FXUS63 KPAH 062037
AFDPAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
237 PM CST SUN DEC 6 2009
.DISCUSSION...
OUR NEXT WEATHER MAKER IS CURRENTLY PRODUCING SOME LIGHT PRECIP
OVER THE CENTRAL PLAINS. A WEAK BUT NEGATIVELY TILTED SHORTWAVE
TROUGH WILL APPROACH US TONIGHT. AT THE SFC...A LOW PRESSURE
SYSTEM IS CURRENTLY SITUATED OVER TEXAS...BUT MODELS INDICATE A
NEW LOW DEVELOPS ACROSS NORTHWESTERN MISSOURI BY LATER TONIGHT.
MODELS HAVE BEEN INDICATING THAT PRECIP CHANCES WILL BE CONFINED
TO THE WEST THIS EVENING...AND THEN OVERSPREAD THE AREA OVERNIGHT.
THE 12Z NAM IS NOW SLOWER AND LEAVES THE AREA DRY THROUGH 06Z
MONDAY...AND SUBSEQUENTLY LINGERS PRECIP INTO MONDAY MORNING.
HOWEVER...WITH EVERY MODEL RUN...PRECIP AMTS HAVE BEEN LESS AND
LESS...AND WITH THE 12Z RUNS...ARE ONLY PRODUCING A FEW HUNDREDTHS
FOR THIS ENTIRE EVENT. HOWEVER...THE ACTUAL SYSTEM APPEARS TO BE
GETTING A LITTLE STRONGER EACH DAY. THERE ALSO SEEMS TO BE A
FAIRLY GOOD AMOUNT OF LIFT ASSOCIATED WITH THIS SYSTEM...DESPITE
THE PUNY QPF. THE NAM AND GFS DO KEEP THE ENTIRE AREA FAIRLY DRY
THROUGH 06Z MONDAY IN THE LOW LEVELS (BELOW H85).
HOWEVER...LOOKING AT SATELLITE...LOW LEVEL MOISTURE IS DEFINITELY
MOVING UP THIS WAY RATHER QUICKLY.
THEREFORE...THE PROBLEM LIES IN THE MINUTE DETAILS WITH REGARDS
TO PRECIP TYPE...TIMING AND ANY PRECIP AMTS ACROSS THE CWA FROM
NORTH TO SOUTH...AS ALWAYS SEEMS TO BE THE CASE. INSPECTION OF
AREA SOUNDINGS INDICATES A WIDE RANGE OF POSSIBILITIES...WITH
LIGHT SNOW IN THE FAR NORTH...TO POSSIBLY FREEZING RAIN IN THE FAR
SOUTH. WILL ERR ON THE SIDE OF CAUTION...GIVEN ALL OF THE
UNCERTAINTIES...AND GO WITH CHC INSTEAD OF LIKELY...RAIN OR SNOW
ACROSS THE NORTH THIS EVENING...TRANSITIONING TO ALL LIGHT SNOW
WITH POSSIBLY SOME FREEZING DRIZZLE AFTER MIDNIGHT. AND IN THE FAR
SOUTH...RAIN OR FREEZING RAIN THIS EVENING...TO A CHANCE OF
RAIN...FREEZING RAIN AND SLEET AFTER MIDNIGHT. AGAIN...WHERE
EXACTLY THAT INFAMOUS RAIN/SNOW LINE WILL END UP...AND WHERE
EXACTLY SFC TEMPS END UP IS THE TRICK. LOOKING AT ROAD SFC
TEMPS...LOOKS LIKE IF WE STAY IN THE LOWER 30S OVERNIGHT...THE
PAVEMENT TEMPS SHOULD STAY ABOVE FREEZING AND HOPEFULLY PRECLUDE
ANY PROBLEMS ON THE ROADWAYS...IF WE END UP RECEIVING ANY PRECIP.
MEANWHILE...OUR SECOND STORM SYSTEM OF THE WEEK IS CURRENTLY
DEVELOPING OVER THE PACIFIC NORTHWEST. THIS SYSTEM MOVES INTO THE
CENTRAL PLAINS ON TUESDAY. ALL MODELS AND THE GFS ENSEMBLES
INDICATE THE BEST CHANCES FOR PRECIP WILL BE ACROSS OUR SOUTH IN
THE MORNING...WITH CHANCES INCREASING AREA WIDE DURING THE
AFTERNOON AND INTO THE EVENING. THANKFULLY...THIS SYSTEM IS MORE
CLEAR CUT THAN TONIGHTS...AND IT LOOKS TO BE AN ALL LIQUID EVENT
ON TUESDAY AND TUESDAY NIGHT. ON WEDNESDAY MORNING...COULD NOT
RULE OUT A SNOW FLURRY...BUT IT APPEARS AS THOUGH THE BEST
MOISTURE WILL BE SHUNTED NORTHEAST OF US BEFORE THE COLDER AIR HAS
A CHANCE TO FILTER INTO THE AREA. BY WEDNESDAY AFTERNOON...ANY
CHANCES FOR PRECIP WILL BE WELL OFF TO OUR NORTHEAST.
UNFORTUNATELY THE LONG RANGE MODELS HAVE BEGUN TO DIVERGE WITH THE
LATEST RUNS. YESTERDAYS 12Z RUNS WERE IN FAIRLY GOOD AGREEMENT
BRINGING A STORM SYSTEM WITH LIGHT PRECIP/QPF ACROSS THE REGION
FRIDAY INTO FRIDAY NIGHT WHILE SHOWING HIGH PRESSURE AT THE SURFACE.
THE BIGGEST CHALLENGE WAS TRYING TO DETERMINE PRECIP TYPE. TODAYS
12Z GFS AND ECMWF RUNS ARE QUITE DIFFERENT. THE GFS CONTINUES TO
INDICATE A VERY SIMILAR SOLUTION TO YESTERDAY...BUT THE ECMWF IS NOW
KEEPING THE REGION DRY THROUGH FRIDAY NIGHT...THEN BRINGING THE
SYSTEM ACROSS THE REGION SATURDAY INTO SATURDAY NIGHT. WITH THE
REGION REMAINING IN ZONAL FLOW ALOFT THROUGHOUT THE PERIOD...AND
GIVEN THE PROPENSITY FOR THE GFS TO HURRY THINGS ALONG A BIT IN
ZONAL FLOW...THE ECMWF SOLUTION MAY VERY WELL PAN OUT...BUT TO AVOID
FLIP FLOPPING THIS FAR OUT...WILL NOT MAKE ANY CHANGES AT THIS TIME.
THEREFORE...BASED ON THE GFS MODEL DATA AND SOUNDINGS...WILL KEEP A
RAIN/SNOW MIX ON FRIDAY CHANGING TO ALL SNOW FRIDAY NIGHT.
&&
.AVIATION...
HIGH PRESSURE WILL SHIFT EAST OF THE AREA OVER THE NEXT 24 HOURS...
AS WEAK LOW PRESSURE APPROACHES FROM THE WEST. AHEAD OF THIS LOW...
HIGH AND MID LEVEL CLOUDS WILL GRADUALLY LOWER AND THICKEN THIS
AFTERNOON INTO TONIGHT. CONDITIONS SHOULD REMAIN VFR THROUGH MOST OF
THE PERIOD...THEN BECOMING MVFR FROM WEST TO EAST FROM 12Z ON. ANY
PRECIPITATION LATE TONIGHT IN THE FORM OF LIGHT FREEZING RAIN OR
SNOW IS ONLY EXPECTED AT THE KCGI AND KPAH SITES. WINDS THROUGH THE
PERIOD WILL BE SOUTH/SOUTHEASTERLY AT LESS THAN 10 KNOTS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&
$$
