Damaging Winds in Indiana, September 19, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
ISSUED BY NWS INDIANAPOLIS IN
249 PM EST THU SEP 19 2002

FORECAST FOCUS IS ON HOW HIGH TO GO WITH CHANCES FOR RAIN IN THE
SHORT TERM.

SHORT TERM DISCUSSION...
AT 19Z COLD FRONT REAMINED WEST OF MISSISSIPPI RIVER. ATMOSPHERE WAS
MOIST AND UNSTABLE...ALLOWING SCATTERED TSRA TO DEVELOP ACROSS THE
FORECAST AREA (FA). TEMPERATURES REACHED THE UPPER 80S IN RAIN FREE
AREAS WITH DEWPOINTS AROUND 70 ACROSS THE FA.

MODELS IN FAIR AGREEMENT WITH BIG PICTURE...ALTHOUGH AVN CONTINUES
TO BE THE FASTEST. ETA/S SPEED LOOKS BETTER AND ETA ALSO SHOWS
PREFRONTAL SFC TROF THAT OFTEN OCCURS IN THESE SITUATIONS. THUS WILL
LEAN TOWARD ETA THIS FORECAST...ALTHOUGH ETA MAY BE A BIT OVERDONE
WITH QPF.

CURRENT CONVECTION WILL CONTINUE INTO EVENING BEFORE WEAKENING.
APPROACH OF FRONT AND UPPER TROF WILL BRING MORE RAIN INTO WESTERN
FA BY 12Z. WILL THUS GO LIKELY POPS MUCH OF WRN FA WITH SCATTERED
WORDING IN NW OH. THIS IS CLOSER TO MAV NUMBERS. WITH SOUTHERLY
WINDS AND DEWPOINTS AROUND 70...LOW TEMPS WILL BE ON THE HIGH END OF
GUIDANCE VALUES.

ON FRIDAY COLD FRONT AND UPPER TROF WILL GRADUALLY MOVE ACROSS FA.
GOOD DYNAMICS INCLUDING INFLUENCE OF RIGHT ENTRANCE REGION OF UPPER
JET WILL LEAD TO CATEGORICAL POPS MOST OF FA. NW OH WILL BE LAST TO
SEE BEST CHANCES FOR RAIN SO WILL GO HIGH LIKELY POPS THERE. LACK OF
SIGNIFICANT HEATING WILL LIMIT SEVERE POTENTIAL...BUT 850 WINDS OF
OVER 40 KTS COULD PROVIDE FOR A FEW STORMS WITH STRONG WINDS. GIVEN
THOSE WINDS ALOFT WILL GO ABOVE GUIDANCE WIND SPEEDS AND GO BREEZY.
FOR TEMPS WILL COMPROMISE BETWEEN GUIDANCE NUMBERS AS ANY BREAKS IN
CLOUDS/RAIN WILL LEAD TO QUICK WARMING.

WILL KEEP LIKELY POPS FRI NIGHT AS SYSTEM IS SLOW TO EXIT...AND WILL
CONTINUE TIMING OF ENDING EARLY WEST AND LATE EAST.

EXTENDED DISCUSSION...
WILL CHANGE LITTLE IN EXTENDED AS CURRENT FORECAST LOOKS ON TRACK.
COULD BE MORE CLOUDS ON SUNDAY AND TUESDAY WITH PASSAGE OF COLD
FRONTS...BUT NO PRECIPITATION EXPECTED. WILL KEEP IT SIMPLE AND GO
PARTLY CLOUDY.

.IWX...NONE.

CS