Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 210801
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
301 AM EST SUN DEC 21 2014

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

&&

.SYNOPSIS...
ISSUED AT 301 AM EST SUN DEC 21 2014

A LOW PRESSURE SYSTEM WILL BRING PRECIPITATION TO CENTRAL INDIANA
MONDAY THROUGH WEDNESDAY. AFTER A DRY CHRISTMAS...CHANCES FOR
PRECIPITATION WILL RETURN FRIDAY WITH A WEAKER SYSTEM. WARM AIR
AHEAD OF THE FIRST SYSTEM COULD BRING THE WARMEST READINGS OF
DECEMBER ON TUESDAY...THEN TEMPERATURES WILL RETURN TO CLOSER TO
AVERAGE BY CHRISTMAS.

&&

.NEAR TERM.../TODAY/
ISSUED AT 301 AM EST SUN DEC 21 2014

SKIES HAVE CLEARED ACROSS A GOOD PORTION OF CENTRAL INDIANA EARLY
THIS MORNING...BUT ADDITIONAL LOW CLOUDS WERE NEAR THE
ILLINOIS/INDIANA BORDER AND MOVING SLOWLY EAST.

CLOUD COVER WILL BE TOUGH TO PIN DOWN TODAY AND ONCE AGAIN
CONFIDENCE IS LOW IN THE DETAILS. LOW CLOUDS WILL MARCH INTO WESTERN
AND NORTHWESTERN SECTIONS OF THE AREA THIS MORNING. HOWEVER DRIER
AIR WILL FLOW INTO THE AREA AS WINDS INCREASE OUT OF THE SOUTHEAST.

FOR NOW WILL GO MOSTLY CLOUDY ACROSS THE NORTHWEST FORECAST
AREA...WITH SKIES REMAINING/BECOMING PARTLY CLOUDY ELSEWHERE.
ADJUSTMENTS WILL LIKELY HAVE TO BE MADE LATER THIS MORNING AS THE
EVOLUTION OF THE CLOUDS BECOMES CLEARER.

TEMPERATURES HAVE COOLED MORE THAN EXPECTED EARLY THIS MORNING DUE
TO THE PARTIAL CLEARING. THIS COLD START WILL HELP KEEP TEMPERATURES
BELOW MAV MOS AND CLOSER TO THE MET MOS TODAY.

&&

.SHORT TERM.../TONIGHT THROUGH TUESDAY NIGHT/
ISSUED AT 301 AM EST SUN DEC 21 2014

FOCUS IS ON CHANCES FOR PRECIPITATION THROUGH THE PERIOD. MODELS ARE
SHOWING DIFFERENCES AS WOULD BE EXPECTED WITH THE INCOMING SYSTEM
NOT FULLY SAMPLED YET. CANADIAN LOOKS TOO STRONG WITH THE
SYSTEM...WHILE THE LARGER CHANGE IN SOLUTIONS BETWEEN THE 12Z/00Z
ECMWF LEADS TO LOWER CONFIDENCE IN ITS SOLUTION THIS RUN. WILL USE A
BLEND OF REMAINING MODELS.

CLOUDS WILL INCREASE TONIGHT AS THE SYSTEM APPROACHES FROM THE WEST.
WILL GO A LITTLE WARMER THAN MAV MOS MOST AREAS.

ON MONDAY ISENTROPIC LIFT INCREASES DURING THE AFTERNOON. HOWEVER
DEEPER MOISTURE WILL BE SLOWER TO RETURN THANKS IN PART TO SOUTHEAST
WINDS IN THE LOWER LEVELS. WILL KEEP THE MORNING DRY AND GO WITH
SLIGHT CHANCE TO CHANCE POPS IN THE AFTERNOON. WITH THE CLOUDS AND
SOUTHEAST FLOW...MOS LOOKS TOO WARM FOR HIGHS. WILL CUT SOME.

MONDAY NIGHT AND TUESDAY FORCING RAMPS UP WITH SURFACE FRONT MOVING
INTO THE AREA...850MB WINDS APPROACHING 50KT...AND AN UPPER JET
MOVING IN. THUS WENT LIKELY POPS MOST AREAS BY LATE MONDAY NIGHT AND
LIKELY TO CATEGORICAL POPS ON TUESDAY.

CONTINUED LIKELY TO CATEGORICAL POPS TUESDAY NIGHT AS A SURFACE LOW
RIDES ALONG THE FRONT TOWARD CENTRAL INDIANA. LOOKS LIKE COLDER AIR
WILL BE SLOWER TO ARRIVE THAN PREVIOUSLY THOUGHT...SO WENT ALL RAIN
THROUGH TUESDAY NIGHT.

THE SYSTEM LOOKS TO BRING ENOUGH WARM UP INTO THE AREA ON TUESDAY
FOR HIGHS IN THE LOWER TO MIDDLE 50S...WHICH WILL BE THE WARMEST AIR
THIS MONTH ACROSS THE AREA.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/...

ISSUED AT 236 PM EST SAT DEC 20 2014

A STRONG SYSTEM IS STILL PROGGED TO IMPACT CENTRAL INDIANA DURING
THE CHRISTMAS HOLIDAY. LATEST GFS AND EURO ARE DIFFERING SLIGHTLY
ON TRACK OF FIRST LOW PRESSURE SYSTEM...WITH THE GFS NOW TAKING A
BIT MORE NORTHERLY PATH THAN THE EURO. TUESDAY NIGHT...THE GFS HAS
THE UPPER LOW CENTERED OVER THE NORTHERN GREAT LAKES
REGION...WHILE THE EURO HAS IT TRACKING ACROSS WISCONSIN.
MEANWHILE...A SURFACE FRONTAL SYSTEM WILL TRACK ACROSS CENTRAL
INDIANA...AND ASSOCIATED SOUTHERLY FLOW WILL ADVECT PLENTY OF
MOISTURE INTO THE REGION AHEAD OF THE UPPER LOW. SO...DEFINITE AND
LIKELY POPS ARE STILL REASONABLE FOR TUESDAY NIGHT AND WEDNESDAY
ACROSS ALL OF THE FORECAST AREA.

PRECIP WILL STILL BE IN THE FORM OF RAIN ON TUESDAY EVENING...BUT
A COLD FRONT WILL QUICKLY MOVE IN ON TUESDAY NIGHT...STARTING THE
PRECIP TRANSITION FROM RAIN TO RAIN/SNOW ON TUESDAY NIGHT. THE
FINAL TRANSITION TO ALL SNOW SHOULD OCCUR ON WEDNESDAY AFTERNOON.
AT THAT POINT...A SECONDARY LOW PRESSURE SYSTEM WILL APPROACH FROM
THE MISSOURI VALLEY...PHASING IN WITH THE AFOREMENTIONED PRIMARY
SYSTEM. IT/S THIS SECONDARY LOW THAT WILL CAUSE THE MOST IMPACT AS
THE BEST DYNAMICS TRACK ACROSS CENTRAL INDIANA ON CHRISTMAS EVE. IT
IS TOO EARLY TO LIST SNOWFALL AMOUNTS...BUT STRONG WINDS WILL
CREATE SLICK CONDITIONS REGARDLESS.

FURTHER OUT...HIGH PRESSURE WILL BUILD INTO THE AREA ON
FRIDAY...BUT YET ANOTHER SYSTEM WILL MOVE ACROSS MANITOBA AND
ONTARIO LATE IN THE EXTENDED PERIOD...BRINGING ADDITIONAL CHANCES
FOR RAIN AND SNOW TO CENTRAL INDIANA ON FRIDAY AND FRIDAY NIGHT.

&&

.AVIATION /DISCUSSION FOR THE 210600Z TAF ISSUANCE/...

ISSUED AT 1200 AM EST SUN DEC 21 2014

MODELS HAVE ABSOLUTELY NO HANDLE ON CEILINGS/CLOUD COVER FOR EARLY
THIS MORNING. THEY ARE DOING THE EXACT OPPOSITE OF WHAT THEY HAVE
DONE FOR THE PAST 5-6 DAYS...THEY ARE INDICATING CURRENT MFVR VIS/S
AND CEILING WHILE CENTRAL INDIANA HAS CLEARED OUT (IS VFR!) AND WILL
REMAIN THIS WAY AT LEAST UNTIL MUCH LATER THIS MORNING. THEN
/POSSIBLY/ ANOTHER INVERSION DEVELOPS AND BOTH VISIBILITIES/CEILINGS
WILL DROP TO MFVR WHICH WAS INDICATED IN ALL OF THE TAFS SAVE FOR
KHUF WHICH APPEARS TO REMAIN ON THE FRINGE OF THE CLEARING SIDE.

SO THE REST OF THE TERMINALS KIND/LAF/BMG SHOULD EXPERIENCE
ANOTHER PERIOD OF MVFR FLIGHT CONDITIONS LATER THIS MORNING UNTIL
ABOUT NOON...THEN VFR CONDITIONS LOOK TO PREVAIL THERE AFTER FOR
ALL THE TAFS SITES. CONFIDENCE IS ON LOW-MEDIUM END THAT THESE
MVFR CONDITIONS WILL REDEVELOP...BUT WILL CONTINUE TO MONITOR
TRENDS AND IF OBSERVATIONS REMAIN OPTIMISTIC FOR THE NEXT SEVERAL
HOURS HERE AND UPSTREAM...MFVR CONDITIONS MAY BE PUSHED BACK OR
EVEN OMITTED WITH SUBSEQUENT TAF UPDATES.

WINDS WILL BE LIGHT AND VARIABLE THROUGH EARLY THIS MORNING...THEN
PICK UP TO AROUND 5KT FROM THE SE LATE THIS MORNING AND CONTINUE
INTO THE EVENING HOURS.

&&

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

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....TDUD
AVIATION...SMF

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