Severe Thunderstorm Warning 203, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
300 PM CDT THU MAY 18 2000

STORMS DEVELOPING AS EXPECTED ALONG FRONT/DRYLINE IN NW AR. EXPECT
STORMS TO DEVELOP SOUTHWESTWARD ALONG FRONT INTO SE OK LATER THIS
AFTERNOON. MAIN THREAT SHOULD BE LARGE HAIL. WILL TWEAK 1ST PD POPS
ACCORDING TO LATEST TRENDS HOWEVER CCF POPS MAY BE BIASED TO TSRA
LOCATION AT 7PM ONWARD. ALSO A THREAT OF WAA PRECIP AFTER MIDNIGHT
AND FRI MORNING IN SRN 1/2 SO WILL KEEP SLT CHC GOING EVEN BEHIND
THE FRONT. AS FRONT STALLS IN NRN TX COULD SEE SOME SHRA EVEN IN THE
AFTERNOON ON FRI. MOS TEMPS LOOK PRETTY CLOSE...PREFER WARMER FWC
WHICH IS CLOSER TO IMPLIED MAX TEMPS USING AVN 1000-850MB THICKNESS.

SOME UNCERTAINTY ON NEXT FEW DAYS...MODELS BRING WEAK S/W'S ACROSS
AREA. FIRST IN SW FLOW ALOFT NEXT ONE IN NW FLOW. BOTH MOVING ACROSS
IN WEAK SFC FLOW REGIMES. HARD TO PIN DOWN THIS PATTERN AND WHERE TO
FOCUS POPS. HAVE KEPT CHC POPS IN PLACE FOR FRI NIGHT AND SAT WITH
HIGHER POPS IN SRN ZONES WHERE BETTER MOISTURE SHOULD BE. WILL
LIKELY LEAVE EXTENDED MOSTLY UNCHANGED WITH MODELS FLIP FLOPPING AS
PER NCEP DISCUSSION. MAY HAVE TO ADD SLT CHC FOR MON. BUT TUES
SHOULD BE DRY FOR A WHILE. TEMPS ABOUT NORMAL FOR THE PERIOD WITH A
LITTLE WARMER MINS.

FCSTID = 26
TUL   57  75  55  78 /  10  20  40  30
FSM   61  77  57  78 /  50  30  30  40
MLC   59  76  58  78 /  20  30  40  30
BVO   55  73  52  77 /  10  10  20  20
FYV   58  73  53  76 /  50  10  20  30
BYV   57  72  52  75 /  50  10  20  30
MIO   57  73  54  75 /  10  10  30  30
MKO   59  76  58  78 /  20  30  40  30
F10   58  75  56  78 /  10  20  40  30>
HHW   64  80  60  79 /  60  40  50  30

.TUL...
AR...NONE.
OK...NONE.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-191200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
115 PM CDT THU MAY 18 2000

...A FEW SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND INTO
THIS EVENING ACROSS SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS...

.SYNOPSIS...
EARLY THIS AFTERNOON A SURFACE LOW PRESSURE CENTER WAS LOCATED IN
SOUTHERN IOWA WITH A DRYLINE EXTENDING FROM THE LOW SOUTHWARD ACROSS
MISSOURI...EASTERN OKLAHOMA AND INTO NORTHERN TEXAS. AT 1PM THE
DRYLINE WAS NEAR A BENTONVILLE ARKANSAS TO MCALESTER LINE. A COLD
FRONT WAS MOVING SOUTHWARD THROUGH WESTERN AND CENTRAL KANSAS AND
INTO WESTERN OKLAHOMA AND TEXAS. THE DRYLINE IS EXPECTED TO CONTINUE
TO SLOWLY PUSH EASTWARD THIS AFTERNOON WITH THE COLD FRONT CATCHING
UP TO THE DRYLINE BY THIS EVENING. THE FRONT IS FORECAST TO STALL
OVER NORTHERN TEXAS AND CENTRAL ARKANSAS OVERNIGHT. A STRONG UPPER
LEVEL SYSTEM WAS MOVING NORTHEAST WELL NORTHEAST OF THE AREA.

.PRIMARY HAZARD...
SCATTERED THUNDERSTORMS SHOULD DEVELOP ALONG AND AHEAD OF THE
DRYLINE AS IT MOVES THROUGH SOUTHEAST OKLAHOMA AND INTO NORTHWEST
ARKANSAS DURING THE AFTERNOON AND INTO THIS EVENING. A FEW OF THE STORMS
COULD BECOME SEVERE WITH SHORT LIVED SUPERCELLS POSSIBLE. HAIL TO 3
INCHES IN DIAMETER AND WIND GUSTS OF 70 MPH WILL BE THE MAIN THREATS
IN AREAS SOUTHEAST OF A LINE FROM SPRINGDALE ARKANSAS TO MCALESTER
OKLAHOMA. THE THREAT FOR STORMS WILL DIMINISH AS THE DRYLINE OR COLD
FRONT PASSES...LIKELY BY 9PM THIS EVENING.

.DISCUSSION...
THE CAP WHICH HAS BEEN INHIBITING CONVECTION OVER THE AREA IS
FORECAST TO ERODE DURING THE AFTERNOON. LOW LEVEL MOISTURE HAS
DEEPENED SOUTHEAST OF THE DRYLINE TODAY AND HAS PRODUCED A VERY
UNSTABLE AIRMASS. TEMPERATURES IN THE LOWER 80S COMBINED WITH
DEWPOINTS NEAR 70 WILL PRODUCE SURFACE BASED CAPES TO AROUND 3000
J/KG  OVER SOUTHEAST OKLAHOMA AND PARTS OF NORTHWEST ARKANSAS. WIND
SPEEDS INCREASE WITH HEIGHT IN THE AREA...BUT THE LACK OF
DIRECTIONAL SHEAR WILL LIMIT THE SUPERCELL THREAT. BUT GIVEN THE
AMOUNT OF INSTABILITY...THE MARGINAL SHEAR COULD STILL PRODUCE A
SHORT LIVED SUPERCELL.

FACTORS THAT COULD LIMIT SEVERE STORM DEVELOPMENT...ARE VEERING
SURFACE WINDS JUST AHEAD OF THE BOUNDARIES AND LIMITED SYNOPTIC
SCALE LIFT. IF THE CAP DOES NOT ERODE AS FORECAST...THESE
LIMITATIONS MAY NOT ALLOW CONVECTION TO OVERCOME THE CAP.

.SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON INTO TONIGHT
ACROSS A PORTION OF SOUTHEAST OKLAHOMA AND NORTHWEST ARKANSAS.