Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 310817
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
417 AM EDT THU JUL 31 2014

.SYNOPSIS...
ISSUED AT 405 AM EDT THU JUL 31 2014

A SERIES OF WEAK DISTURBANCES ROTATING AROUND AN UPPER LEVEL LOW
WILL PROVIDE A LOW CHANCE OF MAINLY AFTERNOON SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH SATURDAY. HIGHS EACH DAY ARE FORECAST TO
REACH TO NEAR 80 DEGREES...WITH LOWS GENERALLY NEAR 60.

&&

.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1256 AM EDT THU JUL 31 2014

LIGHT WINDS/MOSTLY CLEAR SKIES ALLOWING TEMPS TO POTENTIALLY
DROP A FEW DEGREES BELOW XOVER VALUES MAY PROMOTE SOME PATCHY
MVFR VIS RESTRICTIONS AT FWA/SBN JUST BEFORE SUNRISE.
OTHERWISE...VFR THROUGH THE PERIOD. MID LEVEL SHORTWAVE TROUGH
AXIS WILL PIVOT THROUGH THE LOWER LAKES TOWARD DAYBREAK...LIKELY
SPREADING SOME MID LEVEL CLOUDS ACROSS NORTHERN INDIANA. SHOWERS
WITH THIS FEATURE SHOULD REMAIN NORTH OF THE TERMINALS. WEAK
DIURNAL DESTABILIZATION MAY ONCE AGAIN ALLOW A FEW AFTN SHOWERS TO
DEVELOP...ALTHOUGH COVERAGE/PROBABILITY APPEARS LOWER THAN
PREVIOUS DAYS GIVEN BUILDING MID LEVEL HEIGHTS/WARMING ALOFT WITH
LOW LEVEL TROUGH FOCUSED WELL NORTH ACROSS THE NRN GREAT LAKES.
OPTED TO HOLD ON TO A DRY FCST AT FWA/SBN AS A RESULT.

&&

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

$$

SYNOPSIS...MARSILI/STEINWEDEL
SHORT TERM...STEINWEDEL
LONG TERM...SKIPPER
AVIATION...STEINWEDEL


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