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000
FXUS63 KIWX 161830
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
230 PM EDT THU MAY 16 2013

.SYNOPSIS...
ISSUED AT 1031 AM EDT THU MAY 16 2013

A FEW LIGHT SHOWERS OR ISOLATED THUNDERSTORMS COULD SKIM THE FAR
SOUTHWEST PORTION OF THE AREA THIS AFTERNOON. OTHERWISE, MOSTLY
DRY CONDITIONS ARE EXPECTED TODAY INTO FRIDAY MORNING, AS HIGH
PRESSURE BUILDS INTO THE GREAT LAKES FORCING A FRONTAL BOUNDARY
SOUTH INTO CENTRAL INDIANA. THIS FRONT IS EXPECTED TO BUCKLE BACK
NORTH LATER FRIDAY INTO THE WEEKEND WITH A LOW CHANCE FOR SHOWERS
AND THUNDERSTORMS MAINLY SOUTH OF ROUTE 30 IN INDIANA AND MICHIGAN
EACH DAY. ABOVE NORMAL TEMPERATURES ARE EXPECTED LATE THIS WEEK
INTO THIS WEEKEND. CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE
EARLY NEXT WEEK AS A STORM SYSTEM APPROACHES FROM THE WEST.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
HIGH PRESSURE HAS KEPT BULK OF MSTR JUST FAR ENOUGH SOUTH OF THE
AREA TODAY TO ALLOW FOR GENERALLY DRY CONDITIONS AND TEMPS MOVING
WELL THROUGH THE 70S IN MOST SPOTS. A FEW LIGHT SHOWERS/SPRINKLES
WERE NOTED ALONG FIRST OF 2 SFC THETA E GRADIENTS ACROSS FAR
SOUTHERN COUNTIES. THIS AREA IS EXPECTED TO SHIFT SOUTH OVER THE
NEXT SEVERAL HOURS AND REMOVE ANY CHANCE FOR PRECIP FOR THE
REMAINDER OF THE NIGHT. SECONDARY GRADIENT WAS LOCATED FURTHER
SOUTH ACROSS SOUTHERN INDIANA WHERE CONVECTION HAS BEEN ONGOING
MUCH OF THE DAY. MODELS TEND TO SUGGEST THAT THIS SECONDARY AREA
OF MSTR/GREATER LIFT SUPPORT WITH MAIN SFC BOUNDARY WILL BRING
INCREASING CHANCES FOR SHOWERS AND STORMS ON FRIDAY. IT WOULD
APPEAR THAT MOST FAVORABLE TIMING WOULD BE MID TO LATE AFTERNOON
FRIDAY IN FAR SW SECTIONS WITH PROGRESSION NE HAMPERED SOMEWHAT BY
DRY AIR/SEMI DRY GROUND CONDITIONS. IF NEW RUN OF SPC 4KM WRF IS
FOLLOWED...CONVECTION WOULD NOT ARRIVE UNTIL AFTER 00Z SAT. HAVE
ADJUSTED GRIDS TO REFLECT THIS WITH SLGT CHC TO CHC POPS CONFINED
TO AFTERNOON.

CLOUD COVER WILL BE ON THE INCREASE...WHICH WILL BUT A DAMPER ON
POTENTIAL CLIMB IN HIGHS. THAT BEING SAID...HIGHS SHOULD STILL END
UP ABOVE NORMAL CLIMBING INTO THE MID AND UPPER 70S.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
WATER VAPOR IMAGERY AND LATEST RAP ANALYSIS THAT IS DEPICTING MID
LEVEL CIRCULATION MOVING EASTWARD ACROSS THE SOUTHERN PLAINS THIS
AFTERNOON WILL HAVE AN IMPACT ON THE BEGINNING OF THE EXTENDED
FCST PERIOD AS IT MOVES ACROSS THE TN VALLEY. THIS WILL ACT ON
STATIONARY SFC BOUNDARY IN ADVECTING MOISTURE IN AN OVERRUNNING
FASHION BACK NORTH OF THE BOUNDARY AND LEND SUPPORT TO WIDELY
SCATTERED CONVECTION OVER THE SW HALF OF THE CWA. FOCUS WILL THEN
SHIFT TO AMPLIFICATION OF THE UPPER LEVEL PATTERN AS STRONG JET
DYNAMICS CURRENTLY WELL OUT IN THE PACIFIC ARE PROGGED BY MEDIUM
RANGE MODELS TO COME ONSHORE AND DEVELOP DEEP UPPER TROF OVER THE
WESTERN US. THIS WILL INDUCE DOWNSTREAM RIDGING THAT WILL BUILD
INTO THE REGION SUN/MON BRINGING WARMER AND MAINLY DRY CONDITIONS
TO THE AREA. WESTERN CONUS UPPER TROF THEN EXPECTED TO BECOME
VERTICALLY STACKED CLOSED SYSTEM IN THE NORTHERN PLAINS WHICH
MODELS ARE STRUGGLING WITH TIMING OF THE EVENTUAL EJECTION OF THIS
SYSTEM INTO OUR AREA. AS EXPECTED OVERALL TREND CONTINUES TO BE
SLOWER WITH ARRIVAL OF MAIN SYSTEM NOW DELAYED TO TUE/WED
TIMEFRAME AND BRINGING WITH IT THE BEST CHANCES FOR PRECIP. PRIOR
TO ITS ARRIVAL...BECOMING MORE AND MORE DIFFICULT TO PICK OUT
MODELS HANDLING OF INCREASINGLY DIFFUSE SFC BOUNDARY BUT
INDICATIONS ARE BOUNDARY WILL LIFT NORTH OF THE AREA IN
CONJUNCTION WITH UPPER RIDGE MOVING OVER THE AREA WHICH SHOULD
LEAVE MUCH OF THE FORECAST AREA IN A CAPPED WARM SECTOR SUN/MON.
LOW CONFIDENCE IN ANY ONE PARTICULAR SCENARIO WITH THIS SETUP BUT
WILL STILL INJECT A PERIOD OR TWO OF DRY WEATHER TO REFLECT THIS.
ANTICIPATE TEMPS WELL INTO THE 80S ON MONDAY DEPENDING ON AMOUNT
OF SUN...BUMPED ALLBLEND UP A DEGREE TO START UPWARD TREND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 125 PM EDT THU MAY 16 2013

MAIN FLUX OF MOISTURE AND LIFT TO REMAIN REMOVED TO THE SOUTH OF
BOTH TAF SITES THROUGH THE PERIOD. THIS WILL ALLOW FOR VFR
CONDITIONS ACROSS THE ARE WITH OCCASIONAL MID/HIGH CLOUDS AND
WINDS 10 KNOTS OR LESS.

&&

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

$$

SYNOPSIS...STEINWEDEL/KG
SHORT TERM...FISHER
LONG TERM...JAL
AVIATION...FISHER


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