Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 271040
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
640 AM EDT WED APR 27 2016

.SYNOPSIS...
ISSUED AT 205 AM EDT WED APR 27 2016

DRY AND COOL AIR FILTERING INTO THE REGION WILL ALLOW TEMPERATURES
TO DIP INTO THE 40S OVERNIGHT. MOSTLY CLOUDY CONDITIONS OVERNIGHT
WILL GIVE WAY TO SOME SUN LATER TODAY WITH TEMPERATURES WARMING
TO AROUND 60. RAIN AND A FEW THUNDERSTORMS WILL SPREAD ACROSS THE
AREA TONIGHT. SEVERE WEATHER IS NOT EXPECTED.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 435 AM EDT WED APR 27 2016

A SURFACE RIDGE OF HIGH PRESSURE WAS HELPING TO SPREAD CHILLY AIR
INTO THE AREA FROM CANADA. THIS SYSTEM WILL ATTEMPT TO DEEPEN A
SHALLOW WEDGE OF COLD AIR NORTH OF THE OHIO RIVE. HOWEVER...A
DEVELOPING WEATHER SYSTEM UPSTREAM WILL CAUSE WINDS TO VEER EAST AND
LIMIT FURTHER DEEPENING OF THE COLD AIR. THIS COOL AND DRY AIR WILL
BE PROMINENT IN HOLDING BACK THE DEVELOPMENT OF PRECIPITATION TODAY
GIVEN SLOWER NORTHEAST ADVANCEMENT OF THIS SYSTEM WITH DRY AIR
ENTRAINMENT. THE LATEST NAM/BUFKIT APPEARS ON TRACK HOLDING BACK
RAIN UNTIL AFTER THIS EVENING OVER MOST AREAS. IN THIS REGARD...HAVE
LOWERED RAIN CHANCES SIGNIFICANTLY TODAY. MAINTAINED A SLIGHT CHANCE
FOR THUNDER TONIGHT AS AN UPPER LEVEL SYSTEM MOVES NORTHEAST.
ELEVATED STORMS ARE POSSIBLE...BUT SEVERE WEATHER IS NOT EXPECTED.

&&

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 435 AM EDT WED APR 27 2016

THE UPPER LEVEL CIRCULATION KICKING OUT OF THE SOUTHERN/CENTRAL
ROCKIES THIS MORNING WILL EVENTUALLY MAKE ITS WAY ACROSS THE MID MS
RVR VALLEY THURSDAY AFTERNOON...AND ACROSS THE FAR SOUTHERN GREAT
LAKES/OHIO VALLEY THURSDAY NIGHT. THIS PV ANOMALY SHOULD GRADUALLY
WEAKEN AND BECOME MORE ATTENUATED ACROSS THE AREA. SFC
REFLECTION/OCCLUDED FRONT SHOULD BE WORKING ACROSS FAR SOUTHERN
PORTIONS OF THE FORECAST AREA LATER THURSDAY. A ZONE OF ISENTROPIC
UPGLIDE WITH EASTWARD PROGRESSING LOW LEVEL THERMAL RIDGE AND
VORTICITY ADVECTION ASSOCIATED WITH WEAKENING MID/UPPER LEVEL TROUGH
SHOULD BE SUFFICIENT FOR SCATTERED-NUMEROUS SHOWERS DURING THE DAY
THURSDAY...EVENTUALLY TAPERING THURSDAY NIGHT AS UPPER WAVE
CONTINUES TO DAMPEN/SHIFT EASTWARD. BEST CHANCE OF THUNDER SHOULD BE
ACROSS THE FAR SOUTH GIVEN BETTER POTENTIAL OF LARGER SCALE LOW
LEVEL CONVERGENCE WITH BOUNDARY AND A GREATER LIKELIHOOD OF SFC OR
NEAR SFC BASED INSTABILITY. CONSIDERED REMOVING THUNDER ACROSS THE
FAR NORTH...BUT AT THIS TIME WILL MAINTAIN THE THUNDER MENTION
ACROSS THE ENTIRE FORECAST AREA WITH SOME WEAK ELEVATED INSTABILITY
POSSIBLE ACROSS THE NORTH. A BRIEF WINDOW MAY EXIST ACROSS THE
EXTREME SOUTH/SOUTHEAST FOR A STRONG STORM THURSDAY AFTERNOON BUT
UNCERTAINTY IN MIXING HEIGHTS/INSTABILITY PERSISTS...AND GREATER
POTENTIAL MAY REMAIN SOUTH OF THE AREA. WITH BOUNDARY ACROSS THE
AREA...A FAIRLY SIZABLE NORTH TO SOUTH GRADIENT IN MAX TEMPS IS
EXPECTED FOR THURSDAY WITH HIGHS RANGING FROM MID 50S NORTH TO MID-
UPPER 60S FAR SOUTH.

UPPER RIDGING TO BUILD INTO THE AREA FRIDAY/FRIDAY NIGHT AS NEXT
LONGWAVE TROUGH DIGS ACROSS SOUTHWEST CONUS. NORTHEAST LOW LEVEL
FLOW ON SOUTHERN PERIPHERY OF SOUTHERN CANADA ANTICYCLONE WILL LIMIT
RECOVERY IN TEMPS ON FRIDAY WITH HIGHS GENERALLY FROM UPPER 50S TO
MID 60S...BUT A LITTLE COOLER NEAR LAKE MICHIGAN. SOUTHWEST CONUS
TROUGH WILL LIFT INTO CENTRAL PLAINS SATURDAY...BUT LARGE SCALE
BLOCKING PATTERN SHOULD LIMIT PROGRESSION/INTEGRITY OF THIS TROUGH
WITH EASTWARD EXTENT ACROSS LOCAL AREA. NONETHELESS...AN IMPRESSIVE
LOW/MID LEVEL THETAE SURGE SHOULD WORK INTO THE AREA SATURDAY
SUPPORTING INCREASING RAIN SHOWER CHANCES FROM SOUTHWEST TO
NORTHEAST. 00Z GFS AND TO SOME EXTENT GEFS MEANS REMAIN A BIT MORE
SUPPRESSED WITH THIS FEATURE. HARD TO TOTALLY DISCOUNT THE SLIGHTLY
MORE SUPPRESSED IDEA OF GFS GIVEN BLOCKING NATURE TO THIS PATTERN
BUT WILL CONTINUE WITH FORECAST CONTINUITY OF BLENDED APPROACH TO
POPS FOR SATURDAY-SUNDAY WITH LIKELY POPS SOUTH/HIGH CHANCE NORTH.

REX BLOCK DEVELOPING FOR EARLY NEXT WEEK ACROSS NORTHWEST
CONUS/SOUTHWEST CANADA SHOULD RESULT IN A PRIMARILY NORTHWEST UPPER
FLOW PATTERN DEVELOPING FOR LOCAL AREA WITH TEMPS RIGHT AROUND
SEASONABLE NORMS FROM THE MID TO UPPER 60S FOR HIGHS. PRECIP
POTENTIAL POST-SUNDAY APPEARS TO BE ON THE LOW SIDE GIVEN THE
MID/UPPER LEVEL PATTERN THAT IS EXPECTED TO EVOLVE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 619 AM EDT WED APR 27 2016

IFR AND LOWER END MVFR CIGS PERSIST ACROSS NORTHERN INDIANA EARLY
THIS MORNING WITH LOW LEVEL MOISTURE TRAPPED BENEATH A STRONG LOW
LEVEL INVERSION. EASTERLY LOW LEVEL FLOW WILL MAKE FOR POOR MIXING
THROUGH MIDDAY AND MVFR CIGS WILL CONTINUE THROUGH THE MORNING
HOURS. ANY IFR CIGS SHOULD IMPROVE TO MVFR BY THE 14Z-15Z
TIMEFRAME. DIURNAL IMPROVEMENT TO CIGS NEAR FUEL ALTERNATE
CRITERIA IS EXPECTED BY MID TO LATE MORNING WITH EVENTUAL
TRANSITION TO VFR CONDITIONS THIS AFTERNOON AS LOW LEVEL MIXING
INCREASES. EAST WINDS WILL BE GUSTY TODAY...GENERALLY AROUND 20
KNOTS. CHANCES OF RAIN WILL INCREASE LATER THIS EVENING AS
STRONGER THERMAL/MOISTURE ADVECTION WORKS INTO NORTHERN INDIANA IN
ADVANCE OF APPROACHING UPPER TROUGH. CONDITIONS MAY DETERIORATE
BACK TO IFR TOWARD THE END OF THE PERIOD...BUT WILL MAINTAIN TREND
BACK TO MVFR CIGS TONIGHT.

&&

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

$$

SYNOPSIS...SKIPPER
SHORT TERM...SKIPPER
LONG TERM...MARSILI
AVIATION...SKIPPER/MARSILI


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