Severe Thunderstorm Warning 52, NWS Fort Worth, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
649 PM CST SAT MAR 9 2013

.UPDATE...
GRID AND PRODUCT PUSHED TO DROP COUNTIES WEST OF THE CONVECTION
FROM THE SEVERE THUNDERSTORM WATCH...AND TO ADD LAMPASAS AND
CORYELL. ONLY COSMETIC CHANGES TO GRIDS. 84

&&

.AVIATION...
SQUALL LINE WEST OF METROPLEX TAF SITES MOVING NORTHEAST...WITH
EASTWARD PROGRESSION OF SOUTHERN HALF VERY SLOW. STILL HAVE
CONCERNS WITH TIMING OF TSRA AT METROPLEX WHICH MAY BE A BIT
FASTER THAN FORECAST. THERE MAY ALSO BE SOME CELL TRAINING WITH
THE SLOWING LINE AFTER IT ARRIVES AT TAF SITES. MAIN THREAT
REMAINS FOR THIS EVENING...WITH CAPE STILL FORECAST TO DECREASE
RAPIDLY AFTER MIDNIGHT. COLD FRONT ARRIVES IN MORNING...WITH WINDS
SWITCHING TO NORTHWEST FOR REST OF TAF PERIOD. THERE WILL BE HAIL
POTENTIAL AT TAF SITES...BUT WE HAVE RECEIVED NO DAMAGING WIND
REPORTS AS OF THIS WRITING.

AT WACO...THREAT REMAINS FOR OVERNIGHT CONVECTION...WEAKENING AS
THE NIGHT PROGRESSES. 84

&&

.PREV DISCUSSION... /ISSUED 158 PM CST SAT MAR 9 2013/
THE SURFACE BOUNDARY THAT IS NOW APPROACHING THE WESTERN CWA WOULD
BEST BE CLASSIFIED AS A WEAK PACIFIC FRONT GIVEN THE RISING
PRESSURES AND SLIGHTLY COOLER AIR IN ITS WAKE. THE FRONT WILL
CONTINUE TO MOVE SLOWLY EASTWARD THROUGH THE AFTERNOON HOURS WITH
SCATTERED CONVECTION DEVELOPING ALONG IT. LOCAL OBJECTIVE ANALYSIS
INDICATES THAT THE SURFACE AIRMASS IS UNCAPPED WITH CAPE VALUES
NOW OVER 700 J/KG...BUT INCREASING WITH FURTHER INSOLATION.

THE DIFFICULTY IN THE CONVECTIVE FORECAST THROUGH THIS EVENING IS
THE LACK OF SYNCHRONIZATION OF THIS LINE OF CONVECTION WITH THE
BEST UPPER LEVEL FORCING WHICH DOES NOT ARRIVE UNTIL MID TO LATE
EVENING. HI-RES AND SHORT TERM MODEL GUIDANCE SEEM TO INDICATE
THAT THE CONVECTION ALONG THE FRONT WILL BE CONFINED TO THE NW
ZONES THROUGH 7 OR 8PM...AND MAY ACTUALLY STRUGGLE TO TAKE HOLD OR
EVEN DISSIPATE AS IT APPROACHES THE METROPLEX. OBVIOUSLY STORM
SCALE MODELING CANT BE TRUSTED TO THIS EXTENT...BUT IT IS WORTH
MENTIONING THAT WE ARE NOT COMPLETELY SOLD THAT THIS LINE WILL
BEHAVE AS THEY TYPICALLY DO IN THE SPRING. IF THE AFTERNOON STORMS
DO NOT BECOME INTENSE ENOUGH TO DEVELOP A STRONG COLD POOL AND
OUTFLOW BOUNDARY...THE MODELS ARE ALL IN GOOD AGREEMENT THAT THE
FRONT WILL TEMPORARILY STALL ACROSS THE NORTHWEST ZONES THIS
EVENING. IN ANY CASE...THE CONVECTION ACROSS THE NORTHWEST ZONES
WILL BE MONITORED FOR SEVERE WEATHER POTENTIAL GIVEN THE AMPLE
DEEP LAYER SHEAR AND ADEQUATE INSTABILITY...AND SPC HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR ROUGHLY THE NW HALF OF THE AREA.

CONVECTIVE ACTIVITY WILL BECOME WIDESPREAD ACROSS NORTH TEXAS
AFTER AROUND 8 OR 9 PM AS A SHORTWAVE ROTATING AROUND THE BASE OF
THE TROUGH APPROACHES CENTRAL TEXAS FROM THE SOUTHWEST. CONVECTION
SHOULD INCREASE RAPIDLY ACROSS THE SOUTHWESTERN AND CENTRAL ZONES
AS THIS FORCING ARRIVES AND ANOTHER WATCH WILL LIKELY BE ISSUED BY
SPC FOR THIS PART OF THE CWA LATER. PROVIDED AFTERNOON STORMS DO
NOT CAUSE AN ACCELERATION OF THE COLD FRONT...THE FRONT SHOULD
BE LOCATED ALONG A LINE FROM SHERMAN TO FORT WORTH TO COMANCHE AT
THIS TIME. STORMS DEVELOPING ALONG AND AHEAD OF THE FRONT WILL
HAVE SB CAPE NEAR 1000J/KG EVEN AFTER SUNSET OWING TO THE
STEEPENING LAPSE RATES AHEAD OF THE SHORTWAVE. THIS ACTIVITY WILL
EXPAND AND SPREAD EAST AND NORTHEAST ACROSS THE REMAINDER OF NORTH
TEXAS INTO THE OVERNIGHT HOURS. HAIL AND DAMAGING WINDS WILL BE
THE PRIMARY THREAT...BUT A NON-ZERO TORNADO THREAT EXISTS WITH ANY
CELL THAT CAN BECOME SEPARATED FROM THE MAIN LINE AHEAD OF THE
FRONT. HAVE FORECAST 100 POPS FOR ALL BUT THE NW ZONES FOR TONIGHT
AND EXPECT ABOUT AN INCH OF RAIN NORTH OF I-20 TO 1-2 INCHES SOUTH
OF I-20 WHERE THERE IS THE POTENTIAL FOR MORE CELL TRAINING.

LINGERING SHOWERS AND STORMS WILL CLEAR OUT OF NORTH TEXAS DURING
THE SUNDAY MORNING HOURS FROM WEST TO EAST. COOLER AIR WILL BEGIN
TO POUR INTO THE AREA AS NORTH WINDS INCREASE TO 10-20 MPH BY
MIDDAY. HIGHS WILL BE IN THE UPPER 50S NORTH WHERE MORE WRAP
AROUND CLOUD COVER WILL BE LOCATED...TO THE MID 60S IN THE SOUTH.
BREEZY NORTH WINDS WILL KEEP COLD ADVECTION OCCURRING INTO THE
OVERNIGHT HOURS SUNDAY NIGHT WITH A LIGHT FREEZE EXPECTED ACROSS
THE NORTHERN ZONES MONDAY MORNING. MODEL GUIDANCE HAS TRENDED THE
TEMPS A LITTLE WARMER FOR MONDAY...BUT STILL EXPECT HIGHS NEAR 60
WITH SUNNY SKIES AND DIMINISHING NORTH WINDS. THE SURFACE HIGH
WILL BUILD IN OVER NORTH TEXAS AND BE CENTERED ACROSS EAST TEXAS
TUESDAY MORNING WHERE RADIATIONAL COOLING WILL BE BEST. WILL
CONTINUE TO FORECAST TEMPS NEAR FREEZING FOR MANY LOCATIONS
TUESDAY MORNING...WITH THE TYPICALLY COOLER PLACES ENJOYING A
LIGHT FREEZE AND THE WARMER ONES IN THE MID 30S.

THE REMAINDER OF THE FORECAST IS PRETTY STRAIGHT-FORWARD AS A
QUIET ZONAL FLOW WILL DOMINATE MUCH OF THE COUNTRY THROUGH NEXT
WEEKEND. SKIES WILL BE CLEAR...AND WINDS WILL BE FAIRLY LIGHT FOR
MID MARCH. TEMPERATURES WILL MODERATE A BIT EACH DAY...BUT
GENERALLY RESIDE IN THE 40S FOR LOWS AND 70S FOR HIGHS. ALL IN ALL
IT LOOKS LIKE A GREAT WEEK WEATHER WISE.

TR.92

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  52  60  35  59  35 / 100  20   0   0   0
WACO, TX              52  63  35  61  30 / 100  20   0   0   0
PARIS, TX             52  60  33  53  32 / 100  50   5   0   0
DENTON, TX            50  58  32  58  32 / 100  20   0   0   0
MCKINNEY, TX          51  59  32  56  31 / 100  20   0   0   0
DALLAS, TX            53  60  36  59  37 / 100  20   0   0   0
TERRELL, TX           53  61  35  57  32 / 100  30   5   0   0
CORSICANA, TX         53  63  36  58  33 / 100  30   5   0   0
TEMPLE, TX            52  64  36  63  32 / 100  20   5   0   0
MINERAL WELLS, TX     49  57  32  61  32 /  90  10   0   0   0

&&

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

&&

 /

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
549 PM CST SAT MAR 9 2013

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-101215-
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-
549 PM CST SAT MAR 9 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...TONIGHT.
THUNDERSTORMS ARE EXPECTED THROUGH THE OVERNIGHT HOURS ACROSS
MUCH OF NORTH TEXAS. SOME OF THESE STORMS ARE EXPECTED TO BECOME
SEVERE WITH LARGE HAIL AND DAMAGING WINDS THE MAIN THREATS. AN
ISOLATED TORNADO THREAT REMAINS IN PLACE AS WELL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS LIKELY ACROSS MUCH OF NORTH TEXAS THROUGH
THE OVERNIGHT HOURS.

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