Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 211644
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1244 PM EDT THU MAY 21 2015

.SYNOPSIS...
ISSUED AT 1056 AM EDT THU MAY 21 2015

HIGH PRESSURE OVER THE REGION WILL PROVIDE THE REGION WITH DRY
CONDITIONS THIS AFTERNOON AND EVENING. CLOUD COVERAGE WILL BE ON
THE DECREASE THIS AFTERNOON LEADING TO CLEAR TO MOSTLY CLEAR SKIES
TONIGHT. DRY WEATHER FOR TONIGHT EXCEPT FOR JUST THE NORTHEASTERN
CORNER OF THE REGION SEEING A CHANCE FOR SOME SPRINKLES. HIGHS
TODAY WILL RANGE FROM AROUND 60 IN THE SOUTH TO THE MIDDLE 60S IN
SOUTHERN MICHIGAN. LOWS TONIGHT WILL BE IN THE MIDDLE TO UPPER
40S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 337 AM EDT THU MAY 21 2015

BROAD SFC RIDGE CNTRD THROUGH THE CNTRL PLAINS WILL SHIFT EWD INTO
THE WRN LAKES TONIGHT. SECONDARY MSTR STARVED DISTURBANCE ROTATING
THROUGH BASE OF SW TROUGH THROUGH WRN QB MAY GENERATE A SPRINKLE OR
TWO AFT MIDNIGHT FAR NE AND RETAINED MENTION. OTRWS WX NIL THIS PD
WITHIN SFC RIDGE AXIS AS TEMPS BEGIN TO MODERATE.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 337 AM EDT THU MAY 21 2015

PICTURESQUE WEATHER FOR THE FIRST HALF OF THE UPCOMING HOLIDAY
WEEKEND AS SOUTHERN GREAT LAKES REMAIN ON THE SUBSIDENT DOWNSTREAM
SIDE OF BUILDING CENTRAL CONUS RIDGE. TEMPS WILL STILL BE SLIGHTLY
ON THE COOL SIDE OF CLIMO...ESPECIALLY ON FRIDAY WITH A FRESH PUSH
OF COOL...CANADIAN AIR BEHIND EXITING FRONTAL BOUNDARY.
HOWEVER...FULL MAY SUN AND VERY DRY LOW LEVELS WILL PROMOTE MIXING
TO AROUND 800MB. THIS SHOULD ALLOW AFTERNOON HIGHS TO CLIMB INTO THE
MID TO UPPER 60S FOR MOST LOCATIONS. CLOUDS BEGIN TO INCREASE ON
SATURDAY BUT THERMAL PROFILES ALSO MODERATE AND SHOULD CLIMB INTO
THE LOW TO MID 70S UNDER JUST PARTLY CLOUDY SKIES.

RIDGE AXIS SHIFTS EAST FOR THE LATTER HALF OF THE HOLIDAY WEEKEND
AND INCREASING SOUTHWEST FLOW/WAA WILL BRING INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS. STILL A HIGH DEGREE OF UNCERTAINTY
REGARDING HOW EXACTLY PIECEMEAL EJECTION OF WESTERN CONUS TROUGH
WILL UNFOLD. MODELS HAVE BEEN TRENDING SLOWER...A COMMON OCCURRENCE
IN THESE HIGHLY AMPLIFIED PATTERNS...AND LATEST GFS ACTUALLY KEEPS
US DRY THROUGH SUNDAY NIGHT WITH MAIN BELT OF ISENTROPIC ASCENT
FOCUSED WELL TO OUR NORTH. LATEST 00Z GFS EVEN SHOWS A MORE SUBDUED
(AND LIKELY MORE REALISTIC) DEPICTION OF CONVECTION COVERAGE FOR
MONDAY AND TUESDAY. ECMWF PAINTS A VERY DIFFERENT PICTURE BUT STILL
KEEPS US DRY UNTIL SUNDAY AFTERNOON. PREFER TO LEAN ON THE DRIER GFS
GIVEN POOR PERFORMANCE OF MODEL QPF IN SIMILAR PATTERNS OF LATE.
SEEMS AS THOUGH STUBBORN EASTERN CONUS RIDGE IS A SERIOUS HINDRANCE
TO ANY PRECIP ABSENT ANY WELL DEFINED SHORTWAVES LIFTING NORTHEAST.
NOT THAT WE WONT HAVE THESE SUBTLE WAVES PASSING THROUGH AT TIMES
EARLY NEXT WEEK BUT AS PREVIOUSLY DISCUSSED...PRECIP COVERAGE AND
TIMING WILL DEPEND ON EXACTLY WHEN AND WHERE THESE WAVES PASS AND
THAT IS IMPOSSIBLE TO NAIL DOWN MORE THAN A DAY OR TWO IN ADVANCE.
KEPT SOME LOW END LIKELY POPS IN OUR NORTHWEST AND IT WILL PROBABLY
RAIN AT SOME POINT EARLY NEXT WEEK BUT AGAIN...NOT EXPECTING A
WASHOUT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1237 PM EDT THU MAY 21 2015

VFR CONDITIONS WILL PREVAIL THROUGH THE TAF CYCLE THANKS TO DRIER
NW FLOW REGIME THAT WILL PERSIST. VFR CLOUD DECK ASSOCIATED WITH A
COMPACT SHORTWAVE TROUGH SHOULD SHIFT SE OF KSBN SHORTLY AFTER TAF
ISSUANCE AND KFWA BY LATE AFTERNOON...LEAVING MAINLY CLEARS IN ITS
WAKE INTO THE EVENING. A SECONDARY SFC TROUGH STILL ON TARGET TO
DROP THROUGH LATER TONIGHT/EARLY TOMORROW. COULD SEE A FEW
SPRINKLES/SHOWERS WITH THIS FEATURE...HOWEVER CONFIDENCE/COVERAGE
THIS FAR IN THE ADVANCE REMAINS TOO LOW FOR SHRA INCLUSION.
OTHERWISE...CLOUD DECK BTW 5-10 KFT LIKELY TO ACCOMPANY THE
FRONTAL PASSAGE WITH CLEARING SKIES/LIGHT NORTHERLY FLOW IN ITS
WAKE TOMORROW.

&&

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

$$

SYNOPSIS...LOTHAMER
SHORT TERM...T
LONG TERM...AGD
AVIATION...STEINWEDEL


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