FXUS63 KPAH 151948
AFDPAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
145 PM CST TUE DEC 15 2009
.DISCUSSION...
THE SHORT TERM IS RATHER STRAIGHTFORWARD. COLD HIGH PRESSURE WILL
MOVE EAST ACROSS ILLINOIS EARLY WEDNESDAY...BRINGING CLEAR SKIES AND
LIGHT WINDS CONDUCIVE FOR EXCELLENT RADIATIONAL COOLING. MODELS HAVE
BEEN A LITTLE TOO WARM WITH TEMPS TODAY. GIVEN THIS HISTORY AND THE
DRY AIR ADVECTING INTO OUR AREA...EXPECT LOWS TO AVERAGE BELOW MOS
GUIDANCE /EVEN COLDER NAM MOS/. NO CHANGES PLANNED TO FORECAST FOR
TONIGHT.
HIGH PRESSURE WILL CONTINUE TO BRING CLEAR SKIES AND LIGHT WINDS
THROUGH WEDNESDAY NIGHT. TEMPERATURES WILL LIKELY REMAIN BELOW MOS
GUIDANCE BY A FEW DEGREES.
THURSDAY INTO FRIDAY...SOME RETURN FLOW WILL DEVELOP AROUND THE
HIGH. TEMPERATURES WILL MODERATE TO NEAR NORMAL LEVELS. CLOUDS WILL
INCREASE ON FRIDAY AHEAD OF A STRENGTHENING MID LEVEL SHORTWAVE
MOVING EAST FROM THE SOUTH CENTRAL PLAINS.
A CHANCE OF LIGHT SNOW WILL BE CONTINUED FOR FRIDAY NIGHT AND
SATURDAY AS THE SHORTWAVE PASSES. MODELS DIVERGE ON THE SPEED OF
THIS SYSTEM AS IT STRENGTHENS...WITH THE 12Z GFS QUITE SLOW AND
STRONG COMPARED TO ITS ENSEMBLE MEAN. IN EITHER CASE...QPF LOOKS TO
BE QUITE LIGHT /ONE TENTH INCH OR LESS/ SINCE THE LOW LEVELS WILL BE
DOMINATED BY COLD ADVECTION AND WEAKLY DIVERGENT FLOW AHEAD OF A
STRONG PLAINS HIGH. IF THE PRECIP OCCURS EARLY ENOUGH FRIDAY
EVENING...IT WOULD LIKELY BE RAIN OR A RAIN/SNOW MIX.
BEYOND SATURDAY...MODEL DIFFERENCES BECOME QUITE LARGE. PREFER THE
12Z GFS ENSEMBLE MEAN...WHICH SUGGESTS THE STRONG UPPER LOW OVER THE
EASTERN STATES WILL DEPART SUNDAY AND MONDAY AS ANOTHER UPPER LOW
TAKES ITS PLACE OVER THE GREAT LAKES REGION. WHAT THIS ALL MEANS IS
HIGH CONFIDENCE IN COLD AIR PERSISTING THROUGH EARLY NEXT WEEK. THE
TRICKIER PART IS PRECIP POTENTIAL. DEPENDING ON WHICH MODEL
VERIFIES...THERE COULD BE ONE OR MORE 500 MB IMPULSES ROTATING
AROUND THE LOW STRONG ENOUGH TO INDUCE SOME LIGHT SNOW. PREFER NOT
TO CLUTTER UP THE FORECAST WITH SLIGHT CHANCE POPS FOR THREE DAYS.
WHEN AND IF MODELS CONVERGE ON A STRONGER SIGNAL FOR PRECIP...POPS
CAN BE ADDED FOR ONE OR MORE PERIODS NEXT WEEK.
&&
.AVIATION...
CLEAR SKIES AND UNRESTRICTED VSBY WILL CONTINUE THROUGH THE TAF
PERIOD AS HIGH PRESSURE BUILDS OVERHEAD. WINDS WILL DECREASE THIS
EVENING...AND REMAIN LIGHT ON WEDNESDAY.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&
$$
PUBLIC/AVIATION...MY
