000
FXUS63 KIND 102025
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
324 PM EST TUE DEC 10 2013

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

&&

.SYNOPSIS...
ISSUED AT 154 PM EST TUE DEC 10 2013

HIGH PRESSURE CENTERED OVER THE GULF STATES WILL BE THE MAIN PLAYER
IN INDIANA WEATHER INTO FRIDAY. FRIDAY NIGHT INTO SUNDAY A COMPLEX
PATTERN OF LOW PRESSURE...A WARM FRONT...AND A COLD FRONT IS
FORECAST TO CROSS THE HOOSIER STATE. HIGH PRESSURE IS GOING TO BE
BACK MONDAY. TUESDAY ANOTHER COLD FRONT SHOULD SHOW UP.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 154 PM EST TUE DEC 10 2013

BOTH GFS AND NAM INDICATE TONIGHT PARTLY CLOUDY NORTH AND MOST
CLEAR SOUTH. LATEST SATELLITE PICTURES SUPPORT THIS.

THIS LEAVES TEMPERATURES AS FORECAST PROBLEM. NOT A HIGH CONFIDENCE
FORECAST. DETAILS OF CLOUDS AND WINDS COULD MAKE A BIG DIFFERENCE.

HOWEVER...BOTH MODELS HAVE WARM ADVECTION ALOFT. SATELLITE POINTS TO
MOSTLY CLEAR EARLY. INVERSION SHOULD FORM. WHEN THAT HAPPENS
TEMPERATURES APT TO PLUNGE IN RESPONSE TO ANY MINOR CLOUD BREAKS OR
WIND LULLS.

ALL THAT SUPPORTS USING COLDER MAV IN MOST PLACES. WILL BE ABOUT CAT
LOWER THAN THAT IN EXTREME SOUTH. GUIDANCE THERE DOES NOT SEEM TO BE
TOTALLY ACCOUNTING FOR DEEP SNOW

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...

ISSUED AT 154 PM EST TUE DEC 10 2013

ALL MODELS HOLD OFF PRECIP UNTIL AFTER FRIDAY. OTHERWISE WEAK WAVES
ALOFT RESULTING IN PARTLY CLOUDY.

THIS LEAVES TEMPS AS THE FORECAST PROBLEM. THESE ARE
TRICKY..ESPECIALLY AT NIGHT...SINCE THEY WILL BE SO SENSITIVE TO
CLOUD COVER. BASED ON RECENT TRENDS MAV AT NIGHT AND MAV MET
CONSENSUS DAYS LOOKS BEST. SIGNIFICANT CHANGES MAY BE NEEDED AS WE
GET BETTER HANDLE ON WHAT CLOUDS IN A GIVEN PERIOD.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 248 PM EST TUE DEC 10 2013

MAIN CHALLENGE FOR THE EXTENDED REMAINS FOCUSED ON IMPACTS OF
ANOTHER POTENTIALLY MESSY WINTRY SYSTEM INTO THE REGION FRIDAY NIGHT
AND SATURDAY.

UPPER LOW OVER THE SOUTHWEST U S THURSDAY EVENING WILL EJECT EAST
AND QUICKLY TRACK INTO THE REGION BY EARLY SATURDAY AS AN OPEN WAVE
ALOFT. ENERGY ON THE BACK SIDE OF THE DEEP POLAR VORTEX ROTATING
OVER JAMES BAY WILL DROP INTO THE GREAT LAKES LATE SATURDAY INTO
SUNDAY...CARVING OUT ANOTHER DEEP UPPER TROUGH OVER THE EASTERN U S
AS IT INTERACTS WITH THE INITIAL WAVE ALOFT. AT THE SURFACE...BROAD
DISORGANIZED SURFACE WAVE SET TO TRACK ACROSS THE SOUTHEAST STATES
SATURDAY WHILE A SECONDARY LOW PRESSURE ORGANIZES IN RESPONSE TO THE
INTERACTION BETWEEN THE POLAR AND SUBTROPICAL JETS OVER THE OHIO
VALLEY...EVENTUALLY TRANSITIONING TO A COASTAL LOW BY SUNDAY AS THE
JET ENERGY PHASES.

THE DEGREE AND TIMING OF THE PHASING REMAINS CRITICAL TO SPECIFIC
IMPACTS AND PRECIP TYPE OVER THE REGION SATURDAY BUT AT THIS
POINT...BULK OF THE 12Z GUIDANCE THIS AFTERNOON FAVORING FULL
PHASING OF ENERGY ALOFT TAKING PLACE SATURDAY NIGHT/SUNDAY MORNING
WITH THE SECONDARY LOW TRACKING TO THE SOUTHEAST OF THE FORECAST
AREA. THIS WOULD LIMIT THE INTRUSION OF WARMER AIR WITHIN THE
BOUNDARY LAYER AND SUPPORTS SNOW AS THE PREDOMINANT PRECIP TYPE FOR
MUCH OF CENTRAL INDIANA FOR THE DURATION OF THE EVENT. GFS MODEL
SOUNDINGS ONLY SUPPORTIVE OF MARGINAL CONDITIONS FOR MIXING PRECIP
OVER FAR SOUTHERN COUNTIES DURING THE DAY SATURDAY...WITH THE GLOBAL
MODELS MAINTAINING EVEN COLDER CONDITIONS AND SUBFREEZING AIR
HOLDING THROUGH THE BOUNDARY LAYER. WITH THE COLDER TREND...
POTENTIAL FOR ACCUMULATING SNOWFALL CONTINUES TO GROW FOR MUCH OF
THE REGION FRIDAY NIGHT AND SATURDAY.

BEHIND THE SATURDAY STORM...COLDER AIR WILL ONCE AGAIN RETURN AS THE
UPPER TROUGH PINWHEELS GREAT LAKES. SCATTERED SNOW SHOWERS WILL
PERSIST IN CYCLONIC FLOW SUNDAY...WITH DRIER WEATHER RETURNING
MONDAY UNDER COLD HIGH PRESSURE. HIGH TEMPS WILL FALL INTO THE LOWER
20S FOR BOTH SUNDAY AND MONDAY WITH SOME RECOVERY BY TUESDAY AS
SURFACE FLOW TURNS SOUTHERLY. SINGLE DIGIT LOWS LOOK VERY LIKELY
SUNDAY NIGHT.

&&

.AVIATION /DISCUSSION FOR 102100Z IND TAF UPDATE/...
ISSUED AT 324 PM EST TUE DEC 10 2013

NO NEED FOR CHANGES TO TAF.

PREVIOUS DISCUSSION FOLLOWS...

VFR CONDITIONS EXPECTED THROUGHOUT THE FORECAST PERIOD.

MAIN ISSUE FOR TERMINAL OPERATIONS THIS AFTERNOON WILL BE WINDS.
STRONGER WINDS THROUGH THE BOUNDARY LAYER AND TIGHT SURFACE
PRESSURE GRADIENT CONTRIBUTING TO WIND GUSTS TO 25-30KTS EARLY
THIS AFTERNOON. THIS WILL CONTINUE THROUGHOUT THE AFTERNOON...WITH
WIND DIRECTION GRADUALLY SETTLING AT 240-250...SUSTAINEDS AT
15-20KTS AND GUSTS AT 25-30KTS. GUSTS WILL DROP OFF WITH SUNSET AS
THE NOCTURNAL INVERSION ESTABLISHES...WITH SOUTHWEST WINDS
DROPPING BELOW 10KTS.

AREA OF MID LEVEL CLOUDS WILL PASS THROUGH NORTHERN INDIANA THIS
AFTERNOON...WITH MOSTLY CLEAR SKIES THIS EVENING. MID AND HIGH
LEVEL CLOUDS WILL INCREASE LATE TONIGHT AND EARLY WEDNESDAY AHEAD
OF A FAST MOVING CLIPPER WITH AN ASSOCIATED COLD FRONT. THIS SYSTEM
WILL TRACK THROUGH THE LOWER GREAT LAKES WEDNESDAY MORNING. WINDS
WILL BACK TO S/SW AHEAD OF THE COLD FRONT...SHIFTING TO WESTERLY
BY THE END OF THE PERIOD. NOT OUT OF THE QUESTION TO SEE A FEW
SNOWFLAKES AT KLAF...BUT CHANCES LOOK FAR TOO LOW TO INCLUDE AT
THIS POINT.

&&

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

&&

$$

SYNOPSIS...JK
NEAR TERM...JK
SHORT TERM...JK
LONG TERM....RYAN
AVIATION...RYAN/MK

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