Tornado and Flash Flood in Oklahoma, May 16 to 17, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
230 PM CDT THU MAY 16 2002

SFC COLD FRONT FROM NE KS SWWD INTO TX PANHANDLE AT MIDDAY WITH SFC
LOW REDEVELOPING SWD TO BETWEEN AMA/LBB.  SOUTH OF SFC LOW..DRYLINE
CONTS TO SLOWLY MIX EWD..BUT SHUD STALL AND BEGIN TO RETREAT WWD
MID/LATE AFTERNOON AS STRONG PRESSURE FALLS DEVELOP OVER SE CO IN
RESPONSE TO AMPLIFYING SW TROF DIGGING THRU UT/CO ATTM. RICH
BOUNDARY LAYER MOISTURE CONTS TO SURGE NWD IN THE WARM SECTOR ACROSS
OK..BUT EXPANSIVE CLOUDS HAVE RESULTED IN A BL MUCH COOLER THAN EVEN
THE 12Z ETA HAD FORECAST.  FOR THE SHORT TERM..HAVE BASICALLY
DISCOUNTED THE OPERATIONAL ETA FORECAST IN FAVOR OF THE ETA K/F RUN
AT NSSL.  THE KF CONVECTION SCHEME HAS A MUCH BETTER HANDLE ON THE
WARM LAYER ALOFT AND IS MUCH LESS BULLISH IN REMOVING THE CAPPING
INVERSION THRU ABOUT 3Z.  THERE IS STILL A SMALL CHANCE OF
INITIATION OVER NW/NC OK BETWEEN 22-02Z..BUT PROB 20 PERCENT AT
MOST. MUCH BETTER CHANCE OF PRECIP TO OVERSPREAD THE FA TONITE FROM
THE NW AS CONVECTION EXPECTED TO ORGANIZE INTO ONE OR TWO MCS/S OVER
THE HIGH PLAINS AND RIDE SEWD AS FRONT BEGINS SWD PUSH WITH
MID/UPPER WAVE MOVING INTO KS/OK BY 12Z.  FOCUS FOR ESEWD
PROPAGATION IS LIKELY TO BE THE 850-700 FRONTAL ZONE.  THERE SEEMS
TO BE QUITE A BIT OF DRY AIR IN A PLUME FROM NE NM INTO SW KS
ATTM..AND POTENTIAL EXISTS FOR COLD POOL DEVELOPMENT AND FORWARD
PROPAGATING MCS..BUT THERE IS ALSO UNCERTAINTY W.R.T. WIDESPREAD SVR
POTENTIAL WITH INCREASINGLY STABLE BOUNDARY LAYER.

EXPECT CHANCES FOR CONVECTION TO LINGER OVER THE SRN ZONES FOR PART
OF TOMORROW..BUT LOW LEVEL COOL AIR SHUD DEEPEN ENUF WITH PASSAGE OF
S/W TROF TO SHUNT THE BEST CHANCES FOR ADDITIONAL RAIN SOUTH OF OUR
AREA BY AFTERNOON. THERE ALSO APPEARS TO BE A POTENTIAL FOR HVY
RAINFALL MAINLY LATE TONITE AND FRI MORNING OVR THE SE PARTS OF THE
FORECAST AREA AS INFLOW SHEAR VECTOR BECOMES ORIENTED MORE PARALLEL
TO FOCUSSING MECHANISM. EXPECT POST FRONTAL CLOUDS TO BE SLOW TO
CLEAR FRIDAY..WHICH WILL LEAD TO A RATHER COOL DAY.

WILL CONT WITH DRY FORECAST AND WARMING TEMPS FROM THIS WEEKEND THRU
DAY 7.  THERE MAY BE A WINDOW OF OPPORTUNITY FOR PRECIP MON-WED..
BUT CURRENT FORECAST FLOW PATTERN FROM BOTH AVN/ECMWF IT APPEARS
THAT STRONG CAPPING WILL ONCE AGAIN BUILD INTO THE SRN PLAINS..
WHICH PRECLUDES THE INTRODUCTION OF POPS AT THIS TIME. BEST CHANCE
MAY BE MON/MON NITE IF MOISTURE CAN MANAGE TO RETURN BEFORE STRONG
CAP BECOMES ESTABLISHED. GFE/IFPS HOPEFULLY FIXED FOR THIS
ISSUANCE.. SO FULL SUITE OF PRODUCTS SHUD BE AVAILABLE ALTHOUGH
POSSIBLY DELAYED AS DATABASE THRU DAY 7 IS RECONSTRUCTED.
 MILLER

1ST CUT AT NUMBERS..
OKC   60  67  47  71 /  70  30   0   0
HBR   58  69  47  72 /  60  30   0   0
SPS   65  70  51  74 /  30  30   0   0
GAG   52  65  44  71 /  70  20   0   0
PNC   55  65  45  69 /  70  30   0   0
DUA   68  75  52  71 /  70  60  10   0

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