston Lakes, Fort Bend: 12-15 large trees uprooted. 1 tree crushed a vehicle in a driveway.

Fulshear, Fort Bend: Est 60mph winds.

Cypress, Harris: numerous reports of trees down from strong winds between 706am-715am between SH 249 and US 290 along/just north of FM 1960. Centerpoint outages network indicated extensive power outages in this region.

Edna, Jackson: 1.0 inch diameter hail in Edna

Rollover Pass, Galveston: AWOS site recorded 19g 42 with outflow boundary passage

Clear Lake Shores, Galveston: 43mph recorded on Mesonet site

Surfside Beach, Brazoria: 44mph recorded at AWOS site with outflow boundary passage

Galveston, Galveston: golfball size hail reported by law enforcement at Heards and 68th St

North Jetty, Galveston Bay: 51mph recorded at TCOON site.

South Texas Bow Echo Event:

An incredible bow echo moved out of Mexico late yesterday evening and into South Texas resulting in a long lived corridor of extensive wind damage.

Bow echo crossed the Rio Grande 3 miles S of Elsa in Hidalgo County with damage immediately starting on the US side of the Rio Grande River. 100’s of large trees were snapped near their base indicated sustained wind speeds to 65-75mph. The bow echo struck the community of Aurora Valley where 24 trailer homes were heavily damaged and at least 6 were demolished. Since none of the trailer homes were tied-down estimated wind speeds of 70-80mph were likely. The event then impacted the more populated town of Weslaco, TX where two 100 pound BBQ pits were thrown over 100 ft. A storm spotter recorded sustained wind speeds of 72mph in Weslaco. Widespread tree and power line damage occurred in Weslaco with 15,000 residents without power…many of the town’s above ground poles were either blown down or snapped off. In the town of Donna, 10 ft foot wide outbuilding was destroyed and portions of a garage wall collapsed suggesting winds speeds of 75-85mph. Residents indicated that the strongest winds with the bow only lasted 3-5 minutes near the leading edge.

“Head Up”
Monday continues to look like a potentially rough weather day across the region. An impressive storm system will approach the area with a very unstable and moist air mass in place. Low level shear values look impressive along with surface based instability for numerous supercell thunderstorms to develop with all severe modes possible including tornadoes.

[srainhoutx]

Morning briefing from Jeff:

Highly active 48 hours for Texas with several rounds of severe weather likely across much of the state including the potential for tornadoes, damaging straight line winds, and large hail.

Discussion:
Large and cold upper level low over the SW US will begin to move slowly eastward today with colder air aloft and strong lift starting to overspread a very humid and unstable air mass over SC-NC TX. Shear values increase through the day and low level winds back a little to the ESE supporting a significant increase in low level shear. Instability greatly increases by mid to late afternoon and current mid level capping with erode and be broken. Surface based instability surges below the capping into the 3000-4500 J/kg range and once the cap breaks this energy will be violently released vertically into the atmosphere.

Expect supercell development along and ahead of the dry line over SW/W/NW TX by late this afternoon with tornadoes and very large hail the main threats. A few long tracked and violent tornadoes will be possible in the region from NW TX to SW TX. Supercells should gradually congeal into a couple of storm clusters of MCS’s overnight and move ESE across much of N/C/E TX. Favorable low level inflow off the Gulf of Mexico should maintain storms overnight and in fact the tornado threat may actually increase some this evening in the Austin/Waco/Temple corridor.

High resolution models then redevelop a large MCS over C/SC TX late tonight and bring that across SE TX into the coastal bend early on Monday. Main threat would be wind damage with this system….but all severe modes will be possible.

SPC is considering upgrading portions of the slight risk area into a moderate risk due to the increasing tornado threat. Should this upgraded happen it would likely be along and W of I-35. Convective modes will have to be watched closely this afternoon and evening to time impacts into SE TX overnight into Monday morning. All severe modes will be likely with this activity tonight/Monday.

Day 1 Severe Weather Outlook:

04262015 SPC day1otlk_1300.gif

[srainhoutx]

04262015 mcd0465.gif

MESOSCALE DISCUSSION 0465
NWS STORM PREDICTION CENTER NORMAN OK
1055 AM CDT SUN APR 26 2015

AREAS AFFECTED...PARTS OF NORTHWEST/NORTH-CENTRAL TX INCLUDING TX
BIG COUNTRY INTO SOUTHERN OK

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 261555Z - 261800Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO STEADILY INCREASE THROUGH
LATE MORNING/AFTERNOON AND INTENSIFY ACROSS PORTIONS OF THE
NORTHWEST/NORTH-CENTRAL TX...AND EVENTUALLY REACH PORTIONS OF
SOUTHERN OK LATER THIS AFTERNOON. INITIALLY ELEVATED STORMS COULD
POSE A HAIL RISK LATE THIS MORNING...WHILE THE POTENTIAL FOR
SURFACE-BASED SEVERE THUNDERSTORMS OTHERWISE INCREASES THIS
AFTERNOON. THE NEED FOR A WATCH WILL BECOME INCREASINGLY LIKELY BY
MIDDAY/EARLY AFTERNOON.

DISCUSSION...MULTIPLE BANDS OF INITIALLY ELEVATED THUNDERSTORMS HAVE
INCREASED ACROSS PARTS OF THE TX BIG COUNTRY SINCE MID-MORNING
GENERALLY NEAR THE ABILENE AREA AS OF 1530Z. THIS GENERAL INCREASE
SEEMS VERY LIKELY TO CONTINUE...PARTICULARLY GIVEN THAT
EAST-NORTHEASTWARD-SHIFTING IMPLIED INCREASING FORCING-FOR-ASCENT IS
READILY APPARENT INTO WEST TX PER MORNING IR/WV SATELLITE TRENDS.

SEVERE HAIL MAY BE THE INITIAL RISK LATE THIS MORNING. HOWEVER...AS
MIDDLE/UPPER 60S F SURFACE DEWPOINTS CONTINUE TO STEADILY STREAM
NORTHWARD WITHIN A BROADENING MOIST SECTOR...DEVELOPMENT SHOULD
INCREASINGLY CONNECT WITH THE BOUNDARY LAYER WITH SURFACE-BASED
STORMS BECOMING AN INCREASING CONCERN THIS AFTERNOON...INITIALLY
ACROSS PORTIONS OF NORTHWEST/NORTH-CENTRAL TX.
ACCORDINGLY...ISOLATED TORNADO AND DAMAGING WIND POTENTIAL SHOULD
ALSO INCREASE.

..GUYER/MEAD.. 04/26/2015


ATTN...WFO...FWD...OUN...EWX...SJT...LUB...

[srainhoutx]

Texas A & M will be launching a special sounding shortly.

[srainhoutx]

The Storm Prediction Center Upgrades to a Moderate Risk across portions of N Central Texas this afternoon/evening.

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT SUN APR 26 2015

VALID 261630Z - 271200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF NRN AND CNTRL
TX...

...THERE IS AN ENH RISK OF SVR TSTMS FROM NRN INTO CNTRL AND ERN
TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SRN PLAINS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER THE SRN PLAINS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER A PART OF THE FL
PENINSULA...

...THERE IS A MRGL RISK OF SVR TSTMS OVER SC...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED OVER PARTS OF THE
SOUTHERN PLAINS THIS AFTERNOON THROUGH TONIGHT...WITH THE STORMS
SPREADING SOUTH AND EAST TOWARD THE TEXAS GULF COAST EARLY MONDAY.
VERY LARGE HAIL...TORNADOES...A COUPLE OF WHICH COULD BE
STRONG...AND DAMAGING WINDS WILL ACCOMPANY THESE STORMS. ISOLATED
STRONG TO POTENTIALLY SEVERE STORMS ALSO MAY OCCUR THIS AFTERNOON
OVER PARTS OF SOUTH CAROLINA AND FLORIDA.

...SYNOPSIS...

THE SRN SEGMENT OF AN AMPLIFIED TROUGH OVER THE INTERIOR WEST WILL
FORM A CLOSED UPPER LOW WHICH WILL DEVELOP FROM THE SRN ROCKIES INTO
SRN HIGH PLAINS BY 12Z/MONDAY. AN ASSOCIATED 70-80 KT MID-LEVEL JET
STREAK CURRENTLY ROUNDING THE TROUGH BASE OVER NWRN MEXICO WILL
DEVELOP EWD INTO CNTRL TX WITHIN THE SRN SEMICIRCLE OF THE EVOLVING
LOW.

AT THE SURFACE...A LEE CYCLONE OVER ERN NM WILL DEVELOP GENERALLY
ESEWD INTO CNTRL TX IN RESPONSE TO THE EVOLVING UPPER LOW WITH A
DRYLINE BECOMING ESTABLISHED BY AFTERNOON FROM THE VICINITY OF THE
SURFACE LOW SWD INTO THE EDWARDS PLATEAU. MEANWHILE...A BACKING AND
STRENGTHENING LOW-LEVEL FLOW REGIME WILL PROMOTE THE NWD MOVEMENT OF
A WARM FRONT THROUGH THE RED RIVER VALLEY.

...SRN PLAINS TODAY THROUGH TONIGHT...

MID-MORNING SATELLITE DATA INDICATE A BELT OF IMPLIED ASCENT
SPREADING EWD THROUGH FAR WRN TX AND FAR ERN NM IN ASSOCIATION WITH
A LEAD VORTICITY MAXIMUM PRECEDING THE MAIN UPPER-AIR SYSTEM. AT
THE SAME TIME...AN INCREASINGLY MOIST BOUNDARY LAYER IS RAPIDLY
DEVELOPING NWD THROUGH W-CNTRL TX ALONG AND TO THE S OF THE WARM
FRONT AND BENEATH A PLUME OF STEEP MID-LEVEL LAPSE RATES /SEE 12Z
DRT SOUNDING/. THE OVERLAP OF THESE PROCESSES SHOULD FOSTER AN
INCREASE IN MAINLY ELEVATED TSTMS LATE THIS MORNING INTO AFTERNOON
NWD THROUGH THE RED RIVER VALLEY. INCREASING CLOUD-BEARING SHEAR
AND THE DESTABILIZING ENVIRONMENT WILL PROMOTE VIGOROUS UPDRAFTS
WITH A RISK FOR PRIMARILY LARGE HAIL. FOR ADDITIONAL
INFORMATION...SEE MCD 465.

IN THE WAKE OF THIS EARLY-DAY ACTIVITY OR ALONG ITS SRN
FLANK...SURFACE-BASED STORM DEVELOPMENT IS EXPECTED TO OCCUR BY MID
TO LATE AFTERNOON INTO EVENING FROM THE VICINITY OF THE SURFACE
TRIPLE POINT OVER NWRN TX SWD ALONG THE DRYLINE. THIS ACTIVITY WILL
BE ENCOURAGED BY THE FORCING FOR ASCENT WITHIN THE EXIT REGION OF
THE MID-LEVEL JET STREAK EMERGING FROM SWRN TX WHERE THE COMBINATION
OF 1500-2000+ J/KG MLCAPE AND STEADILY STRENGTHENING LOW-LEVEL AND
DEEP-LAYER SHEAR WILL PROMOTE INTENSE SUPERCELLS CAPABLE OF VERY
LARGE HAIL AND TORNADOES...SOME OF WHICH COULD BE STRONG.

EXPECT STORMS TO GROW UPSCALE INTO ONE OR MULTIPLE MCSS OVERNIGHT
WITH THE RISK FOR POTENTIALLY MORE WIDESPREAD DAMAGING WINDS
INCREASING ACROSS PORTIONS OF CNTRL INTO ERN TX. LARGE HAIL AND A
FEW TORNADOES WILL ALSO REMAIN A CONCERN.

...FL TODAY...

TSTMS HAVE INCREASED IN AREAL COVERAGE THIS MORNING ALONG A RESIDUAL
OUTFLOW BOUNDARY/CONFLUENCE ZONE FROM THE FAR NERN GULF OF MEXICO
EWD ALONG AN OCF-DAB LINE. TO THE SOUTH OF THIS ACTIVITY...DIABATIC
SURFACE HEATING IN CONJUNCTION WITH BOUNDARY-LAYER DEWPOINTS IN THE
LOWER 70S SHOULD RESULT MODERATE AFTERNOON INSTABILITY AMIDST A
KINEMATIC ENVIRONMENT EXHIBITING A RELATIVELY STRONG WLY DEEP-LAYER
WIND FIELD. AS SUCH...THE POTENTIAL WILL EXIST FOR SOME SUPERCELL
AND/OR BOWING STRUCTURES CAPABLE OF MAINLY DAMAGING WIND GUSTS.

FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE MCD 464.

...SC THIS AFTERNOON...

HEATING OF A MOIST AIR MASS PRECEDING A SWD-MOVING COLD FRONT WILL
SUPPORT THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND AT LEAST
A MARGINALLY UNSTABLE AIR MASS LATER TODAY. DIRECT THERMAL
CIRCULATIONS ARISING FROM DIFFERENTIAL HEATING ALONG THE FRONT
SHOULD FOSTER A FEW STORMS BY AFTERNOON WITH LOCALLY STRONG WIND
GUSTS POSSIBLE OWING TO THE DOWNWARD TRANSPORT OF STRONG WNWLY FLOW
ALOFT.

..MEAD/GLEASON.. 04/26/2015

[srainhoutx]

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1205 PM CDT SUN APR 26 2015

VALID 271200Z - 281200Z

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

...THERE IS A MRGL RISK OF SVR TSTMS IMMEDIATELY SURROUNDING THE
SLIGHT RISK...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS WILL DEVELOP FROM EASTERN AND
SOUTHEASTERN TEXAS EASTWARD INTO THE CENTRAL GULF COAST STATES ON
MONDAY.

...TX TO THE CNTRL GULF COAST...
A LOW-LEVEL MOISTURE FEED FROM THE NWRN GULF INTO TX/LA DURING THE
MORNING WILL CONTINUE TO MOISTEN/DESTABILIZE THE BOUNDARY LAYER OVER
THE NWRN GULF COAST REGION AHEAD OF A MID-LEVEL LOW LOCATED OVER
NWRN TX TO START THE PERIOD. THE PRIMARY FEATURE OF INTEREST FOR
MONDAY IS THE DEVELOPMENT/EVOLUTION OF A THUNDERSTORM
CLUSTER/COMPLEX THAT IS FORECAST TO DEVELOP ACROSS PORTIONS OF CNTRL
TX PRIOR TO THE START OF THE DAY 2 PERIOD. AS THE UPPER TROUGH/LOW
MEANDERS EWD ACROSS NWRN TX AND OK DURING THE DAY...THIS FEATURE AND
A POWERFUL UPPER JET LOCATED OVER SRN/SERN TX WILL PROVIDE STRONG
UPPER-LEVEL FORCING FOR ASCENT AND IN TURN AID IN MAINTAINING
WHATEVER MANAGES TO EVOLVE BY MONDAY MORNING. BASED ON STRONG MODEL
CONSENSUS TO THIS POINT...THE WRN AND NWRN BOUNDS OF THE SEVERE
THREAT WILL PROBABLY BE DEMARCATED DUE TO EARLY DAY STORMS.

WITH THE ABOVE CONVECTIVE-SCALE INFLUENCING FACTORS AND ASSOCIATED
UNCERTAINTY IN MIND...A MOISTURE RICH BOUNDARY LAYER /CHARACTERIZED
BY MEAN MIXING RATIOS 14-16 G PER KG/ BENEATH STEEP MID-LEVEL LAPSE
RATES --TO THE S OF A WEST-EAST ORIENTED FRONTAL ZONE-- WILL
CONTRIBUTE TO A MODERATE TO STRONGLY UNSTABLE AIR MASS. A VEERING
AND INCREASING WIND PROFILE WITH HEIGHT WILL SUPPORT ORGANIZED STORM
STRUCTURES CAPABLE OF A STRONG TO SEVERE STORM RISK. THE WIND
DAMAGE RISK MAY EVOLVE TO BE PERHAPS THE GREATEST RISK AS STORMS
MOVE EWD ALONG THE CNTRL GULF COAST DURING THE DAY. IN WAKE OF
EARLY-DAY CONVECTION FARTHER W OVER TX...IF SUFFICIENT
DESTABILIZATION CAN OCCUR...A FEW STRONG STORMS MAY DEVELOP PRIOR TO
EVENING BEFORE THIS ACTIVITY LIKELY WEAKENS TOWARDS DARK.

..SMITH.. 04/26/2015

[srainhoutx]

Excellent analysis by Forecaster Cavanaugh from NWS Ft Worth/Dallas. As mentioned yesterday with the 12Z guidance recap 04/25/2015, the trends are continuing to suggest a very strong and possibly severe squall line developing and marching across Central/SE Texas into Louisiana overnight tonight into tomorrow. Cavanaugh mentions the derecho possibility since the updated 00Z and 12Z operational guidance as well as the short term meso guidance are latching onto this potential. The main threat would be damaging winds associated with such a strong organized squall line with an isolated tornado or two embedded in the leading edge of a the potential squall line.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
1239 PM CDT SUN APR 26 2015

.UPDATE...

...MESOSCALE FORECAST UPDATE REGARDING THE FORECAST FOR SEVERE
STORMS ACROSS NORTH AND CENTRAL TEXAS TODAY...

12Z UPPER AIR ANALYSIS SHOWED AN INTENSE UPPER LEVEL TROUGH
LOCATED OVER THE SOUTHERN ARIZONA AND NEW MEXICO BORDER. 500 MB
HEIGHT FALLS OF 6 TO 12 DM WERE OBSERVED DOWNSTREAM OF THIS UPPER
TROUGH...AND THE MAGNITUDE OF THESE HEIGHT FALLS IS INDICATIVE OF
STRONG LARGE SCALE FORCING FOR ASCENT TO THE EAST. AT THE 700 MB
LEVEL...A PLUME OF STEEP MID-LEVEL LAPSE RATES WAS OBSERVED...WITH
A TEMPERATURE DIFFERENCE IN THE 700 TO 500 MB LAYER OF 22 DEG C
LOCATED SOUTHWEST OF NORTH AND CENTRAL TEXAS. TO THE SOUTHWEST OF
THIS PLUME OF ENHANCED LAPSE RATES...A 50 KT MID-LEVEL JET CORE
WAS OBSERVED OVER NORTHERN MEXICO. CLOSER TO THE SURFACE...AT THE
850 MB LEVEL...DEEP MOISTURE WAS ONLY OBSERVED OVER SOUTHWEST
TEXAS WITH A DRYLINE SUBJECTIVELY ANALYZED NEAR THE TX/OK
BORDER...EXTENDING SOUTHWEST OVER WEST CENTRAL TEXAS AND INTO
NORTHERN MEXICO ABOUT 60 MILES WEST OF DEL RIO. A 15Z SURFACE
ANALYSIS OBSERVED RICH MOISTURE IN PLACE ALONG THE TX GULF COAST
WITH MID 70S DEW POINTS OBSERVED WEST AND SOUTHWEST OF HOUSTON.

FOR TODAY...NEARLY ALL SHORT RANGE MODEL GUIDANCE INDICATES THAT A
SURFACE LOW PRESSURE SYSTEM WILL INTENSIFY RAPIDLY THIS AFTERNOON
OVER WEST CENTRAL TEXAS. MOST GUIDANCE SHOWS SURFACE PRESSURE
FALLING AT A RATE OF 2-3 MB PER HOUR LEADING UP TO 00Z. AT
15Z...THE LOWEST SURFACE PRESSURE OVER THE SOUTHERN HIGH PLAINS
WAS AROUND 1002 MB...MOST GUIDANCE INDICATES THE SURFACE LOW'S
PRESSURE WILL FALL TO 993 TO 995 MB BY 00Z. THAT MAGNITUDE OF
PRESSURE FALL ASSOCIATED WITH THE SURFACE LOW IS FAIRLY
INTENSE...AND SHOULD RESULT IN A CONVERGENCE OF PARAMETERS THAT
WILL SUPPORT A LOCALIZED SEVERE WEATHER OUTBREAK ACROSS THE
REGION THIS AFTERNOON AND EVENING. ONE OF THE KEY FORECAST
CHALLENGES TODAY WILL BE DETERMINING WHERE THE SURFACE LOW MOVES
AS THE RELATIVE THREATS FOR SUPERCELLS AND TORNADOES WILL VARY
DEPENDING ON THE EXACT POSITION OF THIS LOW LATER THIS AFTERNOON.

THE 12Z NAM AND 16Z HRRR INDICATE THE SURFACE LOW WILL BE LOCATED
JUST SOUTH OF INTERSTATE 20 AND JUST NORTH OF SAN ANGELO. IF THIS
POSITION FOR THE SURFACE LOW IS CORRECT...THE THREAT FOR DISCRETE
SUPERCELLS WOULD BE MAXIMIZED TO THE EAST OF THE SURFACE
LOW...WHERE A TRIPLE POINT WOULD LIKELY SET UP. SUPERCELLS WOULD
BE MOST LIKELY TO DEVELOP NEAR THIS TRIPLE POINT...AND THEN MOVE
EAST IN THE RELATIVELY STRONG SOUTHWESTERLY FLOW ALOFT. STORMS
APPEAR TO BE VERY LIKELY IN A SUPERCELL STORM MODE IF THEY DEVELOP
IN THIS TRIPLE POINT BY 00Z AS CAPE IS FORECAST TO BE ON THE ORDER
OF 3000 J/KG WITH DEEP LAYER SHEAR OF 50 KTS IN THE 0-6 KM AGL
LAYER. THE SHAPE OF THE 0-3 KM HODOGRAPH IS EXPECTED TO BE
CLOCKWISE LOOPING...AND DYNAMICALLY MORE FAVORABLE FOR RIGHT
MOVING SUPERCELLS. AS A RESULT...EXPECT SUPERCELL STORM MOTION TO
BE ALMOST DUE EAST LATE THIS AFTERNOON AND EARLY THIS EVENING.

RIGHT MOVING SUPERCELLS LOOK MOST LIKELY SOUTH OF INTERSTATE 20
BASED ON THE FORECAST POSITION OF THE SURFACE LOW. THIS PLACES
MUCH OF CENTRAL TEXAS IN THE PRIMARY THREAT CORRIDOR FOR DISCRETE
SUPERCELLS. THE ENVIRONMENT IS SUPPORTIVE OF WELL-ORGANIZED
SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL...DAMAGING WIND
GUSTS AND TORNADOES. THE RESIDENTS OF CENTRAL TEXAS ARE ENCOURAGED
TO PAY VERY CLOSE ATTENTION TO THE WEATHER THIS AFTERNOON AND
EVENING AS A RESULT. OF COURSE IF THE SURFACE LOW IS FARTHER NORTH
...THE PRIMARY THREAT CORRIDOR FOR DISCRETE SUPERCELLS WILL MOVE
NORTH WITH IT. AWAY FROM THIS PRIMARY THREAT CORRIDOR...IT IS
CERTAINLY POSSIBLE FOR SUPERCELLS TO DEVELOP JUST ABOUT ANYWHERE
IN THE WARM AIR ADVECTION REGIME INDICATED BY THE CLOCKWISE
LOOPING LOW-LEVEL HODOGRAPH. THIS LIFT/FORCING IS NOT AS STRONG
AND FOCUSED...SO IT IS SIMPLY MORE DIFFICULT TO KNOW IF...WHEN
AND WHERE A SUPERCELL MAY DEVELOP IN THIS WARM AIR ADVECTION
REGIME.

AFTER 00Z...THE VERY STRONG FORCING FOR ASCENT ASSOCIATED WITH THE
UPPER TROUGH OVER SOUTHERN ARIZONA AND NEW MEXICO IS EXPECTED TO
LIFT OUT OVER THE SOUTHERN PLAINS. THE LATEST MODEL GUIDANCE IS
CONVERGING ON A SOLUTION THAT SUGGESTS A VERY WELL ORGANIZED
SQUALL LINE WILL DEVELOP NEAR CHILDRESS...AND MOVE SOUTHEAST
TOWARDS NORTH TEXAS THIS EVENING. THERE ARE HINTS IN THE MODEL
MASS FIELDS THAT THIS SQUALL LINE COULD POTENTIALLY BE VERY WELL
ORGANIZED...AND MAY POSE A WIDESPREAD DAMAGING WIND THREAT AS IT
MOVES SOUTHEAST ACROSS NORTH TEXAS OVERNIGHT. IF THIS SQUALL LINE
DOES INDEED ORGANIZE...IT MAY PERSIST LONG ENOUGH AND PRODUCE
ENOUGH STRAIGHT LINE WIND DAMAGE TO QUALIFY AS A DERECHO BY THE
TIME IT EXITS THE CWA TO THE EAST WELL AFTER MIDNIGHT. THE PRIMARY
TIME THIS SQUALL LINE/BOW-ECHO IS EXPECTED TO MOVE OVER NORTH
TEXAS IS FROM 10 PM TO 3 AM. THE EXISTENCE OF THIS SQUALL LINE IS
FAR FROM 100 PERCENT CERTAIN...BUT IT WILL PROBABLY ORGANIZE BASED
ON THE CONSISTENT SIGNAL IN THIS MORNING'S HIGH RESOLUTION MODEL
GUIDANCE. THE PRIMARY THREATS WITHIN THIS SQUALL LINE WOULD BE
DAMAGING STRAIGHT LINE WINDS. ASSUMING THE SQUALL LINE MOVES
THROUGH THE AREA AFTER SUNSET AS CURRENTLY FORECAST...THIS MAY
REDUCE THE POTENTIAL FOR HIGH-END DAMAGING WINDS. REGARDLESS...
WIND DAMAGE WOULD STILL BE LIKELY AS THIS SQUALL LIKE WOULD
PROBABLY BE VERY WELL ORGANIZED. LARGE HAIL AND A BRIEF TORNADO
MAY ALSO OCCUR IN THIS LINE...ASSUMING IT DEVELOPS.

LAST BUT NOT LEAST...WE WILL ALSO BE MONITORING FOR HEAVY RAINFALL
AND FLASH FLOODING POTENTIAL THIS AFTERNOON AND EVENING. IF A WARM
FRONT SETS UP ALONG THE INTERSTATE 20 CORRIDOR...SCATTERED
THUNDERSTORMS COULD DEVELOP ALONG THIS BOUNDARY AND TRAIN OVER
AREAS TO THE NORTHEAST. THIS MAY EVOLVE INTO ANOTHER LOCALIZED
FLASH FLOODING EVENT NORTH OF INTERSTATE 20 AND GENERALLY EAST OF
INTERSTATE 35...VERY SIMILAR TO WHAT HAPPENED ON FRIDAY. WILL HOLD
OFF ON A FLASH FLOOD WATCH FOR NOW AS CONFIDENCE IN THIS TAKING
PLACE IS NOT HIGH AT THIS TIME. IF IT OCCURS...THESE LOCATIONS
HAVE ALREADY RECEIVED QUITE A BIT OF RAINFALL ON FRIDAY...SO
FLOODING WOULD TEND TO OCCUR QUICKLY IF STORMS BEGIN TO TRAIN OVER
THIS REGION THROUGH TONIGHT.

WILL CONTINUE TO MAKE SHORT TERM FORECAST UPDATES FOR CONVECTION
MODE THROUGH THIS EVENING. EXPECT STORMS WILL START DEVELOPING
NEAR THE SURFACE LOW AND EVOLVE INTO DISCRETE SUPERCELLS BY/AFTER
4 PM/21Z.

CAVANAUGH

[srainhoutx]

Tornado Watch issued for portions N Central Texas until 8:00PM CDT. The Watch does NOT include Dallas or Ft Worth...at this time..

Code: Select all

BULLETIN - IMMEDIATE BROADCAST REQUESTED
   TORNADO WATCH OUTLINE UPDATE FOR WT 119
   NWS STORM PREDICTION CENTER NORMAN OK
   105 PM CDT SUN APR 26 2015

   TORNADO WATCH 119 IS IN EFFECT UNTIL 800 PM CDT FOR THE
    FOLLOWING LOCATIONS


   TX 
   .    TEXAS COUNTIES INCLUDED ARE

   ARCHER               BAYLOR              BROWN               
   CALLAHAN             CHILDRESS           CLAY                
   COKE                 COLEMAN             COMANCHE            
   COTTLE               EASTLAND            ERATH               
   FISHER               FOARD               HARDEMAN            
   HASKELL              JACK                JONES               
   KING                 KNOX                NOLAN               
   PALO PINTO           RUNNELS             SHACKELFORD         
   STEPHENS             STONEWALL           TAYLOR              
   THROCKMORTON         WICHITA             WILBARGER           
   YOUNG                


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

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0251 PM CDT SUN APR 26 2015

VALID 262000Z - 271200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF NRN AND CNTRL
TX...

...THERE IS AN ENH RISK OF SVR TSTMS FROM NRN INTO CNTRL AND ERN
TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SRN PLAINS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER THE SRN PLAINS...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED OVER PARTS OF THE
SOUTHERN PLAINS THIS AFTERNOON THROUGH TONIGHT...WITH THE STORMS
SPREADING SOUTH AND EAST TOWARD THE TEXAS GULF COAST EARLY MONDAY.
VERY LARGE HAIL...TORNADOES...A COUPLE OF WHICH COULD BE
STRONG...AND DAMAGING WINDS WILL ACCOMPANY THESE STORMS. ISOLATED
STRONG TO POTENTIALLY SEVERE STORMS ALSO MAY OCCUR THIS AFTERNOON
OVER PARTS OF SOUTH CAROLINA AND FLORIDA.

THE ONLY SUBSTANTIAL CHANGES MADE TO THE PREVIOUS OUTLOOK INCLUDE 1)
THE REMOVAL OF MARGINAL SEVERE PROBABILITIES IN SC AND THE N-CNTRL
FL PENINSULA...2) INCLUDING THE AREA OF WRN N-CNTRL TX INTO THE 30
PERCENT SIGNIFICANT HAIL PROBABILITY BASED ON ONGOING SUPERCELLS
POSING A LARGE TO VERY LARGE HAIL THREAT OVER THE NEXT SEVERAL
HOURS.

..SMITH.. 04/26/2015

.PREV DISCUSSION... /ISSUED 1128 AM CDT SUN APR 26 2015/

...SYNOPSIS...

THE SRN SEGMENT OF AN AMPLIFIED TROUGH OVER THE INTERIOR WEST WILL
FORM A CLOSED UPPER LOW WHICH WILL DEVELOP FROM THE SRN ROCKIES INTO
SRN HIGH PLAINS BY 12Z/MONDAY. AN ASSOCIATED 70-80 KT MID-LEVEL JET
STREAK CURRENTLY ROUNDING THE TROUGH BASE OVER NWRN MEXICO WILL
DEVELOP EWD INTO CNTRL TX WITHIN THE SRN SEMICIRCLE OF THE EVOLVING
LOW.

AT THE SURFACE...A LEE CYCLONE OVER ERN NM WILL DEVELOP GENERALLY
ESEWD INTO CNTRL TX IN RESPONSE TO THE EVOLVING UPPER LOW WITH A
DRYLINE BECOMING ESTABLISHED BY AFTERNOON FROM THE VICINITY OF THE
SURFACE LOW SWD INTO THE EDWARDS PLATEAU. MEANWHILE...A BACKING AND
STRENGTHENING LOW-LEVEL FLOW REGIME WILL PROMOTE THE NWD MOVEMENT OF
A WARM FRONT THROUGH THE RED RIVER VALLEY.

...SRN PLAINS TODAY THROUGH TONIGHT...

MID-MORNING SATELLITE DATA INDICATE A BELT OF IMPLIED ASCENT
SPREADING EWD THROUGH FAR WRN TX AND FAR ERN NM IN ASSOCIATION WITH
A LEAD VORTICITY MAXIMUM PRECEDING THE MAIN UPPER-AIR SYSTEM. AT
THE SAME TIME...AN INCREASINGLY MOIST BOUNDARY LAYER IS RAPIDLY
DEVELOPING NWD THROUGH W-CNTRL TX ALONG AND TO THE S OF THE WARM
FRONT AND BENEATH A PLUME OF STEEP MID-LEVEL LAPSE RATES /SEE 12Z
DRT SOUNDING/. THE OVERLAP OF THESE PROCESSES SHOULD FOSTER AN
INCREASE IN MAINLY ELEVATED TSTMS LATE THIS MORNING INTO AFTERNOON
NWD THROUGH THE RED RIVER VALLEY. INCREASING CLOUD-BEARING SHEAR
AND THE DESTABILIZING ENVIRONMENT WILL PROMOTE VIGOROUS UPDRAFTS
WITH A RISK FOR PRIMARILY LARGE HAIL. FOR ADDITIONAL
INFORMATION...SEE MCD 465.

IN THE WAKE OF THIS EARLY-DAY ACTIVITY OR ALONG ITS SRN
FLANK...SURFACE-BASED STORM DEVELOPMENT IS EXPECTED TO OCCUR BY MID
TO LATE AFTERNOON INTO EVENING FROM THE VICINITY OF THE SURFACE
TRIPLE POINT OVER NWRN TX SWD ALONG THE DRYLINE. THIS ACTIVITY WILL
BE ENCOURAGED BY THE FORCING FOR ASCENT WITHIN THE EXIT REGION OF
THE MID-LEVEL JET STREAK EMERGING FROM SWRN TX WHERE THE COMBINATION
OF 1500-2000+ J/KG MLCAPE AND STEADILY STRENGTHENING LOW-LEVEL AND
DEEP-LAYER SHEAR WILL PROMOTE INTENSE SUPERCELLS CAPABLE OF VERY
LARGE HAIL AND TORNADOES...SOME OF WHICH COULD BE STRONG.

EXPECT STORMS TO GROW UPSCALE INTO ONE OR MULTIPLE MCSS OVERNIGHT
WITH THE RISK FOR POTENTIALLY MORE WIDESPREAD DAMAGING WINDS
INCREASING ACROSS PORTIONS OF CNTRL INTO ERN TX. LARGE HAIL AND A
FEW TORNADOES WILL ALSO REMAIN A CONCERN.

...FL TODAY...

TSTMS HAVE INCREASED IN AREAL COVERAGE THIS MORNING ALONG A RESIDUAL
OUTFLOW BOUNDARY/CONFLUENCE ZONE FROM THE FAR NERN GULF OF MEXICO
EWD ALONG AN OCF-DAB LINE. TO THE SOUTH OF THIS ACTIVITY...DIABATIC
SURFACE HEATING IN CONJUNCTION WITH BOUNDARY-LAYER DEWPOINTS IN THE
LOWER 70S SHOULD RESULT MODERATE AFTERNOON INSTABILITY AMIDST A
KINEMATIC ENVIRONMENT EXHIBITING A RELATIVELY STRONG WLY DEEP-LAYER
WIND FIELD. AS SUCH...THE POTENTIAL WILL EXIST FOR SOME SUPERCELL
AND/OR BOWING STRUCTURES CAPABLE OF MAINLY DAMAGING WIND GUSTS.

FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE MCD 464.

...SC THIS AFTERNOON...

HEATING OF A MOIST AIR MASS PRECEDING A SWD-MOVING COLD FRONT WILL
SUPPORT THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND AT LEAST
A MARGINALLY UNSTABLE AIR MASS LATER TODAY. DIRECT THERMAL
CIRCULATIONS ARISING FROM DIFFERENTIAL HEATING ALONG THE FRONT
SHOULD FOSTER A FEW STORMS BY AFTERNOON WITH LOCALLY STRONG WIND
GUSTS POSSIBLE OWING TO THE DOWNWARD TRANSPORT OF STRONG WNWLY FLOW
ALOFT.


NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z

[srainhoutx]

Afternoon update from HGX says it all. Keep an eye on the weather folks and inform those that may not be so weather wise to be aware as well.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
340 PM CDT SUN APR 26 2015

.DISCUSSION...
A FEW SHOWERS STILL GOING FROM THIS MORNINGS S/W IMPULSE THAT
MOVED INTO THE COASTAL AREAS NOW OVER NORTHEAST AREAS AND ISOLATED
STORMS IN THE GULF. BOUNDARY STILL EVIDENT FROM AROUND BEAUMONT TO
HOUSTON TO COLLEGE STATION AND LIFTING NORTH. LIFT LOOKS TO BE
INCREASING ACROSS S TX AND WHERE PRESSURES HAVE FALLEN 3 MB IN THE
LAST FEW HOURS.

VERY ACTIVE WEATHER EXPECTED OVERNIGHT AND THROUGHOUT THE DAY
MONDAY FOR SETX.

EXPECTING RAPID INTENSIFICATION OF STORMS ALONG THE DRYLINE IN
WESTERN HILL COUNTRY REGION THIS EVENING AND AS UPPER JET SLOWLY
SHIFTS EASTWARD OVER SETX THESE STORMS SHOULD ADVANCE EASTWARD
MOVING INTO THE WESTERN CWA BETWEEN MIDNIGHT AND 4 AM THEN INTO
THE CENTRAL AREAS PERHAPS AS EARLY AS 6 AM. SURFACE LOW TRACKING
JUST INLAND FROM S TX THROUGH CRP INTO GALVESTON BAY AREA AROUND
18Z WILL HELP TO INCREASE LL EASTERLY FLOW AND SHEAR IN OUR
HODOGRAPHS. (COULD ALSO HELP TO MAKE FOR SOME LIGHT-MODERATE
ADVECTION FOG EARLY IN THE MORNING FOR COASTAL AREAS) PW SHOULD
CLIMB TO NEAR 1.8-2" WITH THE ARRIVAL OF THE STORMS AND FORECAST
SOUNDINGS ARE IMPRESSIVE. HIGH CAPE ENVIRONMENT 1900-4000J/KG
(HIGHER CAPE SCENARIOS ARRIVE MONDAY AFTERNOON. MEDIAN CAPE VALUES
AROUND 2500 SEEM MORE REASONABLE. SHEAR IS SUFFICIENT FOR
SUPERCELLS AND BOWING SEGMENTS (EHI OF 1.5 TO 4) WITH STRONG MID
LEVEL SW FLOW TO BOOT. EXPECT TO SEE TRAINING AND REDEVELOPMENT
ON SW FLANKS SO SOME BACK BUILDING MAY OCCUR ACROSS THE CENTRAL
CWA MONDAY MORNING/EARLY AFTERNOON. HAVE RAISED POPS FOR MONDAY
AND WILL CARRY HEAVY RAINFALL THREAT AND SEVERE AS WELL CENTERED
AROUND MONDAY...AFTER MIDNIGHT TONIGHT MAY REACH INTO WESTERN CWA.
RAINFALL SHOULD BE WIDESPREAD AND A LARGE EAST TO WEST SWATH OF
1-2" AMOUNTS LOOKS LIKELY AND IF THE TRAINING/BACK-BUILDING
REDEVELOPMENT SHOULD TAKE PLACE THEN ISOLATED AMOUNTS MAY EXCEED
5"...MONDAY LOOKS LIKE A WASHOUT. MAY NEED A FLASH FLOOD WATCH AND
WILL BE LETTING EVENING SHIFT EVALUATE THE 00Z GUIDANCE TO MAKE
THAT CALL. SECOND S/W ROTATING AROUND THE MAIN TROUGH COULD BE
ENOUGH TO KEEP SOME LINGERING POPS MONDAY NIGHT CENTERED MAINLY
OVER THE NORTHEASTERN AREA. IMPRESSIVE LATE SEASON COLD FRONT
POURS DOWN AND THROUGH THE AREA EARLY TUESDAY MORNING PROBABLY OFF
THE COAST BY 09-12Z. WINDS IN THE WAKE OF THE FRONT WILL LIKELY
SUPPORT WIND ADVISORIES FOR COASTAL COUNTIES AND PERHAPS EVEN A
FEW MORE COUNTIES INLAND. DRY HIGH PRESSURE FILLS AND THE
REMAINDER OF THE WEEK LOOKS LIKE VERY PLEASANT WEATHER WITH LIGHT
WINDS/ABUNDANT SUNSHINE/VERY LOW RAIN CHANCES IF ANY. RETURN FLOW
COMES BACK IN SATURDAY AND DEEPER MOISTURE SHOULD ARRIVE NEXT
SUNDAY. 45

[srainhoutx]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 04/26/15 2115Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES-EAST:2045Z JS
.
LOCATION...N CENT TEXAS...
.
ATTN WFOS...FWD...OUN...SJT...LUB...MAF...
ATTN RFCS...ABRFC...WGRFC...
.
EVENT...MAIN EVENT NOW INITIATING WITH HEAVY RAIN THREAT INITIALLY ALONG
AND EAST OF DRYLINE.
.
SATELLITE ANALYSIS AND TRENDS...EVENT NOW UNDERWAY SO MESSAGES WILL
TRANSITION FROM EARLIER THOUGHTS PROVIDED VIA 12 PLANET COORDINATION TO
A FOCUS ON THE SHORT TERM OUTLOOK. AFTER EXAMINATION OF LLJ, MOISTURE
TRENDS FROM GOES SOUNDER/BLENDED TPW ANIMATION AND SFC ANALYSIS, BELIEVE
THE INITIAL AREA OF HEAVY RAIN CONCERN EXISTS WITH THE ACTIVITY INITIALLY
CENTERED AROUND JONES COUNTY IN N CENT TX. THE LOW LEVEL INFLOW SEEN IN
THE VISIBLE ANIMATION ALONG WITH NEW CELL DEVELOPMENT/RAPIDLY FORMING
TOWERING CU TO THE S OF THIS AREA PROMOTES BACK BUILDING/TRAINING
IN SPOT WHERE MEAN FLOW ALOFT SPLITS AND ALSO APPEARS TO HAVE
ALIGNED ITSELF PARALLEL TO THE AXIS OF CELL DEVELOPMENT/LINE SEGMENT
ORIENTATION. OBJECTIVE SFC ANALYSIS ALSO POINTS TOWARD SFC MOISTURE
CONVERGENCE BEING MAXIMIZED IN THIS LOCATION AS WELL. ANALYSIS ALONG WITH
THE EXPERIMENTAL CIMSS/NOAA-NSSL WIND DIVERGENCE PRODUCT HIGHLIGHTS THIS
AREA ALSO AS BEING THE SWEET SPOT FOR MAXIMUM UPPER LEVEL DIVERGENCE. AT
THIS TIME, THE ONLY PARAMETERS WHICH ARE NOT PRECISELY COLLOCATED IN
THIS SPOT WOULD BE THE DEEPER MOISTURE AND ABSOLUTE GREATEST REGIONAL
INSTABILITY AS SEEN IN THE GOES SOUNDER PRODUCTS AND THE NEARCAST VERTICAL
THETA-E DIFFERENCING PRODUCT WHICH ARE LOCATED SLIGHTLY FARTHER TO THE
SE AND E OF THIS AREA.
.
FOR THE NEXT SEVERAL HOURS, EXPECT ADDITIONAL DEVELOPMENT TO
CONTINUE TO OCCUR TOWARD THE CONFLUENT LOW LEVEL INFLOW ON THE
S AND SE PERIPHERY OF THE AFOREMENTIONED ACTIVITY CENTERED AROUND
JONES/SHACKELFORD/HASKELL/THROCKMORTON COUNTIES IN REGION WHERE CINH HAS
ALSO ERODED THE MOST PER GOES SOUNDER ANIMATION. BACK BUILDING/TRAINING
ARE THE MAIN THREATS WITH CELLS FORMING IN REGION WHERE MEAN FLOW
SPLITS. FARTHER TO THE NW, CELLS DEVELOPING IN ENVIRONMENT INITIALLY
WITH SOMEWHAT LESS OVERALL MOISTURE APPEAR TO BE TAKING ON MORE OF A
COMMA-HEAD TYPE SIGNATURE NEAR THE INTERSECTION OF THE DRY LINE AND WAVY
STATIONARY SFC BOUNDARY FROM JUST S OF CHILDRESS TO THE NW TX PANHANDLE
NW OF AMARILLO. SOME TRAINING FROM SE TO NW IS LIKELY TO EVENTUALLY
SET UP ALONG THIS AXIS AS WELL OVER THE NEXT FEW HOURS AS CELL COVERAGE
INCREASES. SEE OUTLINED THREAT AREAS ON GRAPHIC APPENDED TO TEXT MESSAGE
ON INTERNET IN APPROX 10 MINUTES.

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
423 PM CDT SUN APR 26 2015

JACKSON TX-COLORADO TX-WHARTON TX-
423 PM CDT SUN APR 26 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN COLORADO...
NORTHWESTERN WHARTON AND NORTH CENTRAL JACKSON COUNTIES UNTIL 515 PM
CDT...

AT 423 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
SPEAKS...OR 20 MILES NORTH OF EDNA...MOVING NORTHEAST AT 25 MPH.

DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
EGYPT...SHERIDAN...ALTAIR...ROCK ISLAND...GARWOOD...CORDELE AND NADA.

[srainhoutx]

Shortwave and colder mid level temperatures moving into Central Texas at this time. Expect rapid thunderstorm development to begin along and ahead of the dryline across portions of S Central/Central Texas and on N to near the Childress area.

[srainhoutx]

Update from Jeff:

Supercell thunderstorm has developed along weak low level boundary in region of strong surface heating this afternoon. Cell is feeding off good low level influx of rich Gulf moisture and favorable upper level divergence from incoming upper level storm system.

Thus far radar has shown no low level rotation, but this cell is all by itself and has plenty of strong instability to feed from as it moves generally ENE. Would not be surprised to see the supercell become severe and possibly tornadic especially if it turns toward the right (ESE) into better low level inflow and enhances its low level shear values.

[srainhoutx]

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
458 PM CDT SUN APR 26 2015

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
SOUTHEASTERN COLORADO COUNTY IN SOUTHEASTERN TEXAS...
CENTRAL WHARTON COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 530 PM CDT

* AT 457 PM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN EXCESS
OF 60 MPH. THIS STORM WAS LOCATED 12 MILES NORTHWEST OF EL CAMPO...
AND MOVING NORTHEAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...
WHARTON...EGYPT...NADA AND HUNGERFORD.