000
FXUS63 KIWX 152344
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
744 PM EDT SAT JUN 15 2013

.SYNOPSIS...
ISSUED AT 417 PM EDT SAT JUN 15 2013

A SLOWLY APPROACHING LOW PRESSURE SYSTEM WILL BRING SHOWERS ALONG
WITH A FEW THUNDERSTORMS THROUGH THE REGION TONIGHT AND INTO
SUNDAY MORNING. LOW TEMPERATURES TONIGHT WILL ONLY FALL INTO THE
MID TO UPPER 60S. HIGHS ON SUNDAY ARE EXPECTED TO RISE INTO THE
UPPER 70S.

&&

.UPDATE...
ISSUED AT 740 PM EDT SAT JUN 15 2013

SHRTWV MOVG INTO MO/IA RESULTING IN SHOWERS/TSTMS OVER THE MID MS
VALLEY. DVLPG WSW LLJ IN ADVANCE OF THIS SHRTWV TONIGHT SHOULD
DESTABILIZE AIRMASS SUFFICIENTLY ACROSS OUR AREA TO SUSTAIN THIS
CONVECTION AS THE SHRTWV MOVES EAST OVERNIGHT. THUS WILL INCREASE
POPS INTO LIKELY RANGE ACROSS THE ENTIRE AREA FOR LATE TONIGHT.
NO OTHER CHANGES PLANNED ATTM.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 431 PM EDT SAT JUN 15 2013

MESO-VORT OVER NORTHWEST INDIANA CONTINUES TO SHIFT EAST. ISOLD
SHOWERS ASSOCIATED WITH THE SYSTEM HAVE BEEN ABLE TO PRODUCE
UPWARDS OF A TENTH OF AN INCH OF RAINFALL...BUT MOST LOCATIONS
HAVE SEEN MUCH LESS. HAVE KEPT POP/WX IN THE FORECAST THROUGH THE
NIGHT AS THE SYSTEM CONTINUES EASTWARD.

IN THE WAKE OF THE MCV...MESO HIGH COVERS MUCH OF NORTHERN IL/SRN
WI. BOUNDARY LAYER MOISTURE GRADIENT IS PRONOUNCED ON THE SOUTHERN
EDGE OF THE HIGH. SHORTWAVE INDUCED CONVECTION OVER IOWA HAS BECOME
MORE ORGANIZED OVER THE PAST FEW HOURS. POSITION AND INTENSIFICATION
IS CAPTURED WELL BY THE LATEST SHORT RANGE MODEL RUNS. JET STREAK
OVER THE MN IS LIFTING RAPIDLY NORTH AND SECOND JET STREAK HAS
DEVELOPED OVER NV/UT/WY SHOULD BE ENOUGH TO STRENGTHEN THE RIDGE ON
THE LEE SIDE OF THE ROCKIES DURING THE OVERNIGHT. THIS RIDGING AND
JET STREAK ARE EXPECTED TO KEEP THE IOWA CONVECTION ADVANCING
EASTWARD DURING THE EVENING...THEN TURN SHARPLY SOUTHWARD ALONG THE
MOISTURE AXIS INTO CENTRAL INDIANA OVERNIGHT INTO SUNDAY MORNING.

HAVE REDUCED POP/QPF OVER THE AREA AS THE STABLE AIRMASS WILL KEEP
MOST CONVECTION NORTH AND SOUTH OF THE AREA DURING THE OVERNIGHT.
NOT DISMISSING THE CHANCE OF PRECIPIATION...HOWEVER IT DOES APPEAR
THAT THE BEST CHANCE/HEAVIEST RAINFALL WILL BE OVER MI/WI AND INTO
CENTRAL IL/IN OVERNIGHT INTO SUNDAY MORNING.

TEMPERATURES HAVE BEEN CUT A BIT ON SUNDAY TO REFLECT THE CLOUD
COVER AND COOLER/STABLE AIRMASS OVER THE REGION. GENERALLY JUST CUT
TEMPS A COUPLE DEGREES.

&&

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 431 PM EDT SAT JUN 15 2013

THE MAIN CHALLENGES THIS PERIOD INCLUDE TIMING AND TRACK OF WEAK
SHORT WAVES IN NW FLOW EARLY THIS PERIOD. TRIED TO STAY CLOSE TO
FCST PERSISTENCE EARLY THIS WEEK AS UPPER LEVEL TROFS DROP
SOUTHEAST OUT OF CANADA INTO THE LONGWAVE PATTERN TOWARD THE
WESTERN GREAT LAKES REGION. NCEP AND OTHER MODELS SHOWING A VERY
LARGE VARIETY IN HANDLING THESE WEAK SYSTEMS. UPPER LEVEL FORCING
SHOULD REMAIN WEAK AND MOISTURE WILL STAY LIMITED. OVERALL
RAINFALL AMOUNTS SHOULD REMAIN LIGHT. THE ECMWF AND GFS WERE
GENERATING WAY TOO MUCH RAINFALL WITH THE INITIAL SYSTEM
TODAY...CAUSING CONFIDENCE TO BE LOW IN THE HANDLING OF SUBSEQUENT
SHORT WAVES. OTHERWISE...AN UPPER LEVEL RIDGE SHOULD GRADUALLY
BUILD INTO THE OHIO VALLY REGION AS MORE SHORT WAVE TROFS HAVE THE
POTENTIAL TO TOP THE RIDGE AND MOVE INTO THE AREA. FOR NOW...KEPT
THE REST OF THE FORECAST AFTER MONDAY NIGHT DRY THROUGH FRIDAY
NIGHT DUE TO VERY LOW CONFIDENCE LATE IN THE PERIOD. THE GFS AND
CANADIAN GEM SUPPORT HIGHS MUCH ABOVE NORMAL BY LATE IN THE PERIOD
AS 850 MB TEMPS TOP 20C. HIGHS SATURDAY OVER SOUTHERN AREAS SHOULD
BE NEAR 90 DEGREES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 722 PM EDT SAT JUN 15 2013

SHRTWV OVER WRN IA/MO EXPECTED TO MOVE EAST ACROSS NRN IL/IN
OVERNIGHT. SHRA AND TS AHEAD OF THIS SYSTEM WILL LIKELY PERSIST
AS IT MOVES EAST ACROSS OUR AREA OVERNIGHT... THOUGH COVERAGE MAY
DIMINISH SOME AS INSTABILITY WILL BE LOWER ACROSS OUR AREA THAN IT
WAS UPSTREAM THIS AFTN/EVE. CONTD WITH A PERIOD OF VCTS OVERNIGHT AT
BOTH TERMINALS AND ADDED PREDOMINATE SHRA AS SYSTEM MOVES THROUGH.
SOME MVFR CONDITIONS PSBL TOWARD DAWN AS LOWER LEVELS SATURATE...
THEN SUBSIDENCE AND DIURNAL HEATING/MIXING SHOULD RESULT IN VFR
CONDITIONS BY LATE MORNING CONTG THROUGH THE AFTN WITH WESTERLY
WINDS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

UPDATE...JT
SYNOPSIS...KG
SHORT TERM...LEWIS
LONG TERM...SKIPPER
AVIATION...JT


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