Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 011149
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
749 AM EDT MON SEP 1 2014

.SYNOPSIS...
ISSUED AT 441 AM EDT MON SEP 1 2014

ANOTHER COLD FRONT WILL PUSH IN FROM THE WEST TODAY INTO THIS EVENING
BRINGING RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS. THE CHANCE
OF THUNDERSTORMS WILL PERSIST INTO TONIGHT. HIGHS TODAY WILL REACH
THE LOWER TO MIDDLE 80S. LOWS TONIGHT WILL BE IN THE UPPER 60S TO
AROUND 70.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 439 AM EDT MON SEP 1 2014

FEW ISOLD SHRA LIFTING NNEWD WITHIN DEEP LAYER WAA INTO SRN CWA
FOR PRE DAYBREAK MENTION. OTHERWISE FOCUS ALL ONTO UPSTREAM
CONVECTION ACROSS EASTERN IA CROSSING INTO NWRN IL ATTM.
DOWNSTREAM CONVECTIVE MAINTENANCE PARAMETERS APPEAR POOR...WITH
BEST LOW LEVEL JET FORCING LIFTING NWD THROUGH LONGWAVE TROF INTO
FAR NORTHWEST GREAT LAKES BY MID/LATE AM...WITH NWRN GREAT LAKES
CONVECTION PREFERRED COINCIDENT WITH BETTER KINEMATICS COLLOCATED
WITH STRONG HEIGHT FALL CENTROID. WELL DEVELOPED COMPOSITE OUTFLOW
ASSOCIATED WITH OZARKS/ERN KS CONVECTION TO CONTINUE ESEWD
PROGRESSION AND LIKELY DECAY AS WELL AS IT IMPINGES ONTO HIR
LEADING EDGE MLCIN. THIS CONVECTIVE SPLIT WILL RENDER A
LESSENED/VEERED 8H FLOW ACROSS IA/MO/IL REGION THROUGH LATE
AM...WITH ANTICIPATED RAPID CONVECTIVE DECAY AS REMAINING
CONVECTION ENCOUNTERS 150-250 J/KG MLCIN ROOTED FROM NERN IL TO
ECNTL MO. WHILE DEGREE OF CONVECTIVE DEBRIS TO INITIALLY PROVIDE
SOME RESTRAINT OF DOWNSTREAM DESTABILIZATION...BY LATE AFTERNOON
EVEN CONSERVATIVELY MODIFIED LOWER 80S/71F YIELD 2500-3000 J/KG
SBCAPES. DESTABILIZATION COINCIDENT WITH RAMPING DEEP LAYER SHEAR
ASSOCIATED WITH MID LEVEL JETLET OVER MID MS VLY NOSING INTO
SOUTHERN LOWER MICHIGAN...WITH BOTH LEESIDE LAKE MICHIGAN
CONVERGENCE WITHIN LOWEST 100 MB AND SOUTHERN PERIPHERY OF HEIGHT
FALLS STILL PROVIDING 20-40M/12 HR FALLS INTO SW LWR MICHIGAN...OR
/AND MORE PROBABLE/ THE EJECTION OF NORTHERN MO MESOVORT SHOULD
PROVIDE SUFFICIENT IMPETUS FOR CONVECTIVE
REDEVELOPMENT...ESPECIALLY ACROSS NWRN CWA BY LATE AFTERNOON.
GIVEN MESOSCALE UNCERTAINTIES HAVE KEPT POPS RESTRAINED...THOUGH
OPT FOR COVERAGE WORDING NW IN 21-24 UTC TIMEFRAME. WILL COVER
WIND/HAIL POTENTIAL WITHIN HWO FOR LATE AFTERNOON/EVENING. AS
CONVECTION SPREADS EASTWARD ENHANCEMENT ANTICIPATED AS UPPER LEVEL
JET STREAK RAMPS TO 120 KTS AS IT LIFTS FROM SRN WI TO NRN LOWER
MICHIGAN...LEAVING CWA WITHIN RIGHT ENTRANCE REGION. GRADUAL
DEEPENING OF LONGWAVE TROF AS IT MOVES EASTWARD THROUGH THE GREAT
LAKES ALONG WITH LOW LEVEL JET RAMPING FROM THE OZARK PLATEAU INTO
SOUTHERN INDIANA BY 12 UTC TUE TO FAVORS PERSISTENT UPDRAFT
GENERATION. HIGH PRECIP EFFICIENCIES WITH NEARLY 2.0 INCHES PWAT
LAID OUT ACROSS SOUTHERN CWA AMID DEEP 12-13KFT WARM CLOUD LAYER
AND PERIOD OF LOW AOB 5 KTS MESOBETA ELEMENT VELOCITIES...HERE
AGAIN PRIMARILY ACROSS SOUTHERN CWA...LENDS CONTINUE HWO MENTION
OF POSSIBLE OVERNIGHT HEAVY RAFL RATES/LOCALIZED FLOODING POTNL.

&&

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 439 AM EDT MON SEP 1 2014

FRONTAL BOUNDARY PUSHING SOUTHEAST OF THE FCST AREA WILL RESULT
IN A DRYING TREND ON TUESDAY WITH LOW CLOUDS SLOW TO SCOUR OUT
SOUTHEAST. FAIR/SEASONABLE WX WILL THEN PERIST INTO TUESDAY NIGHT
AND WEDNESDAY AS MID LEVEL HEIGHT RISES OVERSPREAD IN MORE ZONAL
FLOW. AN OPEN/POSITIVELY TILTED MID LEVEL WAVE WILL TRANSLATE
EAST THROUGH THE CANADIAN PRAIRIES/NORTH-CENTRAL US
THURSDAY...AND INTO ONTARIO/GREAT LAKES FRIDAY-FRIDAY NIGHT PER
LATEST MODEL CONSENSUS. THETA-E/WARM FRONT SURGE IN RESPONSE TO
ATTENDANT CENTRAL PLAINS TO UPPER MIDWEST SFC TROUGH DEVELOPMENT
BRINGS CONVECTIVE CHANCES INTO QUESTION BY LATER WEDNESDAY
NIGHT/THURSDAY MORNING. CONTINUED TO FAVOR THE DRIER ECMWF/GEM
OUTPUT AS MORE PRONOUNCED MOISTURE CONVERGENCE SETS UP NORTHWEST
OF THE FA ON NOSE OF LLJ. CAPPED WARM SECTOR LIKELY BECOMES
FIRMLY ESTABLISHED LATER THURSDAY INTO THURSDAY NIGHT. 850MB
TEMPS INCREASING TO 20-21C IN STRENGTHENING LOW LEVEL SW FLOW
HINT AT POTENTIAL FOR HIGHS TO MAKE A RUN AT 90F THURSDAY...WITH
THIS HIGHLY DEPENDENT ON CONVECTION/CLOUD DEBRIS TRENDS.

BETTER SHOWER/STORM CHANCES RETURN FRIDAY INTO FRIDAY NIGHT AS
TRAILING COLD FRONT SAGS SOUTH INTO A MOIST/UNSTABLE ENVIRONMENT.
WEAK MID LVL FORCING/LAPSE RATES WELL REMOVED FROM PRIMARY
SHORTWAVE/SFC REFLECTION TRACK EAST THROUGH THE NRN
LAKES/ONTARIO...AND SLIGHT TIMING DIFFERENCES IN
GUIDANCE...SUGGEST 30-40 TYPE POPS THE WAY TO GO AT THIS FCST
RANGE. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE IF CONVECTION
FIRES GIVEN HIGH MOISTURE CONTENT/POOLING AS BOUNDARY LAYS OUT
MORE W-E ON SRN FRINGE OF HEIGHT FALLS. THE RISK FOR ORGANIZED
SEVERE WEATHER APPEARS LOW FRIDAY AFTN-EVE AS STRONGER MID LEVEL
FLOW LIKELY LAGS BEHIND FRONT. OTHERWISE...LOW LEVEL ANTICYCLONE
BUILDING INTO THE GREAT LAKES IN WAKE OF FRONT SHOULD ENSURE A
NOTEWORTHY COOL DOWN NEXT WEEKEND.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 734 AM EDT MON SEP 1 2014

A FEW HOURS OF FUELING/ALTERNATE IMPACT ACROSS NORTHERN INDIANA
THIS MORNING WITH HIGH END IFR CIGS DEVELOPING WITH STRONGLY
MIXED/MOIST NEAR SURFACE BOUNDARY LAYER. KIWX VWP SHOWING 25 KTS
OFF FIRST GATE. GREATER MIXED DEPTH BY LATE MORNING AND INTO
AFTERNOON PORTENDS TO HIR SSWLY GUSTS. ANTICIPATE CONVECTIVE
DEVELOPMENT ACROSS NERN IL/NWRN IN AS AIRMASS REACHES NEAR PEAK
DESTABILIZATION AND APPROACH OF MESOVORT...PRESENTLY OVER NERN MO.
CONVECTION SPREADING EWD TO KFWA TOWARD SUNSET. ADDITIONAL ROUNDS
OF CONVECTION LIKELY INTO THE OVERNIGHT HOURS...ASSOCIATED NEAR
COLD FRONT AND FRONTAL WAVE SLOWLY SLIDING EASTWARD THROUGH THE
SOUTHERN GREAT LAKES. ONLY MENTION VCTS FOR NOW GIVEN LATTER
PORTION OF TAF PERIOD AND TEMPORAL/SPATIAL UNCERTAINTIES
ASSOCIATED WITH CONVECTION.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...BEACH HAZARDS STATEMENT FROM 11 AM EDT THIS MORNING THROUGH THIS
     EVENING FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 11 PM EDT THIS
     EVENING FOR LMZ043-046.

&&

$$

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


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