Severe Thunderstorm Warning 571, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
322 PM CDT SAT SEP 8 2001

ANOTHER ACTIVE EVENING LIKELY ACROSS SE PART OF CWA. 18Z OUN SOUNDING
SHOWS DRY ADIABATIC LAPSE RATE IN 750-550 MB LAYER, RESULTING IN
MODERATELY STRONG ELEVATED INSTABILITY ABOVE CLOUDY, COOL SURFACE
LAYER. ELEVATED STORMS LIKELY TO INCREASE FROM NCENTRAL TX TOWARD
CENTRAL/EC OK AS UPPER WAVE APPROACHES, WITH POTENTIAL FOR SURFACE-
BASED CONVECTION FROM S OF SPS INTO SC/SE OK CLOSER TO SLOW-MOVING
SURFACE FRONT. MAIN SEVERE THREAT LIKELY TO BE HAIL DUE TO ELEVATED
NATURE OF STORMS, ALTHO THERE MAY BE A HIGHER RISK OF WINDS/ISOLATED
TORNADOES CLOSER TO THE SURFACE BOUNDARY. SECONDARY SURGE OF COOL
AIR SHOULD OVERSPREAD MUCH OF AREA THIS EVENING AND CONTINUE SE
TO REINFORCE THE SURFACE FRONTAL ZONE THEREAFTER. THIS SHOULD SHOVE
ALL THE CONVECTION INTO FAR SE PART OF AREA AFTER MIDNIGHT, ALTHO
SOME LIGHTER RAIN/SHOWERS WITH THE UPPER TROF LIKELY TO SPREAD SE
BEHIND THE 2ND COOL SURGE. HIGH POPS MAINLY S AND E OVERNIGHT. WILL
KEEP LOW POPS ACROSS THE S AND ESPECIALLY FAR SE FOR EARLY SUN, BUT
PASSAGE OF UPPER TROF AND DEVELOPING SUBSIDENCE EXPECTED TO RESULT
IN CLEARING AREAWIDE DURING DAY.

FLASH FLOOD WATCH WAS CONSIDERED FOR PARTS OF SC/SE OK WHERE HIGH
PRECIPITABLE WATER AND MID-70 SURFACE DEWPOINTS ARE RESULTING IN
ENHANCED MOISTURE CONVERGENCE. SOME OF THESE AREAS HAVE BEEN DUMPED
ON MORE THAN ONCE OVER THE PAST WEEK, INCLUDING 1-2 INCH AMOUNTS
LAST NIGHT. HOWEVER, WE HAVE DECIDED TO HOLD OFF ON A WATCH AT THIS
POINT DUE TO GENERAL TREND FOR LOW-LEVEL FEATURES TO MOVE S,
INCLUDING THE EXISTING BOUNDARY ACROSS N TX AND S OK AS WELL AS THE
REINFORCING SURGE CURRENTLY ENTERING NW OK. ALL THIS SUGGESTS THAT
THE GREATER THREAT OF EXCESSIVE RAINFALL EVENTUALLY WILL SHIFT S OF
THE AREA. LACK OF RECENT HEAVY RAINS FARTHER W IN THE SPS AREA, AND
RESULTING HIGHER FLASH FLOOD GUIDANCE, LIMITS THE THREAT THERE.

DRY AND PLEASANT LATE-SUMMER WX EXPECTED FOR MOST OF NEXT WEEK WITH
RIDGING ALOFT RETURNING TO CENTRAL U.S.  HIGHS GENERALLY IN 80S AND
LOWS IN 50S NW TO 60S ELSEWHERE, PER PREVIOUS FORECAST AND LATEST
MRF GUIDANCE. SOME POTENTIAL FOR A BACKDOOR FRONT AROUND MIDWEEK,
BUT UPPER PATTERN INDICATES MAIN EFFECTS WILL BE WELL NE OF HERE.

FCSTID = 24
OKC   58  77  53  81 /  70  10  10   0
HBR   57  78  54  83 /  60  10   0   0
SPS   60  78  55  84 /  70  20   0   0
GAG   50  75  48  82 /  40  10   0   0
PNC   56  75  52  82 /  60  10   0   0
DUA   63  78  55  80 /  80  30  10   0

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