Damaging Wind in Indiana, May 11, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
255 PM EST SAT MAY 11 2002

PRIMARY FORECAST CONCERN IS FLOODING POTENTIAL...WITH SOME
ATTENTION PAYED TO SEVERE POTENTIAL FOR LATER TONIGHT AND SUN.

LATEST SURFACE ANALYSIS INDICATED A LOW PRESSURE CENTER OVR KS...WITH
A WARM FRONT ARCING EASTWARD TO WEST CENTRAL IL...THEN SOUTHEAST INTO
CENTRAL KY.  88D NETWORK INDICATED SHRA AND EMBEDDED TSRA OVER
NORTHERN SECTIONS OF IL AND IN.

AT 5H...MODELS IN DECENT AGREEMENT THROUGH F48 IN BRINGING A SERIES
OF SHORTWAVES ACROSS REGION...THOUGH IN F48 TO F60 TIME PERIOD...ETA
IS FARTHER SOUTH WITH SIGNIFICANT ENERGY THAN NGM AND AVN.  ETA HAS
BACKED OFF A BIT ON THIS DEEPER SOLUTION...SO FAVOR AVN IN LATER
PERIODS. AT THE SFC...MODELS ALL BRING WARM FRONT INTO NRN INDIANA
TONIGHT AND TRACK A SFC LOW ALONG IT.  DIFFERENCES SHOW UP DURING DAY
AS AVN DROPS FRONT FARTHER SOUTH THAN ETA AND NGM...WITH NGM BEING
SLOWEST.  WITH ETA TRENDING SLOWER WITH FRONTAL MOVEMENT AND
WAVE OF LOW PRESSURE LIFTING UP...AM INCLINED TO GO WITH ETA
COMPROMISE SOLUTION.  WITH DEEP MOISTURE...PRECIPITABLE WATER VALUES
OF 1.75 INCHES AND GOOD UPWARD VERTICAL MOTION DUE TO PVA...LOW LEVEL
CONVERGENCE...JET HELP AND ISENTROPIC UPGLIDE...MODEL QPF AMOUNTS UP
TO 2 INCHES LOOK GOOD.  THESE VALUES ARE ABOVE HEADWATER GUIDANCE
VALUES IN SOME LOCATIONS AND NEAR FFG VALUES.  THUS...WILL ISSUE
FLOOD WATCH FOR TONIGHT AND SUN.  REGARDING SVR THREAT...WITH
INCREASING INSTABILITY OVERNIGHT AND STRONG UPWARD VERTICAL
MOTION...SOME POTENTIAL EXISTS FOR LARGE HAIL.  GIVEN UNCERTAINTY...
WILL NOT INCLUDE IN ZFP WORDING.  ANY SVR THREAT FOR SUN SHOULD BE
OVR FAR SOUTHERN COUNTIES AND POINTS SOUTH GIVEN FRONTAL POSITION.
WL BUMP UP POPS...ESPECIALLY SOUTHERN SECTIONS OF CWFA FOR SUNDAY
NIGHT GIVEN VICINITY OF FRONT AND SECOND WAVE OF LOW PRESSURE
RUNNING ALONG IT. WILL EVEN KEEP A LOW CHANCE POP FAR SOUTHERN
SECTIONS FOR MON.  TUE SHOULD BE DRY BUT COOL.

WITH LOW DEWPOINTS AND PRECIPITATION...TEMPS HAVE COOLED
SIGNIFICANTLY THIS AFTERNOON OVER PARTS OF FAR NORTHERN INDIANA AND
NORTHWEST OHIO...SO READINGS WILL START BELOW FWC LOWS...BUT THEN
RISE OVERNIGHT.  WILL STAY CLOSE TO COOLER FWC NUMBERS FOR SUNDAY AS
CLOUDY SKIES AND RAIN WILL OFFSET WARM 85H AND BLYR TEMPS.  A
COMPROMISE OF COOLER FWC AND WARMER MAV NUMBERS LOOKS GOOD FOR
SUNDAY NIGHT AND DEFINITELY PREFER COOLER FWC NUMBERS FOR MONDAY
GIVEN COLD AIR ADVECTION AND CLOUDINESS.

EXTENDED
AVN STILL TRYING TO RESOLVE THE POSTN AND STRENGTH OF TROF EXTENDING
INTO MONTANA THURS MORNING. OVERALL...AVN HAS SLOWED MOVEMENT OF
THIS SYSTEM FROM 00Z RUN...CHARACTERISTIC OF RUNS LAST FEW WEEKS.
ECMWF HINTING AT MORE OF A RIDGE OVER THE MIDWEST THURSDAY. THEREFORE
WILL REMOVE PCPN FROM THURS AS SFC FRONT SHOULD EXTEND FROM NW IA
INTO WRN UPPER MI AND AIRMASS OVER NRN INDIANA AND SURROUNDING AREAS
SHOULD BE RELATIVELY DRY. WILL KEEP CHC FOR STORMS FRIDAY AND
INTRODUCE STORMS SATURDAY AS FRONT SHOULD ADVANCE TOWARD THE AREA.

.IWX...FLOOD WATCH TONIGHT AND SUNDAY ENTIRE CWFA.

BARJENBRUCH/SKIP