Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 202024
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
325 PM EST SAT DEC 20 2014

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

&&

.SYNOPSIS...
ISSUED AT 226 PM EST SAT DEC 20 2014

HIGH PRESSURE IN PLACE OVER THE EASTERN GREAT LAKES AND INDIANA
THROUGH SUNDAY WILL KEEP DRY WEATHER IN PLACE ACROSS CENTRAL
INDIANA THROUGH THE WEEKEND. BY SUNDAY NIGHT...THE HIGH WILL REACH
NEW ENGLAND AND WARMER...SOUTHERLY FLOW WILL RETURN TO INDIANA AND
THE OHIO VALLEY.

HIGH CLOUDS ARE EXPECTED TO ARRIVE ON SUNDAY NIGHT AHEAD OF A WARM
FRONT...AS LOW PRESSURE BUILDS ACROSS THE PLAINS STATES. A WARM
FRONT WILL THEN SURGE INTO INDIANA BY MONDAY NIGHT AND TUESDAY
PROVIDING GOOD CHANCES FOR RAIN.

LOW PRESSURE WILL THEN MOVE THROUGH THE TENNESSEE AND OHIO RIVER
VALLEYS ON CHRISTMAS EVE...BRINGING CHANCES FOR LIGHT SNOWFALL
ACROSS CENTRAL INDIANA FOR MID WEEK. DRY BUT COLDER WEATHER IS
EXPECTED FOR CHRISTMAS.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 226 PM EST SAT DEC 20 2014

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS WEAK HIGH PRESSURE IN
PLACE ACROSS INDIANA. IR IMAGES CONTINUE TO SHOW EXTENSIVE
CLOUDINESS ACROSS CENTRAL INDIANA AND THE ENTIRE MIDWEST. RADAR
WAS QUIET.

MAIN FORECAST CHALLENGE TONIGHT WILL BE TEMPS. CLOUDY SKIES WILL
BE EXPECTED THROUGH THE NIGHT. TIME HEIGHT SECTIONS CONTINUE TO
SHOW PLENTY OF LOWER LEVEL MOISTURE LINGERING THROUGH THE NIGHT.
GIVEN THIS AND OUR SATELLITE IMAGES...EXPECT CLOUDY SKIES TO
REMAIN THROUGH THE NIGHT. TEMPERATURE ADVECTION THROUGH THE NIGHT
APPEARS RATHER NEUTRAL. THUS WILL TREND LOWS AT OR ABOVE
MAVMOS...CLOSER TO PERSISTENCE.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...

ISSUED AT 226 PM EST SAT DEC 20 2014

MAIN FORECAST CHALLENGE WILL BE TEMPS INITIALLY...FOLLOWED BY
PRECIP CHANCES ON MONDAY INTO TUESDAY.

DRY WEATHER IS EXPECTED THROUGH AT LEAST MONDAY AS MODELS SUGGEST
WEAK RIDGING IN PLACE ALOFT AS TROUGHING BUILDS ACROSS THE
CENTRAL PLAINS. LITTLE IN THE WAY OF UPPER SUPPORT APPEARS TO
PASS THROUGH THE OHIO VALLEY ON SUNDAY AND SUNDAY NIGHT. TIME
HEIGHT SECTIONS CONTINUE TO SHOW LOWER LEVEL SATURATION LINGERING
ON SUNDAY AND SUNDAY NIGHT. EVEN IF THE STRATUS DOES BEGIN TO
BREAK UP ON SUNDAY AFTERNOON...THE START OF WARM AIR ADVECTION ON
SUNDAY NIGHT AND MONDAY ON THE BACKSIDE OF THE HIGH SHOULD RESULT
IN A RETURN OF HIGH CLOUD. THUS THE OUTLOOK FOR SUNSHINE IS LOW.
WILL TREND TOWARD MOSTLY CLOUDY SUNDAY AND SUNDAY NIGHT. AS FOR
TEMPS...GIVEN THE ONGOING WARM AIR ADVECTION ON THE BACKSIDE OF
THE HIGH AS 850MB TEMPS RISE TOWARD 0C BY 12Z MONDAY WILL TREND
HIGHS SUNDAY COOLER THAN MAVMOS WITH CLOUDS AND LOWS SUNDAY NIGHT
WARMER THAN MAVMOS.

ON MONDAY AND MONDAY NIGHT GFS AND NAM SUGGESTS A DEEP TROUGH
DIGGING OVER THE CENTRAL PLAINS AS TE SURFACE HIGH REACHES NEW
ENGLAND. STRONG WARM AIR ADVECTION BEGINS TO TAKE SHAPE ON MONDAY
AS SOUTHEAST WINDS DEVELOP ACROSS THE STATE. BY MONDAY
AFTERNOON...FORECAST SOUNDINGS ARE HINTING AT DEEP SATURATION AS
IN INITIAL SHORT WAVE IS PUSHED ACROSS CENTRAL INDIANA AS IT IS
EJECTED OUT OF THE TROUGH TO THE WEST. MEANWHILE THE 295K GFS
ISENTROPIC SURFACE CONTINUES TO SHOW VERY STRING UPGLIDE STARTING
MONDAY AFTERNOON WITH SPECIFIC HUMIDITIES IN EXCESS OF 3 G/KG.
THUS FEEL GOOD INGREDIENTS ARE AVAILABLE FOR PRECIP ON MONDAY
AFTERNOON. WILL TREND POPS HIGHER THAN MAVMOS AND ALSO TREND TEMPS
HIGHER ALSO GIVEN.

ON MONDAY NIGHT AND TUESDAY...STRONG ISENTROPIC LIFT IS EXPECTED
TO CONTINUES AS THE STRONG TROUGH ALOFT DIGS THROUGH THE CENTRAL
PLAINS MEANWHILE FORECAST SOUNDINGS CONTINUE TO SHOW GOOD
SATURATION. BEST SATURATION APPEARS ON TUESDAY AFTERNOON AS STRONG
LOW PRESSURE PUSHES INTO THE MISSISSIPPI RIVER VALLEY AND A SURGE OF
WARM AIR ARRIVES IN CENTRAL INDIANA. FURTHERMORE THE GFS SUGGESTS A
50 KTS LLJ PROVIDING ADDITIONAL LIFT. THUS WITH ALL THESE
INGREDIENTS WILL AGAIN TREND POPS UPWARDS...AND AGAIN TREND TEMPS
WARMER ON LOWS AND COOLER ON HIGHS. FURTHERMORE...BEING IN THE WARM
SECTOR...AND FORECAST SOUNDINGS SOLIDLY ABOVE
FREEZING...PRECIP TYPE WILL BE RAIN.

&&

.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 20/2100Z TAF ISSUANCE/...

ISSUED AT 325 PM EST SAT DEC 20 2014

TWEAKED CURRENT CONDITIONS ONLY. PREVIOUS DISCUSSION FOLLOWS...

PERSISTENT LOW LEVEL CLOUD DECK CONTINUES TO AFFECT TAF SITES.
MVFR/VFR CONDITIONS WILL PREVAIL FOR DURATION OF TAF PERIOD
DESPITE HIGH PRESSURE OVER THE AREA. TIME CROSS SECTIONS CONTINUE
TO SHOW SUBSTANTIAL LOW LEVEL MOISTURE. VARIABLE WINDS WILL BECOME
MAINLY SOUTHEASTERLY TONIGHT WITH SUSTAINED SPEEDS OF 2 TO 4 KTS.

&&

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

&&

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....TDUD
AVIATION...TDUD/CP

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