Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 280819
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
419 AM EDT TUE APR 28 2015

.SYNOPSIS...
ISSUED AT 218 AM EDT TUE APR 28 2015

CLEAR SKIES AND LIGHT WINDS WILL SET THE STAGE FOR FROST ACROSS
MUCH OF THE REGION. THE GREATEST RISK FOR FROST IS ACROSS MUCH OF
NORTHERN INDIANA INTO SOUTHWESTERN LOWER MICHIGAN AS LOWS FALL
INTO THE LOWER TO MIDDLE 30S. TEMPERATURES WILL REBOUND LATER
TODAY WITH HIGHS REACHING INTO THE LOWER 60S IN MOST LOCATIONS.
AREAS ALONG THE LAKE SHORE WILL SEE HIGHS AROUND 50 TO THE MID
50S. LOWS TONIGHT WILL BE AROUND 40.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 417 AM EDT TUE APR 28 2015

WINDS HAD DECOUPLED COMPLETELY OVER NEARLY ALL OF THE FORECAST
AREA WITH CALM WINDS EARLY THIS MORNING. SKIES HAD CLEARED WITH 3
AM EDT TEMPS 32F TO 37F. KEPT THE FROST ADVISORY UNTIL 9 AM GIVEN
FROST FORMING WITH TEMPERATURES EXPECTED TO FALL A FEW MORE
DEGREES. UPSTREAM SOUNDINGS SHOWED THE SUBSIDENCE INVERSION WAS
STRENGTHENING WITH THE BASE OF THE INVERSION ABOVE 850 MB. EXPECT
SOME CLOUDS TO FORM TODAY WITH DAYTIME HEATING UNDER THE BASE OF
THE INVERSION. THE 12 NAM WAS VERIFYING TOO COOL AND TOO MOIST IN
THE LOW LEVELS BASED ON AIRCRAFT SOUNDINGS...SO CLOUD COVER MAY BE
MORE SCATTERED THAN INDICATED IN THE FORECAST. OTHERWISE...WINDS
SHOULD REMAIN LIGHT WITH WEAK RIDGING OVER THE AREA. FAVORED THE
WARMER GFS WITH HIGHS MAINLY IN THE LOWER 60S.

&&

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 417 AM EDT TUE APR 28 2015

AMPLIFYING UPR LEVEL FLOW ACROSS WRN CANADA/U.S. OVER THE NEXT 24HRS
IS EXPECTED TO RESULT IN SHRTWV OVER THE UPR MIDWEST THIS MORNING
TRANSITIONING TO A CLOSED LOW OVER THE UPR GRTLKS BY WED NGT...
WHICH PROCEEDS S-SE INTO THE OH VALLEY BY THU NGT... MERGING/PHASING
WITH LOW CURRENTLY MOVG ENE FROM TX. MODELS CONT TO HAVE
CONSIDERABLE DIFFERENCES ON STRENGTH/TIMING/TRACK OF THIS SYSTEM...
SO FOR NOW HAVE CONTD TO FOLLOW CONSENSUS. ALTHOUGH MODEL
DIFFERENCES SUGGEST CONSIDERABLE UNCERTAINTY ON IMPACTS IN OUR AREA
FROM THIS SYSTEM... IT DOES APPEAR IT WILL BE STRONG ENOUGH TO CAUSE
AT LEAST SCT SHOWERS IN OUR CWA DESPITE LIMITED MOISTURE. THIS LOW
EXPECTED TO MOVE ESE TO THE MID ATLANTIC COAST FRI WITH AN UPR RIDGE
BUILDING INTO THE WRN GRTLKS IN ITS WAKE. THIS SHOULD RESULT IN FAIR
WX WITH WARMER TEMPS IN OUR AREA... THOUGH LIGHT NORTHERLY GRADIENT
WILL PERSIST... LIMITING WARMUP... ESPECIALLY NEAR LAKE MICHIGAN.
FLOW ALOFT EXPECTED TO TRANSITION TO ZONAL OVER OUR AREA AND ACROSS
THE NRN PLAINS/ROCKIES SATURDAY WITH SFC HIGH MOVG TO THE SERN
CONUS. THIS SHOULD FINALLY RESULT IN SWLY LOW LEVEL FLOW DVLPG
ACROSS OUR AREA WHICH SHOULD THEN PERSIST INTO EARLY NEXT WEEK
RESULTING IN A CONTD WARMING TREND WITH ABOVE NORMAL TEMPS. TROF
EXPECTED TO MOVE EAST FROM THE NRN ROCKIES SUNDAY TO THE UPR GRTLKS
MONDAY OR TUE WITH A LEAD WEAKER SHRTWV PSBLY MOVG THROUGH THE AREA
AHEAD OF THE MAIN SYSTEM SUNDAY. SUFFICIENT DIFFERENCES IN MEDIUM
RANGE MODELS HANDLING OF BOTH SYSTEMS TO MAINTAIN A CONSENSUS FCST
FOR NOW RESULTING IN BROAD BRUSHED LOW-MEDIUM POPS SUNDAY-MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 130 AM EDT TUE APR 28 2015

WINDS HAD DECOUPLED TO CALM WINDS OVER NEARLY ALL OF NORTHERN
INDIANA EARLY THIS MORNING. UPSTREAM SOUNDINGS SHOWED THE
SUBSIDENCE INVERSION WAS STRENGTHENING WITH THE BASE OF THE
INVERSION ABOVE 850 MB. KEPT VFR CIGS TODAY AS MOISTURE UNDER THE
BASE OF THE INVERSION WILL FORM CLOUDS WITH DAYTIME MIXING. SBN
MAY BE MORE SCATTERED TODAY GIVEN THE 12 NAM WAS VERIFYING TOO
COOL AND TOO MOIST IN THE LOW LEVELS BASED ON AIRCRAFT SOUNDINGS.
OTHERWISE...WINDS SHOULD REMAIN LIGHT WITH WEAK RIDGING OVER THE
AREA.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR
     INZ003>006-012>016-020-022.

MI...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ077>080.

OH...NONE.
LM...NONE.
&&

$$

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


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