FXUS61 KILN 060344
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
1044 PM EST SAT DEC 5 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE MISSISSIPPI VALLEY WILL BUILD INTO THE
MIDDLE OHIO VALLEY OVERNIGHT. A WEAKENING UPPER SHORTWAVE WILL
SEND A WEAK SURFACE LOW AND COLD FRONT ACROSS THE GREAT LAKES AND
OHIO VALLEY ON MONDAY. A STRONGER SYSTEM WILL DIG INTO THE MIDWEST
ON WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
UPPER SHORTWAVE OVER THE EASTERN GREAT LAKES WILL CONTINUE MOVING
OFF TO THE EAST...ALLOWING SFC HIGH PRESSURE TO BUILD IN FROM THE
WEST OVERNIGHT. THIS WILL ALLOW LINGERING STRATOCUMULUS ACROSS THE
FAR NE TO DISSIPATE AND MOVE OUT OF ILN/S FA. WITH HIGH PRESSURE
BUILDING IN...HAVE CONTD PREV FCST THINKING GOING BELOW GUIDANCE.
HAVE ADJUSTED SKY CONDITION TO ACCOUNT FOR THESE CLDS CLEARING AND
ADJUSTED LOWS DOWN SLIGHTLY.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
IN PROGRESSIVE UPPER PATTERN...HIGH PRESSURE QUICKLY SLIDES EAST
OF THE CWA ON SUNDAY. 850 HPA TEMPS WILL REBOUND TO BETWEEN -6 AND
-4 C ACROSS THE SOUTHERN THIRD OF THE CWA BY AFTERNOON...BUT WILL
BE SLOWER TO WARM ACROSS THE NORTH. TRENDED CLOSER TO COOLER MET
NUMBERS ACROSS THE NORTH AND NEAR A MAV/MET BLEND FURTHER SOUTH.
MID AND HIGH CLOUDS WILL INCREASE LATE SUNDAY AHEAD OF A WEAK
UPPER SHORTWAVE. THIS FEATURE WILL FLATTEN AS IT TRACKS INTO THE
GREAT LAKES EARLY MONDAY...AND WILL BRING A WEAKENING SURFACE LOW
AND COLD FRONT INTO THE OHIO VALLEY. LOW LEVELS WILL INITIALLY BE
DRY...BUT ISENTROPIC LIFT LOOKS DEEP ENOUGH LATE SUNDAY NIGHT AND
EARLY MONDAY TO WARRANT AT LEAST 50 POPS ACROSS THE WEST. THERMAL
PROFILES WILL INITIALLY FAVOR ALL SNOW...THOUGH ANY ACCUM SHOULD
BE LESS THAN A HALF INCH WITH BEST CHANCE FOR SNOW ACCUM BEING
ACROSS THE NORTHWEST CWA. LIFT WILL DECREASE THROUGH THE DAY
MONDAY AS MIDLEVEL SYSTEM WEAKENS AND EXPECT A DECREASING TREND TO
PRECIP. WITH ABOUT 24-HOURS OF SOUTHERLY FLOW AHEAD OF THE
FRONT...THINK THE WARMER NAM HAS A BETTER HANDLE ON TEMPS WHICH
SHOULD ALLOW FOR A CHANGEOVER TO RAIN ACROSS THE SOUTHEAST TWO-
THIRDS OF THE CWA ON MONDAY AND A RA/SN MIXTURE ELSEWHERE. WEAK
FRONT WILL SWEEP THROUGH MONDAY AFTERNOON WITH LITTLE LIFT
ASSOCIATED WITH IT. ANY LINGERING LIGHT SHOWERS WILL MIX TO SNOW
SHOWERS AS THE SYSTEM DEPARTS EARLY MONDAY EVENING WITH LITTLE TO
NO ACCUM. HIGH PRESSURE WILL QUICKLY BUILD IN BEHIND THIS SYSTEM
MONDAY NIGHT WITH CLEARING SKIES FROM SOUTHWEST TO NORTHEAST.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
12Z MODELS ARE IN FAIRLY GOOD AGREEMENT WITH POTENT SYSTEM FOR THE
MIDDLE PART OF NEXT WEEK. SHORT WAVE ENERGY MOVING OUT OF THE
ROCKIES ON TUESDAY WILL LIFT OUT OF THE CENTRAL PLAINS TUESDAY NIGHT
AND INTO THE LOWER GREAT LAKES THROUGH WEDNESDAY.
STRENGTHENING LOW LEVEL JET AHEAD OF THE SYSTEM WILL LEAD TO
INCREASING ISENTROPIC LIFT TUESDAY AFTERNOON INTO TUESDAY NIGHT.
THIS WILL RESULT IN A CHANCE OF SHOWERS ACROSS OUR SOUTHWEST AS
EARLY AS TUESDAY AFTERNOON WITH WIDESPREAD PCPN THEN OVERSPREADING
THE REST OF OUR FA TUESDAY NIGHT. PCPN TYPE COULD BE A LITTLE TRICKY
AT PCPN ONSET TIME AS TEMPS MAY BE CLOSE TO FREEZING NEAR THE
SURFACE. THIS COULD LEAD TO A PERIOD OF SLEET OR FREEZING
RAIN...ESPECIALLY ACROSS OUR NORTH. WITH STRONG WAA JUST OFF THE
SURFACE...ANY FREEZING TEMPS SHOULD SLOWLY RISE ABOVE FREEZING
THROUGH THE OVERNIGHT HOURS WITH ANY MIXED PCPN TRANSITIONING OVER
TO ALL RAIN. RAIN WILL THEN CONTINUE INTO WEDNESDAY BEFORE CHANGING
TO SNOW FROM THE NORTHWEST WEDNESDAY AFTERNOON AS COOLER AIR BEGINS
TO MOVE IN. BY THIS TIME THOUGH...LOW IS LIFTING OFF TO THE
NORTHEAST SO PCPN ACROSS OUR AREA SHOULD BE TRANSITIONING TO
SHOWERS.
WINDY CONDITIONS ARE LIKELY WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT
AS LOW LIFTS OFF TO THE NORTHEAST AND STRONG CAA DEVELOPS. MODELS
ARE INDICATING 40 TO 60 KNOTS FROM 925 TO 850 MB AND IT SEEMS LIKELY
THAT THE POSSIBILITY EXISTS FOR SOME OF THIS TO TRANSFER DOWN TO THE
SURFACE.
HIGH PRESSURE TRIES TO BUILD INTO THE AREA THROUGH THE END OF THE
WEEK...BUT MODELS ARE HINTING AT SOME ISENTROPIC LIFT DEVELOPING
FRIDAY INTO FRIDAY NIGHT. WILL THEREFORE HANG ON TO SOME LOW POPS OF
RAIN OR SNOW DURING THAT TIME FRAME.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
CONDITIONS WILL REMAIN VFR THROUGH THE FORECAST. SKIES WILL BE
MAINLY CLEAR WITH CLOUDS AROUND 4000 FEET AFFECTING THE NRN TAF
SITES EARLY. CIRRUS WILL MOVE IN LATE TONIGHT AND THICKEN UP ON SUNDAY.
WINDS WILL BE LIGHT OVERNIGHT WITH HIGH PRESSURE BUILDING IN AND THEN
BECOME SOUTHEAST ON SUNDAY.
OUTLOOK...MVFR CIGS/VSBYS POSSIBLE MONDAY AND TUESDAY. WIDESPREAD
PRECIPITATION WITH MVFR/IFR CIGS/VSBYS AND GUSTY WINDS ARE POSSIBLE
TUESDAY NIGHT AND WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HAWBLITZEL
NEAR TERM...AR
SHORT TERM...HAWBLITZEL
LONG TERM...JGL
AVIATION...AR
