Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 251016
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
616 AM EDT WED MAR 25 2015

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 237 AM EDT WED MAR 25 2015

A WEAK COLD FRONT WILL PASS INDIANA TODAY. OVERNIGHT A LOW
PRESSURE SYSTEM WILL CROSS THE SOUTHERN PART OF OUR STATE. THIS
SYSTEM WILL BE STRONG ENOUGH TO KEEP CONTROL OF THE WEATHER
THROUGH THURSDAY NIGHT AS IT HEADS OFF THE EAST.

FRIDAY A HIGH PRESSURE SYSTEM WILL MOVE IN AND DOMINATE HOOSIER
WEATHER INTO SUNDAY. NEXT...LOW PRESSURE AND AN ASSOCIATED COLD
FRONT SHOULD MOVE BY. AS MONDAY GOES ON...MORE HIGH PRESSURE IS
PREDICTED TO ARRIVE FROM THE WEST.

&&

.NEAR TERM /TODAY/...

ISSUED AT 237 AM EDT WED MAR 25 2015

WITH ALL THE MODELS PUSHING PRECIPITATION OFF TO THE EAST BY
12Z...THE MAIN ISSUE BECOMES TEMPERATURES.

THESE WILL BE EXTREMELY DEPENDENT ON THE EXACT LOCATION OF
BOUNDARIES OVER AREA. GIVEN THE TENDENCY OF MOS TO SMOOTH THINGS
WITH LARGE GRADIENTS...BASING THE FORECAST ON A DETERMINISTIC MODEL
SEEMS MORE APPROPRIATE. THE CONSHORT MODEL WILL BE USED BECAUSE IT
IS NORMALLY THE MOST ROBUST.

BASED ON WHAT IS UPSTREAM BEHIND THE RAIN NOW OVER THE AREA...

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...

ISSUED AT 237 AM EDT WED MAR 25 2015

THE MOST DIFFICULT PROBLEM IS TEMPERATURES.

THE MODELS CONCUR ABOUT STRONG COLD ADVECTION DEVELOPING LATE
TONIGHT AND CONTINUING THURSDAY. GRADIENTS ARE GOING TO BE TIGHT. A
TIMING ERROR OF A FEW HOURS COULD MAKE A BIG DIFFERENCE.

THIS RELATIVELY UNUSUAL SITUATION IS NOT THE SORT OF THING MOS IS
BEST AT. SOMETHING FROM A GOOD DETERMINISTIC MODELS IS APT TO BE
BETTER. GIVEN CONSHORT IS A GOOD DETERMINISTIC MODEL IT WILL BE USED.

AFTER THURSDAY TEMPERATURE GRADIENTS WILL WEAKEN AND NORMAL DIURNAL
PATTERNS BECOME BETTER ESTABLISHED. THIS IS WHERE MOS COMES INTO ITS
OWN. THE MAV WILL BE USED BECAUSE OF ITS LONGER TRAINING PERIOD.

ALL THE GUIDANCE POINTS TO RAIN TONIGHT...ENDING FROM THE
NORTHWEST THURSDAY...AND THEN A DRY PERIOD. CLOUDS ARE APT TO HANG
ON AT LEAST INTO FRIDAY AS WE RETAIN A SLIGHT CYCLONIC FLOW ACROSS
THE EASTERN LAKES.

CAPES ARE JUST HIGH ENOUGH TO MENTION THUNDER IN THE FORECAST
TONIGHT. THE RAIN MAY BE HEAVY AT TIMES IN THE SOUTHERN CWA THANKS
TO PROXIMITY TO THE WELL DEVELOPED SURFACE LOW WHILE A RATHER STRONG
WAVE PASSES ALOFT.

THICKNESS PATTERNS THURSDAY SUGGEST THE RACE WILL BE ON WHETHER THE
PRECIPITATION WILL END BEFORE IT CHANGES TO SNOW. GIVEN THE
UNCERTAINTY ABOUT THIS A CHANCE OF SNOW WILL BE INCLUDED IN THE
FORECAST.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...

ISSUED AT 306 AM EDT WED MAR 25 2015

ECMWF AND GFS DEPICT COOL HIGH PRESSURE DEPARTING ON SATURDAY
NIGHT AS A LOW PRESSURE SYSTEM AND SECONDARY COLD FRONT IS POISED
TO PUSH ACROSS THE GREAT LAKES AND OHIO VALLEY ON SUNDAY. THUS
WILL INCLUDE CHANCES FOR SOME SHRA WITH THIS FRONTAL
PASSAGE...HOWEVER ANY PRECIP AMOUNT SHOULD REMAIN RATHER LIGHT AS
GULF FLOW OF THE BACKSIDE OF THE DEPARTING HIGH FAILS TO DEVELOP
FOR AN EXTENDED PERIOD OF TIME.

ANOTHER HIGH PRESSURE SYSTEM BUILDS ACROSS THE REGION FOR MONDAY
AND INTO TUESDAY...PROVIDING DRY WEATHER ALONG WITH SEASONABLE
TEMPERATURES. AS THE HIGH DEPARTS ON TUESDAY NIGHT...MODELS
SUGGEST A WARM FRONT APPROACHING AND THIS COULD RESULT IN ANOTHER
ROUND OF SHOWERS. OVERALL SUPERBLEND HANDLES THE TEMPS OK AND NO
MAJOR CHANGES MADE THERE.

&&

.AVIATION /DISCUSSION FOR THE 251200Z TAFS/...

ISSUED AT 610 AM EDT WED MAR 25 2015

MVFR CIGS ACROSS CENTRAL INDIANA WILL IMPROVE TO VFR BY LATE
MORNING. A RETURN TO MVFR OR WORSE CONDITIONS IS EXPECTED THIS EVENING.

A WARM FRONT HAS PUSHES ACROSS THE TAF SITES...ALLOWING A SW FLOW
OF WARMER AND DRY AIR INTO CENTRAL INDIANA. FORECAST SOUNDINGS
SHOW CONVECTIVE TEMPS NEAR 50 THIS MORNING WHICH WILL RESULT IN
BKN MVFR CIGS IMPROVING TO VFR AS HEATING RESUMES. BY AFTERNOON
CONVECTIVE TEMPS SOAR INTO THE 70S AS DRIER AIR ARRIVES AND
CLOUDS MAY BECOME SCT AT VFR HEIGHTS.

A STRONGER COLD FRONT WILL ARRIVE LATE TONIGHT AND BRING A RETURN
OF MVFR OR WORSE CIGS ALONG WITH MORE SHRA. GOOD MOISTURE AND
FORCING APPEARS AVAILABLE AS THE VIGOROUS ASSOCIATED SHORT WAVE
PASSES ALOFT.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....PUMA
AVIATION...JP

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