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000
FXUS64 KFWD 180903
AFDFWD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
403 AM CDT SAT MAY 18 2013

...SEVERE WEATHER THREAT WILL EXIST ACROSS PARTS OF NORTHERN/WESTERN
NORTH TEXAS THIS WEEKEND AND INTO THE EARLY NEXT WEEK...

.SYNOPSIS...
AN UPPER RIDGE HAS SHIFTED INTO THE SOUTHERN/CENTRAL PLAINS AND
INTO THE OZARKS/MISSISSIPPI VALLEY THE PAST 12 HOURS OR SO. THE
CAPPING INVERSION HAS LOWERED AND STRENGTHENED COMPARED TO 24 HOURS
AGO WHEN PREDAWN/ELEVATED SEVERE STORMS DEVELOPED AROUND DAYBREAK
FRIDAY. VERY STEEP LAPSE RATES ALOFT OVER 8 DEG C/KM BETWEEN
575-850MB AND SBCAPE VALUES NEAR 4000 J/KG EXISTED THIS PAST
EVENING ON THE 00Z FWD SOUNDING. A LONGWAVE UPPER TROUGH WAS
ORGANIZING ACROSS THE GREAT BASIN AND CENTRAL ROCKIES EARLY THIS
MORNING. THIS FEATURE WILL BE A PLAYER ALONG WITH THE SURFACE
DRYLINE...THEN EVENTUALLY A WEAK COLD FRONT FOR EPISODES OF SEVERE
WEATHER ACROSS THE PLAINS INTO THE OZARKS THE NEXT SEVERAL DAYS.

&&

.SHORT TERM...
A SHORTWAVE DISTURBANCE WAS SEEN VIA WATER VAPOR SATELLITE IMAGERY
EARLY THIS MORNING ROTATING THROUGH CENTRAL/EASTERN NEW MEXICO.
THIS FEATURE WILL EJECT WITHIN INCREASING SOUTHWEST FLOW ALOFT
ACROSS WEST TX/OK BY AFTERNOON. THIS WILL DEEPEN AND MOVE THE
SURFACE DRYLINE INTO THE SOUTH PLAINS BY EARLY EVENING. LIFT FROM
BOTH OF THESE FEATURES WILL COMBINE WITH HIGH TEMPERATURES AROUND
100 DEGREES AND THE RESULTING VERY HIGH INSTABILITY FOR THE
DEVELOPMENT OF A FEW SUPERCELLS LATE IN THE DAY. THIS IS TYPICALLY
THE TIME OF THE YEAR/MID MAY-LATE JUNE/ THAT THE DRYLINE OUT WEST IS
THE MOST ACTIVE...USUALLY PRODUCING DIURNAL SEVERE WEATHER IN THE
LATE AFTERNOONS AND EARLY EVENINGS. EXPECT MORE DISCRETE SUPERCELLS
LATE TODAY AND THIS EVENING IN AND NEAR OUR FAR WESTERN COUNTIES.
CURRENT SHEAR AND BUNKERS METHOD INDICATE THERE WILL BE MORE
STEERING CURRENTS TO THE NORTHEAST VERSUS YESTERDAY WITH UPPER
TROUGH APPROACHING. HOWEVER...AS WITH ANY SUPERCELL DEVIANT
MOTIONS CANNOT BE RULED OUT ONCE ANY MESOCYCLONES DEVELOP WITHIN
THE STORMS THEMSELVES. DESPITE RELATIVELY HIGH LCLS WITH THE HOT
AND UNSTABLE AIRMASS...JUST ABOUT ALL TYPES OF SEVERE WEATHER WILL
BE POSSIBLE WITH THIS ACTIVITY. EXPECT ABOUT 20-30 PERCENT COVERAGE
OF SEVERE STORMS ACROSS THE NORTHWEST COUNTIES. THE INVERSION
STRENGTHENS ONCE AGAIN BY LATE EVENING AND EXPECT THE MAJORITY OF
ACTIVITY TO DIMINISH QUICKLY.

THE NEXT ROUND OF SEVERE WEATHER LATE SUNDAY WILL LIKELY BE MORE
ACROSS THE NORTHERN TIER COUNTIES VERSUS JUST THE WEST...AS A
NEGATIVE TILT SHORTWAVE DISTURBANCE ROTATES ACROSS THE TX/OK
PANHANDLES INTO WESTERN OK/KS. THE SURFACE DRYLINE WILL HAVE A
BETTER PUSH TO EAST ACROSS THOSE AREAS NORTH OF I-20 IN RESPONSE
TO THIS SHORTWAVE. THE HIGHER COVERAGE OF SEVERE WEATHER AND RISK
WILL BE OVER EASTERN OK INTO THE OZARKS...BUT SHOULD ZIPPER A FEW
STORMS SOUTH-SOUTHWEST ACROSS THE RED RIVER BY EVENING. ALL THREATS
WILL BE POSSIBLE ONCE AGAIN.

&&

.LONG TERM...
FOR LATER MONDAY INTO EARLY WEDNESDAY...ZONAL FLOW ALOFT WILL
STRENGTHEN OVER NORTH TEXAS WITH A BROAD UPPER TROUGH OVER THE
NORTHERN CONUS. THIS WILL HELP A WEAK COLD FRONT MOVE INTO THE
AREA TUESDAY/TUESDAY NIGHT WITH HIGHER CHANCES FOR STORMS. A
SEVERE WEATHER RISK WILL LIKELY CONTINUE. THE MAIN FORCING FROM
THE MAIN UPPER TROUGH WILL LIFT OUT OVER THE PLAINS TUESDAY NIGHT
INTO EARLY WEDNESDAY AND WILL ASSIST THE SOUTHEAST MOVEMENT OF
THE COLD FRONT THROUGH THE AREA. THE COLD FRONT AND THREAT FOR
STORMS WILL END FROM WEST TO EAST ON WEDNESDAY. WE FINALLY SEE A
QUIET PERIOD FOR THE LATTER HALF OF THE WEEK...THE THE UPPER
TROUGH DEPARTS TO THE EAST AND IS REPLACED BY AN UPPER RIDGE.
THE DRYLINE WILL BE ACTIVE TO OUR WEST...BUT EXPECT THE UPPER
RIDGE AND RESULTING STRONG CAP TO KEEP OUR CWA SUPPRESSED AND DRY.
NEXT WEEKEND LOOKS MORE MUDDLED AS WE GO BEYOND THE 7 DAY
FORECAST AND HAVE LEFT A DRY FORECAST FOR NOW.

.TEMPERATURES...
LOOK FOR TEMPERATURES TO STAY ABOVE NORMAL THROUGH MONDAY WITH
BREEZY AND HUMID CONDITIONS. SOME MODIFICATION BACK TOWARD
SEASONABLE NORMALS MAY OCCUR BRIEFLY AFTER THE COLD FRONT AROUND
MID WEEK...BEFORE WARMING BACK UP ABOVE NORMAL AGAIN LATE IN THE
WEEK.

05/

&&

.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX  93  73  92  72  91 /   5   5  10  20  10
WACO, TX              92  71  91  73  90 /   5   5  10  10  10
PARIS, TX             88  70  87  68  87 /  10   5   5  20  10
DENTON, TX            93  72  90  72  90 /   5  10  10  20  10
MCKINNEY, TX          90  72  89  71  88 /   5   5   5  20  10
DALLAS, TX            93  73  91  74  91 /   5   5  10  20  10
TERRELL, TX           90  71  90  71  89 /   5   5   5  10  10
CORSICANA, TX         91  71  89  73  90 /   5   5   5  10  10
TEMPLE, TX            92  71  91  72  90 /   5   5  10  10  10
MINERAL WELLS, TX     96  70  94  69  95 /   5  20  20  20  20

&&

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

&&

$$

05/