Severe Thunderstorm Warning 518, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
245 PM CDT SAT AUG 25 2001

OVERVIEW OF FORECAST NEXT 24 TO 48 HOURS APPEARS FAIRLY
STRAIGHTFORWARD AT FIRST...UNTIL MESOSCALE DIAGNOSTICS ARE THROWN
INTO THE MIX. UPPER LEVEL SUBSIDENCE REGION/ANTICYCLONIC FLOW
INDICATED ON SATELLITE AND PROFILER NETWORK ACROSS CENTRAL PORTIONS
OF OKLAHOMA...EFFECTS FROM DEPARTING S/WV TROF AND SOUTHWEST
OKLAHOMA PERSISTENT CONVECTION. THIS IS EXPECTED TO DELAY ONSET OF
CONVECTIVE DEVELOPMENT ACROSS CENTRAL/EASTERN PORTIONS OF THE
FORECAST AREA. ALTHOUGH THINGS APPEAR BLEAK RIGHT NOW...WE STILL
EXPECT FRONTAL CONVECTION TO FILL IN ACROSS CENTRAL PORTIONS OF THE
FORECAST AREA...AND MOVE SOUTH...LATER THIS EVENING AND OVERNIGHT.
ZONES WILL BE WORDED ACCORDINGLY.

ETA APPEARS TO HAVE THE BEST HANDLE ON LARGER SCALE WEATHER
FEATURES. AVN CHARACTERISTICALLY SUFFERING FROM CONVECTIVE
FEEDBACK...AFFECTING ITS VORTICITY FIELDS AND QPFS. BEST CHANCES FOR
WIDESPREAD HEAVY RAINFALL APPEAR TO BE ACROSS THE EXTREME WEST
CENTRAL AND SOUTHWEST ZONES...CLOSER TO INFLUENCE OF IMPRESSIVE
WAVE/CUTOFF OVER COLORADO AND NORTHERN NEW MEXICO. THIS FEATURE
WILL TAKE MORE OF A DUE SOUTH DIVE...KEEPING BEST FORCING ACROSS THE
TEXAS PANHANDLE.

FOR THE EXTENDED TIME FRAME...WILL DRY THINGS OUT TUESDAY AND
WEDNESDAY BUT WILL KEEP POPS GOING FOR THURSDAY AND FRIDAY WITH NEXT
FRONTAL SYSTEM PROGD.

FCSTID = 11

PRELIMINARY CCF NUMBERS...
OKC   70  91  69  92 /  60  40   0   0
HBR   68  90  67  92 /  80  40  20   0
SPS   73  95  70  93 /  40  60  30   0
GAG   63  88  63  90 /  60  20  10   0
PNC   68  90  68  93 /  30  10   0   0
DUA   73  94  69  94 /  40  60  30  10

.OUN...
OK...NONE.
TX...NONE.

OKZ004>048-050>052-TXZ083>090-252000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
105 PM CDT SAT AUG 25 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS PORTIONS OF WESTERN OKLAHOMA AND A SMALL PART
OF WESTERN NORTH TEXAS. THE SLIGHT RISK AREA IS GENERALLY WEST OF A
WAYNOKA TO WEATHERFORD TO HOBART AND QUANAH...TEXAS LINE.  LARGE
HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS. LOCALLY HEAVY
RAINFALL WILL ALSO BE POSSIBLE.

A COLD FRONT EXTENDING FROM EASTERN KANSAS SOUTHWEST INTO THE
TEXAS PANHANDLE WILL CONTINUE TO PUSH SLOWLY SOUTH THIS AFTERNOON
INTO NORTHWEST AND NORTH CENTRAL OKLAHOMA.  AHEAD OF THE FRONT...
TEMPERATURES WILL WARM INTO THE MID AND UPPER 90S WITH A FEW
100 DEGREE READING ACROSS SOUTHWEST OKLAHOMA AND WESTERN NORTH
TEXAS.  CONVERGENCE AHEAD AND ALONG THE FRONT COMBINED WITH
AN UPPER AIR DISTURBANCE MOVING SOUTH OUT OF COLORADO WILL RESULT
IN SCATTERED SHOWER AND THUNDERSTORM DEVELOPMENT BY MID TO LATE
AFTERNOON.  ALTHOUGH WIND PROFILES WILL REMAIN RATHER WEAK...MID
LEVEL LAPSE RATES SHOULD BE SUFFICIENT FOR A FEW STORMS TO PRODUCE
LARGE HAIL AND DAMAGING WIND GUSTS.  THE SEVERE THREAT SHOULD
DIMINISH LATER THIS EVENING WITH THE LOSS OF DAYTIME HEATING.

FARTHER EAST ACROSS NORTH CENTRAL AND CENTRAL OKLAHOMA...LOCALLY
DAMAGING WIND GUSTS ARE ALSO A POSSIBILITY AS THUNDERSTORMS WEAKEN
LATE IN THE AFTERNOON.  LOCALLY HEAVY RAINFALL WILL ALSO BE A
POSSIBILITY AS STORMS SHOULD BE SLOW TO MOVE INITIALLY.  RESIDENTS
OF WESTERN AND CENTRAL OKLAHOMA PLANNING OUTDOOR ACTIVITIES THIS
AFTERNOON AND EVENING SHOULD REMAIN ALERT TO THE LATEST WEATHER
FORECAST AND POSSIBLE WARNINGS.

FARTHER SOUTH ACROSS WESTERN NORTH TEXAS...THE BEST CHANCE OF SHOWERS
AND THUNDERSTORMS WILL BE LATER IN THE EVENING AS THE FRONT
CONTINUES TO PUSH FARTHER SOUTH.

EMERGENCY MANAGERS AND SPOTTER GROUPS IN THE SLIGHT RISK AREA SHOULD
BE PREPARED FOR POSSIBLE ACTIVATION BEGINNING AROUND MID
AFTERNOON...AND CONTINUING THROUGH THE EVENING.

SIX