Severe Thunderstorm Warning 413, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
927 PM CDT MON AUG 26 2002

MCS CURRENTLY MOVING SEWD THROUGH SWRN KS THIS EVENING.EXPECT
COMPLEX TO CONTINUING PROPAGATING SSEWD INTO INSTAB AXIS WHICH
EXTENDS FROM PANHANDLE INTO WRN OK. GOING FCST HAD THIS SCENARIO
PRETTY WELL IN HAND WITH LIKELY POPS IN THE WESTERNMOST ZONES THEN
TAPERING OFF TO THE EAST. WILL JUST MAKE SOME SLIGHT ADJUSTMENTS TO
POPS AND TMPS IN THE FIRST PD...OTRW NO CHANGES EXPECTED.

02

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
327 PM CDT MON AUG 26 2002

STORMS HAVE DEVELOPED QUICKLY THIS AFTERNOON ACROSS SW NEBRASKA
AND NORTHWEST KANSAS AND THIS IS PROBABLY BEGINNING OF
COMPLEX THAT WILL AFFECT MAINLY WESTERN PARTS OF CWA LATER
THIS EVENING AND OVERNIGHT.  EXPECT AS LF OF UPPER JET OVER SW
US MOVES TOWARD HIGH PLAINS THIS EVENING/TONIGHT AND LLJ INCREASES
WILL SEE MORE DEVELOPMENT SOUTH AND THEN INTO NW OKLAHOMA.
BETTER DEEP LAYER SHEAR WILL BE FARTHER NORTH AND TIMING OF
CONVECTION SHOULD KEEP THE STRONGER TO SEVERE STORMS MAINLY NORTH OF
FA THIS EVENING. STORMS SHOULD LINGER INTO THE MORNING WITH A
DECREASE IN COVERAGE DURING THE AFTERNOON.  HIGH TEMPERATURES COULD
BE TRICKY...BUT SHOULD SEE ENOUGH SUN THAT TEMPERATURES WILL REACH
HIGHER END OF GUIDANCE.

WILL LIKELY SEE SIMILAR SITUATION FOR TUESDAY NIGHT WITH UPSLOPE
FLOW THROUGH A FAIRLY DEEP LAYER AND ACTIVE SOUTHERN STREAM JET.
BEST CHANCE AGAIN APPEARS TO BE ACROSS WESTERN PARTS OF CWA.
HAVE IN ONLY SLIGHT POPS FOR WEDNESDAY DURING THE DAY BUT MAY
NEED TO INCREASE POPS LATER AS TUESDAY NIGHT CONVECTION MAY
LINGER INTO THE MORNING HOURS.

MEDIUM RANGE MODELS SIMILAR IN UPPER AIR FEATURES AT BEGINNING OF
EXTENDED FORECAST (THURS) WITH UPPER RIDGE CENTERED OVER WEST TX AND
UPPER LOW TO THE EAST NEAR GA/AL.  GOING INTO
FRIDAY...TROUGH/SHORTWAVE OVER WESTERN STATES LIFTS NORTHEAST INTO
CENTRAL AND NORTHERN PLAINS AND APPEARS BEST CHANCE FOR TSRA WITH
THIS FEATURE WILL BE ACROSS NORTHERN PART OF FA THURSDAY NIGHT INTO
FRIDAY MORNING.  CURRENT FORECAST IS DRY AND WILL LIKELY  MAINTAIN
DRY FORECAST AS MOST IF NOT ALL WEATHER SHOULD REMAIN NORTH.  GOING
INTO THE WEEKEND...MODELS DIFFER ON UPPER AIR FEATURES.  ECMWF KEEPS
UPPER RIDGE OVER SOUTHERN 2/3 OF US WITH WEAK WESTWARD MOVING TROUGH
OVER SW GULF. MRF MAINTAINS WEAKNESS/LOW IN RIDGE AND MOVES IT WEST
OVER THE WEEKEND.  OVERALL...PLAN ON KEEPING EXTENDED FORECAST DRY
WITH WEAKER UPPER FLOW, WEAK SURFACE GRADIENT, AND MAIN CONVECTION
WITH GULF SYSTEM REMAINING ON EASTERN SIDE.  EXTENDED GRIDS OUT
SHORTLY.  LOOKING AT NEW ETA AND AVN WILL GO AHEAD AND PUT IN
SLIGHT CHANCES OF TSRA FOR THURSDAY NIGHT INTO FRIDAY.

FCSTID = SIX

OKC  68 89 69 88 /  30 20 20 20
HBR  67 88 68 88 /  60 40 40 20
SPS  69 93 71 94 /  40 30 40 20
GAG  65 86 65 87 /  60 40 40 20
PNC  67 88 69 88 /  20 20 20 20
DUA  70 94 70 92 /  20 20 20 20

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