Severe Thunderstorm Warning 55, NWS Fort Worth, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
416 AM CDT SAT MAR 23 2013

.DISCUSSION...

SHORT TERM FORECAST CONCERNS...FOR A DETAILED DISCUSSION REGARDING
THUNDERSTORMS THIS MORNING ACROSS NORTH TEXAS...PLEASE REFER TO
THE AREA WEATHER UPDATE /AWUFWD/ SENT AROUND 2 AM CDT.

CHANGES FROM THE 2 AM AREA WEATHER UPDATE...REGIONAL RADARS
OBSERVED A LINE OF THUNDERSTORMS EXTENDING FROM BIG SPRING TX TO
BRECKENRIDGE AT 0830Z /330 AM CDT/. THIS IS MORE OR LESS IN LINE
WITH THE EXPECTED EVOLUTION OF CONVECTION INITIATION DISCUSSED IN
THE AREA WEATHER UPDATE THIS MORNING...SO NOT MUCH TO ADD HERE AT
THIS TIME. THIS LINE OF STORMS WILL LIKELY MOVE EAST AND SHOULD
SPREAD IN COVERAGE NORTH AND SOUTH A BIT FROM THE NARROW BAND OF
CONVECTION BEING OBSERVED AT THE TIME OF THIS DISCUSSION. THE
STORM PREDICTION CENTERS MESOSCALE SURFACE OBJECTIVE ANALYSIS
SCHEME /SPC SFCOA/ INDICATES THAT THE H850 MOISTURE MAXIMA WAS
LOCATED JUST TO THE SOUTH OF THIS LINE OF STORMS AT 08Z. AREA VAD
WIND PROFILES FROM REGIONAL RADARS INDICATE THAT THE LLJ HAS
STRENGTHENED SLIGHTLY...TO 35 KTS UPSTREAM OF THIS LINE OF STORMS.
THE LLJ WILL CONTINUE TO FEED THESE STORMS AS THEY SPREAD EAST
THIS MORNING INTO NORTH TX AND TOWARDS THE INTERSTATE 35 CORRIDOR
AFTER SUNRISE.

THE 08Z SFCOA INDICATED THAT THERE WAS AROUND 2000 J/KG OF MOST
UNSTABLE CAPE /MUCAPE/ ASSOCIATED WITH THE H850 MOISTURE MAXIMA.
FORECAST SOUNDINGS ACROSS NORTH TX FOR THIS MORNING INDICATE ABOUT
HALF THIS MUCH ELEVATED OR MUCAPE SO ITS NOT ENTIRELY OBVIOUS HOW
MUCH POTENTIAL ENERGY WILL BE AVAILABLE FOR STORMS WHEN THEY
SPREAD EAST INTO NORTH TX. AT THIS TIME...JUST LOOKING AT THE
INTENSITY OF ONGOING CONVECTION...TEND TO SIDE WITH THE MORE
CONSERVATIVE FORECAST FOR MUCAPE ADVERTISED IN RAP/NAM FORECAST
SOUNDINGS AS I WOULD EXPECT TO SEE MORE EXPLOSIVE THUNDERSTORM
DEVELOPMENT WITH NEARLY 2000 J/KG OF MUCAPE TO WORK WITH.

REGARDLESS...500 TO 1000 J/KG OF MUCAPE COMBINED WITH RELATIVELY
STRONG EFFECTIVE BULK SHEAR WILL CONTINUE TO SUPPORT A MARGINAL
SEVERE HAIL THREAT ACROSS NORTH TX TODAY. IF STORMS CAN MAINTAIN A
DISCRETE MODE...SUPERCELL STRUCTURES ARE POSSIBLE AND ANY
SUPERCELLS THAT DEVELOP WOULD BE CAPABLE OF PRODUCING LARGER HAIL.
OF COURSE IF SFCOA IS ACTUALLY MORE REALISTIC WITH MUCAPE VALUES
THAT MAY BE AVAILABLE OVER NORTH TX LATER THIS MORNING...A MORE
WIDESPREAD HAIL THREAT MAY BE WARRANTED IN GENERAL. AS IT
STANDS...NEARLY ALL HIGH RESOLUTION GUIDANCE CONTINUES TO FAVOR A
MULTI-CELLULAR STORM MODE WHICH WILL LIKELY LIMIT THE POTENTIAL
FOR GREATER THAN QUARTER SIZED HAIL.

STORMS ARE STILL EXPECTED TO MOVE EAST OF INTERSTATE 35 BY THIS
AFTERNOON...SO NO CHANGES MADE TO THE PREVIOUS FORECAST FOR THIS
PERIOD. FOR TONIGHT...A STRONG UPPER LEVEL TROUGH WILL SWING A
STRONG LOBE OF ENERGY OUT OVER THE PLAINS WHICH WILL SEND A
POWERFUL COLD FRONT SOUTH THROUGH NORTH TX OVERNIGHT. HIGH
RESOLUTION GUIDANCE YESTERDAY INDICATED THAT A NARROW FETCH OF
MOISTURE WOULD BE FED INTO A SURFACE LOW CURRENTLY LOCATED NEAR
THE TX PANHANDLE AS THE FRONT SURGES SOUTH TONIGHT. THIS LED TO A
CLUSTER OF THUNDERSTORMS THAT RACED SOUTHEAST JUST OUT AHEAD OF
THE STRONG COLD FRONT LATE THIS EVENING THROUGH THE OVERNIGHT HRS.
LATEST /TODAYS/ HIGH RESOLUTION GUIDANCE IS MUCH LESS OPTIMISTIC
WITH AVAILABLE POTENTIAL ENERGY FOR CONVECTION...SO WENT AHEAD AND
BUMPED DOWN POPS ALONG THE FRONT AND REMOVED A MENTION OF THUNDER
FROM THE FORECAST THIS EVENING AND OVERNIGHT. THINK WE WILL STILL
SEE A BRIEF LINE OF RAIN SHOWERS ALONG THE FRONT...BUT RAINFALL
AMOUNTS WILL LIKELY BE A FEW HUNDREDTHS OF AN INCH AT BEST. OF
COURSE WILL CONTINUE TO MONITOR SHORT TERM SURFACE OBSERVATION
TRENDS FOR SIGNS THAT A NARROW BAND OF MOISTURE IS BEING ADVECTED
OUT AHEAD OF THE SURFACE LOW THIS EVENING.

BEHIND THE STRONG COLD FRONT...WE MAY NEED TO CONSIDER A WIND
ADVISORY TONIGHT INTO TOMORROW AS NORTH WINDS BEHIND THE FRONT ARE
EXPECTED TO BE QUITE STRONG. DID NOT GO WITH A WIND ADVISORY AT
THIS TIME BECAUSE CONFIDENCE IN STRONG WINDS MIXING DOWN TO THE
SURFACE IS TEMPERED BY THE FACT THAT THE FRONT IS PROGGED TO MOVE
THROUGH OVERNIGHT...WHEN LOW-LEVEL MIXING IS DAMPENED BY THE
NOCTURNAL INVERSION. GRANTED...THE COLD AIR ADVECTION BEHIND THE
FRONT IS EXPECTED TO BE VERY STRONG...AND THIS MAY REDUCE LOW-
LEVEL STABILITY SUFFICIENTLY TO MIX STRONG WINDS ALOFT DOWN TO THE
SURFACE. AT ANY RATE...THIS IS SOMETHING THAT WILL BE REASSESSED
THIS AFTERNOON OR EVENING. WINDS BEHIND THE FRONT WILL LIKELY BE
STRONGEST WEST OF INTERSTATE 35 WHERE SUSTAINED WINDS OF AT LEAST
25 MPH ARE POSSIBLE AFTER MIDNIGHT. AFTER SOME SUNSHINE SUNDAY
MORNING...SURFACE HEATING MAY BE ENOUGH TO MIX STRONGER WINDS DOWN
TO THE SURFACE IF THEY REMAINED ELEVATED THROUGH THE OVERNIGHT
HOURS. IF WINDS ALOFT CONTINUE TO HOLD IN THE 30 KT RANGE...WE MAY
NEED TO CONSIDER A WIND ADVISORY ACROSS PART OR ALL OF
NORTH/CENTRAL TX ON SUNDAY.

TEMPERATURES TONIGHT MAY APPROACH FREEZING...BUT WILL LIKELY
REMAIN JUST ABOVE FREEZING BEHIND THE FRONT DUE TO STRONG
MECHANICAL TURBULENCE ASSOCIATED WITH WINDS BEHIND THE FRONT.
LIGHTER WINDS AND MOSTLY CLEAR SKIES SUNDAY NIGHT INTO MONDAY
MORNING WILL LIKELY ALLOW TEMPERATURES TO FALL BELOW FREEZING FOR
MOST OUTLYING AREAS ACROSS THE CWA. URBAN AREAS WILL LIKELY BE THE
ONLY LOCATIONS THAT DO NOT SEE TEMPERATURES FALL BELOW FREEZING
BY MONDAY MORNING. HIGHS WILL REMAIN COOL EARLY IN THE UPCOMING
WEEK WITH A CANADIAN AIR MASS FIRMLY ENTRENCHED IN THE REGION.
THIS AIR WILL BE MODIFIED BY MOSTLY SUNNY SKIES EACH DAY...BUT ANY
WARM UP WILL BE SLOW UNTIL WE SEE A RETURN TO SOUTH WINDS AND THAT
SEEMS LIKELY TO OCCUR TUESDAY NIGHT INTO WEDNESDAY MORNING. THAT
MEANS THAT TUESDAY MORNING WILL LIKELY BE ANOTHER FREEZE FOR MANY
LOCATIONS ACROSS NORTH TX. WEDNESDAY MORNING SHOULD STAY JUST
ABOVE FREEZING WITH LIGHT SOUTH WINDS RETURNING TO THE CWA.

OUR NEXT STORM SYSTEM APPROACHES THE REGION TOWARDS THE END OF
NEXT WEEK INTO NEXT WEEKEND. THE GFS AND ECMWF BOTH INDICATE THAT
A STRONG UPPER TROUGH WILL BECOME CUT OFF OVER THE SOUTHWESTERN
CONUS DURING THE PERIOD. ASSUMING THIS OCCURS...THIS WOULD LEAD TO
AN EXTENDED PERIOD OF SOUTHWEST FLOW ALOFT OVER NORTH TX AND THE
SOUTH PLAINS IN GENERAL. THIS COULD BRING A WET PATTERN TO NORTH
TX LATE NEXT WEEK THROUGH THE WEEKEND ASSUMING THE GFS AND ECMWF
ARE DOING A GOOD JOB RESOLVING THIS SYSTEM. AT THIS TIME WENT
AHEAD WITH BROAD BRUSHED 20 POPS DURING THE PERIOD AS WE SHOULD
HAVE PLENTY OF MOISTURE IN PLACE WITH PERSISTENT LOW-LEVEL SOUTH
FLOW THAT RETURNS TO NORTH TX WEDNESDAY MORNING. THERE COULD BE
SOME CHANCES FOR SEVERE STORMS DURING THIS PERIOD...BUT IT IS TOO
DIFFICULT TO WHITTLE DOWN TO ANY PARTICULAR TIME THIS FAR OUT AS
SEVERE STORM CHANCES WILL DEPEND ON SMALLER PIECES OF ENERGY THAT
THE MODELS ARE NOT RESOLVING WELL AT THIS TIME.

CAVANAUGH

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  61  40  56  33  56 /  50  20   5   0   0
WACO, TX              69  40  59  30  60 /  40  20   5   0   0
PARIS, TX             56  38  51  29  53 /  50  20   5   0   0
DENTON, TX            60  35  54  28  53 /  50  20   5   0   0
MCKINNEY, TX          58  37  53  29  55 /  50  20   5   0   0
DALLAS, TX            61  41  57  36  58 /  50  20   5   0   0
TERRELL, TX           60  40  56  31  56 /  50  20   5   0   0
CORSICANA, TX         64  44  57  34  58 /  40  20   5   0   0
TEMPLE, TX            73  42  60  32  59 /  30  20   5   0   0
MINERAL WELLS, TX     65  34  55  29  55 /  50  20   5   0   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
427 AM CDT SAT MAR 23 2013

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-240930-
MONTAGUE-COOKE-GRAYSON-FANNIN-LAMAR-YOUNG-JACK-WISE-DENTON-COLLIN-
HUNT-DELTA-HOPKINS-STEPHENS-PALO PINTO-PARKER-TARRANT-DALLAS-
ROCKWALL-KAUFMAN-VAN ZANDT-RAINS-EASTLAND-ERATH-HOOD-SOMERVELL-
JOHNSON-ELLIS-HENDERSON-COMANCHE-MILLS-HAMILTON-BOSQUE-HILL-NAVARRO-
FREESTONE-ANDERSON-LAMPASAS-CORYELL-BELL-MCLENNAN-FALLS-LIMESTONE-
LEON-MILAM-ROBERTSON-
427 AM CDT SAT MAR 23 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...TODAY AND TONIGHT.
THUNDERSTORMS ARE EXPECTED TO SPREAD FROM WEST TO EAST ACROSS NORTH
TEXAS THIS MORNING. A FEW STORMS MAY BECOME SEVERE...WITH LARGE
HAIL BEING THE MAIN THREAT.

THUNDERSTORM CHANCES WILL CONTINUE EAST OF INTERSTATE 35 THIS
AFTERNOON WITH AN ATTENDANT RISK FOR QUARTER SIZE HAIL PERSISTING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
THERE IS A CHANCE OF THUNDERSTORMS ACROSS ALL OF NORTH TEXAS ON
FRIDAY.

.SPOTTER INFORMATION STATEMENT...
LIMITED SPOTTER ACTIVATION MAY BE REQUESTED TODAY ACROSS ALL OF
NORTH TEXAS.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
435 AM CDT SAT MAR 23 2013

TXZ129-231000-
EASTLAND TX-
435 AM CDT SAT MAR 23 2013

...SIGNIFICANT WEATHER ADVISORY FOR...
  EASTLAND COUNTY

AT 435 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 12 MILES SOUTHWEST OF CISCO...MOVING EAST AT 40
MPH.

PENNY-SIZED HAIL CAN BE EXPECTED FROM THIS STORM.

LAT...LON 3237 9911 3251 9911 3251 9848 3230 9848
      3229 9849 3208 9893 3208 9912 3236 9913
TIME...MOT...LOC 0935Z 261DEG 34KT 3227 9910

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
537 AM CDT SAT MAR 23 2013

TXZ115-129-231100-
EASTLAND TX-STEPHENS TX-
537 AM CDT SAT MAR 23 2013

...SIGNIFICANT WEATHER ADVISORY FOR...
  EASTLAND COUNTY
  STEPHENS COUNTY

AT 537 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 11 MILES NORTHWEST OF CISCO...MOVING NORTHEAST AT
50 MPH.

PENNY-SIZED HAIL AND WIND GUSTS TO 40 MPH CAN BE EXPECTED FROM THIS
STORM.

IF THIS STORM INTENSIFIES...A SEVERE WEATHER WARNING MAY BE NEEDED.

LAT...LON 3251 9912 3252 9910 3295 9909 3296 9858
      3252 9858 3251 9848 3230 9848 3208 9893
      3208 9912
TIME...MOT...LOC 1037Z 246DEG 42KT 3253 9906

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
547 AM CDT SAT MAR 23 2013

TXZ131-132-231115-
HOOD TX-SOMERVELL TX-
547 AM CDT SAT MAR 23 2013

...SIGNIFICANT WEATHER ADVISORY FOR...
  HOOD COUNTY
  SOMERVELL COUNTY

AT 547 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 11 MILES NORTHEAST OF STEPHENVILLE...MOVING EAST
AT 50 MPH.

PENNY-SIZED HAIL CAN BE EXPECTED FROM THIS STORM.

LAT...LON 3256 9807 3255 9762 3220 9761 3220 9765
      3209 9787 3220 9793 3245 9805 3251 9807
TIME...MOT...LOC 1047Z 255DEG 44KT 3233 9803

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
613 AM CDT SAT MAR 23 2013

TXZ115-116-129-130-231145-
EASTLAND TX-ERATH TX-PALO PINTO TX-STEPHENS TX-
613 AM CDT SAT MAR 23 2013

...SIGNIFICANT WEATHER ADVISORY FOR...
  EASTLAND COUNTY
  NORTHERN ERATH COUNTY
  PALO PINTO COUNTY
  STEPHENS COUNTY

AT 613 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 5 MILES NORTHEAST OF RANGER...MOVING EAST AT 50
MPH.

PENNY-SIZED HAIL CAN BE EXPECTED FROM THIS STORM.

IF THIS STORM INTENSIFIES...A SEVERE WEATHER WARNING MAY BE NEEDED.

LAT...LON 3295 9909 3295 9843 3301 9842 3301 9806
      3300 9806 3251 9807 3242 9803 3231 9848
      3208 9893 3208 9912
TIME...MOT...LOC 1113Z 265DEG 45KT 3251 9855