Severe Thunderstorm Warning 203, NWS Topeka, KS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE  TOPEKA KS
309 PM CDT SUN SEP 20 1998

TEMPERATURES AND PRECIPITATION MAIN FORECAST PROBLEMS.

19Z SURFACE SHOWS A COUPLE OF DIFFERENT BOUNDARIES IN THE PLAINS.
SURFACE LOW IN THE VICINITY OF KDDC...AND A WARM FRONT INTO CENTRAL
THEN SOUTHEAST KANSAS.  MAIN COLD FRONT LOOKS TO BE HANGING BACK IN
NEBRASKA AS DEW POINTS IN THE 40S AND 50S ARE NOTED IN MUCH OF
KLBFS CWA.  SOME CONVECTION STARTING TO FIRE IN WARM SECTOR OVER
SOUTHCENTRAL KANSAS WHERE ADAP SHOWS LIS AROUND -8 AND WEAK CAP.
SOME OF THIS CONVECTION COULD SKIRT SOUTHERN CWA THIS EVENING.

MODELS DIFFER IN HANDLING LOW LEVEL COLD AIR WITH AVN MOST
AGGRESSIVE DRIVING IT SOUTH AND NGMS NORTHWARD BIAS HOLDING COLD
AIR OFF AWHILE.  ETA NORMALLY BEST IN THESE SITUATIONS SO WAS
FOLLOWED.  EXPECT NEBRASKA COLD FRONT TO GRADUALLY WORK ITS WAY
SOUTH OVERNIGHT MAKING IT INTO NORTHERN KS BY MORNING THEN THROUGH
CWA BY MONDAY AFTERNOON.  MEANWHILE MID LEVEL IMPULSES EJECT FROM
GREAT BASIN UPPER LOW AND INTO THE PLAINS.  CONVERGING Q-VECTORS
SUGGEST LIFT INTO CENTRAL THEN EASTERN KS TONIGHT WHILE SOUTHERLY
FLOW RIDES UP AND OVER SOUTHERN KANSAS WARM FRONT.  310K ISENTROPIC
ANALYSIS INDICATES DECENT PRESSURE ADVECTION INTO THE CWA AS WELL.
THUS WILL KEEP LIKELY POPS GOING TONIGHT OVER ALL OF THE AREA AND
WILL TAPER TEMPS NORTH TO SOUTH.  DEW POINTS STILL IN THE 60S ACROSS
THE CWA SO ONLY THE NORTHERN ZONES SHOULD DROP BELOW 60 AS FRONT
APPROACHES.

AS FRONT DROPS SOUTH MONDAY...PRECIP POSSIBLE RIGHT ON THROUGH
TUESDAY AS EAST TO NORTHEAST LOW LEVEL FLOW IS OVERRUN BY SOUTHERLY
THEN WESTERLY FLOW ALOFT.  BEST CHANCES WILL COME MONDAY NIGHT AS
NEXT PIECE OF ENERGY EJECTS INTO THE PLAINS.  COOL AIR WILL CONTINUE
TO BE REINFORCED THROUGH TUESDAY SO WILL KNOCK A COUPLE OF CATEGORIES
OFF HIGHS AND LOWS.  FINAL NUMBERS LOOK TO BE A BLEND OF FWC/FAN
GUIDANCE VALUES...MORE IN LINE WITH ETA SURFACE TEMPERATURE PROGS.

.TOP...NONE.

SD