Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 201745
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
145 PM EDT SAT SEP 20 2014

.UPDATE...
THE SYNOPSIS...NEAR TERM...SHORT TERM
AND LONG TERM SECTIONS HAVE BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 145 PM EDT SAT SEP 20 2014

A COLD FRONT OVER WISCONSIN AND IOWA IS EXPECTED TO PUSH TOWARD
AND ACROSS INDIANA TONIGHT. SCATTERED RAIN SHOWERS AND PERHAPS A
THUNDERSTORM ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE
FRONT...RESULTING IN SOME LIGHT RAIN AMOUNTS TONIGHT.

THE FRONT WILL QUICKLY PUSH SOUTHEAST OF INDIANA ON SUNDAY MORNING
AND TAKE ANY RAIN CHANCES WITH IT. BY SUNDAY AFTERNOON...ANOTHER
COOL CANADIAN HIGH PRESSURE SYSTEM WILL BEGIN TO BUILD ACROSS THE
REGION. THIS WILL BRING DRY WEATHER ALONG WITH SEASONABLE
TEMPERATURES TO INDIANA FOR MUCH OF THE NEXT WORK WEEK.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 145 PM EDT SAT SEP 20 2014

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS A COLD FRONT
STRETCHING FROM CENTRAL WISCONSIN TO CENTRAL IOWA AND NORTHEASTERN
KANSAS. A WARMER AND MORE HUMID SOUTHWESTERLY FLOW WAS IN PLACE
ACROSS CENTRAL INDIANA AHEAD OF THE FRONT AS DEW POINTS HAD
CLIMBED INTO THE 60S. RADAR MOSAICS BEGINNING TO SHOW SOME RETURNS
AHEAD OF THE FRONT IN WISCONSIN AND IOWA. SATELLITE ALSO SHOWING
HIGH CLOUD STEAMING ACROSS THE STATE.

MAIN FORECAST CHALLENGE TONIGHT WILL BE POPS. GFS AND NAM BOTH
SUGGEST A THIN BAND OF HIGH RH PUSHING SOUTHEAST THROUGH THE STATE
DURING THE EVENING HOURS. AGAIN FORECAST SOUNDINGS FAIL TO SHOW
COMPLETE DEEP SATURATION...BUT DO SHOW A NOTEWORTHY AMOUNT OF
MOISTURE AS PWATS RISE TO OVER 1.5 INCHES. ALOFT A MODERATE TROUGH
WILL BE WORKING OUT OF THE UPPER MIDWEST...SLIDING EAST SOUTHEAST
INTO THE GREAT LAKES. INSTABILITY APPEARS MARGINAL AS LIFTED
INDICES FAIL TO GET GREATER THAN -5...BUT NONETHELESS FORECAST
SOUNDING LAPSE RATES APPEAR STEEP ENOUGH TO SUGGEST ISOLATED
THUNDER. THUS AS THE MODELS CONTINUE TO REMAIN VERY CONSISTENT
FROM RUN TO RUN...CONFIDENCE IN A LIGHT PRECIP EVENT CONTINUES TO
GROW. WILL ONCE AGAIN RAISE POPS ACROSS MUCH OF THE FORECAST AREA
AFTER 00Z...PARTICULARLY ACROSS THE NORTHERN PARTS OF THE FORECAST
AREA WHERE FORCING IS BETTER. AS FOR TEMPS WILL TREND LOWS WARMER
THAN GUIDANCE DUE TO EXPECTED CLOUDS AND RAIN.


&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...

ISSUED AT 145 PM EDT SAT SEP 20 2014

ONLY CHALLENGE DURING THIS PERIOD WILL BE TEMPS. IN THE WAKE OF
THE COLD FRONT...COLD AIR ADVECTION BEGINS ON NORTHERLY WINDS
ACROSS THE OHIO VALLEY ON SUNDAY. LARGE...EXTENSIVE HIGH PRESSURE
IS EXPECTED TO DIVE SOUTHEAST OUT OF THE THE NORTHERN PLAINS AND
SOUTHERN CANADA. THIS RESULTING DRY WEATHER TO CENTRAL INDIANA
THROUGH THIS PERIOD. FORECAST SOUNDINGS SUPPORT THIS...DRYING OUT
DRAMATICALLY THROUGH THE PERIOD ALONG WITH SHOWING UNATTAINABLE
CONVECTIVE TEMPERATURES THROUGH THE DAY. THUS WILL AIM FOR MOSTLY
SUNNY DAYS AND MOSTLY SUNNY NIGHTS.

COLD AIR ADVECTION IS EXPECTED TO BEGIN ON SUNDAY AND CONTINUE
INTO MONDAY NIGHT. IT IS ONLY BY TUESDAY THAT THE SURFACE HIGH IS
EXPECTED TO SETTLE OVER CENTRAL INDIANA...ALLOWING A MORE EASTERLY
OR SOUTHEASTERLY FLOW TO DEVELOP. THUS WITH GOOD RADIATIONAL
COOLING EXPECTED AMID THE COLD AIR ADVECTION WILL TREND LOWS AT OR
BELOW A BLEND OF MAVMOS AND METMOS. AS FOR HIGHS WILL A BLEND WILL
WORK NICELY WITH A SLOW WARNING TREND BEGINNING ON TUESDAY. WILL
NOTE HERE THAT MAVMOS HIGHS ON SUNDAY APPEAR A BIT WARM WITH
EXPECTED COLD AIR ADVECTION AND A FEW LINGERING CLOUDS IN THE WAKE
OF THE COLD FRONT.

&&

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

ENSEMBLES INDICATE A LARGE UPPER RIDGE WILL DOMINATE ACROSS THE AREA
DURING THIS PERIOD. THIS SHOULD RESULT IN DRY CONDITIONS LOCALLY.
ENSEMBLES AGREE...INDICATING VERY LITTLE THREAT FOR PRECIPITATION
THROUGH NEXT SATURDAY.

&&

.AVIATION /DISCUSSION FOR THE 201800Z TAFS/...
ISSUED AT 1232 PM EDT SAT SEP 20 2014

SOME CLOUD COVER BASED AROUND 040 WITH HIGHER LAYERS ABOVE EXPECTED
DURING THE AFTERNOON HOURS. OCCASIONAL SURFACE WIND GUSTS 15-20 KTS
FROM 210-230 DEGREES EXPECTED TO DIMINISH TO 6-9 KTS AFTER DARK.

APPROACHING COLD FRONT AND UPPER TROUGH SHOULD BEGIN MOVING INTO THE
AREA AFTER SUNSET. MODEL DATA INDICATE DEEP LAYER SHEAR BECOMES
QUITE FAVORABLE FOR ORGANIZED CONVECTION BY LATE THIS EVENING...
AND 850MB FLOW AROUND 30 KTS IS PROGGED INTO THE FRONTAL ZONE AS
WELL. THIS SUGGESTS GOOD POTENTIAL FOR A PERIOD OF CONVECTIVE
ACTIVITY AT AND IN THE VICINITY OF THE TAF SITES TONIGHT. THE BEST
POTENTIAL AT THIS TIME LOOKS TO BE IN THE 210100Z-210900Z. BRIEF IFR
VISIBILITY RESTRICTIONS AND GUSTY SHIFTING WINDS POSSIBLE IN AND
NEAR THE HEAVIER CELLS.

&&

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

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...JAS

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