Severe Thunderstorm Warning 35, NWS Fort Worth, TX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE FORT WORTH TX
850 PM CST TUE MAR 16 2004

.UPDATE...
ELEVATED SHOWERS AND THUNDERSTORMS HAVE WEAKENED AND MOVED INTO EAST
TEXAS.  A FEW SHOWERS ARE STILL POSSIBLE ACROSS THE EXTREME EAST AND
SOUTH TONIGHT...AS WEAK LARGE SCALE LIFT ASSOCIATED WITH AN EXITING
SHORTWAVE...INTERACTS WITH DECENT MID LEVEL INSTABILITY AND ELEVATED
MOISTURE.

PARTLY TO MOSTLY CLOUDY SKIES WILL CONTINUE OVERNIGHT AND LIGHT
NORTHEAST WINDS WILL BECOME SOUTHEAST...AS SURFACE HIGH PRESSURE
MOVES INTO THE LOWER MISSISSIPPI VALLEY AND A SURFACE LOW DEVELOPS
IN SOUTHEAST COLORADO.

ONLY OTHER CHANGES TO THE PREVIOUS FORECAST PACKAGE WILL BE TO
ADJUST SURFACE DEWPOINTS AND RELATIVE HUMIDITIES FOR THE OVERNIGHT
HOURS.

/79
&&

.AVIATION...
MID-LEVEL COOLING AND WEAK QG ASCENT ASSOCIATED WITH NW-FLOW VORT
MAX WILL SUPPORT CONTINUED DEVELOPMENT OF TSRA THROUGHOUT THE
EVENING ACROSS NORTH TEXAS. SHORT TERM GUIDANCE SUGGESTS THAT BETTER
CHANCES FOR TSRA WILL SHIFT SWD TOWARD THE KACT TRACON IN THE NEXT
COUPLE HOURS...WHERE SLIGHTLY BETTER MID-LEVEL LAPSE RATES RESIDE
PER ACCAS FIELD ON LATEST VISIBLE IMAGERY. WE WILL INCLUDE A VCTS
AND CB GROUP FROM 03-08Z FOR KACT TO ACCOUNT FOR THIS POSSIBILITY.
OTHERWISE...BKN/VFR DECKS SHOULD CLEAR THE METROPLEX SITES BY 06-07Z
AND THE WACO AREA BY 07-08Z. MID-LEVEL NW FLOW PATTERN IS PROGGED TO
PERSIST THROUGH THE FORECAST PERIOD...WITH MID-LEVEL CIGS RETURNING
TO THE KDFW/KACT TRACONS AHEAD OF ANOTHER UPSTREAM VORT MAX ON
WEDNESDAY AFTENROON. SFC WINDS SHOULD BE LIGHT E/SE FOR FIRST HALF
OF THE TAF...BEFORE VEERING TO SOUTH AND INCREASING TO 10-16 KTS ON
WEDNESDAY AFTERNOON.

65/DD

&&

.PREV DISCUSSION...
215 PM CST TUE MAR 16 2004

A WEAK SURFACE LOW WILL DEVELOP OVER NORTH TEXAS AND MOVE EAST
DURING THE DAY WEDNESDAY. ASSOCIATED SFC PRESSURE FALLS WILL CAUSE
FRONT TO OUR SOUTH TO ADVANCE NWD.  DEWPOINTS OVER S TX ARE IN THE
MID TO UPPER 60S ATTM AND THIS MOIST AIR WILL HAVE NO PROBLEM
ADVECTING NWD. IN FACT...ETA PROG DEWPOINTS MAY BE A BIT LOW WHICH
MAY BE CAUSING AN UNDERESTIMATE OF SB/MLCAPES.  REGARDLESS...
MLCAPES SHOULD EXCEED 1500 J/KG OVER THE SOUTHERN HALF OF CWA BY WED
AFTERNOON.  MID-LEVEL LAPSE RATES OF NEAR 7 DEG/KG AND ONLY WEAK
CAPPING WILL ALLOW FOR THUNDERSTORMS TO DEVELOP IN WARM SECTOR.
FORECAST 0-3KG SHEAR OF 60 TO 70 KT OVER THE SOUTHEASTERN QUARTER OF
THE CWA LATE WED INTO WED NIGHT (AS 35-45 KT LLJ DEVELOPS) WILL BE
SUFFICIENT FOR SUPERCELLS DESPITE RELATIVELY WEAK UPPER-LEVEL
WINDS.  CONSISTENT WITH RECENT MODEL DATA AND SPS SLIGHT RISK...WE
WILL CONFINE MENTION OF SVR WED/WED NIGHT TO EASTERN HALF OF CWA
WHERE PARAMETERS DISCUSSED ABOVE APPEAR MOST FAVORABLE.  SINCE LIFT
WILL BE GENERATED PRIMARILY THROUGH LOW-LEVEL MESOSCALE/CONVECTIVE
PROCESSES (LITTLE IN THE WAY OF UPPER-LEVEL FORCING)...THUNDERSTORMS
SHOULD BE SCATTERED (AT LEAST INITIALLY).

SFC LOW WILL MOVE EAST OF AREA WED NIGHT...BUT FRONT WILL LINGER AND
THEN DRIFT NORTHWARD ACRS THE AREA THURS.  THEREFORE...WE WILL
INCLUDE 20 POP FOR POSSIBLE THUNDERSTORMS THURS AS WELL...BUT SVR
POTENTIAL APPEARS GREATLY DIMINISHED AS LLJ PUSHES EAST.

REGARDING TEMPERATURES...WE FEEL THAT MOS HIGHS FOR WED AND THURS
ARE TOO HIGH.  THERE IS STILL CONSIDERABLE GROUND MOISTURE TO BE
EVAPORATED.  FURTHERMORE...INCREASING SFC MOISTURE ON THE HEELS OF
LOW LEVEL SELY FLOW DOES NOT BODE WELL FOR HIGHS NEAR 80 THIS TIME
OF YEAR.  THURSDAY...WITH FRONT IN THE AREA...RESIDUAL CLOUDS...AND
AN EAST TO SOUTHEAST SURFACE WINDS...HIGHS NEAR 80 STILL SEEM TOO
WARM.

ANOTHER FRONT WILL APPROACH NORTH TEXAS SAT NIGHT...AND CLEAR THE
AREA SUNDAY BEFORE STALLING.  SO...ANOTHER ROUND OF SLIGHT CHANCE
POPS IS WARRANTED GIVEN INSTABILITY AND RELATIVELY HIGH SFC MOISTURE
EXPECTED.

ROBBINS

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX        50  74  56  74 /   0  40  50  20
WACO,TX                     53  76  60  79 /   0  40  50  20
PARIS, TX                   47  72  54  71 /   0  20  30  20
DENTON, TX                  48  72  56  73 /   0  20  30  20
MCKINNEY, TX                48  72  56  73 /   0  20  30  20
DALLAS, TX                  50  74  56  74 /   0  40  50  20
TERRELL, TX                 50  74  57  74 /   0  40  50  20
CORSICANA, TX               52  75  59  77 /   0  40  50  20
TEMPLE, TX                  53  76  60  79 /   0  40  50  20

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FORT WORTH TX
900 PM CST TUE MAR 16 2004

TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175-171200-
ANDERSON-BELL-BOSQUE-COLLIN-COMANCHE-COOKE-CORYELL-DALLAS-DELTA-
DENTON-EASTLAND-ELLIS-ERATH-FALLS-FANNIN-FREESTONE-GRAYSON-HAMILTON-
HENDERSON-HILL-HOOD-HOPKINS-HUNT-JACK-JOHNSON-KAUFMAN-LAMAR-LAMPASAS-
LEON-LIMESTONE-MCLENNAN-MILAM-MILLS-MONTAGUE-NAVARRO-PALO PINTO-
PARKER-RAINS-ROBERTSON-ROCKWALL-SOMERVELL-STEPHENS-TARRANT-VAN ZANDT-
WISE-YOUNG-

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH TEXAS.

.DAY ONE...
ISOLATED THUNDERSTORMS ARE POSSIBLE OVERNIGHT...GENERALLY ALONG AND
SOUTHEAST OF A LINE FROM COMANCHE...TO WAXAHACHIE AND BONHAM.
OCCASIONAL CLOUD TO GROUND LIGHTNING STRIKES AND BRIEF HEAVY
RAINFALL ARE POSSIBLE WITH ANY STORM THAT DEVELOPS.

.DAYS TWO THROUGH SEVEN...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE EASTERN
HALF OF NORTH TEXAS WEDNESDAY AFTERNOON AND EVENING...GENERALLY
EAST OF INTERSTATE 35.  THE MAIN THREATS WILL BE FROM LARGE HAIL AND
DAMAGING WINDS.

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS NORTH TEXAS
THURSDAY...AND AGAIN SATURDAY AFTERNOON INTO SUNDAY.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH WEDNESDAY MORNING.

65/DD