FXUS63 KIND 270011
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
711 PM EST SAT DEC 26 2009

.AVIATION...
/00Z TAFS/
MVFR AND IFR CONDITIONS PREVAILED THE LAST SEVERAL HOURS AS THE
FIRST BAND OF SNOW PASSED OVER CENTRAL INDIANA. ANTICIPATE MVFR
CONDITIONS TO LAST THROUGH MOST OF TAF PERIOD AS DECENT MOISTURE
REMAINS IN THE LOWER LEVELS. HOWEVER...THERE IS A CHANCE FOR BRIEF 
VFR CONDITIONS BETWEEN BANDS OF SNOW. CURRENT OBSERVATIONS ARE
SHOWING IMPROVED CEILINGS AT KIND AND KLAF...BUT DO NOT ANTICIPATE
THESE CONDITIONS TO LAST LONG ENOUGH FOR EVEN A TEMPO GROUP.
UPSTREAM OBSERVATIONS ARE INDICATING A QUICK SHIFT BACK TO MVFR.

SNOW SHOULD TAPER OFF OVER THE NEXT FEW HOURS AS TIME SECTIONS
INDICATE SOME DRIER AIR FILTERING INTO THE AREA. SOME LIGHT SNOW
SHOWERS OR FLURRIES WILL BE POSSIBLE OVERNIGHT...BUT THE NEXT ROUND
OF SNOW WILL NOT START UNTIL AFTER DAYBREAK. SNOW WILL REMAIN IN
THE FORECAST THROUGH TOMORROW AFTERNOON. THERE ARE INDICATIONS OF
VFR CONDITIONS RETURNING TOMORROW EVENING...BUT THIS WILL HAVE TO
BE DETERMINED IN NEXT TAF ISSUANCE.

&&

.PREV DISCUSSION... /ISSUED 335 PM EST SAT DEC 26 2009/ 

DISCUSSION...DEEP UPPER LOW CENTERED OVER WISCONSIN WILL DOMINATE 
OUR WEATHER BEFORE IT MOVES EASTWARD BEGINNING LATE SUNDAY.  MODELS 
HAVE BEEN CONSISTENT PAST FEW RUNS IN GIVING UP SOME MEASURABLE SNOW 
AS THIS SYSTEM STARTS TO MOVE BY ON SUNDAY.  THUS THE MAIN FORECAST 
CONCERNS ARE SNOW CHANCES SUNDAY AND HOW MUCH SNOW WILL FALL.  ALSO 
TEMPERATURES NEXT SEVERAL DAYS AND HOW LONG TO KEEP ANY RESIDUAL 
LAKE EFFECT SNOW IN OUR NORTH AFTER THIS SYSTEM MOVES BY.

IN THE SHORT TERM NAM...GFS AND GEM MODELS ARE IN GENERAL AGREEMENT 
AND WILL USE BLEND.  THERE IS PRESENTLY AN AREA OF SNOW OVER CENTRAL 
ILLINOIS AND THIS MAY ROTATE ACROSS OUR NORTHWEST ZONES THIS EVENING 
PRODUCING LIGHT SNOW AMOUNTS THERE.  AS THE MAIN SHORT WAVE LOBE 
ROTATES ACROSS OUR REGION MODELS GIVE .1 TO .2 INCHES OF 
PRECIPITATION WHICH WOULD TRANSLATE TO 1 TO 2 INCHES OF SNOW. SNOW 
WILL END OVER ALL SECTIONS SUNDAY NIGHT AS THIS SYSTEM MOVES 
EASTWARD...BUT LAKE EFFECT FLURRIES MAY LINGER ON INTO OUR NORTH ON 
MONDAY.

CONCERNING TEMPERATURES WENT CLOSER TO A BLEND OF NAM SURFACE 
TEMPERATURES AND MET TEMPERATURES.  ASSUMING THERE MAY BE A LITTLE 
SNOW COVER ACROSS OUR NORTH AND CENTRAL WENT ON THE LOW SIDE OF 
GUIDANCE NUMBERS SUNDAY NIGHT THROUGH TUESDAY.

MODELS MOVE A WEAK UPPER RIDGE ACROSS OUR REGION AROUND TUESDAY. BY 
WEDNESDAY THERE IS A SPLIT FLOW OVER THE WESTERN U.S.  THERE IS ONE 
UPPER DISTURBANCE IN THE SOUTHERN STREAM OVER THE SOUTHWEST U.S. 
WHILE ANOTHER UPPER SYSTEM IN THE NORTHERN STREAM STARTS TO DIG 
ACROSS SOUTHWEST TEXAS.  THE GFS KEEPS THESE SYSTEMS SEPARATE UNTIL 
THE SOUTHERN SYSTEM PASSES BY...WHILE THE EUROPEAN SHOWS MUCH MORE 
PHASING BETWEEN THE NORTHERN AND SOUTHERN SYSTEMS.  MODELS HAVE 
TRENDED A TAD SLOWER SO WILL DROP PRECIPITATION CHANCES MOST AREAS 
FOR WEDNESDAY MORNING. I HAVE DECIDED TO NOT MAKE ANY SIGNIFICANT 
CHANGES IN THE LATER PERIODS FROM HPC NUMBERS BECAUSE OF UNCERTAINTY 
BETWEEN DIFFERENT MODELS IN THE EXTENDED PERIOD REGARDING SNOW 
CHANCES.  EITHER CASE TEMPERATURES WILL BECOME QUITE COLD NEAR END 
THE END OF THE 7 DAY PERIOD.

&&

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

&&

$$

PUBLIC...JH
AVIATION...TDUD