Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 202306
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
606 PM EST THU NOV 20 2014

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

&&

.SYNOPSIS...

ISSUED AT 302 PM EST THU NOV 20 2014

HIGH PRESSURE WILL BRING A CONTINUATION OF COLD DRY WEATHER THROUGH
FRIDAY. A WARMER AND MORE UNSETTLED PATTERN SETS UP FOR THE WEEKEND
AS A WARM FRONT LIFTS THROUGH THE REGION FOLLOWED BY A STRONG LOW
PRESSURE SYSTEM. THESE FEATURES WILL BRING RAIN FOR THE WEEKEND AND
POSSIBLY THUNDERSTORMS ON SUNDAY. BEHIND THIS SYSTEM...COLDER
WEATHER WILL RETURN FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /REST OF THIS AFTERNOON THROUGH TONIGHT/...

ISSUED AT 302 PM EST THU NOV 20 2014

THANKS TO STRONG HIGH PRESSURE OVERHEAD THE WEATHER WILL REMAIN VERY
QUIET FOR THE REST OF THIS AFTERNOON THROUGH TONIGHT. SCT-BKN CU WILL
DISSIPATE AROUND SUNSET AND CLEAR SKIES AND MUCH LIGHTER WINDS ARE
EXPECTED FOR TONIGHT. UNDERCUT GUIDANCE BASED ON SOME RADIATIONAL
COOLING JUST A TAD FOR LOWS RANGING FROM 10-17 DEGREES...WITH COLDER
TEMPERATURES ACROSS THE NORTHERN COUNTIES.

&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...

ISSUED AT 302 PM EST THU NOV 20 2014

HIGH PRESSURE DRIFTS ACROSS THE OHIO VALLEY ON FRIDAY KEEPING THE
WEATHER DRY ACROSS THE CWA. EXPECT A SLOW INCREASE IN MID AND HIGH
CLOUDS DURING THE AFTERNOON AS MOISTURE RETURNS NORTH ON THE BACK
SIDE OF THE HIGH. STUCK CLOSE TO A MOS BLEND FOR HIGHS RANGING FROM
THE MID 20S TO MID 30S.

THE FIRST WAVE OF MOISTURE WITH THE NEXT SYSTEM COMES NORTH INTO THE
REGION BY EARLY FRIDAY EVENING...AIDED BY THE ARRIVAL OF A FAIRLY
STRONG 40 KT LOW LEVEL JET. BASED ON THICKNESSES...LOW LEVEL AND
SURFACE TEMPERATURES AGREE WITH PREVIOUS THINKING THAT MUCH OF THE
PRECIP WILL FALL IN THE FORM OF FREEZING RAIN...WITH A SMALL AREA OF
JUST RAIN ACROSS THE FAR SOUTH WHERE IT WILL STAY WARM ENOUGH. BASED
ON LATEST GUIDANCE ALSO INDICATED A PERIOD OF A IP/FZRA MIX ACROSS
THE NW COUNTIES BEFORE MIDNIGHT. QPF AMOUNTS REMAIN EXTREMELY
LIGHT...ONLY A FEW HUNDREDTHS OF AN INCH AT BEST...SO WILL NOT BE
ISSUING ANY TYPE OF HEADLINE OR STATEMENT AT THIS TIME AND CONTINUE
MENTION IN THE FORECAST...HWO...AND WX STORY.

THANKS TO GOOD WARM AIR ADVECTION TEMPERATURES WILL QUICKLY GO
ABOVE FREEZING FROM SOUTHWEST TO NORTHEAST BY EARLY SATURDAY
MORNING...WITH THE ENTIRE FORECAST AREA ABOVE FREEZING BY 12-14Z
AT THE LATEST. HAVE THEREFORE WENT WITH JUST RAIN IN THE FORECAST
FOR ALL AREAS ACROSS THE CWA SATURDAY MORNING AND CONTINUING
THROUGH THE DAY. AGREE WITH PREVIOUS ASSESSMENT THAT CENTRAL
INDIANA MAY SEE A LULL IN PRECIP THROUGH THE FIRST HALF OF
SATURDAY BEFORE A RENEWED SURGE OF MOISTURE LIFTS INTO THE AREA
LATE AFTERNOON INTO SATURDAY NIGHT WITH ADDITIONAL RAINFALL ALONG
A WARM FRONT. THE BOUNDARY WILL LIFT NORTH SATURDAY NIGHT WITH THE MOST
WIDESPREAD RAINFALL FOCUSING OVER NORTHERN COUNTIES.

THEN ON SUNDAY/SUNDAY NIGHT A STRONG SHORT WAVE WILL EJECT OUT OF
THE PLAINS TROUGH. ALL OF THE MODELS INDICATE A STRONG SURFACE LOW
TRACKING NORTH THROUGH ILLINOIS INTO THE GREAT LAKES SUNDAY
NIGHT...AND THEY HAVE BEEN FAIRLY CONSISTENT WITH THIS SCENARIO...SO
WILL GO WITH VERY HIGH POPS FOR SUNDAY (90 PERCENT). CONVECTIVE
PARAMETERS SUGGEST SOME ELEVATED THUNDERSTORMS ARE ALSO POSSIBLE.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...

ISSUED AT 302 PM EST THU NOV 20 2014

HIGH PRESSURE DRIFTS ACROSS THE OHIO VALLEY ON FRIDAY KEEPING THE
WEATHER DRY ACROSS THE CWA. EXPECT A SLOW INCREASE IN MID AND HIGH
CLOUDS DURING THE AFTERNOON AS MOISTURE RETURNS NORTH ON THE BACK
SIDE OF THE HIGH. STUCK CLOSE TO A MOS BLEND FOR HIGHS RANGING FROM
THE MID 20S TO MID 30S.

THE FIRST WAVE OF MOISTURE WITH THE NEXT SYSTEM COMES NORTH INTO THE
REGION BY EARLY FRIDAY EVENING...AIDED BY THE ARRIVAL OF A FAIRLY
STRONG 40 KT LOW LEVEL JET. BASED ON THICKNESSES...LOW LEVEL AND
SURFACE TEMPERATURES AGREE WITH PREVIOUS THINKING THAT MUCH OF THE
PRECIP WILL FALL IN THE FORM OF FREEZING RAIN...WITH A SMALL AREA OF
JUST RAIN ACROSS THE FAR SOUTH WHERE IT WILL STAY WARM ENOUGH. BASED
ON LATEST GUIDANCE ALSO INDICATED A PERIOD OF A IP/FZRA MIX ACROSS
THE NW COUNTIES BEFORE MIDNIGHT. QPF AMOUNTS REMAIN EXTREMELY
LIGHT...ONLY A FEW HUNDREDTHS OF AN INCH AT BEST...SO WILL NOT BE
ISSUING ANY TYPE OF HEADLINE OR STATEMENT AT THIS TIME AND CONTINUE
MENTION IN THE FORECAST...HWO...AND WX STORY.

THANKS TO GOOD WARM AIR ADVECTION TEMPERATURES WILL QUICKLY GO
ABOVE FREEZING FROM SOUTHWEST TO NORTHEAST BY EARLY SATURDAY
MORNING...WITH THE ENTIRE FORECAST AREA ABOVE FREEZING BY 12-14Z
AT THE LATEST. HAVE THEREFORE WENT WITH JUST RAIN IN THE FORECAST
FOR ALL AREAS ACROSS THE CWA SATURDAY MORNING AND CONTINUING
THROUGH THE DAY. AGREE WITH PREVIOUS ASSESSMENT THAT CENTRAL
INDIANA MAY SEE A LULL IN PRECIP THROUGH THE FIRST HALF OF
SATURDAY BEFORE A RENEWED SURGE OF MOISTURE LIFTS INTO THE AREA
LATE AFTERNOON INTO SATURDAY NIGHT WITH ADDITIONAL RAINFALL ALONG
A WARM FRONT. THE BOUNDARY WILL LIFT NORTH SATURDAY NIGHT WITH THE MOST
WIDESPREAD RAINFALL FOCUSING OVER NORTHERN COUNTIES.

THEN ON SUNDAY/SUNDAY NIGHT A STRONG SHORT WAVE WILL EJECT OUT OF
THE PLAINS TROUGH. ALL OF THE MODELS INDICATE A STRONG SURFACE LOW
TRACKING NORTH THROUGH ILLINOIS INTO THE GREAT LAKES SUNDAY
NIGHT...AND THEY HAVE BEEN FAIRLY CONSISTENT WITH THIS SCENARIO...SO
WILL GO WITH VERY HIGH POPS FOR SUNDAY (90 PERCENT). CONVECTIVE
PARAMETERS SUGGEST SOME ELEVATED THUNDERSTORMS ARE ALSO POSSIBLE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...

ISSUED AT 244 PM EST THU NOV 20 2014

A STRONG SYSTEM WILL BE MOVING THROUGH CENTRAL INDIANA TO START THE
LONG TERM PERIOD. VERY DYNAMIC STRENGTHENING SURFACE LOW WILL MOVE
THROUGH ILLINOIS AND THE GREAT LAKES. THIS WILL KEEP LIKELY POPS
GOING FOR SUNDAY NIGHT. THE ECMWF IS SHOWING SOME ELEVATED
INSTABILITY DURING THIS TIME WHILE THE GFS DOES NOT. WILL INCLUDE A
SLIGHT CHANCE FOR THUNDER THROUGH THE NIGHT. REGARDLESS BY MONDAY
MORNING ANY INSTABILITY SHOULD BE GONE AND RAIN WILL BE ONGOING.
THIS SET OF RUNS HAS THE COLD AIR RUSHING IN A LITTLE FASTER AND
THUS WILL BRING RAIN/SNOW MIX TO THE NORTHERN HALF OF THE AREA FOR
THE AFTERNOON. SYSTEM IS MOSTLY GONE BY MONDAY NIGHT BUT WITH
CYCLONIC FLOW CONTINUE WITH SMALL CHANCES FOR SNOW SHOWERS IN THE
NORTHERN HALF MONDAY NIGHT AND TUESDAY. A LOT OF VARIABILITY IN THE
ENSEMBLES AFTER THAT SO KEPT INITIALIZATION OF DRY TUESDAY
NIGHT/WEDNESDAY AND SMALL CHANCES THEN ON. BIG UNCERTAINTY REGARDING
TEMPERATURES AND POPS FOR WEDNESDAY NIGHT AND THURSDAY WITH GFS AND
ECMWF SHOWING VERY DIFFERENT SOLUTIONS AND LARGE SPREAD IN ENSEMBLE
OPTIONS.

&&

.AVIATION /DISCUSSION FOR THE 210000Z TAFS/...

ISSUED AT 553 PM EST THU NOV 20 2014

VFR CONDITIONS ARE EXPECTED DURING THIS TAF PERIOD.

HIGH PRESSURE CENTERED OVER IOWA AND SOUTHERN ILLINOIS IS EXPECTED
TO BUILD EAST ACROSS INDIANA DURING THE PERIOD. FORECAST SOUNDINGS
AND TIME HEIGHTS ARE DRY THROUGH THE PERIOD. AS HEATING IS LOST
THIS EVENING AND THE PRESSURE GRADIENT RELAXES AS THE SURFACE HIGH
BUILDS ACROSS THE AREA...WINDS ARE EXPECTED TO BECOME LIGHT.

CONVECTIVE TEMPS WILL NOT BE REACHED AS THE HIGH DEPARTS ON
FRIDAY. LOW CLOUDS ARE EXPECTED TO INVADE AFT 00Z SAT AS WARM AIR
ADVECTION BEGINS ON BACKSIDE OF THE HIGH...RESULTING IN VFR CIGS.

&&

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

$$

SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM....CP
AVIATION...JP

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