Flooding in Indiana, April 5 to 30, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
730 AM EDT SUN APR 5 2009

.AVIATION DISCUSSION...FOR THE 12Z TAFS
MAIN PROBLEM FOR AVIATION WILL BE QUICKLY CHANGING WEATHER
CONDITIONS. ALL TAFS WILL START OUT VFR. A VERY STRONG LOW PRESSURE
WAS OVER NRN MO. A WARM FRONT EXTENDS INTO KY WITH A COLD FRONT INTO
AR. ALL COMPUTER MODELS ARE FAIRLY CONSISTANT WITH MOVING THE LOW
THROUGH INDIANA FROM 20Z-02Z. SHOWERS AND THUNDERSTORMS WILL DEVELOP
AHEAD OF THE LOW. CONDITIONS WILL QUICKLY DECREASE TO MVFR AS THE
LOW APPROACHES. SOME OF THE THUNDERSTORMS COULD BE SEVERE. THE MAIN
THREAT WILL BE SEVERE GUSTS AND HAIL. AFTER THE LOW MOVES THROUGH
MUCH COLDER AIR WILL BEGIN TO QUICKLY MOVE IN. THE AIR WILL REMAIN
MOIST AND UNSTABLE SO MVFR CONDITIONS WILL CONTINUE IN SHOWERS. AS
TEMPS CONTINUE TO DECREASE THE RAIN WILL MIX WITH SNOW AFTER 09Z.
THE PRESSURE GRADIENT WILL INCREASE AS THE LOW APPROACHES AND
ESPECIALLY AFTER FROPA. THIS WILL GIVE WIND GUSTS NEAR 30 KTS.

&&

.DISCUSSION...

FORECAST FOCUS ON SEVERE WEATHER THREAT THIS AFTERNOON.

THIS MORNINGS SURFACE MAP SHOWS HIGH PRESSURE REMAINING RIDGED
FROM THE LAKES REGION SOUTHEAST INTO THE MID ATLANTIC. A LOW
PRESSURE SYSTEM WAS CURRENTLY CENTERED IN NORTHEAST KS AND TRAILED
A COLD FRONT SOUTH THROUGH EASTERN OKLAHOMA INTO CENTRAL TEXAS.
ALOFT AT H5 THE GENERAL PATTERN WAS CHARACTERIZED BY RIDGING
ACROSS THE OHIO VALLEY AND LAKES REGION AND ALSO ACROSS THE WEST
COAST. THERE WAS A SIGNIFICANT TROUGH PRESENT OVER NEW ENGLAND AND
BROAD TROUGH ACROSS THE ROCKIES AND PLAINS STATES WITH A CUTOFF
LOW ACROSS EASTERN NEBRASKA.

MODELS ARE INITIALIZED WELL AND ARE FAIRLY SIMILAR...SO A BLEND
WAS ONCE AGAIN UTILIZED FOR POPS AND TEMPS.

TODAYS FORECAST WILL REVOLVE AROUND THE EASTWARD PROGRESSION OF A
CYCLONE CURRENTLY ACROSS THE PLAINS. WHAT IS CURRENTLY A WEAKENING
SURFACE LOW WILL STRENGTHEN THIS AFTERNOON AS A VORT MAX EJECTS
FROM THE SOUTHERN ROCKIES AND INTO AN H5 LOW ACROSS EASTERN
NEBRASKA. THE SURFACE LOW IS EXPECTED TO TRACK RIGHT ACROSS
CENTRAL INDIANA...WITH A WARM FRONT BOUNDARY EXTENDING AHEAD OF
IT...AND THIS WARM FRONT IS LOOKING TO SETTLE ACROSS THE I-70
CORRIDOR BY EARLY THIS AFTERNOON.

SWODY1 INDICATES A SLIGHT RISK OF SEVERE FOR THE SOUTHERN HALF OF
THE FA TODAY. PROBABILITIES OF SEVERE ARE QUITE HIGH AND AN
ANALYSIS OF THE SITUATION SUGGESTS THAT SEVERE WEATHER IS LIKELY
TODAY. INITIALLY THIS MORNING AND TOWARDS NOON THERE WILL BE A
STRONG CAPPING INVERSION PRESENT IN SOUTHERN INDIANA. A NAM
SOUNDING FROM THIS REGION SHOWS A WARM NOSE AT AROUND H9 THIS
MORNING BEING THE REASON FOR INHIBITION. THIS SHOULD BE OVERCOME
EASILY BY SURFACE HEATING AS THE WARM FRONT LIFTS NORTH.

STRONG DEEP LAYER LIFT WILL BE PROVIDED THIS AFTERNOON AS THE H5
TROUGH APPROACHES INDIANA. H5-H7 OMEGA SHOWS A CONCENTRATED STRONG
AREA OF LIFT. THERE WILL BE FAVORABLE JET LEVEL DYNAMIC WITH THE
AREA SITUATED IN THE LEFT EXIT REGION OF A 120KT JET STREAK
ROUNDING THE BASE OF THE H3 TROUGH OVER THE UPPER MIDWEST. STRONG
JET LEVEL DIVERGENCE ASSOCIATED WITH THIS FEATURE IS EVIDENT IN
THE MODEL FIELDS.

INSTABILITY WILL BE MODERATE THIS AFTERNOON IN AREAS SOUTH OF THE
WARM FRONT. SOME MORNING CLOUDINESS MAY INHIBIT WARMING EARLY BUT
FEEL THAT THERE WILL BE ENOUGH SUN ACTING ON THE +9C H8 AIRMASS TO
BOOST TEMPS IN THE LOW 70S SOUTH. NAM CAPES OF 500-1000 J/KG
ACROSS SOUTH CENTRAL INDIANA WILL BE PLENTY TO SUPPORT
THUNDERSTORMS.

SHEAR IS ALSO PRESENT IN LARGE QUANTITIES...WITH 0-6KM BULK SHEAR
VALUES OF 50-80KTS IN SOUTHERN INDIANA. LOW LEVEL SHEAR IS
ABUNDANT...ESPECIALLY IN THE VICINITY OF THE WARM FRONT WHICH
MIGHT SERVE AS A FOCUS FOR ENHANCED TORNADIC POTENTIAL. 0-6KM MEAN
WIND VECTORS SUGGEST VERY QUICK STORM MOTIONS OF 30-40KTS.

THIS LOOKS LIKE A RATHER TYPICAL EARLY APRIL SEVERE SCENARIO WITH
A MODERATE CAPE/HIGH SHEAR ENVIRONMENT AND A SURFACE WARM FRONT.
THE LIMITING FACTOR HERE APPEARS TO BE ABUNDANT DEEP MOISTURE.
THERE IS A DECENT SURFACE MOISTURE RETURN TO SOUTHERN INDIANA AND
DEWPOINTS SHOULD BREAK 50 IN THE SOUTHERN ZONES. BUT THE GULF WAS
JUST RECENTLY SCOURED OUT BY A COLD FRONT AND SO IT WILL NOT HAVE
TIME TO RECOVER TO BRING REAL DEEP MOISTURE INTO THE AREA.
STILL...WILL HIT THE PROBABILITY OF SEVERE WEATHER HARD IN THE HWO
MENTIONING A VARIETY OF THREATS. THE FAST STORM MOTIONS AND STRONG
H5-H7 WINDS WILL SUPPORT DAMAGING WINDS. COLD AIR ALOFT WILL
SUPPORT HAIL THREAT. AND ENHANCED LOW LEVEL SHEAR AND WARM
FRONTAL BOUNDARY WILL SUPPORT TORNADIC THREAT. FLASH FLOODING IS
NOT LIKELY TO BE MUCH OF AN ISSUE GIVEN QUICK STORM MOTION.

STORMS SHOULD IGNITE IN THE 18-21Z TIME FRAME. GREATEST THREAT OF
SEVERE WEATHER BEING SOUTH OF I-70 AND THE THREAT WILL INCREASE
CLOSER TO THE OHIO RIVER WHERE THINGS WILL BE MORE UNSTABLE WITH
HIGHER SURFACE MOISTURE. THE SYSTEM WILL MOVE EAST QUICKLY AND THE
SEVERE THREAT SHOULD DIMINISH BY 03Z.

FOLLOWING THE LOW PRESSURE WILL BE A SIGNIFICANT COLD AIR
OUTBREAK. THE H8 PATTERN SHOWS STRONG COLD ADVECTION WITH TEMPS
FALLING TO -4C BY MONDAY MORNING. STRONG COLD ADVECTION ALL DAY
WITH OVERCAST SKIES WILL LIMIT WARMING TO JUST A FEW DEGREES. SNOW
SHOWERS ARE EXPECTED ACROSS THE AREA ALL DAY MONDAY. LIGHT ACCUMS
WILL BE POSSIBLE IN THE NORTH ON GRASSY SURFACES.

OVERNIGHT MONDAY WILL BE THE THREAT OF A HARD FREEZE. ALL GUIDANCE
SUGGESTS MID 20S. SKIES WILL LIKELY REMAIN CLOUDY WITH SNOW
SHOWERS AND WIND WHICH MAY LIMIT THE OVERALL COOLING DESPITE H8
TEMPS NEAR -12C.

THERE WILL BE ONLY SMALL MODERATION ON TUESDAY AND TUESDAY NIGHT
AS THE H5 TROUGH WILL BE SLOW TO EXIT. THE KICKER WILL BE PUSHING
ASHORE IN CENTRAL CALIFORNIA BY WEDNESDAY MORNING AND THIS STORM
WILL EVENTUALLY IMPACT CENTRAL INDIANA BY LATE WEEK.

&&

.AVIATION...
DISCUSSION FOR THE 05/0600Z TAFS

VFR THRU NEARLY THE FIRST HALF OF THE PD. EXPECT MID CLOUDS TO
INCREASE OVERNIGHT. WOULD NOT BE SURPRISED TO SEE A FEW SHRA NEAR
LAF BY 12Z...BUT COVERAGE TOO LOW TO MENTION IN THE TAFS.

STRONG SFC LOW WILL MOVE INTO CENTRAL INDIANA BY 00Z. EXPECT CONDS
TO DETERIORATE TO MVFR IN SHRA STARTING IN THE W AFT 18Z AND THEN
SPREADING E DURING THE AFTN. THERE WILL BE AT LEAST SOME EMBEDDED
THUNDER...ESPECIALLY IND/HUF/BMG. ATTM APPEARS BMG HAS THE HIGHEST
CHANCE FOR SEEING THUNDER BASED ON CURRENT FORECAST TRACK OF SFC
LOW. AS LOW EXITS THE AREA AFT 00Z...CONDS WILL WORSEN WITH CIGS
BELOW BKN020 AND WINDS SHIFTING TO THE NW AND GUSTING NEAR 30KT.
WHILE TAFS SHOW SEVERAL HOURS OF SHRA...THERE WILL BE BREAKS IN THE
RAIN...ESPECIALLY AFT LOW MOVES OFF TO THE E.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

AVIATION...SH
PUBLIC...JOHNSON

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
422 AM EDT SUN APR 5 2009

INZ021-028>031-037>042-049-060830-
CARROLL-WARREN-TIPPECANOE-CLINTON-HOWARD-BOONE-TIPTON-HAMILTON-
MADISON-DELAWARE-RANDOLPH-HENRY-
422 AM EDT SUN APR 5 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL INDIANA.

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE EXPECTED AFTER NOON TODAY. SEVERE WEATHER IS
EXPECTED TO REMAIN PRIMARILY IN AREAS ALONG AND SOUTH OF A LINE
FROM CRAWFORDSVILLE TO GREENFIELD. BRIEF HEAVY DOWNPOURS AND
FREQUENT LIGHTING CAN BE EXPECTED TO ACCOMPANY ALL THUNDERSTORMS
TODAY.

MUCH COLDER AIR WILL ARRIVE LATE TONIGHT AND ALLOW SOME SNOW TO
MIX IN WITH RAIN SHOWERS TOWARDS MONDAY MORNING. NO ACCUMULATION
IS EXPECTED TONIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

A VERY COLD AIRMASS OVER CENTRAL INDIANA WILL ALLOW FOR SNOW
SHOWERS TO FALL ON MONDAY AND MONDAY NIGHT. LIGHT ACCUMULATIONS OF
SNOW ON GRASSY SURFACES ARE POSSIBLE IN NORTH CENTRAL INDIANA.
ACCUMULATIONS SHOULD REMAIN LESS THAN HALF AN INCH.

A HARD FREEZE IS LIKELY MONDAY AND TUESDAY NIGHTS WITH
TEMPERATURES FALLING INTO THE MID 20S. THESE TEMPERATURES WILL KILL
ANY TENDER VEGETATION OUTSIDE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

&&

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

INZ035-036-043>048-051>057-060>065-067>072-060830-
FOUNTAIN-MONTGOMERY-VERMILLION-PARKE-PUTNAM-HENDRICKS-MARION-
HANCOCK-VIGO-CLAY-OWEN-MORGAN-JOHNSON-SHELBY-RUSH-SULLIVAN-GREENE-
MONROE-BROWN-BARTHOLOMEW-DECATUR-KNOX-DAVIESS-MARTIN-LAWRENCE-
JACKSON-JENNINGS-
422 AM EDT SUN APR 5 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL INDIANA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY ALONG AND
SOUTH OF A LINE FROM CRAWFORDSVILLE TO GREENFIELD. THE GREATEST
PROBABILITY OF SEVERE WEATHER WILL BE SOUTH OF INTERSTATE 70.

STORMS WILL DEVELOP AROUND 1 PM ACROSS WEST CENTRAL AND SOUTHWEST
INDIANA AND SPREAD TO THE NORTH AND EAST THROUGH THE AFTERNOON AS
A WARM FRONT LIFTS INTO CENTRAL INDIANA. PRIMARY THREATS FROM
SEVERE THUNDERSTORMS TODAY WILL BE DAMAGING WINDS...LARGE
HAIL...AND ISOLATED TORNADOES. BRIEF HEAVY DOWNPOURS AND FREQUENT
CLOUD TO GROUND LIGHTNING WILL ACCOMPANY ALL THUNDERSTORMS. THE
RISK OF SEVERE WEATHER WILL END AFTER 8 PM TONIGHT.

MUCH COLDER AIR WILL ARRIVE LATE TONIGHT AND ALLOW SOME SNOW TO
MIX IN WITH RAIN SHOWERS TOWARDS MONDAY MORNING. NO ACCUMULATION
IS EXPECTED TONIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

A VERY COLD AIRMASS OVER CENTRAL INDIANA WILL ALLOW FOR SNOW
SHOWERS TO FALL ON MONDAY AND MONDAY NIGHT. A SLUSHY DUSTING MAY
BE POSSIBLE ON GRASSY SURFACES.

A HARD FREEZE IS LIKELY MONDAY AND TUESDAY NIGHTS WITH
TEMPERATURES FALLING INTO THE MID 20S. THESE TEMPERATURES WILL KILL
ANY TENDER VEGETATION OUTSIDE.

THERE WILL BE A CHANCE OF THUNDERSTORMS IN SOUTH CENTRAL INDIANA
THURSDAY NIGHT AND FRIDAY. CLOUD TO GROUND LIGHTNING WILL BE THE
PRIMARY HAZARD.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY AFTER 1 PM THIS AFTERNOON.

&&

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

JOHNSON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
853 AM EDT SUN APR 5 2009

INZ028-029-035-043-051330-
FOUNTAIN-TIPPECANOE-VERMILLION-WARREN-
853 AM EDT SUN APR 5 2009

A STRONG THUNDERSTORM CAPABLE OF PRODUCING MARBLE SIZE HAIL WILL
MOVE THROUGH THE TOWNS OF GESSIE...PERRYSVILLE...AND COVINGTON
THROUGH 930 AM. RAINFALL AMOUNTS FROM THIS STORM MAY BE UP TO A
QUARTER INCH. THE STORM SHOULD WEAKEN AS IT MOVES TO THE NORTHEAST
AT 40 MPH.

CP