Flood Watch 5, NWS Indianapolis, IN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
330 PM EDT FRI SEP 22 2006

.DISCUSSION FOR ZONES AND GRIDDS...COMPLICATED FORECAST FOR TONIGHT
THROUGH SATURDAY NIGHT.

A 993 MB SURFACE LOW WAS OVER NORTHWEST IOWA AND A WARM FRONT
EXTENDED SOUTHEAST FROM THIS LOW TO THE SOUTHWEST TIP OF KENTUCKY.
MODELS INDICATE A SECONDARY LOW WAS FORMING OVER OKLAHOMA.  THIS
SECONDARY LOW WILL QUICKLY MOVE TO THE NORTHEAST AND EVENTUALLY
MERGE WITH THE INITIAL LOW AS THEY BOTH MOVE INTO THE GREAT LAKES
PER MODELS.

BOTH GFS AND WRF INDICATE A SEVERE WEATHER AND POSSIBLE HEAVY RAIN
THREAT TONIGHT INTO SATURDAY EVENING.  HOWEVER THERE IS ENOUGH
DIFFERENCES BETWEEN MODELS TO MUDDLE UP THE DEGREE OF SEVERE WEATHER
AND HEAVY RAIN POTENTIAL.  ALSO THE WRF IS ABOUT 6 TO 8 HOURS SLOWER
THAN GFS INDICATING A LULL IN THUNDERSTORMS MUCH OF SATURDAY WITH
MOST OF THE STRONGEST ACTIVITY OCCURRING SATURDAY NIGHT.  GFS BRINGS
THE HEAVIEST BATCH OF PRECIPITATION ACROSS OUR SOUTHERN ZONES
TONIGHT AND WITH A SECONDARY MAX OCCURRING ACROSS THE UPPER WABASH
VALLEY.

BECAUSE OF THESE DIFFERENCES...SPC IS KEEPING US ONLY UNDER A SLIGHT
RISK TOMORROW...BUT THEY MAY QUICKLY UPGRADE THIS TO A MODERATE RISK
ONCE TIMING AND EXACT AREA BECOMES CLEAR IN A LATER FORECAST.

SATELLITE INDICATES THUNDERSTORMS RAPIDLY DEVELOPING ACROSS MISSOURI
AND ILLINOIS.  SINCE BOTH GFS AND WRF INDICATE A PROLONGED PERIOD OF
HEAVY RAIN ACROSS SOUTHERN INDIANA WILL ISSUE FLOOD WATCH FOR
TONIGHT THROUGH MOST OF SATURDAY NIGHT.

AS FAR AS SEVERE WILL CONTINUE TO HIGHLIGHT SEVERE IN GRIDS FOR
SATURDAY AFTERNOON AND EVENING WHICH CORRELATES BEST WITH MODEL
CONSENSUS AND THIS WILL BE ESPECIALLY THE CASE IF WE GET A PERIOD OF
DAYTIME HEATING ON SATURDAY.  PARTS OF WEST CENTRAL AND NORTHWEST
INDIANA COULD EXPECT A SEVERE WEATHER WATCH THIS EVENING.

NO SIGNIFICANT CHANGES TO THE REST OF THE FORECAST. A FEW LEFT OVER
SHOWERS MAY OCCUR AFTER COLD FRONT ON SUNDAY AS INDICATED BY GFS AND
WRF. ALSO WILL KEEP A CHANCE OF SHOWERS AROUND WEDNESDAY NIGHT AS
ANOTHER COLD FRONT MOVES THROUGH.  THE REST OF THE FORECAST WILL BE
DRY AND SEASONABLY COOL.

&&

.AVIATION DISCUSSION FOR 18Z TAFS...CEILINGS HAVE LOWERED TO MVFR
ACROSS TAF SITES AS MOISTURE CONTINUE TO INCREASE ACROSS CTRL
INDIANA. DO NOT ANTICIPATE MUCH IN THE WAY OF PRECIP THROUGH
00Z...ALTHOUGH AN ISOLATED TSRA IS POSSIBLE. CHCS ARE SLIM ENOUGH
THAT HAVE CHOSEN TO ONLY MENTION VCTS ACROSS SITES DURING THIS
TIMEFRAME. AROUND 00Z...COMPLEX OF SHOWERS AND TSRAS WL DEVELOP AND
MOVE ACROSS SITES. EXPECT TO SEE MVFR CONDITIONS FOR THE MOST PART.
COULD SEE A BRIEF WINDOW OF LIFR DUE TO HEAVY RAINFALL...IF TSRA
PASSES OVR SITE. SHOULD SEE VISIBILITIES IMPROVE A BIT AROUND 15Z
BUT CEILING WL REMAIN MVFR THROUGH MUCH OF PD. IN ADDITION TO LOW
CEILINGS...WINDS WL INCREASE AND BECOME GUSTY AS LL JET MVS BACK
ACROSS SITES OVERNIGHT. HAVE LEFT WIND GUSTS IN AT TAF SITES TO
ACCOUNT FOR THIS.

&&

.IND WATCHES/WARNINGS/ADVISORIES...FLOOD WATCH TONIGHT THROUGH ABOUT
06Z SUNDAY ALONG AND SOUTH OF A LINE FROM SULLIVAN TO COLUMBUS TO 20
MILES NORTH OF NORTH VERNON.

&&

PUBLIC...JEH
AVIATION...JB

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
945 AM EDT FRI SEP 22 2006

INZ021-028>031-035>049-051>057-060>065-067>072-230815-
CARROLL-WARREN-TIPPECANOE-CLINTON-HOWARD-FOUNTAIN-MONTGOMERY-
BOONE-TIPTON-HAMILTON-MADISON-DELAWARE-RANDOLPH-VERMILLION-PARKE-
PUTNAM-HENDRICKS-MARION-HANCOCK-HENRY-VIGO-CLAY-OWEN-MORGAN-
JOHNSON-SHELBY-RUSH-SULLIVAN-GREENE-MONROE-BROWN-BARTHOLOMEW-
DECATUR-KNOX-DAVIESS-MARTIN-LAWRENCE-JACKSON-JENNINGS-
845 AM CDT FRI SEP 22 2006 /945 AM EDT FRI SEP 22 2006/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL INDIANA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS TODAY AND TONIGHT.
A DEEPENING LOW PRESSURE SYSTEM TO THE WEST WILL PUMP WARM MOIST
AIR INTO INDIANA FROM THE GULF OF MEXICO. THIS INCREASING MOISTURE
COMBINED WITH DAYTIME HEATING WILL CREATE AN OPPORTUNITY FOR
THUNDERSTORM DEVELOPMENT.

THUNDERSTORMS ARE NOT EXPECTED TO BE CONTINUOUS THROUGHOUT THE DAY
AND NIGHT TIME BUT INSTEAD MORE SCATTERED IN NATURE. SOME OF THESE
STORMS COULD BECOME SEVERE WITH DAMAGING WIND THE MAIN THREAT BUT AN
ISOLATED TORNADO OR TWO CANNOT BE RULED OUT. HEAVY RAIN AND FREQUENT
LIGHTNING WILL ALSO OCCUR WITH THESE STORMS. HEAVY RAIN MAY CAUSE
FLOODING. BE AWARE WHEN TRAVELING THAT WATER CAN QUICKLY COVER THE
ROADWAY. USE EXTRA CAUTION AND NEVER DRIVE THROUGH FLOOD COVERED
ROADS.

IN ADDITION TO THE THUNDERSTORM RISK...STRONG WINDS FROM THE SOUTH AT
15 TO 20 MPH COULD GUST TO AROUND 30 MPH AT TIMES.

STAY TUNED TO NOAA ALL HAZARDS RADIO OR OUR WEB SITE FOR FURTHER
UPDATES ON THIS RAPIDLY CHANGING WEATHER SITUATION.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

AS THE VIGOROUS UPPER SYSTEM CONTINUES TO MOVE CLOSER TO INDIANA
THERE REMAINS A CHANCE OF SEVERE WEATHER ON SATURDAY. THE MAIN
THREAT ON SATURDAY WILL BE DAMAGING WIND. IN ADDITION...ISOLATED
TORNADOES...LARGE HAIL...HEAVY RAIN AND FREQUENT LIGHTNING WILL ALSO
BE POSSIBLE. THE HEAVY RAINFALL MAY CAUSE FLOODING. WATER CAN
QUICKLY COVER THE ROADWAYS SO USE EXTRA CAUTION WHEN TRAVELING.
NEVER DRIVE ACROSS FLOODED ROADS.

INDIVIDUAL THUNDERSTORMS COULD FORM OUT AHEAD OF A MAIN SQUALL LINE
THAT WILL BEGIN IN ILLINOIS AND MOVE EAST. THE EXPECTED TIME FRAME
FOR THUNDERSTORM DEVELOPMENT WILL BE SATURDAY AFTERNOON MAINLY AFTER
200 PM EDT. THUNDERSTORMS SHOULD BE EAST OF THE STATE BY MIDNIGHT.

SATURDAY WILL ALSO BE VERY WINDY WITH SOUTH WINDS AT 15 TO 20 MPH
GUSTING TO AROUND 30 MPH.

AFTER SUNDAY...THE NEXT CHANCE OF RAIN WILL BE ON WEDNESDAY NIGHT
AND THURSDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY AND IS LIKELY ON SATURDAY.

&&

MORE INFORMATION...ALONG WITH OTHER WEATHER...HYDROLOGICAL AND
CLIMATE INFORMATION CAN BE FOUND...AT HTTP://WEATHER.GOV/IND (ALL
LOWERCASE)