Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 250605
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
205 AM EDT SAT JUL 25 2015

.SYNOPSIS...
ISSUED AT 128 AM EDT SAT JUL 25 2015

WARM AND HUMID CONDITIONS ARE EXPECTED TODAY IN ADVANCE OF A COLD
FRONT THAT WILL TRACK ACROSS THE REGION LATE THIS AFTERNOON INTO
THIS EVENING. THIS FRONT WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TODAY INTO THIS EVENING. HIGH TEMPERATURES THIS
AFTERNOON WILL REACH INTO THE MID 80S. LOW TEMPERATURES TONIGHT
WILL DROP BACK INTO THE MID TO UPPER 60S.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 254 PM EDT FRI JUL 24 2015

LATEST SURFACE ANALYSIS STILL HAS HIGH PRESSURE THAT HAS PROVIDED
SUCH PLEASANT WEATHER OVER THE PAST FEW DAYS CENTERED OVER THE
REGION. ONGOING MCS IN THE MID MS VALLEY THAT DEVELOPED AHEAD OF A
QUASI-STATIONARY FRONTAL BOUNDARY NOW TAKING A SOUTHERLY DIVE DOWN
THE EASTERN EDGE OF THICKNESS RIDGE THROUGH IOWA AND TOWARD MISSOURI
THIS AFTERNOON. FRONTAL WAVE FORMING ALONG BOUNDARY IN THE CENTRAL
PLAINS EXPECTED TO BE FOCUS FOR NOCTURNAL CONVECTION TONIGHT WHILE
LOW PRESSURE CENTERED OVER NORTHERN ONTARIO AND SHORT WAVE ENERGY
ENTERING NW GREAT LAKES REGION WILL KEEP LARGE SCALE FORCING AND
ASSOCIATED PRECIP NORTH OF OUR AREA. FRONTAL BOUNDARY WILL APPROACH
THE AREA ON SATURDAY WITH AN INCREASINGLY UNSTABLE AIRMASS OUT AHEAD
OF IT AS CAPES EXPECTED TO APPROACH 2500-3000J/KG BY LATE SATURDAY
AFTN OVER THE AREA. HOWEVER...LARGE SCALE FORCING ABSENT AS WEAK
MASS CONVERGENCE ALONG SURFACE BOUNDARY AND EFFECTIVE BULK SHEAR
AROUND 30KTS WILL LIMIT CONVECTIVE DEVELOPMENT IN BOTH CHANCE AND
AREAL EXTENT. THIS IS REFLECTED IN SLIGHT/CHANCE POPS IN GRIDS AND
WILL CONTINUE THIS TREND. CONTINUED INCREASE IN HUMIDITY IN SW FLOW
AHEAD OF APPROACHING FRONT WILL HAVE DEWPOINTS APPROACHING 70F IN
THE SOUTHERN CWA SATURDAY AFTERNOON...THIS WILL CONTINUE UPWARD
TREND IN LOWS WITH MID-UPPER 60S TONIGHT. ADDL CLOUD COVER EXPECTED
ON SATURDAY WILL MAINTAIN HIGHS IN THE MID 80S.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 254 PM EDT FRI JUL 24 2015

DRIER/MORE STABLE POST-FRONTAL AIR WILL BUILD INTO AT LEAST
NORTHERN/EASTERN PORTIONS OF THE FORECAST AREA UNDER MID LEVEL
NORTHWEST FLOW SATURDAY NIGHT INTO SUNDAY. LATEST GUIDANCE ALSO MORE
AGGRESSIVE IN DRYING REACHING AREAS SOUTHWEST OF HIGHWAY 30...THOUGH
HELD ONTO LOW POPS HERE GIVEN CLOSE PROXIMITY TO STALLED THETA-
E/INSTABILITY GRADIENT.

HUMIDITY/TEMPS WILL BE ON THE INCREASE MONDAY THROUGH WEDNESDAY AS
MID LEVEL HEIGHTS BUILD AND LOW LEVEL THETA-E RIDGE SHIFTS INTO THE
AREA ON THE NORTHEAST FRINGE OF AN EXPANDING SOUTH-CENTRAL
CONUS UPPER RIDGE. HIGH TEMPS BY TUESDAY COULD REACH NEAR 90F WITH
HEAT INDICES PUSHING 100F...ALTHOUGH THIS IS LOW CONFIDENCE GIVEN
POTENTIAL FOR A REMNANT MCS TO DROP THROUGH ON RIDGE PERIPHERY
MONDAY AND TUESDAY. AS A RESULT REMAINED SOMEWHAT CONSERVATIVE
REGARDING HIGHS AND RETAINED LOW POPS LATER SUNDAY NIGHT THROUGH
TUESDAY GIVEN RING OF FIRE CONCERNS.

NEXT/STRONGER LARGE SCALE UPPER TROUGH STILL ON TRACK TO FLATTEN THE
AFOREMENTIONED RIDGE AND DRIVE A SEASONABLY STRONG COLD FRONT THROUGH
THE LOCAL AREA LATER WEDNESDAY/EARLY THURSDAY PER LAST SEVERAL MODEL
CYCLES. A ROUND OF CONVECTION WILL LIKELY ACCOMPANY THIS FEATURE BUT
TIMING/COVERAGE/INTENSITY AT THIS FCST RANGE REMAINS UNCERTAIN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 128 AM EDT SAT JUL 25 2015

NO MAJOR CHANGES FOR THE 06Z TAFS WITH APPROACHING FRONTAL
BOUNDARY BEING THE MAIN FEATURE OF INTEREST. AT LEAST MODERATE
INSTABILITY IS EXPECTED TO DEVELOP THIS AFTERNOON AHEAD OF THE
COLD FRONT...ALTHOUGH LOW/MID LEVEL THERMAL PROFILES DO SUGGEST
SOME POTENTIAL OF WEAK CAPPING. OUTSIDE OF WEAK FRONTAL
CIRCULATION...MID/UPPER LEVEL FORCING LOOKS TO BE QUITE WEAKER
MEAGER. WHILE ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE
THIS AFTERNOON ACROSS NORTHERN INDIANA...HAVE OPTED TO LIMIT
MENTION TO VCSH AT TERMINALS THIS AFTERNOON WITH LOW CONFIDENCE IN
ANY TERMINAL BEING AFFECTED. FRONT WILL SAG SOUTH THIS EVENING
ENDING THE PRECIP THREAT BY 06Z. SOUTH/SOUTHWEST WINDS THIS
MORNING WILL VEER TO THE NORTHWEST AT KSBN THIS AFTERNOON...AND
EARLY THIS EVENING AT KFWA FOLLOWING THE FRONTAL PROGRESSION. WILL
MAINTAIN VFR CONDITIONS THROUGH THIS FORECAST VALID PERIOD.

&&

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

$$

SYNOPSIS...MARSILI
SHORT TERM...LOGSDON
LONG TERM...STEINWEDEL
AVIATION...MARSILI


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