Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 020946 CCA
AFDIWX

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
545 AM EDT THU OCT 2 2014

.SYNOPSIS...
ISSUED AT 1250 AM EDT THU OCT 2 2014

A WARM FRONT LIFTING NORTH INTO THE REGION TODAY WILL BRING
WARMER TEMPERATURES AND CHANCES FOR A FEW SHOWERS TO INDIANA AND
MICHIGAN. WIDESPREAD SHOWERS AND POSSIBLY A FEW THUNDERSTORMS ARE
EXPECTED TONIGHT INTO FRIDAY IN ADVANCE OF A STRONG COLD FRONT
THAT WILL USHER IN MUCH COOLER AIR FOR FRIDAY INTO THE WEEKEND.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 423 AM EDT THU OCT 2 2014

STRENGTHENING SW FLOW IN ADVANCE OF AN AMPLIFYING PLAINS UPPER
TROUGH WILL HELP FORCE A CENTRAL MO/SOUTHERN IL WARM FRONT
NORTHEAST INTO THE AREA LATER TODAY/THIS EVENING. MORNING
CONVECTION ALONG WARM FRONT WILL LIKELY SLOW/MODULATE THE
NORTHWARD ADVANCEMENT OF THIS BOUNDARY...WITH PRIMARY ADJUSTMENT
IN GRIDS TO LOWER MAX TEMPS AND INCREASE SKY COVER (MAINLY
WESTERN/NORTHERN ZONES). WEAK MOISTURE CONVERGENCE/ADVECTION
WITHIN 9-7H THETA-E RIDGE AXIS WILL SLOWLY FOLD EAST INTO AREAS
MAINLY WEST OF I-69 THIS MORNING/EARLY AFTERNOON. THIS IN
CONJUNCTION WITH POTENTIAL FOR LOWER AMPLITUDE SHORTWAVE ENERGY
TO EJECT NE TOWARD LAKE MI IN MEAN SW FLOW SUPPORT GOING CHC POPS
FOR SHOWERS THIS MORNING.

PROSPECTS FOR SCATTERED CONVECTION INCREASE LATER THIS
AFTERNOON/EVENING ACROSS MAINLY WESTERN ZONES AS WARM FRONT AND
WEAK INSTABILITY MIX NORTHEAST IN ADVANCE OF A POTENT LEAD
SHORTWAVE EJECTING ENE TOWARD THE MID MS VALLEY. INCREASING
FLOW/LOW INSTABILITY/CURVED HODO IN VICINITY OF WARM FRONT HINTS
AT CONDITIONAL LOW TOPPED SUPERCELL THREAT SOUTHWEST CWA DURING
THIS TIME. THIS VERY LOW RISK (TOO LOW FOR A HWO MENTION) FOR A
BRIEF TORNADO/DOWNBURST WILL BE DEPENDENT ON DEGREE OF SURFACE
DESTABILIZATION WHICH SHOULD BE LIMITED THIS FAR EAST. STILL BEARS
WATCHING...ESPECIALLY IF NAM LEVEL SBCAPE VALUES ARE REALIZED
WESTERN ZONES.

INTERACTION OF THE ABOVE MENTIONED LEAD SHORTWAVE WITH VIGOROUS
SHORTWAVE AND 140 KT UPPER JET DIGGING SOUTHEAST INTO THE NORTH-
CENTRAL CONUS WILL PROMPT A STRONG CYCLOGENETIC RESPONSE TONIGHT
INTO FRIDAY...WITH DEEPENING SFC REFLECTION TRACK MODELED INTO
THE WESTERN LAKES BY 12Z FRI. RESULTING STRENGTHENING OF TRAILING
COLD FRONT INTO THE AREA BY LATER TONIGHT SHOULD FAVOR INCREASED
COVERAGE OF RAIN/EMBEDDED THUNDER THAT SHOULD REACH OUR OHIO
COUNTIES BY/NEAR DAYBREAK FRIDAY WITHIN RAMPED LLJ/DEEP UVM
PLUME. PRIMARY CHANGE TO THE FCST WAS TO ADD SOME TEMPORAL DETAIL
(LOWER POPS IN THE EVENING AND EARLY OVERNIGHT) TO ACCOUNT FOR
OVERALL SLOWING TREND SHOWN IN LAST SEVERAL MODEL CYCLES.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 423 AM EDT THU OCT 2 2014

LARGELY STATUS QUO WITH RESPECT TO LONG TERM FORECAST. CONTINUED
UPWARD BUMP IN POPS EARLY FRIDAY TO NEAR 100 PERCENT IN ADVANCE
OF STRONG FRONTAL BOUNDARY AMID 99TH PERCENTILE/1.75 INCHES PWAT
MOISTURE. ADDED CHC MENTION TSRA PRIMARILY EAST OF I69 IN 12-15
UTC TIMEFRAME WITH MID LEVEL LAPSE RATES NEAR 6.0 C/KM AFFORDING
NARROW PLUME OF 300-500 J/KG MUCAPE. THIS SHOULD PROVE SUFFICIENT
INSTABILITY FOR AT LEAST CHC EMBEDDED CONVECTION IMMEDIATELY
AHEAD OF FRONTAL BOUNDARY WITH FORCED PARCEL ASCENT AS 925 MB
40-50 KT ACROSS LWR OHIO VALLEY LIFTS NORTHWARD/IMPINGING NW OHIO
NEAR DAYBREAK. CONTINUAL RAMP OF MID TROPOSPHERIC HEIGHT FALLS
ALSO FOSTERING GENERALIZED ASCENT. ONLY FEW HOURS TSRA MENTION AS
JET FEATURE LIFTS NNEWD BY 15 UTC INTO WESTERN LAKE ERIE/EXTREME
SWRN ONTARIO...THOUGH POSTFRONTAL CAA/ASCENT TO CONTINUE EPISODIC
SHRA WELL INTO THE WEEKEND AS WEST CENTRAL SASK SHORTWAVE DRIVES
SOUTHEAST THROUGH UPPER MS VALLEY FRIDAY. EXTRACTED HIGHS/LOWS
THIS WEEKEND FROM MODIFICATION OF 3 HRLY TEMPS NUDGED TOWARD
LATEST CONSENSUS BELND WITH NON DIURNAL TEMP CURVE FRIDAY/STRONG
CAA AND SUBDUED DIURNAL SPREAD INTO SATURDAY WITH CLOUD
COVER/PRECIP. VORTEX CULMINATES SATURDAY MORNING WITH IDEAL
CONSENSUS CLOSED LOW OVER SWRN LWR MI...WITH EXCEPTIONAL 450-500M
5H HEIGHT ADJUSTMENTS F18-F60. CONTINUED UPTICK OF HIGHER POPS
FRIDAY NIGHT INTO EARLY SATURDAY WITH APPROACH OF SYSTEM THAT
WILL LIKELY EXHIBIT EMBEDDED SHORTWAVE SPURS/SHARPENING SECONDARY
TROF TO ROTATE THROUGH SOUTHERN GRTLKS. PRIMARY SOUTHERN GREAT
LAKES TROF SHIFTS EWD INTO LOWER GREAT LAKES SAT AFTN/SAT NIGHT.
THIS SHOULD ALLOW CYCLONIC LOW LEVEL FLOW TO RELAX...ESPECIALLY
ACROSS SOUTHERN/SOUTHWESTERN CWA.

CONTINUED MENTION CHC/SLGHT CHC SHRA NORTH DURING THIS TIMEFRAME
WITH LESSER SHORTWAVE INFLUENCE FROM ANCHOR NORTH OF LAKE
SUPERIOR. 925MB COLD POOL TROF PLANTED OVER CWA SUNDAY MORNING
AND HAVE TRENDED TEMPS A COUPLE DEGREES LOWER IN LINE WITH MID
30S ENSEMBLE GFS MOS AVERAGES WHICH EXHIBIT EXTREMELY LOW SPREAD
ON ORDER OF 0-1 SD IN BOTH 01/00 AND 02/00 RUNS. WOULD NOT BE
SURPRISED WITH A FEW STATIONS BRIEFLY DIPPING TO 32F ESPECIALLY
SOUTHWEST INTO INTERIOR CWA...THOUGH BOUNDARY LAYER TO LIKELY
REMAIN AT LEAST SLIGHTLY MIXED AND WET/WARM GROUND SHOULD
PRECLUDE NEED FOR FROST MENTION. BLOCKY SYSTEM RETROGRADES
SLIGHTLY WESTWARD EARLY NEXT WEEK WITH PERSISTENT LOW GRADE POPS
PER BLENDED APPROACH ACCEPTABLE.

THEREAFTER...CONTINUED DRY TOWARD END OF FORECAST AMID A
GENERALIZED...ALBEIT POOR CONSENSUS...FOR CYCLONE TO GRADUAL LIFT
NORTHWARD WHILE FILLING...AFFORDING GRADUAL AIRMASS MODERATION TO
NEAR NORMAL BY MIDDLE NEXT WEEK WITH NIL SENSIBLE WX. LATEST
ECMWF INTERESTING OUTLIER WITH FINAL SHORTWAVE DIGGING THROUGH
MID MS VALLEY INTO KY/TN TO FOSTER CYCLOGENESIS TUE OVER
SMOKIES...LIFTING NORTH INTO LOWER GREAT LAKES WED. WHILE THIS
SOLUTION LIKELY TO REMAIN DRY FOR US COULD TEMPER WARMUP.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 520 AM EDT THU OCT 2 2014

WEAK MCV EMANATING FROM MID MS VALLEY CONVECTION (NOW EVIDENT ON
RADAR ACROSS EAST-CENTRAL IL) SHOULD WORK ENE AND BRING AN AREA OF
DECAYING SHOWERS INTO NORTHERN INDIANA THIS MORNING. INITIAL DRY
LOW LEVELS SHOULD HELD KEEP FLIGHT CONDITIONS MAINLY IN THE VFR
CATEGORY. CHANCES FOR SHOWERS/STORMS AND ASSOCIATED RESTRICTIONS
INCREASE LATER THIS AFTERNOON/EVENING AT MAINLY SBN AS WARM FRONT
LIFTS IN. A STRENGTHENING COLD FRONT AND ASSOCIATED LEAD SHORTWAVE
WILL LIKELY BRING MORE WIDESPREAD RESTRICTIONS/RAIN/WIND TO THE
REGION TOWARD THE END OF THE TAF CYCLE.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...GALE WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING FOR
     LMZ043-046.

&&

$$

SYNOPSIS...LASHLEY
SHORT TERM...STEINWEDEL
LONG TERM...MURPHY
AVIATION...STEINWEDEL


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