Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 192343
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
643 PM EST FRI DEC 19 2014

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

&&

.SYNOPSIS...
ISSUED AT 205 PM EST FRI DEC 19 2014

A HIGH PRESSURE SYSTEM WILL DOMINATE INDIANA WEATHER INTO SUNDAY AS
ITS CENTER SHIFTS FROM THE MID MISSISSIPPI VALLEY TO NEW ENGLAND.

FROM MONDAY INTO THURSDAY THE MOST IMPORTANT INFLUENCE ON HOOSIER
WEATHER IS GOING TO BE A LOW PRESSURE SYSTEM. THIS SYSTEM IS
FORECAST TO START DEVELOPING OVER THE PLAINS LATE IN THE WEEKEND. IT
IS EXPECTED TO HEAD EAST...GAINING STRENGTH AS IT DOES.

BY TUESDAY MORNING LOW PRESSURE WILL HAVE ARRIVED IN THE UPPER
MISSISSIPPI VALLEY. BY WEDNESDAY IT IS EXPECTED TO BE
VERY...VERY...STRONG AND CENTERED OVER SOUTHERN ONTARIO. LATE
CHRISTMAS DAY ITS INFLUENCE ON INDIANA WILL WEAKEN AS IT HEADS INTO
QUEBEC.

FRIDAY OUR WEATHER IS PREDICTED COME UNDER THE INFLUENCE OF ANOTHER
LOW PRESSURE SYSTEM COMING FROM THE PLAINS.

&&

.NEAR TERM /TONIGHT AND SATURDAY/...

ISSUED AT 205 PM EST FRI DEC 19 2014

THE MAIN ISSUE IS CLOUDINESS AND ITS AFFECT ON TEMPERATURES.

CLEARING DEVELOPED OVER MUCH OF ILLINOIS AND SOUTHWEST INDIANA
TODAY. HOWEVER LATEST SATELLITE PICTURES SHOW STRATUS MOVING TOWARD
THE CLEAR AREA FROM THE NORTHEAST...AND CLOUDS WITH A SHORT WAVE
APPROACHING FROM THE SOUTHWEST. TONIGHT SHOULD BE CLOUDY.

THE MODELS AGREE BY LATE SATURDAY THE SHORT WAVE IS GOING TO BE TO
OUR EAST AND THE ATMOSPHERIC COLUMN WILL BE DRYING. THEY ALSO AGREE
WE WILL BE UNDER AN INVERSION ON THE EAST SIDE OF A RIDGE WITH 925
MILLIBAR RELATIVE HUMIDITIES 70 PERCENT OR HIGHER.

SUCH A PATTERN FAVORS STRATUS. SATURDAY IS GOING TO BE ANOTHER
MOSTLY CLOUDY DAY. THE SOUTHWEST MIGHT GET A LITTLE SUN IN THE
AFTERNOON.

CLOUDS ARE GOING TO DAMPEN DIURNAL TEMPERATURES CHANGES. MAV AND MET
MINIMUMS ARE CLOSE OVERNIGHT. THEY LOOK OK CONSIDERING WHAT WE HAVE
NOW. THERE HAS BEEN A STRONG WARM BIAS IN SIMILAR SITUATIONS WITH
DAYTIME TEMPERATURES LATELY. THE COOLER MET TEMPERATURES ARE
PREFERRED SATURDAY. POSSIBLY EVEN THEY WILL BE TOO WARM.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...

ISSUED AT 205 PM EST FRI DEC 19 2014

ALL THE MODELS AGREE IT WILL BE DRY THROUGH SUNDAY NIGHT WITH A
CHANCE OF RAIN MONDAY AS A WARM FRONT DEVELOPS OVER THE AREA. CLOUDS
AND TEMPERATURES ARE THE MAIN FORECAST ISSUES.

SATURDAY NIGHT WE SHOULD MOVE TO THE WEST SIDE OF A WEAK SURFACE
RIDGE. THIS WILL GIVE A CHANCE TO SCOUR OUT THE LOW LEVEL MOISTURE
THAT HAS BEEN PERSISTENT RECENTLY. HOWEVER AS THAT HAPPENS WARM
ADVECTION ALOFT SHOULD CAUSE MID LEVEL CLOUDINESS. WE CAN EXPECT
CLOUDY WEATHER TO CONTINUE.

THE RESULT IS GOING TO BE DAMPENED TEMPERATURE CHANGES...ALTHOUGH
NOT QUITE TO EXTENT AS EARLIER IN THE WEEK SINCE THE CLOUDS SHOULD
BE MID LEVEL AS OPPOSED TO LOW LEVEL. GUIDANCE TEMPERATES MAY BE
OK SATURDAY NIGHT CONSIDERING WHAT DAYTIME READINGS WILL BE. AFTER
THAT THE COOLER MET LOOKS BETTER FOR SUNDAY AND THE WARMER MAV
FOR SUNDAY NIGHT.

ON MONDAY STRONG WARM ADVECTION WILL COUNTERACT THICKENING CLOUDS AND
POSSIBLY RAIN AS A WARM FRONT FORMS OVER US. TEMPERATURES COULD
SURGE INTO THE 50S OR STAY IN THE 40S DEPENDING ON HOW THINGS COME
TOGETHER. A CONSENSUS BETWEEN THE MEX AND THE EUROPEAN GUIDANCE
WILL BE USED.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY NIGHT/...

ISSUED AT 235 PM EST FRI DEC 19 2014

THE MAIN FOCUS OF THE LONG TERM PERIOD WILL BE A STORM SYSTEM
PROGGED TO HIT CENTRAL INDIANA OVER THE CHRISTMAS HOLIDAY.

MODELS ARE IN DECENT CONSENSUS FOR THAT FAR OUT IN THE FORECAST.
EURO AND GFS BOTH INDICATE A RATHER STRONG CUT-OFF LOW CENTERED
OVER THE NORTHERN PLAINS ON MONDAY NIGHT WITH SIGNIFICANT RIDGING
OVER THE WEST COAST. PRECIP WILL BE IN THE FORECAST FOR THE
DURATION OF LONG TERM PERIOD...BUT IN THE FORM OF RAIN FROM MONDAY
NIGHT THROUGH TUESDAY NIGHT AS WARM ADVECTION AT THE SURFACE MOVES
IN AHEAD OF THE UPPER SYSTEM. AS ASSOCIATED COLD FRONT MOVES IN ON
TUESDAY NIGHT...RAIN WILL SLOWLY TRANSITION TO A RAIN/SNOW MIX.
PRECIP CHANCES ARE CURRENTLY IN THE 50 TO 60 PERCENT RANGE...BUT
ANTICIPATE THESE CHANCES TO INCREASE IN COMING DAYS. AT THIS
TIME...BEST VORTICITY MAXIMA SHOULD MOVE THROUGH THE FORECAST AREA
ON TUESDAY NIGHT/WEDNESDAY MORNING. AT THAT POINT...THE COLDER AIR
WILL START FILTERING INTO CENTRAL INDIANA...BUT SINCE BEST
DYNAMICS WILL ALREADY BE TO THE EAST OF FORECAST AREA...DO NOT
EXPECT HIGH SNOW ACCUMULATIONS AT THIS TIME. NONETHELESS...GUSTY
WEST WINDS COULD STILL RESULT IN BLOWING SNOW AND TRAVEL HAZARDS
ON WEDNESDAY AND THURSDAY.

THOSE WITH TRAVEL PLANS DURING THIS TIME PERIOD ARE ENCOURAGED TO
STAY TUNED IN THE COMING DAYS.

&&

.AVIATION /DISCUSSION FOR THE 200000Z TAF ISSUANCE/...

ISSUED AT 640 PM EST FRI DEC 19 2014

AN INVERSION WILL CONTINUE TO TRAP MOISTURE NEAR THE
SURFACE...RESULTING IN MVFR CONDITIONS FOR DURATION OF TAF PERIOD.

WINDS WILL BE LIGHT AND VARIABLE. GUIDANCE IS HINTING AT SOME LOW
END VFR BY SAT AFTERNOON...HOWEVER BASED ON LAST 4-5 DAYS...BELIEVE
EVEN IF THIS DOES HAPPEN AT A FEW OF THE SITES IT WILL BE BRIEF AND
ALL TERMINALS WILL RETURN TO MFVR BY SAT EVENING.

&&

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

$$

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

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