Severe Thunderstorm Warning 409, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
957 PM CDT SAT AUG 24 2002

MESONET DOES A GOOD JOB DEPICTING EAST-WEST BOUNDARY LYING ALONG I40
THIS EVENING. MESONET AND WSR-88D INDICATE BOUNDARY CONTINUES TO
MAKES SOUTHWARD PROGRESS...THOUGH SLOWER THAN A COUPLE OF HOURS AGO.
EXPECT STORMS MOVING IN FROM WEST TO CONTINUE MOVING SOUTHEAST NEXT
FEW HOURS AS LOW-LEVEL JET STRENGTHENS AND INCREASES STORM RELATIVE
INFLOW.  BEST COVERAGE OF STORMS WILL BE NEAR AND NORTH OF BOUNDARY
ACROSS CENTRAL AND NORTHCENTRAL OKLAHOMA. ADDITIONAL CONVECTION
COULD REFIRE EVEN IN NORTHWEST WHERE WEAK UPSLOPE AND LOW-LEVEL WARM
ADVECTION COULD HELP DEVELOP A FEW ELEVATED STORMS LATER.

ZONES ADJUSTED TO REFLECT TRENDS IN SKY COVER...POPS...AND WINDS.

..16..
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
315 PM CDT SAT AUG 24 2002

NOT A HIGH-CONFIDENCE FORECAST. SEVERAL FAVORABLE PARAMETERS FOR
CONVECTIVE DEVELOPMENT BY EVENING, AND MCS OVERNIGHT, FROM CENTRAL
HI PLAINS INTO OK. FRONT/OUTFLOW BOUNDARY EXPECTED TO REMAIN ACROSS
S/SW PART OF CWA...SETTING UP FAVORABLE ISENTROPIC LIFT/WAA TO N AND
NE OF SURFACE BOUNDARY TONIGHT AS LLJ INCREASES. FAVORABLE UPSLOPE
LL FLOW ALSO TO CONTINUE N OF BOUNDARY...FURTHER INCREASING LL
FORCING. UNSEASONABLY STRONG NW FLOW AT MID/UPPER LEVELS WILL RESULT
IN UNUSUALLY STRONG VERTICAL SHEAR AND FAIRLY HIGH SEVERE POTENTIAL.
PROFILER 300MB WINDS NOW 60-80KT OVER CO. BUT...LACK OF MID/UPPER
LEVEL FORCING MAY BECOME AN OBSTACLE. MID-LEVEL HIGH OVER S AZ/NM IS
LEADING TO LARGE-SCALE RIDGING N-WARD INTO CENTRAL ROCKIES. MODEL
PROGS AND CURRENT WV SATELLITE DO NOT INDICATE ANY WELL-DEFINED
IMPULSES MOVING THRU THE CENTRAL ROCKIES...SO MID LEVEL SUPPORT FOR
TONIGHT APPEARS TO BE LACKING. STRONG UPPER JET IS PROGGED TONIGHT
FROM S WY SE-WARD ACROSS KS INTO NE OK...PLACING CWA IN LESS-THAN-
FAVORABLE RIGHT EXIT REGION. SURE ENOUGH...300MB DIVERGENCE IS
PROGGED TO REMAIN MOSTLY NEGATIVE. MODELS GIVE SIGNS OF A SECONDARY
JET AXIS DEVELOPING OVERNIGHT FROM CO INTO SW OK. RESULTING
STRONGLY-DIFLUENT FLOW WOULD FAVOR AREAS FROM KS INTO E AND SE OK
FOR DEVELOPMENT LATE TONIGHT. MODEL QPFS INDEED SUPPORT MORE
ORGANIZED PRECIP AREA FROM E OK E-WARD LATE TONIGHT...BUT ARE
RELATIVELY DRY FROM W KS SE-WARD. THIS MAY BE TELLING...ALTHO MODELS
LAST NIGHT APPARENTLY MISSED THE STORMS OVER N OK. PLAN TO CONTINUE
HIGHEST POPS IN NE...LOWEST SW...BUT MIGHT HAVE TO DEVELOP ANOTHER
PLAN IF THE OUTFLOW BOUNDARY BECOMES MORE ACTIVE BEFORE PRESS TIME.

NEED TO KEEP SOME POPS GOING MOST AREAS THRU MON WITH CONTINUED NW
FLOW AND PROXIMITY OF LL BOUNDARY - WITH OR WITHOUT REINFORCEMENT
FROM PRIOR CONVECTION - NEAR OR JUST S OF AREA. LOW LATS BECOME MORE
BLOCKED BY LATE MON AS UPPER LOW FORMS OVER KY-TN. THIS SHUD HOLD
UPSTREAM RIDGING INVOF FRONT RANGE AND LIMIT ANY EFFECTS OF
SHORTWAVE IMPULSES MOVING INTO PLAINS. THUS POPS KEPT LOW.

AFOREMENTIONED RIDGE MOVES ONLY SLOWLY OUT INTO PLAINS AREA BY
MIDWEEK AND THEN STAYS THERE AS BLOCKING PATTERN SETS UP. HOTTER
CONDITIONS LIKELY TO BE TO OUR SW...OVER E NM AND W TX BENEATH UPPER
HIGH. LL FLOW REMAINS MOSTLY EASTERLY ACROSS OUR AREA...WHICH IS
NORMALLY NOT VERY HOT EVEN WITH A BUILDING MID-LEVEL RIDGE OVERHEAD.
WILL TREND THE HIGHS DAYS 3-7 DOWNWARD...CLOSER TO CLIMO AND
GUIDANCE. PROGGED PATTERN LOOKS LIKE A DRY ONE W/RIDGING ALOFT...BUT
FOR CONTINUITY WILL LEAVE THE LOW POPS WED/THU ALONE FOR NOW AS
THERE ARE SIGNS OF A SLIGHT W-WARD SHIFT OF THE RIDGE AXIS AND
ANOTHER PERIOD OF NW FLOW.

FCSTID = 24

OKC  72 92 71 94 /  30 20 10 10
HBR  72 95 71 95 /  30 20 20 20
SPS  75 100 73 97 /  20 20 20 20
GAG  65 89 66 94 /  30 20 20 20
PNC  70 88 70 91 /  50 20 10 10
DUA  73 94 73 94 /  40 20 10 10

.OKC...
OK...NONE.
TX...NONE.