Area Forecast Discussion
Issued by NWS Northern Indiana

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304
FXUS63 KIWX 291723
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
123 PM EDT FRI APR 29 2016

.SYNOPSIS...
ISSUED AT 130 PM EDT FRI APR 29 2016

MOSTLY CLOUDY SKIES ARE EXPECTED THIS EVENING AND OVERNIGHT. RAIN
IS EXPECTED TO DEVELOP TO THE SOUTH AND MOVE NORTH ACROSS THE
REGION ON SATURDAY INTO SATURDAY NIGHT. RAINFALL AMOUNTS BETWEEN
ONE HALF AND ONE INCH ARE POSSIBLE. HIGHS THIS AFTERNOON WILL
RANGE FROM THE MIDDLE 50S IN FAR SOUTHERN LOWER MICHIGAN TO THE
MIDDLE 60S TOWARDS CENTRAL INDIANA. LOWS TONIGHT WILL BE IN THE
MIDDLE 40S NORTH TO LOWER 50S SOUTH.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM EDT FRI APR 29 2016

FORECAST ISSUES WILL INVOLVE 1) AMOUNT OF CLOUD COVER AND SUBSEQUENT
TEMPS TODAY 2) TIMING OF LIGHT RAIN INTO FAR SOUTHERN AREAS LATER
TONIGHT

THROUGH SUNRISE FRIDAY...SOUNDINGS AND PATTERN WOULD SUGGEST
LOW CLOUDS WILL HOLD GIVEN EAST TO NORTHEAST FLOW. HOWEVER TRENDS
ACROSS ILLINOIS INTO CENTRAL INDIANA SHOW CLEARING TAKING PLACE WITH
NOTED NORTHWARD PROGRESS. FAR SW AREAS MAY SEE SOME CLEARING TOWARDS
SUNRISE BUT NOT CONVINCED IT WILL MAKE A LOT OF PROGRESS NORTHWARD
GIVEN PROXIMITY OF FILLING UPPER LOW. UPDATE TO SKY COVER MAY
BE NEEDED TO ACCOUNT FOR TRENDS BUT WILL STICK WITH MOSTLY CLOUDY
TO CLOUDY FOR NOW. PRECIP CHANCES WILL NEED TO BE INTRODUCED (AT
LEAST FOR SPRINKLES OR LIGHT SHOWERS) AS BAND OF RADAR RETURNS
WORKING NORTHEAST SHOWING SIGNS OF REACHING THE GROUND. LOOKS LIKE
ONLY A FEW HOURS TO DEAL WITH IT SO WILL ATTEMPT TO ADD SOME TIMING
TO THE AREA.

TODAY INTO THIS EVENING...  ALL GUIDANCE POINTS TOWARDS THE CLOUDS
HOLDING ON STRONG. GIVEN NEAR TERM TRENDS...WILL REMAIN SOMEWHAT
OPTIMISTIC WITH CLOUDS TRENDING TOWARDS MOSTLY CLOUDY THIS AFTERNOON
INTO THIS EVENING. WITH THE WARMER AIR TRAPPED TO THE
SOUTH...ANOTHER COLD DAY BY LATE APRIL STANDARDS WILL BE IN STORE
WITH HIGHS REACHING THE MIDDLE 50S TO LOWER 60S.

OVERNIGHT...STATIONARY BOUNDARY THAT HAS RESIDED SOUTH OF THE AREA
THE PAST COUPLE OF DAYS WILL BEGIN TO EDGE NORTH IN RESPONSE TO LOW
PRESSURE MOVING SLOWLY OUT OF TEXAS INTO NE KANSAS BY 12Z SAT. NAM
MOST AGGRESSIVE WITH LIGHT RAIN STARTING TO MOVE INTO FAR SW/S AREAS
TOWARDS 12Z WITH ECMWF/GFS MUCH SLOWER (INTO LONG TERM PERIOD).
AFTER IN HOUSE DISCUSSION AND GENERAL CONSENSUS OF MOST SURROUNDING
OFFICES HAVE INTRODUCE SLGT CHC TO CHC POPS IN FAR SOUTH IN THE 9 TO
12Z WINDOW FOR CONSISTENCY SAKE.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 340 AM EDT FRI APR 29 2016

LONG TERM PERIOD TO BEGIN UNSETTLED AS A 40-50 KNOT LOW LEVEL JET
ALLOWS FOR LOW LEVEL MOISTURE/THERMAL SURGE NORTHWARD INTO THE
FORECAST AREA. WHILE WIDESPREAD RAIN LOOKS PROBABLE BY
AFTERNOON...STILL SOME UNCERTAINTY REGARDING EXACT TIMING OF
INCREASING RAIN CHANCES FROM SOUTHWEST TO NORTHEAST SATURDAY MORNING
WITH SOME UPSTREAM CONVECTIVE ENHANCEMENT POSSIBLE TO A SOUTHWEST
FLOW VORT MAX MOVING INTO THE AREA FROM THE SOUTHERN PLAINS. LOW/MID
LEVEL FLOW WILL ALSO BECOME INCREASINGLY FRONTOGENETIC IN NATURE
DUE TO EMERGENCE OF MAIN UPPER PV ANOMALY ACROSS THE CENTRAL PLAINS
SATURDAY AND NORTHERN STREAM VORT MAX DROPPING SOUTHWARD ACROSS THE
NORTHERN GREAT LAKES. THE ABOVE FACTORS STILL SUPPORT
LIKELY/CATEGORICAL POPS SATURDAY FOR MOST OF THE AREA...WITH
EASTERLY WINDS GUSTING INTO THE 20 TO 25 MPH RANGE. NOT MUCH
TEMPERATURE RECOVERY IS EXPECTED SATURDAY DUE TO EASTERLY FLOW AND
INITIAL EVAPORATIVE COOLING EFFECTS WITH PRECIP. WARMEST MINS CLOSE
TO 60 ARE POSSIBLE ESPECIALLY ACROSS NORTH/NORTHEAST PORTIONS OF THE
AREA WHERE A LATER PRECIP ARRIVAL IS EXPECTED.

LULL IN GREATER RAIN COVERAGE IS STILL EXPECTED LATER SATURDAY NIGHT
INTO SUNDAY AS LEAD SHORT WAVE DAMPENS AND LOW LEVEL WINDS VEER.
WITH WEAK FORCING PERSISTING OVERNIGHT AND DIMINISHING MOISTURE
DEPTHS SOME PATCHY LIGHT RAIN/DRIZZLE LIKELY TO PERSIST ACROSS
PORTIONS OF THE AREA THROUGH SUNDAY MORNING. SUNDAY AFTERNOON
FORECAST IS OF RELATIVELY LOW CONFIDENCE DUE TO UNCERTAINTY IN FINER
DETAILS REGARDING EVOLUTION OF WEAKENING UPPER VORT MAX ACROSS THE
CENTRAL PLAINS AS IT BECOMES MORE SHEARED ACROSS THE SOUTHERN GREAT
LAKES. SOME INCREASE IN MOISTURE DEPTH SHOULD ACCOMPANY EASTWARD
PROGRESSION OF THIS FEATURE WITH A POSSIBILITY OF LINGERING LOW/MID
LEVEL FGEN FORCING ACROSS SOUTH/SOUTHEAST PORTIONS OF THE AREA. BEST
CHANCES OF SCATTERED SHOWER REDEVELOPMENT SUNDAY AFTERNOON APPEAR TO
BE ACROSS THE SOUTH BUT WILL CONTINUE TO CARRY JUST CHANCE POPS DUE
TO ABOVE UNCERTAINTY.

MONDAY SHOULD BE QUIET AS THIS UPPER VORT MAX DEPARTS TO THE EAST.
COOLER LEVEL TEMPS WILL ADVECT INTO THE AREA BEHIND THIS FEATURE BUT
BETTER INSOLATION ON MONDAY SHOULD KEEP HIGHS IN THE LOWER 60S.
MEDIUM RANGE MODELS REMAIN FAIRLY INCONSISTENT IN RESOLVING
TIMING/STRENGTH/TRACK OF ADDITIONAL SHORT WAVES DROPPING INTO THE
GREAT LAKES FOR TUESDAY-THURSDAY AND THUS HAVE TRIED TO KEEP PERIODS
OF MENTIONABLE POPS TO A MINIMUM. IT DOES APPEAR AS THOUGH BEST
CHANCE OF A FRONTAL PASSAGE SOME TIME IN THE TUESDAY NIGHT/WEDNESDAY
TIMEFRAME WHERE HAVE MAINTAINED LOW CHANCE POPS. CONFIDENCE IN TEMP
FORECAST DOES DECREASE SOMEWHAT POST-TUESDAY WITH DEPENDENCE OF
STRENGTH OF THERMAL ADVECTION ON SHORT WAVE TRACK/INTENSITY...BUT
OVERALL...PERIOD SHOULD BE CHARACTERIZED BY SEASONABLE TEMPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 116 PM EDT FRI APR 29 2016

CONDITIONS WERE SLOWLY IMPROVING EARLY THIS AFTERNOON WITH KFWA UP
TO LOW END MVFR BUT KSBN STILL AT IFR WITH ISSUANCE. SHOULD SEE
CIGS SLOWLY RISE WITH WARMING AND WEAK MIXING THIS AFTERNOON. KEPT
TREND OF HIRES GUIDANCE WITH MVFR CIGS THIS AFTERNOON AND
OPTIMISTIC VFR LATER THIS EVENING. EASTERLY LOW LEVEL WINDS TO
INCREASE TOWARD SUNRISE AS SYSTEM TO OUR SOUTHWEST APPROACHES.
RAIN WILL SPREAD NORTH ON SATURDAY BUT LOWER CIGS AND VIS WITH
RAIN ONSET EXPECTED TO BE CLOSER TO OR JUST AFTER 18Z AT KSBN AND
KFWA SO KEPT THESE SITES VFR. EXPECT SIGNIFICANT DOWN TURN IN
FLIGHT CONDITIONS SAT AFTERNOON WITH NEXT ISSUANCE.

&&

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

$$

SYNOPSIS...FISHER/LASHLEY
SHORT TERM...FISHER
LONG TERM...MARSILI
AVIATION...LASHLEY


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