Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 070039
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
839 PM EDT WED MAY 6 2015

.SYNOPSIS...
ISSUED AT 431 PM EDT WED MAY 6 2015

HIGH PRESSURE WILL MAINTAIN WARM AND MAINLY DRY CONDITIONS
THROUGH TOMORROW. LOWS TONIGHT WILL BE AROUND 60 DEGREES WITH
HIGHS TOMORROW CLIMBING INTO THE MID 80S. A FRONTAL BOUNDARY WILL
THEN SET UP OVER THE REGION ON FRIDAY AND BRING A CHANCE OF
SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND.

&&

.UPDATE...
ISSUED AT 802 PM EDT WED MAY 6 2015

PREVIOUS FORECAST IS IN GOOD SHAPE THIS EVENING WITH ONLY A COUPLE
OF MINOR TWEAKS. A FEW ISOLATED SHOWERS HAVE DEVELOPED EARLY THIS
EVENING ACROSS SOUTHWEST LOWER MICHIGAN. THIS SMALL AREA OF
SHOWERS APPEARS TO HAVE BEEN AIDED BY SOME WEAK LOW LEVEL
CONVERGENCE ASSOCIATED WITH MARINE INFLUENCE...WHICH IS ALSO
COLOCATED WITH WESTERN FRINGE OF POCKET OF 500-1000 J/KG MLCAPES.
THIS INSTABILITY SHOULD BE STRONGERLY CORRELATED TO DIURNAL CYCLE
AND WITH LITTLE TO NO MID/UPPER FORCING...THESE SHOWERS SHOULD
DISSIPATE OVER THE NEXT HOUR OR SO. ONLY OTHER TWEAK WAS TO FOCUS
GREATEST FOG POTENTIAL ACROSS THE NORTHEAST FOR THE OVERNIGHT
HOURS WITH MORE FAVORABLE CROSSOVER TEMPS.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 414 PM EDT WED MAY 6 2015

TODAY`S SHORT TERM FORECAST CAN BE CHARACTERIZED AS GENERALLY
BENIGN BUT VERY SUMMER-LIKE. HIGH AMPLITUDE RIDGE WILL CONTINUE TO
SLOWLY MIGRATE EASTWARD THROUGH TOMORROW WITH DEEP SW FLOW
ADVECTING EVEN WARMER TEMPERATURES INTO OUR AREA. A FEW EXTREMELY
ISOLATED SHOWERS HAVE MANAGED TO DEVELOP IN OUR CWA THIS AFTERNOON
GIVEN MODEST INSTABILITY (MLCAPE AROUND 500 J/KG) AND A WEAK CAP.
LACK OF SYNOPTIC FORCING AND MARGINAL INSTABILITY/LOW LEVEL
MOISTURE WILL KEEP ANY ACTIVITY VERY ISOLATED THROUGH THE EVENING.
GIVEN PALTRY RADAR RETURNS AND CLOUD BASES OF 6-7 KFT DECIDED TO
REMOVE BLANKET POP MENTION AND GO WITH A "SILENT" 14 POP.

DID INTRODUCE SOME PATCHY FOG WORDING GIVEN OVERNIGHT LOWS DROPPING
NEAR CROSS-OVER TEMPS OF UPPER 50S WITH VERY LIGHT SE WINDS.
BOUNDARY LAYER GOT MIXED OUT FAIRLY WELL TODAY AND AFTERNOON
DEWPOINTS ARE A BIT LOWER. OVERNIGHT LOWS WILL ALSO BE MILDER GIVEN
CONTINUED WAA SO CONFIDENCE IN WIDESPREAD/DENSE FOG IS LOW. IF IT
DOES OCCUR...OUR EASTERN COUNTIES ONCE AGAIN HAVE THE HIGHEST THREAT
AND WILL CONTINUE TO MONITOR TRENDS OVERNIGHT.

AS ALLUDED TO EARLIER...WARM TEMPS WILL BE THE MAIN STORY FOR
TOMORROW. DEEP MIXING...JUST PARTLY CLOUDY SKIES...AND WARM THERMAL
PROFILES ALOFT WILL SUPPORT HIGHS EASILY IN THE LOW TO MID 80S. SOME
GUIDANCE...MAV IN PARTICULAR...SUGGEST UPPER 80S POSSIBLE AND MAY
NOT BE OUTSIDE THE REALM OF POSSIBILITY BASED ON CURRENT TEMPS JUST
UPSTREAM OVER CENTRAL ILLINOIS. MIXING HEIGHTS AT OR ABOVE 800MB
SUGGEST SIDING ON THE WARM SIDE OF GUIDANCE BUT WILL HOLD WITH
GENERALLY MID 80S FOR NOW. SOME CONCERN FOR VERY ISOLATED AFTERNOON
CONVECTION TO POP UP BUT WARM TEMPS ALOFT WITH SURFACE DEWPOINTS
ONLY IN THE UPPER 50S SUGGESTS INSTABILITY WILL BE AT A PREMIUM.
FORECAST SOUNDINGS ALSO HINT AT A DECENT SPEED BUMP AROUND 600-700
MB THAT WILL LIKELY CAP MOST (IF NOT ALL) CONVECTION. ANOTHER
"SILENT" 14 POP STILL APPEARS TO BE THE MOST PRUDENT APPROACH.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 414 PM EDT WED MAY 6 2015

UPR RIDGE OVER THE OH VALLEY/WRN GRTLKS THIS AFTN EXPECTED TO MOVE
TO THE EAST OF OUR AREA BY THU EVE AS UPR LOW OVER WRN NEB SHEARS
OUT AND LIFTS NE INTO SWRN ONTARIO/UPR MS VALLEY. SFC LOW ASSOCIATED
WITH THIS FEATURE EXPECTED TO MOVE THROUGH CENTRAL ONTARIO OVERNIGHT
WITH CDFNT TRAILING SW INTO ERN IA BY FRI MORNING. DVLPG SWLY FLOW
AHEAD OF THE FRONT WILL RESULT IN GRDLY INCRSG THETA-E OVERNIGHT.
MANY OF THE 12Z MODELS SUGGEST SOME POTENTIAL FOR SHOWERS REACHING
PORTIONS OF WRN CWA EARLY FRIDAY MORNING AS WK SHRTWV MOVES
THROUGH THE MOISTURE PLUME FROM THE SW. APPEARS IF ANY SHOWERS DO
REACH THE AREA IT WOULD BE IN THE 09Z-12Z TIMEFRAME WHICH IS AROUND
DAWN THIS TIME OF YEAR SO FOR NOW LEFT FCST DRY WHICH IS ALSO
SUPPORTED BY 12Z GEM AND HIRES NMM.

DIURNAL HEATING EXPECTED TO LEAD TO MODERATE INSTABILITY FRIDAY
WHICH SHOULD ALLOW SCT TSTMS TO DEVELOP AS THE CDFNT SLOWLY
APPROACHES FROM THE NW AND PSBLY WK SHRTWVS MOVE THROUGH THE SWLY
FLOW ALOFT OVER THE AREA. HIGHEST POPS ACROSS THE NW CLOSER TO
FRONTAL BOUNDARY AND WITHIN DEEP MOISTURE PLUME.

MEDIUM RANGE MODELS SUGGEST THE CDFNT WILL BECOME STNRY ACROSS OUR
AREA BY SATURDAY AS SFC LOW ASSOCIATED WITH TROF DIGGING THROUGH WRN
U.S. TODAY DEEPENS OVER WRN KS. DIURNAL HEATING/DESTABILIZATION
SHOULD LEAD TO SCT TSTM DEVELOPMENT ONCE AGAIN WITH AXIS OF HIGHEST
POPS SHIFTING TO SERN 1/2 OF CWA ALONG/AHEAD OF FRONT.

STNRY FRONT EXPECTED TO LIFT SLOWLY NORTH SUNDAY AS KS LOW EJECTS NE
INTO IA. AGAIN DIURNAL HEATING/DESTABILIZATION SHOULD LEAD TO SCT
TSTM DEVELOPMENT DURING THE DAY IN THE VCNTY OF THE FRONT. APPEARS
TO BE SOME POTENTIAL FOR LOCALLY HEAVY RAINFALL OVER THE WEEKEND
GIVEN RATHER MOIST AIRMASS WITH PRECIP WATER PROGGED AROUND
1.5"...SMALL MBE VECTORS/POTENTIAL FOR TRAINING.

LOW EXPECTED TO MOVE NE ACROSS THE UPR GRTLKS MONDAY-MONDAY NIGHT
WITH TRAILING CDFNT MOVG THROUGH OUR AREA. STILL APPEARS BEST CHC OF
TSTMS DURING THE LONG TERM FCST PERIOD WILL BE MONDAY ALONG/AHEAD OF
THE CDFNT. STRONGER WINDS ALOFT/INCREASING SHEAR ASSOCIATED UPR
LEVEL TROF MOVG THROUGH THE UPR MIDWEST/GRTLKS SUGGESTS POTENTIAL
FOR MORE ORGANIZED STORMS MONDAY IF DIURNAL HEATING/DESTABILIZATION
ISN`T SIGNIFICANTLY HINDERED BY WIDESPREAD CLOUDS/SHOWERS.

CAA IN WAKE OF MONDAYS GRTLKS LOW SHOULD RESULT IN CONSIDERABLY
COOLER TEMPS TUE-WED WITH LINGERING WRAP AROUND STRATO CU AND PSBLY
A FEW SHOWERS TUE. HIGH PRESSURE SHOULD BUILD INTO THE AREA WED
PROVIDING FAIR WX WITH A LITTLE MORE SUNSHINE BUT TEMPS PRBLY WILL
STILL BE A BIT BLO NORMAL AS LOW LEVEL THERMAL TROF MOVES THROUGH
THE AREA.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 802 PM EDT WED MAY 6 2015

UPPER RIDGING TO PERSIST ACROSS THE REGION THROUGH THIS FORECAST
PERIOD WILL PROVIDE MAINLY DRY CONDITIONS. A FEW ISOLATED SHOWERS
HAVE DEVELOPED EARLY THIS EVENING ACROSS SOUTHWEST LOWER MICHIGAN
WHERE SOME LAKE BREEZE ENHANCEMENT HAS AIDED LOW LEVEL
CONVERGENCE. INSTABILITY WILL QUICKLY WANE THIS EVENING AND
TERMINALS WILL REMAIN DRY. HIGHER CROSSOVER TEMPS EXIST ACROSS
NORTHEAST INDIANA/NORTHWEST OHIO WHERE FOG POTENTIAL SHOULD BE THE
GREATEST TONIGHT. WHILE CONDITIONS ARE NOT EXPECTED TO DETERIORATE
TO THE LEVEL OF EARLIER THIS MORNING...AT LEAST SOME IFR VSBYS ARE
POSSIBLE AT KFWA EARLY THURSDAY MORNING. BOUNDARY SHOULD MIX
NORTHWARD FOR THURSDAY WITH SOUTH WINDS OF 10 TO 15 KNOTS AT
TERMINALS THURSDAY AFTERNOON.

&&

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

$$

UPDATE...MARSILI
SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...JT
AVIATION...MARSILI


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