FXUS63 KIND 260205
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
905 PM EST WED NOV 25 2009
.UPDATE...
MADE VERY FEW CHANGES TO THE OVERNIGHT FORECAST. UPDATED THE 3-6Z
TIME FRAME TO DROP POPS TO CHANCE IN THE NORTH AND EXTEND THE SLIGHT
CHANCE IN THE SOUTH TO REFLECT CURRENT RADAR TRENDS WITH THE BACK
EDGE OF THE AREA OF RAIN TO AFFECT THE FORECAST AREA ALMOST TO THE
ILLINOIS/INDIANA BORDER. WITH -5C TEMPERATURES AT H8 OVER CENTRAL
ILLINOIS AT 0Z PER THE RAOB AND A MIX OF RAIN AND SNOW AT SEVERAL
SITES IN IOWA SINCE BEFORE THEN AND A SHORTWAVE MOVING INTO
ILLINOIS...THINK THE FORECAST FOR LOW CHANCE IN THE NORTH AND SLIGHT
CHANCE IN THE SOUTH FOR A MIX OF RAIN AND SNOW AFTER 6Z IS STILL
VALID.
&&
.AVIATION...DISCUSSION FOR THE 00Z TAFS
LOW PRESSURE WAS FOUND ACROSS THE GREAT LAKES EARLY THIS EVENING.
CURRENT RADAR TRENDS SHOW AREAS LIGHT RAIN SHOWERS OVER ILLINOIS AND
WESTERN INDIANA. EXTENSIVE MVFR CONDITIONS WERE FOUND ACROSS
INDIANA...ILLINOIS AND IOWA. WATER VAPOR IMAGERY SHOWS AN UPPER
DISTURBANCE OVER IOWA...DIVING SOUTHEAST.
MVFR CONDITIONS ALONG WITH BRIEF IFR CONDITIONS ARE EXPECTED DURING
THIS TAF PERIOD.
FORECAST SOUNDINGS AND TIME HEIGHT SECTIONS SHOW SATURATED LOWER
LEVELS THROUGH AT LEAST 06Z FRIDAY. TWO SHORT WAVES WILL PUSH ACROSS
INDIANA DURING THE PERIOD...THE FIRST BEING TONIGHT AS THE CURRENT
RADAR TRENDS SUGGEST. THE SECOND WILL BE ON THURSDAY AFTERNOON AS
THE SECONDARY UPPER TROUGH PUSHES THROUGH INDIANA. AT THAT TIME
FORECAST SOUNDINGS APPEAR COLD ENOUGH TO SUPPORT SOME SNOW ACROSS
THE NORTHERN TAF SITES AND HAVE INCLUDED A MIX. IFR CONDITIONS MAY
BE POSSIBLE DURING THE PRECIPITATION WINDOWS TONIGHT AND ON THURSDAY
AFTERNOON...OTHERWISE MVFR.
&&
.PREV DISCUSSION...AT 20Z...TEMPERATURES ACROSS THE COUNTY WARNING
AREA RANGED FROM THE MID 40S TO THE MID 50S...WITH DEWPOINTS IN THE
LOW TO MID 40S. WINDS WERE OUT OF THE SOUTHWEST GENERALLY AT OR
BELOW 10 KNOTS. RADAR SHOWED A FEW SPRINKLES/LIGHT SHOWERS ACROSS
THE NORTHERN HALF OF THE AREA. NATIONAL RADAR MOSAICS SHOWED AN AREA
OF SHOWERS NEAR THE MISSISSIPPI RIVER PUSHING EASTWARD...WHICH LOOKS
TO BE OUR FIRST ROUND OF PRECIPITATION OVERNIGHT.
FORECAST CHALLENGE OF THE DAY WILL BE POPS AND PRECIPITATION TYPE
TONIGHT THROUGH EARLY TOMORROW NIGHT.
GFS IS THE PREFERRED MODEL TODAY...AS THE NAM APPEARS TO BE
DEVELOPING THE APPROACHING UPPER LOW TOO STRONGLY...AND GFS HAS THE
SUPPORT OF THE SREF. EXPECT INITIAL WAVE OF PRECIPITATION TO PUSH
THROUGH THE AREA DURING THE FIRST HALF OR SO OF THE EVENING...WITH A
POSSIBLE LULL IN PRECIPITATION DURING THE LATTER HALF OF THE NIGHT.
HOWEVER...THERE WILL STILL BE A LOW CHANCE OF PRECIPITATION
LATE...AND LOW LEVEL THICKNESSES BECOME SUPPORTIVE OF A RAIN/SNOW
MIX LATE TONIGHT THROUGH TOMORROW AND INTO TOMORROW EVENING. WILL
CONTINUE WITH LIKELY POPS OVER THE NORTHERN HALF TO TWO THIRDS OF
THE FORECAST AREA TOMORROW...AS A PERIOD OF MODESTLY STRONG
ISENTROPIC LIFT IS EXPECTED.
THROUGHOUT THE LATE TONIGHT THROUGH TOMORROW EVENING SCENARIO...RAIN
WILL LIKELY BE PREDOMINANT...WITH A FEW SNOWFLAKES MIXING IN.
HOWEVER...DURING THE PERIODS OF STRONGEST LIFT...AND AS THE CENTER
OF LOWEST THICKNESSES PASS OVER MIDDAY THURSDAY...A BRIEF BURST OF
MOSTLY SNOW WILL BE POSSIBLE...BUT THE THRUST OF THIS IS THAT
SURFACE TEMPERATURES WILL REMAIN ABOVE FREEZING...AND GROUND
TEMPERATURES ARE WARM...SO ACCUMULATIONS ARE NOT EXPECTED.
ON TEMPERATURES...WENT WITH THE MAV TONIGHT WITH CLOUDY SKIES AND
PRECIPITATION. THIS ALSO HAS THE SUPPORT OF THE ANTICIPATED 850 MB
TEMPERATURES. USED A BLEND FOR TOMORROW...AS MET IS VERY COLD...BUT
DO NOT BUY THE WARMING DEPICTED BY THE MAV ENTIRELY...AGAIN WITH
CLOUD COVER AND PRECIPITATION OCCURRING. TOMORROW NIGHT...A BLEND
WAS USED AS AGREEMENT WAS EXCELLENT...AND FOR FRIDAY THROUGH THE
REMAINDER OF THE SHORT TERM...USED THE WARM SIDE OF MOS...AS STRONG
WARM ADVECTION BEGINS AND CONTINUES THROUGH THE SHORT TERM.
MUCH DISAGREEMENT IN THE EXTENDED AND GENERALLY LEANED TO A MIX OF
ECMWF/GEM/HPC GUIDANCE...AS THE GFS SOLUTION DOES NOT LOOK REALISTIC
FOR THE LATTER PORTION OF THE FORECAST PERIOD.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...NIELD
AVIATION...JP
UPDATE...CP
