Severe Thunderstorm Warning 99, NWS Tulsa, OK

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
358 PM CDT WED APR 14 1999

PROBLEM(S) OF THE DAY:
STRONG WINDS (GUSTS > 35 MPH)
WILL THE CONVECTION BE SCATTERED OR NUMEROUS?
TEMPERATURES

NOT MUCH TIME TO WRITE SO WILL KEEP IT SHORT AND SIMPLE. UPPER LOW
VISIBLE IN VISIBLE...IR...AND WATOR VAPOR NEAR THE RED RIVER IN
SOUTHWEST OKLAHOMA.  THIS FEATURE TO TRACK EAST ACROSS FORECAST AREA
THIS EVENING AND THEN ITS VORTICITY MAXIMUM TRACKS NORTHEAST TO
SOUTHERN ILLINOIS BY 12Z THURSDAY.  HOWEVER...FLY IN OINTMENT IS THAT
AN UPPER LOW CONSOLIDATES BETWEEN NORTHERN AND SOUTHERN STREAM
SEGMENTS OF THE JET OVER THE CENTRAL U.S. THURSDAY.  THUS...MAY NOT
GET OF THE CLOUDS AND RAIN AS QUICKLY AS MIGHT EXPECT.  WILL CARRY
RAIN INTO TOMORROW MORNING USING BEST MEAN RH'S AS GUIDANCE.  WILL
CARRY CLOUDS THROUGH THE DAY TOMORROW BEFORE BREAKING THEM OUT FOR
TOMORROW NIGHT.

BIG STORY WILL BE THE WIND THOUGH.  SURFACE LOW REALLY CRANKS UP AS
IT TRACKS NORTHEAST FROM CENTRAL OKLAHOMA.  GIVEN GRADIENT SHOULD
EASILY MEET WIND ADVISORY CRITERIA OF 20 TO 30 MPH AND GUSTY.  LATER
SHIFTS MAY HAVE TO UPDATE FOR TIMING AND TO MAKE THEM EVEN STRONGER.

TEMPERATURES ALSO A PROBLEM.  WIND AND CLOUDS SHOULD KEEP TEMPS FROM
DROPPING TOO MUCH TONIGHT AND FROM RISING TOO MUCH TOMORROW.
TOMORROW NIGHT WILL BE VERY INTERESTING.  IF CLOUDS BREAK UP AS
EXPECTED AND WIND WOULD DIE DOWN COULD HAVE A HARD FREEZE.  WILL PLAY
IT THAT THE WIND WILL STAY UP ENOUGH TO JUST BARELY KEEP THAT FROM
HAPPENING.

FCSTID = 17
TUL   44  50  35  55 /  60  30   0   0
FSM   46  53  36  55 /  60  30   0   0
MLC   46  53  36  57 /  70  20   0   0
BVO   42  48  33  53 /  60  30   0   0
FYV   44  50  32  50 /  60  30   0   0
IDB   48  57  37  60 /  60   0   0  10
BYV   44  50  32  50 /  60  30   0   0
MIO   43  50  33  52 /  60  30   0   0
MKO   44  50  35  55 /  60  30   0   0
F10   44  50  35  55 /  60  30   0   0
HHW   48  57  37  60 /  60   0   0  10

.TUL...
OK...WIND ADVISORY FOR WEDNESDAY NIGHT AND THURSDAY FOR ZONES
OKZ049...OKZ053>077.

AR...WIND ADVISORY FOR WEDNESDAY NIGHT AND THURSDAY FOR ZONES
ARZ001>002...ARZ010>011...ARZ019>020...ARZ029.

ABBAS

--------------------
EXPERIMENTAL OUTPUT:

HAZARDOUS WEATHER EXPECTED NEXT 24 HOURS: SLIGHT CHANCE NONE
NGM CONFIDENCE:  7 ON A SCALE OF 0 TO 10
ETA CONFIDENCE:  8 ON A SCALE OF 0 TO 10
AVN CONFI4DENCE:  7 ON A SCALE OF 0 TO 10
FCST CONFIDENCE: 9 ON A SCALE OF 0 TO 10

ARZ001-002-010-011-019-020-029-OKZ049-053>076-151200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT WED APR 14 1999

...A FEW SEVERE THUNDERSTORMS ARE POSSIBLE OVER SOUTHEAST OKLAHOMA AND
WEST CENTRAL ARKANSAS THIS AFTERNOON AND EVENING...

.SYNOPSIS...
EARLY THIS AFTERNOON A LOW PRESSURE SYSTEM WAS LOCATED NEAR THE RED
RIVER IN FAR SOUTHWEST OKLAHOMA.  A DRYLINE TRAILED SOUTH FROM THE LOW
INTO NORTHERN TEXAS.  THE LOW PRESSURE SYSTEM WILL TRACK ACROSS SOUTHERN
OKLAHOMA THROUGH THIS EVENING...THEN INTO ARKANSAS EARLY TONIGHT.

.DISCUSSION...
A FEW SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND THIS EVENING
MAINLY ALONG AND TO THE SOUTH OF I-40.  SUNSHINE HAD RETURNED TO MUCH OF
SOUTHWEST AND SOUTH CENTRAL OKLAHOMA THIS AFTERNOON AS DRIER AIR WRAPPED
INTO AN UPPER LEVEL STORM SYSTEM LOCATED ALONG THE RED RIVER.  THE ADDED
SUNSHINE WARMED SURFACE TEMPERATURES TO AROUND 70 DEGREES.  THE WARMER
SURFACE TEMPERATURES COMBINED WITH COLDER AIR ALOFT ASSOCIATED WITH THE
UPPER LOW WILL CAUSE THE ATMOSPHERE TO BECOME INCREASINGLY UNSTABLE OVER
SOUTHERN OKLAHOMA AS THE UPPER LEVEL SYSTEM DRAWS CLOSER.  SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE VICINITY OF THE SURFACE LOW
AND TRAILING DRYLINE AS IT MOVES EASTWARD THIS AFTERNOON AND THIS
EVENING.  GIVEN ENOUGH INSTABILITY A FEW OF THESE STORMS MAY BECOME
SEVERE OVER SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS WITH LARGE HAIL
AND STRONG GUSTY WINDS THE PRIMARY THREAT.

.EMERGENCY MANAGEMENT AGENCY AND SPOTTER ACTIVATION...
STORM SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD BE PREPARED FOR
POSSIBLE ACTIVATION THIS AFTERNOON AND THIS EVENING MAINLY IN AREAS TO
ALONG AND TO THE SOUTH OF I-40.

ARZ001-002-010-011-019-020-029-OKZ049-053>076-151200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT WED APR 14 1999

...A FEW SEVERE THUNDERSTORMS ARE POSSIBLE OVER SOUTHEAST OKLAHOMA AND
WEST CENTRAL ARKANSAS THIS AFTERNOON AND EVENING...

.SYNOPSIS...
EARLY THIS AFTERNOON A LOW PRESSURE SYSTEM WAS LOCATED NEAR THE RED
RIVER IN FAR SOUTHWEST OKLAHOMA.  A DRYLINE TRAILED SOUTH FROM THE LOW
INTO NORTHERN TEXAS.  THE LOW PRESSURE SYSTEM WILL TRACK ACROSS SOUTHERN
OKLAHOMA THROUGH THIS EVENING...THEN INTO ARKANSAS EARLY TONIGHT.

.DISCUSSION...
A FEW SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND THIS EVENING
MAINLY ALONG AND TO THE SOUTH OF I-40.  SUNSHINE HAD RETURNED TO MUCH OF
SOUTHWEST AND SOUTH CENTRAL OKLAHOMA THIS AFTERNOON AS DRIER AIR WRAPPED
INTO AN UPPER LEVEL STORM SYSTEM LOCATED ALONG THE RED RIVER.  THE ADDED
SUNSHINE WARMED SURFACE TEMPERATURES TO AROUND 70 DEGREES.  THE WARMER
SURFACE TEMPERATURES COMBINED WITH COLDER AIR ALOFT ASSOCIATED WITH THE
UPPER LOW WILL CAUSE THE ATMOSPHERE TO BECOME INCREASINGLY UNSTABLE OVER
SOUTHERN OKLAHOMA AS THE UPPER LEVEL SYSTEM DRAWS CLOSER.  SCATTERED
THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE VICINITY OF THE SURFACE LOW
AND TRAILING DRYLINE AS IT MOVES EASTWARD THIS AFTERNOON AND THIS
EVENING.  GIVEN ENOUGH INSTABILITY A FEW OF THESE STORMS MAY BECOME
SEVERE OVER SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS WITH LARGE HAIL
AND STRONG GUSTY WINDS THE PRIMARY THREAT.

.EMERGENCY MANAGEMENT AGENCY AND SPOTTER ACTIVATION...
STORM SPOTTER GROUPS AND EMERGENCY MANAGERS SHOULD BE PREPARED FOR
POSSIBLE ACTIVATION THIS AFTERNOON AND THIS EVENING MAINLY IN AREAS TO
ALONG AND TO THE SOUTH OF I-40.