Severe Thunderstorm Warning 11, NWS Northern Indiana

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
655 AM EDT THU APR 18 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM EDT THU APR 18 2013

THE MAIN FOCUS IS ON SEVERE WX AND HEAVY RAIN POTENTIAL MAINLY
THIS AFTERNOON AND EVENING...

SYNOPTICALLY...08Z SFC ANALYSIS REVEALS A WARM FRONT DRAPED ACROSS
CENTRAL IN/IL BACK TO A DEVELOPING SFC LOW OVER CENTRAL MO...WITH A
COLD FRONT EXTENDING SOUTH INTO THE SOUTHERN PLAINS. THE SFC
REFLECTION WILL DEEPEN AS IT TRANSLATES NE TOWARD THE IL/IA BORDER
AND EVENTUALLY SOUTHERN WI. THIS WILL OCCUR AS AN INTENSE PV
ANOMALY IN BASE OF DEEP UPPER TROUGH JUST ENTERING THE CENTRAL
HIGH PLAINS LIFTS NORTHEAST INTO THE UPPER MIDWEST BY
TONIGHT...WITH A ROBUST 100-110 KNOT MID LEVEL JET MAX ROUNDING
THE BASE OF TROUGH INTO THE MID MISSISSIPPI VALLEY. ASSOCIATED
~180 METER CENTRAL CONUS MID LEVEL HEIGHT FALLS WILL ALLOW A 60-70
KNOT LOW LEVEL JET TO TAKE SHAPE TODAY FROM AR AND EASTERN MO
NORTHEAST INTO IL/NW INDIANA/MI. THIS JET WILL CARRY AN ABUNDANCE
OF MOISTURE WITH IT AND HELP FINALLY MIX THE WARM FRONT NORTH
THROUGH AT LEAST SOUTHERN/EASTERN ZONES BY 12-13Z.

ELEVATED SHOWERS/STORMS WITH LOCALLY HEAVY RAINFALL IN AREA OF MOIST
ISENTROPIC ASCENT NORTH OF THE FRONT WILL CONTINUE TO CLIP OUR FAR
NORTHWEST INDIANA AND SW LOWER MI ZONES THROUGH THE MORNING HOURS
WITH LIKELY POPS RETAINED HERE. THIS WILL LIMIT DIURNAL HEATING
AHEAD OF PRIMARY PRE-FRONTAL BOUNDARY THIS MORNING. SOUTHERN AND
EASTERN PORTIONS OF THE FORECAST AREA ARE NOW FORECAST TO BECOME
FIRMLY ENTRENCHED IN THE WARM SECTOR THIS MORNING WITH DRY/WINDY
CONDITIONS EXPECTED SHORTLY AFTER DAYBREAK. WIND GUSTS FOR A TIME
MAY APPROACH 45-50 MPH IN WARM SECTOR.

RICH BOUNDARY LAYER MOISTURE FOR MID APRIL (LOW TO MID 60S
DEWPOINTS) IN ADVANCING WARM SECTOR UNDER REMNANT EML AND DEEP
LAYERED 40-50 KNOT SHEAR SUGGEST A FAVORABLE ENVIRONMENT FOR SEVERE
THUNDERSTORMS BY THIS AFTERNOON/EVENING. THE INITIAL FOCUS FOR
CONVECTION WILL LIKELY BE A PRE-FRONTAL CONVECTIVE OUTFLOW
BOUNDARY THAT LATEST HI-RES GUIDANCE FORCES INTO OUR FAR WESTERN
ZONES BTW 15-17Z AND CENTRAL PORTIONS OF THE FA BTW 17-20Z. SPC
DOWNGRADED OUR FAR NORTHWEST (BENTON HARBOR/LA PORTE) DOWN TO A
SLIGHT RISK FOR SEVERE GIVEN THE EARLIER TIMING AND LACK OF
DIURNAL TEMP RECOVERY / BOUNDARY LAYER DESTABILIZATION. MODERATE
RISK WAS SHIFTED FARTHER EAST AND NOW ENCOMPASSES THE REST OF OUR
INDIANA AND MICHIGAN COUNTIES. ENOUGH INSOLATION/SFC HEATING INTO
THE 75-82F RANGE HERE SHOULD YIELD MLCAPE VALUES INTO THE
1000-1500 J/KG RANGE WITH LITTLE CONVECTIVE INHIBITION BY THIS
AFTERNOON.

AS FOR CONVECTIVE MODE/EVOLUTION/THREATS...QLCS DEVELOPMENT IS FAVORED
OVER DISCRETE SUPERCELLS AS LOW/MID LEVEL FLOW REMAINS NEARLY
PARALLEL TO THE LOW LEVEL CONVERGENT BOUNDARY RESULTING IN LESS
HODOGRAPH CURVATURE. THE MAIN THREAT IN THIS SETUP IS DAMAGING
WINDS...ALTHOUGH PROGGED 0-1 KM SHEAR IN EXCESS OF 30 KNOTS DOES
HINT AT THE POTENTIAL FOR MESOVORT TORNADO SPINUPS IN ANY BOWING
SEGMENTS.

THE OTHER THREAT IS HEAVY RAIN/FLOODING...MAINLY OVER NORTHWESTERN
PORTIONS OF THE FORECAST AREA AS PIVOT OF STRONGLY FORCED FRONT
THROUGH OUR OHIO ZONES WILL BE MORE TRANSITORY IN NATURE TONIGHT.
PWATS IN EXCESS OF 1.5" (99TH PERCENTILE), CONVECTIVE ELEMENT, AND
SATURATED SOILS WITH 1-3" (LOCALIZED 3-4" IN THE NW) OF ADDITIONAL
RAIN ANTICIPATED WARRANT CONTINUING THE AREA FLOOD WATCH THIS
AFTERNOON INTO TONIGHT.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 352 AM EDT THU APR 18 2013

STRONG CDFNT SHOULD BE EAST OF OUR CWA BY 12Z FRIDAY. SOME LINGERING
POST FRONTAL SHOWERS LIKELY OVER ERN PORTIONS OF THE AREA FRI
MORNING. BRIEF CLEARING PSBL BEHIND THE FRONT BEFORE WRAP AROUND
MOISTURE AND MID LEVEL TROF MOVES IN BY MIDDAY BRINGING CLOUDY SKIES
AND SCT SHOWERS BACK INTO THE AREA. STEEP LOW LEVEL LAPSE RATES
WILL EFFICIENTLY MIX DOWN STRONG WINDS ALOFT RESULTING IN ANOTHER
VERY WINDY DAY. A FEW SHOWERS MAY LINGER INTO FRI EVE WHEN BOUNDARY
LAYER SHOULD COOL SUFFICIENTLY TO ALLOW ANY PRECIP REACHING THE
GROUND TO BE SNOW.

HIGH PRESSURE EXPECTED TO MOVE ACROSS THE GRTLKS OVER THE WEEKEND
PROVIDING DRY WX AND COOL TEMPS. LATEST MEDIUM RANGE MODELS CONT TO
SUGGEST THAT ANOTHER RATHER STRONG LOW PRESSURE SYSTEM WILL DEVELOP
OVER THE SRN PLAINS AND TRACK NE INTO THE GRTLKS TUE OR WED.
CONSIDERABLE TIMING DIFFERENCES REMAIN SO LITTLE CHANGE TO PREVIOUS
FCST OF A CHC OF SHOWERS AND TSTMS EARLY NEXT WEEK... WITH TEMPS
NEAR NORMAL MON-TUE... TURNING COOLER BY WED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 652 AM EDT THU APR 18 2013

WARM FRONT WAS LIFTING NORTH THROUGH NRN INDIANA EARLY
THIS MORNING WITH SHRA/TS IN AREA OF ISENT LIFT NORTH OF THE FRONT
OVER SRN-CENTRAL MI AND VFR CONDITIONS ACROSS NRN INDIANA. KIWX VWP
SHOWING VERY STRONG WINDS ALOFT... OVER 50KT AT 2KFT. WITH DIURNAL
HEATING TODAY... STRONG WINDS IN THE WARM SECTOR SHOULD MIX TO
THE SFC WITH GUSTS OF 30-35KT EXPECTED BY MIDDAY... STRONGEST AT
FWA. TS ARE EXPECTED TO MOVE EAST FROM IL AHEAD OF THE CDFNT AND
IMPACT THE TERMINALS THIS AFTN/EVE. SEVERE WINDS AND HAIL ARE PSBL
WITH THESE STORMS BUT HELD OFF ADDING THIS TO TAFS UNTIL BETTER
CONFIDENCE IN TIMING/OCCURRENCE IS EVIDENT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH FROM 2 PM EDT /1 PM CDT/ THIS AFTERNOON THROUGH
     FRIDAY MORNING FOR INZ003>009-012>018-020-022>027-032>034.

     WIND ADVISORY FROM 11 AM EDT /10 AM CDT/ THIS MORNING TO 8 PM
     EDT /7 PM CDT/ THIS EVENING FOR INZ003-012>018-020-022>027-
     032>034.

MI...FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH FRIDAY MORNING
     FOR MIZ077>081.

OH...FLOOD WATCH FROM 5 PM EDT THIS AFTERNOON THROUGH FRIDAY MORNING
     FOR OHZ002-004-005-015-016-024-025.

     FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH FRIDAY MORNING
     FOR OHZ001.

LM...GALE WARNING UNTIL 2 AM EDT SATURDAY FOR LMZ043-046.

&&

SHORT TERM...STEINWEDEL
LONG TERM...JT
AVIATION...JT

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1007 AM EDT THU APR 18 2013

INZ003>009-012>018-020-022>027-032>034-MIZ077>081-OHZ001-002-004-005-
015-016-024-025-191415-
LA PORTE-ST. JOSEPH IN-ELKHART-LAGRANGE-STEUBEN-NOBLE-DE KALB-STARKE-
PULASKI-MARSHALL-FULTON IN-KOSCIUSKO-WHITLEY-ALLEN IN-WHITE-CASS IN-
MIAMI-WABASH-HUNTINGTON-WELLS-ADAMS-GRANT-BLACKFORD-JAY-BERRIEN-
CASS MI-ST. JOSEPH MI-BRANCH-HILLSDALE-WILLIAMS-FULTON OH-DEFIANCE-
HENRY-PAULDING-PUTNAM-VAN WERT-ALLEN OH-
INCLUDING THE CITIES OF...MICHIGAN CITY...LA PORTE...SOUTH BEND...
MISHAWAKA...ELKHART...GOSHEN...LAGRANGE...TOPEKA...ANGOLA...
KENDALLVILLE...LIGONIER...AUBURN...GARRETT...KNOX...NORTH JUDSON...
WINAMAC...FRANCESVILLE...PLYMOUTH...BREMEN...ROCHESTER...WARSAW...
WINONA LAKE...COLUMBIA CITY...SOUTH WHITLEY...FORT WAYNE...
MONTICELLO...BROOKSTON...LOGANSPORT...PERU...WABASH...
NORTH MANCHESTER...HUNTINGTON...BLUFFTON...OSSIAN...DECATUR...
BERNE...MARION...HARTFORD CITY...MONTPELIER...PORTLAND...NILES...
BENTON HARBOR...ST. JOSEPH...BUCHANAN...DOWAGIAC...CASSOPOLIS...
STURGIS...THREE RIVERS...COLDWATER...HILLSDALE...BRYAN...WAUSEON...
ARCHBOLD...DEFIANCE...NAPOLEON...PAULDING...ANTWERP...OTTAWA...
PANDORA...VAN WERT...DELPHOS...LIMA
1007 AM EDT THU APR 18 2013 /907 AM CDT THU APR 18 2013/

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS MOST OF
THE AREA TODAY AND TONIGHT. THE MOST LIKELY TIMEFRAME FOR SEVERE
THUNDERSTORMS IS LATE THIS MORNING THROUGH THIS EVENING. A LINE OF
THUNDERSTORMS WILL MOVE INTO NORTHWEST AND NORTH CENTRAL INDIANA
ALONG WITH SOUTHWEST LOWER MICHIGAN THROUGH LATE MORNING. THIS
LINE OF THUNDERSTORMS IS EXPECTED TO INTENSIFY AS IT TRACKS
EASTWARD THROUGH THIS AFTERNOON...REACHING NORTHWEST OHIO DURING
THE MID TO LATE AFTERNOON HOURS. IN ADDITION TO THE RISK OF LARGE
HAIL AND DAMAGING WINDS...ISOLATED TORNADOES MAY ALSO OCCUR.

A FLOOD WATCH IS ALSO IN EFFECT TODAY AND TONIGHT.

A WIND ADVISORY IS IN EFFECT ALONG AND SOUTH OF ROUTE 30 IN
NORTHERN INDIANA TODAY.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

VERY WINDY CONDITIONS ARE EXPECTED AGAIN FRIDAY.

THERE IS A CHANCE OF THUNDERSTORMS AGAIN ON TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION FOR SEVERE THUNDERSTORMS WILL BE NEEDED FROM
LATE THIS MORNING THROUGH THIS EVENING. SPOTTER REPORTS OF ANY
FLOODING TODAY AND TONIGHT WILL ALSO BE APPRECIATED.

&&

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

LMZ043-046-191415-
NEW BUFFALO MI TO ST JOSEPH MI-MICHIGAN CITY IN TO NEW BUFFALO MI-
1007 AM EDT THU APR 18 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NEARSHORE WATERS OF
SOUTHEASTERN LAKE MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A GALE WARNING IS IN EFFECT. THUNDERSTORMS ARE ALSO EXPECTED...
SOME MAY BE SEVERE FROM THIS MORNING THROUGH EARLY THIS EVENING
WITH LARGE HAIL...AND WIND GUSTS IN EXCESS OF 50 KNOTS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A GALE WARNING IS IN EFFECT THROUGH LATE FRIDAY NIGHT. A SMALL
CRAFT ADVISORY MAY BE NEEDED FOR SATURDAY MORNING.

THUNDERSTORMS ARE POSSIBLE TUESDAY.

&&

STAY TUNED TO NOAA WEATHER RADIO FOR FURTHER DETAILS OR UPDATES...OR
CHECK OUR WEB SITE AT WEATHER.GOV/IWX/?N=MARINE