Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 211858
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
258 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...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM EDT THU MAY 21 2015

QUIET/SEASONABLY COOL WX WILL PERSIST THIS PERIOD IN NW FLOW AS
JAMES BAY NEGATIVE HEIGHT ANOMALY DROPS INTO SOUTHERN QUEBEC. VORT
LOBE ROTATING THROUGH THE SOUTHWEST FRINGE OF THIS FEATURE WILL
DROP A WEAKENING COLD FRONT THROUGH THE AREA LATER TONIGHT. DECENT
CONVERGENCE/LAPSE RATES NOTED IN THE NORTH BUT EXPECTING NOTHING
MORE THAN ISO-SCT SPRINKLES/LIGHT SHOWERS AT BEST ACROSS
NORTHERN/EASTERN ZONES LATER TONIGHT GIVEN SHALLOW MOISTURE/LIFT.
DRY/MAINLY CLEAR OTHERWISE POST FRONTAL TOMORROW WITH DEEP
MIXING/AMPLE SUNSHINE LIKELY ENOUGH TO OFFSET WEAK CAA...WHICH
SHOULD ALLOW AFTERNOON HIGHS TO MAKE A RUN AT THE MID-UPPER 60S
(COOLER NEAR LAKE MI).

&&

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM EDT THU MAY 21 2015

WATER VAPOR SHOWS UPPER LOW OFF THE WEST COAST THIS AFTERNOON AND
THIS WILL BE OUR MAIN IMPACT PLAYER FOR LATER IN THE HOLIDAY WEEKEND
THROUGH THE MIDDLE PART OF NEXT WEEK. UPPER TROUGH TO DRIFT INTO
WESTERN CONUS WHILE HEIGHTS RISE OVER OUR AREA AND SOUTHWEST FLOW
DEVELOPS. THIS WILL LEAD TO SLOW WARMING TREND ALONG WITH INCREASING
HUMIDITY. SHORT WAVE RIDGING ALONG WITH SFC HIGH TO OUR EAST SHOULD
KEEP THE AREA DRY UNTIL AT LEAST SUNDAY. AS WE HAVE DISCUSSED FOR
DAYS...MODELS WERE INITIALLY OVERDONE WITH QPF AND CONVECTIVE
DEVELOPMENT AND ARE CONTINUING TO TREND SLOWER WITH LESS COVERAGE
ASSOCIATED WITH LEAD SHORT WAVES. HAVE CONTINUED TO SCALE POPS BACK
FOR SATURDAY NIGHT AND EARLY SUNDAY AND CONFINED JUST TO THE WESTERN
THIRD SUNDAY MORNING.

BY LATER SUNDAY INTO MONDAY HEIGHTS BEGIN TO FALL AS UPPER TROUGH
INCHES CLOSER. BETTER LOW LEVEL MOISTURE IN PLACE AND SCATTERED
SHOWERS AND THUNDERSTORMS BECOME MORE LIKELY WITH ANY SHORT
WAVES...ESPECIALLY WEST. WILL KEEP LIKELY POPS CONFINED TO WEST AND
NORTH WHERE BETTER FORCING AND MOISTURE WILL COEXIST AND LEAVE
CENTRAL AND EASTERN AREAS IN CHANCE CATEGORY.

TROUGH WILL OPEN AND FILL AS IT MOVES EAST BUT WEAK QUASI STATIONARY
BOUNDARY LIKELY WILL BE LEFT BEHIND IN THE GREAT LAKES OR MIDWEST
REGION. EXPECT SOME CONVECTIVE DEVELOPMENT AND POSSIBLE MCS ACTIVITY
WHICH COULD IMPACT OUR AREA. BROAD CHANCE POPS THROUGH END OF PERIOD
GIVEN THIS SETUP BUT AGAIN...EXPECT SCATTERED CONVECTION AND MANY
HOURS OF DRY TIME.

&&

.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...STEINWEDEL
LONG TERM...LASHLEY
AVIATION...STEINWEDEL


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