Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 270553
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
153 AM EDT WED AUG 27 2014

.SYNOPSIS...
ISSUED AT 725 PM EDT TUE AUG 26 2014

A COLD FRONT WILL CONTINUE TO SAG SOUTH ACROSS THE REGION TONIGHT.
DRIER AND COOLER AIR WILL SLOWLY FOLLOW. THERE WILL BE A SMALL
CHANCE FOR A SHOWER OR THUNDERSTORM ACROSS THE SOUTHERN PART OF
THE AREA...MAINLY SOUTH OF THE HIGHWAY 24 CORRIDOR. LOW
TEMPERATURES WILL BE IN THE LOWER 60S NORTH TO MIDDLE 60S SOUTH.
WEDNESDAY SHOULD GENERALLY BE DRY WITH HIGH PRESSURE OVER THE
GREAT LAKES. HIGHS WILL BE IN THE UPPER 70S AND LOWER 80S.

&&

.UPDATE...
ISSUED AT 142 AM EDT WED AUG 27 2014

QUICK UPDATE TO ADJUST COVERAGE OF PATCHY DENSE FOG AND REMOVE
PRECIP MENTION REMAINDER OF THE NIGHT.

HI RES MODELS ALL POINT TOWARDS ANY SHOWERS/STORMS THAT MAY
DEVELOP THE REMAINDER OF THE NIGHT SHOULD BE SOUTH OF THE FORECAST
AREA. THIS TREND LIKELY WILL CONTINUE INTO WEDS NGT. HAVE
ORIENTED PATCHY DENSE FOG MENTION MORE ACROSS THE NORTH WHERE
CIRRUS CANOPY IS NOT IMPACTING RADIATIONAL COOLING.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 317 PM EDT TUE AUG 26 2014

BROKEN LINE OF THUNDERSTORMS ASSOCIATED WITH APPROACHING COLD
FRONT IS CURRENTLY PUSHING THROUGH THE CWA. WEAK FORCING FOR
ASCENT IS BEING AIDED BY SHORTWAVE LEFTOVER FROM NOCTURNAL
CONVECTION UPSTREAM BUT OVERALL FORCING IS VERY NONDESCRIPT.
MLCAPE VALUES HAVE MANAGED TO CLIMB TO AROUND 3000 J/KG IN OUR
EXTREME SOUTHWEST BUT EARLY DAY CLOUDS/PRECIP HAVE LIMITED DIURNAL
INSTABILITY IN OUR NORTHEAST HALF. STILL HAVE SURFACE DEWPOINTS
AROUND 70F AND MIDLEVEL LAPSE RATES AROUND 6 C/KM TO AID UPDRAFTS
THOUGH. THE PROBLEM IS WE HAVE LITTLE TO NO DEEP...OR LOWER
LEVEL...SHEAR IN OUR AREA. THIS HAS PREVENTED THUNDERSTORMS FROM
ORGANIZING INTO A MORE CONGEALED FORWARD PROPAGATING LINE. LATEST
RADAR MOSAIC SHOWS OUTFLOW ALREADY RACING AHEAD OF THE MAIN
LINE...CHOKING OFF THE UPDRAFTS. INDIVIDUAL CLUSTERS THAT MANAGE
TO CAPITALIZE ON BETTER INSTABILITY TO OUR SOUTH/SOUTHWEST MAY
STILL POSE A RISK FOR DAMAGING WINDS AND PERHAPS SOME LARGE HAIL
BUT THREAT FOR WIDESPREAD SEVERE WEATHER IS LOW. THE BEST CHANCES
WILL CONTINUE TO BE ALONG OUR FAR SOUTHERN COUNTIES WHERE THE
BETTER 0-1KM MLCAPE RESIDES. HEAVY RAIN WILL ALSO BE A THREAT WITH
PW VALUES AROUND 2 INCHES AND FAIRLY DEEP WARM CLOUD LAYER. STORM
MOTION IS LARGELY ORTHOGONAL TO THE BOUNDARY THOUGH AND WILL LIMIT
DURATION OF HEAVY RAINFALL AT ANY ONE LOCATION.

SUSPECT CONVECTION WILL QUICKLY EXIT AND DISSIPATE BY LATER THIS
EVENING...AN IDEA SUPPORTED BY MOST OF THE LATEST HI-RES GUIDANCE.
LOSS OF DAYTIME HEATING AND INCREASING COOL/DRY ADVECTION BEHIND
FRONT WILL LIKELY KEEP MOST CONVECTION SOUTH OF OUR AREA THROUGH
TOMORROW MORNING. WILL HOLD ONTO LOW CHANCE ACROSS OUR FAR SOUTHERN
COUNTIES BUT REMOVE MENTIONABLE POPS ACROSS THE NORTH. MUCH COOLER
AND LESS HUMID CONDITIONS EXPECTED FOR TOMORROW WITH HIGHS AROUND
80F AND DEWPOINTS RETURNING TO MORE COMFORTABLE LOW 60S.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 317 PM EDT TUE AUG 26 2014

BIGGEST CHALLENGE OF LONG TERM WILL REVOLVE AROUND PRECIP CHANCES
AND TIMING THRU MOST OF THE PERIOD. SFC HIGH WILL BE BUILDING INTO
THE REGION FOR START OF LONG TERM IN WAKE OF DEPARTING COLD FRONT
THAT WILL STALL OUT ACROSS OH VALLEY. AS RIDGE TAKES HOLD ON THE
AREA...EXPECT OVERNIGHT WEDS AND MOST OF THURS TO REMAIN DRY.
DRIER/COOLER AIR ADVECTING IN WILL ALLOW FOR TEMPERATURES TO FALL
BACK CLOSER TO NORMAL WITH OVERNIGHT LOWS IN THE LOW TO MID 60S AND
HIGHS THURS IN THE UPPER 70S TO LOW 80S. STALLED SFC BOUNDARY WILL
THEN SHIFT NORTH AS UPPER LEVEL CUTOFF TROUGH ACROSS THE PLAINS
BEGINS TO FORCE SFC RIDGE OFF TO THE EAST. CHANCES FOR SHOWERS AND
TSTORMS RETURN AS THIS FEATURES MOVES NORTH THURS NIGHT INTO FRI.

SHORTWAVE ROTATING THRU IN MORE ZONAL FLOW ACROSS S CANADA WILL MOVE
A COLD FRONT SOUTH INTO THE LOCAL AREA ON SATURDAY BEFORE STALLING
OUT ACROSS THE AREA THROUGH THE WEEKEND. THIS FEATURE WILL BE SLOW
TO MOVE UNTIL UPPER LEVEL TROUGH AND ASSOCIATED SFC LOW MOVES
THROUGH DURING THE DAY SUNDAY. THIS WILL CONTINUE THE CHANCES FOR
SCT SHOWERS AND TSTORMS THROUGHOUT THE WEEKEND ALTHO NOT EXPECTING
ENTIRE PERIOD TO BE A WASHOUT. HEAVY RAINFALL WOULD BE A THREAT WITH
ANY STORM AS PWAT VALUES WILL BE IN THE 1.5 TO 1.9 INCH RANGE. BRIEF
PERIOD OF DRY WX POSSIBLE FOR LABOR DAY IN WAKE OF DEPARTING SYSTEM
AND IN ADVANCE OF NEXT WAVE MOVING EAST FROM THE PLAINS. HAVE KEPT
SLGHT CHC POPS FOR MONDAY AS BOUNDARY WILL STILL BE IN THE VICINITY
BUT THESE MAY BE ABLE TO BE REMOVED BY LATER SHIFTS. THIS NEXT
SYSTEM WILL MOVE INTO THE AREA BY END OF THE PERIOD ALTHO MODEL
DISCREPANCIES IN TIMING/STRENGTH REMAIN THIS FAR OUT. TEMPERATURES
FOR FRIDAY THROUGH LABOR DAY WILL GENERALLY TOP OUT IN THE LOW 80S
WITH LOWS IN THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 142 AM EDT WED AUG 27 2014

FOG/STRATUS WILL BE THE MAIN CHALLENGE FOR THE NEXT 6 TO 9 HOURS
AS STRUGGLE BETWEEN DRIER AIR AND MOIST BOUNDARY LAYER CONTINUES.
CIGS AND VSBYS HAVE BEEN HIGHLY VARIABLE AT KSBN AND SUSPECT THIS
WILL CONTINUE THROUGH THE NIGHT. AS OF WRITING THIS VSBYS RANGED
FROM 4 SM DOWN TO 3/4SM WHICH IS IMPOSSIBLE TO CAPTURE IN TAFS.
HAVE TRIED TO GO WITH WHAT WILL BE THE MOST PREDOMINANT VSBYS AND
CIGS BUT PILOTS WILL NEED TO MONITOR FOR LOCALLY VARIABLE
CONDITIONS AS FOG HAS BEEN RATHER SHALLOW IN NATURE. IF COVERAGE
EXPANDS THEN WILL NEED TO AMEND TAFS. AT KFWA...FOG AND STRATUS
WILL ARRIVE A BIT LATER AND MAY NOT BE AS MUCH OF AN ISSUE SO HAVE
BEEN SLIGHTLY MORE CONSERVATIVE THERE.

AFTER SUNRISE...VFR CONDITIONS SHOULD PREVAIL AS HIGH PRESSURE
BUILDS IN FROM THE NORTH FOR THE REMAINDER OF THE PERIOD WITH A
NORTH TO NORTHEAST WIND.

&&

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

$$

UPDATE...FISHER
SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...CEO
AVIATION...FISHER


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