505 
FXUS63 KIND 161033
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
533 AM EST TUE DEC 16 2014

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

&&

.SYNOPSIS...
ISSUED AT 251 AM EST TUE DEC 16 2014

A LOW PRESSURE SYSTEM WILL EXIT THE AREA TODAY. IN THE WAKE OF THIS 
SYSTEM...HIGH PRESSURE IS EXPECTED INTO THE LATER PORTIONS OF THE 
WEEK. A LOW PRESSURE SYSTEM MAY AFFECT THE AREA OVER THE WEEKEND.

&&

.NEAR TERM /TODAY/...
ISSUED AT 251 AM EST TUE DEC 16 2014

AREA OF RAIN CURRENTLY MOVING THROUGH THE LOCAL AREA IN ASSOCIATION 
WITH A SURFACE LOW AND OCCLUSION. APPEARS MOST OF THIS WILL BE IN 
THE PROCESS OF EXITING THE AREA BY SUNRISE. 

SHORT TERM MODELS SUGGEST THE UPPER TROUGH WILL BE PASSING THROUGH 
LATER THIS MORNING. AS A RESULT...WILL KEEP SOME POPS GOING FOR 
LIGHT RAIN...ESPECIALLY DURING THE MORNING HOURS. AS THE UPPER 
TROUGH PULLS AWAY THIS AFTERNOON...THE PRECIPITATION THREAT SHOULD 
DIMINISH AS WELL. 

GIVEN THE COLD ADVECTION IN THE WAKE OF THE LOW...APPEARS HIGHS 
TODAY WILL BE REACHED THIS MORNING...WITH TEMPERATURES NEARLY 
STEADY OR SLOWLY FALLING THIS AFTERNOON. 

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
ISSUED AT 251 AM EST TUE DEC 16 2014

FAIRLY QUIET WEATHER EXPECTED DURING THIS PERIOD AS ZONAL UPPER FLOW 
UNDERCUTS A BLOCK OVER SOUTHERN CANADA. 

WILL KEEP SOME SMALL CHANCE POPS GOING FOR LIGHT RAIN OR SNOW THIS 
EVENING OVER THE EASTERN ZONES TO COVER ANY LINGERING PRECIPITATION 
POTENTIAL IN THE WAKE OF TODAY/S UPPER TROUGH...BUT THIS DOESN/T 
LOOK LIKE A BIG DEAL. 

OTHERWISE...WILL GO WITH A DRY FORECAST FOR THE REST OF THE PERIOD 
AS SURFACE HIGH PRESSURE NOSES INTO THE AREA FROM THE NORTHERN 
PLAINS. A SUBSIDENCE INVERSION DEVELOPS THIS EVENING WHICH LINGERS 
INTO THURSDAY OR THURSDAY NIGHT. AS A RESULT...THINK THERE WILL BE 
QUITE A BIT OF CLOUD COVER AROUND OVER THE NEXT FEW DAYS.

MODELS SUGGEST THERE MAY BE SOME LIFT DEVELOPING OVER THE SURFACE 
HIGH PRESSURE RIDGE BY THURSDAY. OPERATIONAL AND ENSEMBLE DATA 
SUGGEST LITTLE THREAT OF PRECIPITATION AT THIS TIME...BUT WILL 
MONITOR THE TRENDS.

DUE TO EXPECTED CLOUD COVER OVER THE NEXT FEW DAYS...WILL TEMPER THE 
DIURNAL RANGE OF THE GFS MOS TEMPERATURE GUIDANCE BY ABOUT A 
CATEGORY PER PERIOD.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 332 AM EST TUE DEC 16 2014

MAIN FOCUS FOR THE EXTENDED WILL BE SNOW POTENTIAL ALONG WITH TIMING 
AND TEMPERATURES.

DETERMINISTIC MODELS ARE NOW ATTEMPTING TO CONVERGE ON A SIMILAR 
SOLUTION...ALTHOUGH THE ECMWF LOOKS A BIT SLOW BRINGING QPF ACROSS 
THE FORECAST AREA. THE 00Z GEM AND GFS BOTH HAVE QPF ACROSS OUR 
SOUTHERN COUNTIES FRIDAY NIGHT AS ENERGY LIFTS NORTHEAST FROM THE 
LOWER MISSISSIPPI VALLEY AHEAD OF AN APPROACHING UPPER TROUGH OVER 
THE SOUTHERN PLAINS. STILL...THIS MARKS A CHANGE AS PREVIOUS MODEL 
RUNS SUGGESTING THE PRECIPITATION WOULD BE FURTHER NORTH AND ENVELOP 
OUR ENTIRE FORECAST AREA. FURTHER SOUTHERLY TRACK SUGGESTS AREAS 
NEAR AND NORTH OF INTERSTATE 70 SHOULD BE DRY FRIDAY NIGHT. AS THE 
UPPER TROUGH PASSES THROUGH ON SATURDAY...PRECIPITATION SHOULD 
SPREAD FAR ENOUGH NORTH TO KEEP CHANCE POPS IN ALL OF CENTRAL 
INDIANA. FINALLY...SYSTEM TO DAMPEN SATURDAY NIGHT AS IT MOVES EAST 
AND BECOMES ABSORBED IN NORTHERN STREAM LOW OVER THE UPPER MIDWEST 
AND ONTARIO. THE REST OF THE EXTENDED LOOKS TO BE DRY AS SURFACE 
HIGH PRESSURE SETTLES SOUTHEAST OVER THE GREAT LAKES AND OHIO 
VALLEY. PRECIPITATION TYPE SHOULD BE MOSTLY SNOW BASED ON MODEL 
SOUNDINGS AND CRITICAL THICKNESSES...ALTHOUGH WOULD NOT RULE OUT 
SOME SLEET OR FREEZING RAIN AT THE ONSET FRIDAY NIGHT...FAR SOUTH AS 
WARM LAYER ALOFT MOVES INTO THAT AREA. WILL KEEP IT JUST SNOW FOR 
NOW...HOWEVER AND TAKE ANOTHER LOOK AT IT AFTER SUBSEQUENT MODEL 
RUNS.     

NOT EXPECTING MUCH ACCUMULATION WITH THIS SYSTEM BASED ON THE 
CURRENT TRACK CONSENSUS. EVEN IN THE SOUTHERN SECTIONS...IT DOES NOT 
LOOK LIKE MORE THAN AN INCH AT THIS POINT.  

WITH THE SYSTEM TRENDING FURTHER SOUTH PER THE MORE CONSISTENT ECMWF 
AND ITS ENSEMBLE MEANS...PREFER THE COOLER GFS ENSEMBLE MEMBERS 
ALONG WITH THE ECMWF ENSEMBLE MEANS WHICH MATCH NICELY WITH THE 00Z 
REGIONAL BLEND.  

&&

.AVIATION /DISCUSSION FOR THE 161200Z TAF ISSUANCE/...
ISSUED AT 533 AM EST TUE DEC 16 2014

IFR CEILINGS SHOULD IMPROVE TO MVFR NEAR ISSUANCE TIME PER LATEST 
UPSTREAM OB TRENDS. COULD ALSO SEE A FEW LIGHT SHOWERS AROUND 
THROUGH 20Z OR SO TODAY BEFORE THE LOW PULLS AWAY OVER SOUTHERN 
ONTARIO. 

WINDS WILL BE SOUTHWEST AND THEN WEST AND INREASE TO NEAR 15 KNOTS 
WITH GUSTS TO 20 KNOTS OR MORE AFTER 14Z. WINDS WILL EASE UP A BIT 
AFTER 00Z AS. 

&&

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

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM...MK
AVIATION...MK

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