Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 180635
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
235 AM EDT MON AUG 18 2014

.SYNOPSIS...
ISSUED AT 156 AM EDT MON AUG 18 2014

AN AREA OF LOW PRESSURE OVER THE OHIO VALLEY WILL MOVE EAST OUT OF
THE REGION TONIGHT AS AN UPPER LEVEL SYSTEM AND ASSOCIATED LOW
PRESSURE AREA REACHES THE WESTERN GREAT LAKES REGION BY LATE
TUESDAY. CHANCES FOR THUNDERSTORMS WILL INCREASE TONIGHT AHEAD OF
THIS NEXT SYSTEM...WITH A GOOD CHANCE FOR STORMS TUESDAY.
HIGHS TODAY WILL BE AROUND 80. LOWS TONIGHT WILL BE IN THE LOW TO
MID 60S. HIGHS TUESDAY WILL BE IN THE LOW TO MID 80S.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 303 PM EDT SUN AUG 17 2014

LATEST SATELLITE AND SURFACE OBSERVATIONS INDICATE INCREASINGLY
DIFFUSE FRONTAL BOUNDARY IS STILL DRAPED OVER THE AREA. TAIL END OF
PARENT PV ANOMALY THAT GENERATED ISOLATED SHOWERS OVER SOUTHERN
MICHIGAN THIS MORNING HAS PULLED RAPIDLY EASTWARD TODAY. THIS HAS
LEFT THE SOUTHERN GREAT LAKES IN A REGION OF GEOPOTENTIAL HEIGHT
RISES WITH INCREASING SUBSIDENCE AND FRONTOLYSIS. WATER VAPOR
IMAGERY AND 12Z KDTX SOUNDING ALSO INDICATE VERY DRY CONDITIONS IN
THE MID AND UPPER LEVELS. STILL PLENTY OF LOW LEVEL MOISTURE TO
SUPPORT MOSTLY CLOUDY SKIES AND A FEW ISOLATED SHOWERS IN OUR
NORTHERN COUNTIES...BUT CHANCES OF WIDESPREAD MEASURABLE
PRECIPITATION LOOKING SLIM THIS EVENING AND OVERNIGHT. CONVECTIVELY
ENHANCED VORT MAX TO OUR SOUTH CONTINUES TO TRACK TOO FAR SOUTH TO
SUPPORT ANY MEANINGFUL SHOWER ACTIVITY IN OUR SOUTHERN COUNTIES
EITHER. A STRAY SPRINKLE IN OUR FAR SOUTHERN COUNTIES MAY BE ALL WE
CAN MUSTER. HAVE THEREFORE REMOVED OR REDUCED MOST OF THE POPS FOR
THIS EVENING.

SIMILAR STORY FOR TOMORROW. SOUTHERN GREAT LAKES WILL REMAIN UNDER
THE INFLUENCE OF A DECENT MIDLEVEL RIDGE FOR MUCH OF THE DAY.
RESIDUAL LOW LEVEL MOISTURE CONVERGENCE MAY SPARK A FEW SHOWERS AND
THUNDERSTORMS IN OUR SOUTHEAST COUNTIES BUT LATEST NAM AND GFS KEEP
THE BETTER INSTABILITY CONFINED JUST OUTSIDE OUR CWA. WITH LACK OF
UPPER LEVEL SUPPORT...JUST SLIGHT CHANCE WARRANTED IN THE SOUTHEAST
WITH DRY CONDITIONS ELSEWHERE. MOSTLY CLOUDY SKIES SHOULD KEEP A LID
ON DIURNAL TEMP SWINGS. EXPECT OVERNIGHT LOWS IN THE LOW TO MID 60S
WITH HIGHS TOMORROW GENERALLY AROUND 80F. THIS IS IN LINE WITH BOTH
INHERITED FORECAST AND LATEST MOS GUIDANCE.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 303 PM EDT SUN AUG 17 2014

UPPER LEVEL WAVE WILL CONTINUE TO SHIFT ACROSS THE NORTHERN STATES
INTO THE NORTHERN GREAT LAKES BY TUES NGT INTO WEDS. AT THE SFC A
SLOW MOVING COLD FRONT WILL EDGE EASTWARD WITH SHOWERS AND
THUNDERSTORMS POSSIBLE ALONG AND AHEAD OF IT AT JUST ABOUT ANY TIME
WITH A UNSTABLE AND MOIST ENVIRONMENT IN PLACE. SEVERAL OF THE
MODELS INDICATE CONVECTION FIRING TO THE WEST OF THE FORECAST AREA
IN IA/IL/WI AND MOVING EAST LATE MONDAY NIGHT INTO EARLY TUES. FROM
THIS POINT MODELS DIVERGE SLIGHTLY WITH SOLUTIONS RANGING FROM
CONVECTION THROUGHOUT THE DAY TO A REFOCUSING/DEVELOPMENT OF
CONVECTION ACROSS EASTERN AREAS TUES AFTN/EVE. GIVEN THE SLOW
MOVEMENT OF KEY FEATURES AND LACK OF STRONG FLOW AM INCLINED TO LEAN
TOWARDS A WET AND STORMY TUES INTO TUES EVENING. PRECIPITABLE WATER
ON THE ORDER OF 1.6 TO AS HIGH AS 2 INCHES WILL POOL AHEAD OF THE
FRONT. THIS COMBINED WITH CORFIDI VECTORS OF 5 TO MAYBE 15 KTS AT
BEST SUGGEST A HEAVY RAIN THREAT VS SEVERE WEATHER EVENT. SOMETHING
TO CONTINUE TO WATCH BUT FOR NOW LEAVE OUT OF THE HWO.

UPPER LEVEL RIDGE ACROSS THE SE US WILL GAIN FURTHER STRENGTH AND
BEGIN TO EXTEND ITS INFLUENCE FURTHER NORTH...ALLOWING FOR A PERIOD
OF MORE TYPICAL SUMMER TIME WEATHER. HIGHS SHOULD CLIMB INTO THE 80S
WITH 90S NOT OUT OF THE REALM OF POSSIBILITY ESPECIALLY TOWARDS THE
END OF THE PERIOD AS 588 DM HEIGHTS EDGE IN. A PERTURBED FLOW WILL
EXIST AROUND THE PERIPHERY OF THE RIDGE ("RING OF FIRE") WITH
CHANCES FOR SHOWERS AND STORMS IN THE FORM OF EITHER HIT AND MISS
ACTIVITY OR POTENTIALLY MORE ORGANIZED COMPLEXES. MOST FAVORABLE
TIME FRAME FOR THE FORECAST AREA TO SEE PRECIP CHANCES WILL EXIST IN
THE WEDS TO THURS NGT PERIOD PRIOR TO THE MAIN AXIS OF CONVECTION
SHIFTING INTO THE NORTHERN/CENTRAL GREAT LAKES. WHILE A DRY FORECAST
WILL BE IN PLACE PAST THURSDAY NIGHT...700 MB TEMPS WILL STILL BE
SUFFICIENTLY "COOL" TO ALLOW FOR POP UP SHOWERS AND STORMS EACH
AFTERNOON/EVE BUT NOT WORTHY OF ANY MENTION IN GRIDS FOR NOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 156 AM EDT MON AUG 18 2014

WEAK FLOW WAS OVER NRN INDIANA AND WAS ASSOCIATED WITH A SFC LOW
NEAR THE OHIO RIVER. DRIER AIR WAS SPREADING INTO NW OHIO WITH AN
EAST FLOW...WITH DEW POINTS IN THE UPPER 50S. SKIES HAD CLEARED
OUT OVER FWA...ALTHOUGH DEW POINTS WERE DECREASING WITH DRY AIR
ADVECTION. KEPT TEMPO LOW IFR AT FWA GIVEN THE LIKELIHOOD OF
GROUND FOG GIVEN TEMP/MOISTURE FILE PER BUFKIT SOUNDING.
CONDITIONS SHOULD BECOME VFR BY LATE MORNING GIVEN DAYTIME MIXING.
KEPT THUNDER OUT TONIGHT GIVEN ACTIVITY SHOULD OCCUR AFTER THE
END OF THE TAF PERIOD WITH THE TIMING OF THE UPPER LEVEL SYSTEM
AND ASSOCIATED LOW PRESSURE AREA.

&&

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

$$

SYNOPSIS...SKIPPER
SHORT TERM...AGD
LONG TERM...FISHER
AVIATION...SKIPPER


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