FXUS63 KIND 251055
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
555 AM EST FRI DEC 25 2009

.AVIATION...DISCUSSION FOR 25/12Z TAFS.
INTENSE LOW PRESSURE OVER NORTHEAST MISSOURI EARLY THIS MORNING... 
WITH COLD FRONT INTO SOUTHWEST INDIANA. SCATTERED SHOWERS CONTINUE 
ALONG AND AHEAD OF THE FRONT AT ALL OF THE TERMINALS. CEILINGS HAVE 
DIPPED DOWN INTO MVFR CATEGORY WITHIN THE LAST HOUR OR TWO AND QUICK 
GLANCE AT MODEL SOUNDINGS AND RH PROGS AT 925MB WOULD SUGGEST THAT 
THIS TREND SHOULD CONTINUE THROUGH THE MORNING. WILL MAINTAIN 
CEILINGS GENERALLY BETWEEN 1000-1500FT THROUGH MIDDAY. NOT OUT OF 
THE QUESTION THAT TERMINALS BRIEFLY DROP TO IFR AS THIN BAND OF 
HEAVIER RAIN ACCOMPANIES THE FRONT. THIS LINE SHOULD REACH KHUF 
AROUND OR SHORTLY AFTER 12Z...KBMG BY 14Z...AND KIND AND KLAF BY 
15Z. WINDS WILL REMAIN OUT OF THE SOUTHEAST IN ADVANCE OF THE FRONT 
THIS MORNING...THEN SHIFT TO SOUTH-SOUTHWEST BEHIND THE BOUNDARY. 
GUSTS IN EXCESS OF 30-35KTS ARE LIKELY ALL DAY.

COLDER AIRMASS RUSHES INTO THE REGION IN WAKE OF THE FRONTAL PASSAGE 
THIS AFTERNOON...WITH PRECIPITATION CHANGING TO SNOW BY MID 
AFTERNOON AT ALL TERMINALS. DEEPER MOISTURE WILL HAVE DEPARTED OFF 
TO THE NORTHEAST...SO NOT EXPECTING ANYTHING GREATER MVFR CONDITIONS 
WITH LIGHT SNOW SHOWERS OR FLURRIES INTO THE EVENING. HOWEVER... 
SHALLOW INSTABILITY AND INCREASING LOW LEVEL COLD ADVECTION SHOULD 
ALLOW FOR GOOD COVERAGE TO LIGHT SNOW SHOWERS/FLURRIES. THE ARRIVAL 
OF AN UPPER LEVEL LOW SHOULD ENSURE THAT LIGHT SNOW SHOWERS PERSIST 
FOR THE BETTER PART OF THE NIGHT. SOUTHWEST WINDS WILL REMAIN GUSTY 
ALL NIGHT AS WELL...APPROACHING 30KTS AT TIMES.

HAVE DROPPED ANY MENTION OF LOW LEVEL WIND SHEAR THIS MORNING. 
WINDS ARE STRONG ENOUGH AT THE SURFACE AT ALL TERMINALS TO LIKELY 
REMAIN BELOW CRITERIA...AND LAPS SOUNDINGS INDICATING THAT STRONGEST 
WINDS ASSOCIATED WITH THE LOW LEVEL JET ARE ALREADY SHIFTING 
NORTHEAST OF THE REGION. AS SURFACE WINDS VEER WITH PASSAGE OF FRONT 
DURING THE MORNING...WINDS WILL BECOME UNIDIRECTIONAL THROUGH THE 
LOW LEVELS.

&&

.DISCUSSION...DEEP LONG WAVE UPPER TROUGH CURRENTLY OVER THE PLAINS 
IS EXPECTED TO DRIFT SLOWLY EAST THROUGH THE GREAT LAKES AND OHIO 
VALLEY OVER THE NEXT FEW DAYS. SEVERAL EMBEDDED DISTURBANCES 
ROTATING THROUGH THE LONG WAVE TROUGH WILL KEEP THE WEATHER 
UNSETTLED INTO THE WEEKEND. MODELS IN GOOD AGREEMENT ON THE MAIN 
FEATURES. FORECAST FOCUS CENTERS ON POPS AND PRECIPITATION TYPE 
THROUGH THE SHORT TERM.

FOR TODAY...MODEL DATA SUGGEST THE SURFACE OCCLUSION SHOULD BE CLOSE 
TO THE SOUTHWEST BORDER ZONES BY 251200Z...AND SHOULD PASS THROUGH 
THE NORTHEAST ZONES BY MID AFTERNOON. WILL KEEP HIGH POPS GOING 
AHEAD OF THE FRONT...AND TAPER DOWN TO CHANCE POPS IN THE POST 
FRONTAL ZONE. GIVEN THE STRONG 70-80KT LOW LEVEL JET IN THE PROFILER 
AND MODEL DATA...WILL HAVE TO KEEP AN EYE ON THE ACTIVITY CLOSE TO 
FRONTAL ZONE FOR THE POSSIBILITY OF SOME HIGH WINDS MIXING DOWN TO 
THE SURFACE...ALTHOUGH LAST EVENING/S UPPER AIR INDICATE A STRONG 
INVERSION BELOW ABOUT 2500FT SO THERE IS SOME QUESTION IF THE WINDS 
ALOFT CAN BREAK THROUGH THAT INVERSION. SO FAR...DOESN/T APPEAR THAT 
IS HAPPENING BASED ON SURFACE REPORTS NEAR THE FRONT. OTHERWISE...
CRITICAL THICKNESS DATA FROM THE MODELS SUGGEST AIR MASS WILL GET 
COLD ENOUGH TO SUPPORT SNOW AFTER ABOUT 251700Z FROM SOUTHWEST TO 
NORTHEAST...SO ANY LINGERING PRECIPITATION THIS AFTERNOON MAY BE IN 
THE FORM OF SNOW SHOWERS.

IN THE LATER PERIODS...WILL KEEP CHANCE POPS FOR SNOW SHOWERS ACROSS 
THE AREA THROUGH SUNDAY...AS SEVERAL DISTURBANCES ROTATE AROUND THE 
LONG WAVE TROUGH. AT THIS POINT...APPEARS THE BEST CHANCES MAY BE ON 
SUNDAY WHEN THE BULK OF THE UPPER ENERGY PASSES THROUGH...BUT WON/T 
GET FANCY WITH THE POPS AT THIS POINT. SOME MINOR ACCUMULATIONS 
POSSIBLE.

APPEARS TEMPERATURES WILL PROBABLY RISE INTO THE UPPER 40S TO LOWER 
50S MOST AREAS LATER THIS MORNING BEFORE FRONTAL PASSAGE...WITH 
TEMPERATURES TAILING OFF BY AFTERNOON TO AROUND 30 BY SUNSET. LOW 
LEVEL THICKNESS PROGS SUGGEST THE GFS MOS HIGHS FOR FRIDAY MAY A FEW 
DEGREES TOO WARM...OTHERWISE THE NUMBERS IN THE BALLPARK.

&&

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

&&

$$

PUBLIC...JAS
AVIATION...RYAN