FXUS61 KCLE 250000
AFDCLE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CLEVELAND OH
700 PM EST THU DEC 24 2009

.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM WILL AFFECT MUCH OF THE COUNTRY ON
CHRISTMAS EVE AND CHRISTMAS DAY. THE LOW WILL TRACK FROM
LOUISIANA TO IOWA BR FRIDAY AND THEN SLOW DOWN AND DRIFT SLOWLY
EAST TO THE GREAT LAKES OVER THE WEEKEND. WE WILL SEE AN
INCREASING EAST TO SOUTHEAST WIND WHICH WILL BRING WARMER AIR TO
THE AREA AND SOME SHOWERS FOR CHRISTMAS.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
MODELS ARE SIMILAR AS FAR AS TIMING THE ONSET OF PRECIPITATION LATER 
TONIGHT. EVENING PRECIPITATION MOVING NORTH ACROSS INDIANA MAY JUST 
BRUSH THE I-75 CORRIDOR BUT I HAVE A FEELING THAT PRECIP WILL NOT 
REACH THE GROUND AS THE LOW LEVELS ARE DRY WITH THE EAST WIND. WITH 
THE SLOW ADVANCE OF THE PRECIPITATION SHIELD FROM THE WEST... W2E 
WILL ESSENTIALLY HAVE TO WAIT UNTIL EXTRA MOISTURE AND UPWARD MOTION 
MOVES IN FROM THE SOUTH AND SOUTHWEST. IT WILL TAKE UNTIL THE EARLY 
MORNING HOURS TO MAKE IT EVEN TO THE WESTERN COUNTIES. THE LACK OF 
CLOUDS WILL ENABLE SOME RADIATIONAL COOLING TO OCCUR ACROSS EXTREME 
NE OH/NW PA ALTHOUGH THE EAST WIND WILL KEEP THINGS MIXED SO TEMPS 
WILL NOT TANK. COUNTING ON TEMPS SNEAKING UP ANOTHER DEGREE OR TWO 
BEFORE THE MAIN PRECIPITATION STARTS ACROSS THE TOLEDO AREA BUT 
CANNOT RULE OUT SOME PATCHY FREEZING RAIN. EVEN IF THE AIR 
TEMPERATURE IS 33F OR 34F ODOT TELLS US THAT THE SURFACE TEMPERATURE 
MAY REMAIN AT 32F OR COLDER FOR A WHILE. ELSEWHERE... AFTER A DROP 
IN THE EVENING...TEMPS WILL TREND SLOWLY UPWARD OVERNIGHT AS WIND 
AND CLOUDS INCREASE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
THE NAM/WRF IS STILL SLOWER MOVING THE PRECIPITATION EASTWARD ON 
SATURDAY MORNING. NOT REAL CONFIDENT ON THE START TIME WITH THE DRY 
EAST DOWNSLOPE FLOW IN PLACE AND THE MAIN LOW PRESSURE SYSTEM SO FAR 
WEST. TYPICALLY THE MODELS ARE A LITTLE QUICK IN THIS SITUATION AND 
OFTEN HAVE TOO MUCH QPF...ESPECIALLY ACROSS NE OH/NW PA. I WILL USE 
AN AVERAGE OF THE MODELS FOR THE ONSET OF PRECIPITATION. IF 
PRECIPITATION ARRIVES AT INLAND NORTHWEST PENNSYLVANIA BEFORE 
MIDDAY... THERE WILL LIKELY BE AREAS OF FREEZING RAIN. SHOULD NOT
BE A BIG EVENT BUT IT DOES NOT TAKE MUCH TO MAKE UNTREATED
SURFACES SLIPPERY AND WILL ISSUE A FREEZING RAIN ADVISORY FOR
MORNING AND EARLY AFTERNOON FOR INLAND ERIE AND CRAWFORD COUNTY
PA. TEMPS SHOULD SNEAK JUST ENOUGH ABOVE FREEZING ACROSS THE
REMAINDER OF NORTHERN OHIO TO MINIMIZE THE RISK OF ICE AND THE
SOUTHEAST FLOW DURING THE DAY FRIDAY SHOULD STEADILY WARM THINGS
UP ALTHOUGH THE GUSTY WIND WILL NOT MAKE IT FEEL ALL THAT WARM.

WIND IS A CONCERN ON SATURDAY FOR ERIE AND THE EAST LAKESHORE. NICE 
SOUTH TO SOUTHEAST LOW LEVEL JET PROGGED TO DEVELOP. 12Z GFS NOW UP 
TO 70 KNOTS AT 850 MB WITH THE OTHER MODELS SLIGHTLY LESS. WHILE 
THIS DOWNSLOPE WIND CERTAINLY POSES A THREAT...SOME OF THE OTHER 
HIGH WIND FACTORS DO NOT LINE UP AS WELL. RAIN WILL OCCUR ROUGHLY AT 
THE SAME TIME OF MAX WIND WHICH WILL STABILIZE THE ATMOSPHERE. THE 
MIXING LAYER IS PROGGED TO REMAIN QUITE LOW DUE TO THE RAIN. BUFKIT 
MOMENTUM TRANSFER INDICATES A STABLE CONDITION WITH A PEAK GUST WITH 
25 TO 30 KNOTS. THERE IS A WINDOW OF OPPORTUNITY DURING THE 
AFTERNOON AND EARLY EVENING DURING THE MAXIMUM LOW LEVEL JET AND I 
THINK THE INVERSION CAN POTENTIALLY BE OVERCOME AS IT DRIES OUT 
ALOFT DURING THE LATE AFTERNOON AND MIXING INCREASES. THERE COULD BE 
A FEW HOURS OF GUSTS BETWEEN 40 AND 45 KNOTS WHICH MAY REQUIRE A 
WIND ADVISORY. WITH THE UNCERTAINTY AND THE TIMING LATER ON FRIDAY 
MAY NOT NEED AN ADVISORY AND WILL NOT ISSUE AN ADVISORY AT THIS 
TIME. 

THE COLD AIR RETURNS GRADUALLY...THE STORM SYSTEM IS PROGGED TO STAY 
WELL TO THE WEST. I HAVE SEEN THESE TYPE OF SYSTEMS SPIN FOR A LONG 
TIME BEFORE PRECIPITATION OF ANY SIGNIFICANCE RETURNS ESPECIALLY 
WITH A SOUTHWEST FLOW KEEPING THE LAKE EFFECT/LAKE ENHANCEMENT OFF 
SHORE. WILL CALL IT FLURRIES ON SATURDAY.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
MODELS IN GOOD AGREEMENT WITH WEAKENING LOW PRESSURE MOVING OVER 
NORTHERN GREAT LAKES SUNDAY WHILE CLOSED UPPER LOW SWINGS OVER 
NORTHERN OHIO THROUGH SUNDAY NIGHT. WITH THE APPROACHING UPPER LOW 
WENT WITH LIKELY POPS ACROSS WESTERN AREAS FOR SNOW SHOWERS DURING 
THE DAY AND THEN LIKELY POPS SHIFTING TO EASTERN AREAS FOR SUNDAY 
NIGHT. FOR MONDAY CONTINUED LIKELY POPS ACROSS NORTHEAST OH AND NW 
PA WITH THE REMAINDER OF THE AREA DROPPING BACK TO CHANCE POPS AS 
SNOW SHOWERS BECOME MORE LAKE EFFECT. BOTH GFS AND ECMWF SHOWING 
SURFACE TROUGH DROPPING SOUTH OVER LAKE ERIE LATE MONDAY AND MONDAY 
NIGHT WHICH WOULD ALLOW FOR GOOD POTENTIAL OF ADDITIONAL LAKE EFFECT 
SNOW SHOWERS. SNOW SHOWERS EXPECTED TO LINGER THROUGH MUCH OF 
TUESDAY ACROSS NE OH AND NW PA. MEANWHILE...SURFACE HIGH PRESSURE 
AND RIDGING ALOFT WILL BE BUILDING IN FROM THE WEST ALLOWING FOR AN 
END TO PRECIP ACROSS AT LEAST THE WESTERN HALF OF THE FORECAST AREA. 
MODELS SHOWING HIGH PRESSURE BUILDING OVERHEAD TUESDAY NIGHT 
ALLOWING FOR DRY CONDITIONS ACROSS THE ENTIRE AREA. HIGH PRESSURE 
WILL CONTINUE THROUGH WEDNESDAY...BUT THEN INTRODUCED POPS AT THE 
END OF THE PERIOD WITH A WEAK LOW PRESSURE AND COLD FRONT 
APPROACHING FROM THE UPPER MIDWEST FOR THE END OF THE PERIOD.

WITH UPPER LOW MOVING OVER THE AREA...CLOUDS AND SNOW SHOWERS 
TRENDED A BIT COOLER THAN GUIDANCE SUNDAY AND SUNDAY NIGHT. CONTINUE 
TO LEAN ON COLDER SIDE OF GUIDANCE ON MONDAY...THEN BEGIN A GRADUAL 
RECOVERY ON TUESDAY AND WEDNESDAY. NIGHTTIME LOWS WILL BE TRICKY 
ESPECIALLY LATER IN THE PERIOD WHEN HIGH PRESSURE BUILDS OVER THE 
AREA. WITH THAT LEANED ON COLDER SIDE OF GUIDANCE FOR MINS TO 
ACCOUNT FOR POSSIBLE RADIATING CONDITIONS AND ADDITIONAL SNOW COVER.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL BE COMING TO AN END BY DAYBREAK FRIDAY. WARM
ADVECTION INDUCED PRECIPITATION WILL BE SPREADING UP FROM THE
SOUTHWEST LATE TONIGHT AND FRIDAY MORNING. THE BIGGEST QUESTION IS
THE PRECIPITATION TYPE. DEW POINT ARE IN THE MID 20S AND THE
SOUTHEAST WINDS WILL BE ON THE INCREASE OVERNIGHT AND THAT AND THE
RAIN STARTING OUT LIGHT SHOULD HELP TO KEEP MOST LOCATIONS AS
RAIN. THE ONLY EXCEPTIONS WILL BE EXTREME EASTERN OHIO AND INLAND
NORTHWEST PA. THE ONLY CONCERN IS THE RUNWAY TEMPERATURES. HIGH
CONFIDENCE AT FDY...CAK...ERI AND CLE THAT NO FREEZING RAIN WILL OCCUR
IN THE FIRST HOUR OR SO AFTER THE RAIN STARTS. MEDIUM CONFIDENCE
THAT NO FREEZING RAIN WILL OCCUR AT TOL AND MFD. DO FEEL THAT YNG...HZY
AND GKJ COULD HAVE A BRIEF PERIOD OF FREEZING RAIN FRIDAY MORNING.

ONCE THE RAIN STARTS MAINLY MVFR CONDITIONS WITH SOME OCCASIONAL
IFR CONDITIONS ESPECIALLY IN THE CEILING.

THE OTHER OVERNIGHT CONCERN IS LOW LEVEL WIND SHEAR. AT THIS TIME
I FEEL THAT THE WINDS WILL START TO BECOME GUSTY ABOUT THE TIME
THE STRONGEST WINDS ALOFT OCCUR AND ANY LOW LEVEL WIND SHEAR WILL
BE BELOW CRITERIA.

.OUTLOOK...NON-VFR CONDITIONS...MAINLY MVFR WILL OCCUR THROUGH
MONDAY. GUSTY WINDS WILL ALSO CONTINUE EARLY FRIDAY NIGHT.

&&

.MARINE...
EAST WINDS CONTINUE ON THE LAKE THIS EVENING.  WINDS ALREADY 15 TO 
20 KNOTS OVER THE WESTERN BASIN AND WINDS BEGINNING TO PICK UP IN 
THE EAST.  I WILL KEEP SCA FOR ALL AREAS TONIGHT AND FRIDAY.  WINDS 
WILL GRADUALLY BECOME MORE SE OVERNIGHT AND CONTINUE IN THE 15 TO 25 
KNOT RANGE.  WINDS WILL BECOME MORE SOUTHERLY ON SAT AND SUN. THE 
GRADIENT WILL DECREASE AND WIND SPEEDS WILL SUBSIDE.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...FREEZING RAIN ADVISORY FROM 6 AM FRIDAY TO 2 PM EST SATURDAY 
     FOR PAZ002-003.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR LEZ142>149.

&&

$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...ABE
AVIATION...KIELTYKA
MARINE...GARNET