Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 311740
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
140 PM EDT THU JUL 31 2014

.SYNOPSIS...
ISSUED AT 1100 AM EDT THU JUL 31 2014

LOW PRESSURE CENTERED IN ONTARIO CANADA WILL PASS ANOTHER
SHORTWAVE THROUGH THE REGION TODAY. THIS WILL BRING A SMALL CHANCE
FOR SOME RAIN THIS AFTERNOON. OTHERWISE SKIES WILL BE PARTLY
CLOUDY WITH HIGH TEMPERATURES RANGING FROM THE UPPER 70S IN
SOUTHERN MICHIGAN TO THE LOWER 80S ALONG THE OHIO RIVER. TONIGHT
WILL BE PARTLY CLOUDY WITH LOW TEMPERATURES AROUND 60 DEGREES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT THU JUL 31 2014

MID LEVEL HEIGHT RISES WITH STRONGER/MORE PERTURBED NORTHWEST FLOW
(AND CORE OF COLD AIR ALOFT) SHIFTING ENE OF THE LOCAL AREA WILL
RESULT IN LOWER COVERAGE/PROBABILITY OF DIURNALLY DRIVEN
SHOWERS/THUNDER AND SLIGHTLY WARMER TEMPS WHEN COMPARED TO THE
PREVIOUS TWO DAYS. SUBTLE LOW LEVEL MOISTURE ADVECTION AS WINDS
INCREASE/BACK WESTERLY UNDER LINGERING TROUGH AXIS SHOULD STILL
SUPPORT 500-800 J/KG OF THIN CAPE BY THIS AFTN. THIS AND LACKING
CONVECTIVE INHIBITION MAY BE ENOUGH TO HELP GENERATE ISOLATED
SHOWERS/THUNDER ALONG A WEAK SFC CONVERGENCE AXIS THAT WILL LIKELY
MATERIALIZE DOWNWIND OF LAKE MI. REGARDLESS...ANOTHER MAINLY
DRY/PLEASANT DAY FOR LATE JULY STANDARDS.

LOSS OF HEATING AND LACKING SUPPORT ALOFT WILL LIKELY RESULT IN A
DRY EVENING. THE MID LEVEL FLOW WILL BACK MORE SOUTHWESTERLY BY
LATER TONIGHT IN ADVANCE OF SHORTWAVE ENERGY THAT WILL APPROACH ON
THE BACKSIDE OF THE PRIMARY EASTERN CONUS UPPER TROUGH. MODEST
MOISTURE TRANSPORT WITH THIS FEATURE COULD AID IN BRINGING A FEW
SHOWERS TO NW IN/SW LOWER MI.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 405 AM EDT THU JUL 31 2014

AN UPPER LOW WILL BE NEAR JAMES BAY AT THE START OF THE PERIOD AND
SHOULD BE LIFTING NORTHEAST. THIS WILL ALLOW THE UPPER AIR PATTERN
TO BECOME MORE HIGH ZONAL...WITH SHORT WAVE ENERGY MOVING SOUTHEAST
TOWARD THE WESTERN GREAT LAKES REGION. KEPT A CHANCE FOR MAINLY
AFTERNOON THUNDERSTORMS FRIDAY AND SATURDAY GIVEN LIMITED LOW LEVEL
CONVERGENCE...BUT WITH SUFFICIENT DAYTIME HEATING TO ALLOW AFTERNOON
CAPE VALUES TO ARISE TO BETWEEN 500 AND 1000 J/KG. MOISTURE FLUX
INTO THE AREA WILL REMAIN VERY LIMITED UNTIL NEAR THE END OF THE
FORECAST PERIOD. GIVEN THE VERY LOW CORRELATION COEFFICIENT OF THE
500 MB ANALOGS...AND LIMITED RUN TO RUN CONSISTENCY...KEPT THE
ONGOING CHANCE FOR THUNDERSTORMS TUESDAY AND WEDNESDAY. AS FOR
TEMPERATURES...850 MB TEMPERATURES SHOULD GRADUALLY RECOVER...AND
ALLOW HIGHS TO TOP 80 DEGREES. FAVORED THE COOLER GFS MEX MEAN
ENSEMBLE NUMBERS OVER THE WARMER OPERATIONAL RUN FORECAST
TEMPERATURES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 122 PM EDT THU JUL 31 2014

THREAT FOR ISOLATED SHOWERS AND STORMS CONTINUES THROUGH THE
AFTERNOON WITH PEAK HEATING. BEST CHANCES MAY RESIDE BETWEEN BOTH
TAF SITES SO HAVE OPTED TO CONTINUE NO MENTION IN TAFS. CU WILL
DISSIPATE THIS EVENING WITH NEXT BATCH OF THICKER CLOUDS STARTING
TO STREAM IN AHEAD OF THE NEXT SOMEWHAT STRONGER WAVE. CIGS/VSBY
SHOULD STILL BE VFR. CHANCE OF SHOWERS/STORMS DOES EXIST IN THE 15
TO 18Z BUT CONFIDENCE IN COVERAGE AND LOCATION TOO LOW TO ADD WITH
BETTER CHANCES AFTER 18Z.

&&

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

$$

SYNOPSIS...LOTHAMER
SHORT TERM...STEINWEDEL
LONG TERM...SKIPPER
AVIATION...FISHER


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