Severe Thunderstorm Warning 73, NWS Northern Indiana

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
547 PM EST SAT MAY 10 2003

00Z TAF DISCUSSION...
AREA OF MVFR CLOUDS SEEN MOVING NORTH ON VSBY SATELLITE OUT OF
CENTRAL INDIANA WILL GIVE FWA 025-030 CIGS EARLY...THEN WILL SCATTER
OUT IN TAF AS THE SUN SETS. STORMS MOVE IN FROM THE WEST WITH
APPROACHING COLD FRONT 04Z-08Z. BEHIND THE FRONT WINDS KICK UP AND
MVFR CIGS MOVE IN AS LOW DEEPENS RAPIDLY TO OUR NORTHWEST.  SBN
CLOSE ENOUGH TO THE LOW AND ITS ATTENDANT DEEPER MOISTURE THAT IT
MAY SEE SOME LIGHT RAIN AND LOWER CIGS SUNDAY AFTERNOON.

12

330PM PUBLIC DISCUSSION...
OBVIOUS FORECAST CHALLENGE IS WITH SEVERE POTENTIAL LATE THIS
AFTERNOON AND OVERNIGHT. LARGE MCS HAS SPREAD RAINS ACROSS SOUTHERN
HALF OF CWA THIS MORNING AND EARLY AFTERNOON. BASED ON OBSERVER
REPORTS...RADAR APPEARS TO BE OVERESTIMATING RAIN IN OUR SOUTH BY AT
LEAST A HALF INCH. THIS RAIN IS ENDING AND SATELLITE SHOWS CLEARING
SKIES ACROSS IL AND WESTERN INDIANA. THIS WILL ALLOW DESTABILIZATION
OF ATMOSPHERE AHEAD OF EXPECTED STRONG SQUALL LINE OVERNIGHT.
SUBSIDENCE BEHIND MCS KEEPING SKIES CLEAR AND SUPRESSING
THUNDERSTORM DEVELOPMENT FOR NOW. HOWEVER...AS INSTABILITY INCREASES
AND INTERACTS WITH NUMEROUS BOUNDARIES ACROSS AREA...THUNDERSTORM
DEVELOPMENT WITH SEVERE STORMS POSSIBLE LATE AFTERNOON INTO EVENING.
UPPER SYSTEM KICKS OUT OF WESTERN US AND MOVES INTO MIDWEST TONIGHT.
RAPID DEEPENING OF SFC LOW TAKES PLACE AS IT MOVES INTO WI. SEE SPC
OUTLOOKS FOR DETAILS...BUT VERY INTENSE SQUALL LINE EXPECTED AHEAD
OF FRONT OVERNIGHT. IMPRESSIVE WIND FIELD AND INSTABILITY WILL LEAD
TO DAMAGING WINDS WITH THIS LINE. LATEST ETA ALSO SHOWING DECENT
HELICITY IN LOWER LAYERS AS SFC WINDS REMAIN SOUTHERLY. SFC WINDS
THIS AFTERNOON HAVE RECOVERED TO SOUTHEAST...MORE THAN ETA
INDICATES. THIS ENHANCED HELICITY INCREASE POTENTIAL FOR TORNADOES
WITH SUPERCELLS AHEAD OF MAIN LINE. THIS WILL BE A DANGEROUS
SITUATION AND ALL SHOULD BE ALERT THROUGH THE NIGHT.

NEXT PROBLEM WILL BE SUNDAY AS VERY STRONG WINDS ALOFT MOVE IN WITH
COLD AIR ADVECTION. ETA BUFKIT SHOWING MOMENTUM XFER WINDS OF ALMOST
60KTS FROM 5700 FT LATE AFTERNOON. HOWEVER...CLOUDS EXPECTED TO MOVE
BACK INTO AREA IN AFTERNOON AND THIS SHOULD SLOW MIXING IN
AFTERNOON. STILL...SFC WIND GUSTS TO 40 OR 45 MPH WILL BE POSSIBLE
IN NORTH. WITH CURRENT HEADLINES OF FLOOD WATCH AND GOOD POSSIBILITY
OF CONVECTIVE WATCHES TONIGHT...DO NOT WANT TO COMPLICATE FORECAST
AND CONFUSE PEOPLE WITH ISSUE OF HIGH WIND WATCH FOR AN ADVISORY
SITUATION. WILL STRONGLY WORD FORECAST FOR VERY WINDY AND HIGH GUSTS
AND FIRST PERIOD ADVISORY CAN BE ISSUED IF IT IS WARRANTED WITH
EARLY MORNING PACKAGE.

TEMPERATURES SHOULD BE SHARPLY COOLER ON SUNDAY BEHIND FROPA.
MORNING HIGHS LIKELY...ESPECIALLY EAST. COULD BE SOME RECOVERY MID
DAY WITH SOME SUN IN DRY SLOT BUT STILL QUITE COOL. MOS HAS BEEN
TRENDING COOLER AND WILL SIDE TOWARD COOLER NUMBERS WEST BUT BE
CAUTIOUS OF EARLY HIGHS IN EAST. WL CONTINUE CHC SHOWERS INTO
MONDAY. BEST CHANCES WILL BE NORTH AND EAST.

THOUGH 00Z/10 RUN OF GFS AND GEM INDICATE SFC LO AND 5H TROF TO
ACROSS THE CWFA ON WEDNESDAY...12Z/10 RUN OF AVN/GFS SHOWING RIDGING
AT THE SURFACE AND ALOFT. THURSDAY THROUGH SATURDAY 00Z/10 GFS
SHOWING CLOSED 5H LOW DIGGING INTO THE MID-MS VLY AND TN VLY...INTO
SE US...AND THEN SWINGS IT BACK NW INTO OHIO...ALONG WITH SURFACE
REFLECTION. GEM SHOWS MID LEVEL ZONAL TO SLIGHTLY RIDGING FLOW FOR
THE SAME TIME PERIOD. DUE TO SUCH DISARRAY...WILL NOT MAKE ANY
SIGNIFICANT CHANGES TO THE EXTENDED.

.IWX...
IN...FLOOD WATCH FOR TONIGHT FOR ZONES INZ003>009...INZ012>018...
INZ020...INZ022>027...INZ032>034.

MI...FLOOD WATCH FOR TONIGHT FOR ZONES MIZ077>081.

OH...FLOOD WATCH FOR TONIGHT FOR ZONES OHZ001>002...OHZ004>005...
OHZ015>016...OHZ024>025.

LASHLEY/12

INZ003>009-012>018-020-022>027-032>034-MIZ077>081-OHZ001-002-004-005-
015-016-024-025-111000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORTHERN INDIANA
700 PM EST SAT MAY 10 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN INDIANA...NORTHWEST
OHIO AND SOUTHWEST LOWER MICHIGAN.

.DAY ONE...TONIGHT
SEVERE THUNDERSTORMS ARE LIKELY TONIGHT. SEVERE THUNDERSTORMS WILL
MOVE INTO NORTH CENTRAL INDIANA AND SOUTHWEST MICHIGAN BETWEEN 10 PM
AND MIDNIGHT EST. THE STORMS WILL MOVE EAST INTO NORTHWEST OHIO
DURING THE EARLY MORNING HOURS...MOST LIKELY BETWEEN 1 AM AND 4 AM
EDT.  DAMAGING WIND GUSTS TO 80 MPH IN THE STRONGEST STORMS ARE THE
MOST LIKELY HAZARD. ISOLATED TORNADOES AND LARGE HAIL TO TWO INCHES
IN DIAMETER ARE ALSO POSSIBLE.

IN ADDITION...HEAVY RAINFALL FROM THESE THUNDERSTORMS...COMBINED
WITH SATURATED SOIL CONDITIONS AND SWOLLEN RIVER AND STREAM
LEVELS...MAY RESULT IN FLASH FLOODING IN SOME SPOTS IN THE
OVERNIGHT.

THE STORMS ARE AHEAD OF A COLD FRONT OVER THE MISSISSIPPI VALLEY
THAT WILL PUSH EAST INTO WESTERN OHIO BY DAYBREAK SUNDAY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
BEHIND THE COLD FRONT ON SUNDAY...STRONG SOUTHWEST WINDS ARE
EXPECTED TO DEVELOP OVER THE AREA. WIND GUSTS COULD REACH 45 MPH ON
SUNDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NEEDED TONIGHT.

STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES, OR
CHECK OUR WEB SITE AT WWW.CRH.NOAA.GOV/IWX