FXUS61 KCLE 101030 AAA
AFDCLE

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CLEVELAND OH
530 AM EST THU DEC 10 2009

.SYNOPSIS...
UPDATED FOR SYNOPSIS
DEEP LOW PRESSURE OVER WESTERN QUEBEC WILL MOVE EAST TODAY AND
REACH THE CANADIAN COAST BY FRIDAY MORNING. HIGH PRESSURE OVER THE
CENTRAL UNITED STATES WILL DRIFT EAST TODAY AND REACH THE
TENNESSEE VALLEY BY FRIDAY MORNING. THE HIGH WILL DRIFT TO THE
OHIO VALLEY FOR SATURDAY. 

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WILL CONTINUE THE LAKE EFFECT SNOW WATCH FOR GEAUGA AND CRAWFORD
COUNTIES BUT WILL ADD LAKE AND INLAND ASHTABULA TO THE WARNING.
FOLLOWING CLOSELY THE NAM12 LOW LEVEL LIFT AND WIND CHARTS...THE
MODEL FIRST SHOWS A WNWLY 850MB FLOW AT 12Z THIS MORNING HOWEVER
925MB REMAINS SW. THE INITIAL SHEAR WILL NOT BE A FAVORABLE
PARAMETER HOWEVER THERE IS ENOUGH LIFT AND LAKE TEMP DIFFERENTIAL
FOR SNOW SHOWERS TO MAKE IT INLAND. BY 18Z THE MODEL LOWERS THE
SHEAR TO 10 OR 20 DEGREES WITH STRONG COLD ADVECTION MOVING IN
QUICKLY. THE WIND DIRECTION HOWEVER SUGGESTS THE PRIMARY SNOW
BANDS WOULD MOVE OFF SHORE. BY 00Z THIS EVENING HOWEVER...WINDS
VEER 10 OR 20 DEGREES AND LIFT IS MONSTROUS AND ALREADY ONSHORE
ACROSS THE WARNING AREA. IN ADDITION...FORECAST SOUNDINGS SHOW THE
BEST LIFT IS WITHIN THE FAVORABLE SNOW GROWTH TEMP AREA. ALL IN
ALL...BELIEVE WE GET A MORNING BURST OF LAKE EFFECT SNOW ACROSS
THE WARNING AREA WHICH WILL TAPER AND DRIFT NORTH POSSIBLY
COMPLETELY OFF SHORE LATE MORNING/ EARLY AFTERNOON. AFTER ABOUT
20Z OR SO EXPECT IT TO RETURN AND BECOME HEAVY...ESPECIALLY ACROSS
ERIE COUNTY. ELSEWHERE SCATTERED SNOW SHOWERS WILL TAPER OFF BY
AFTERNOON AND WILL LIKELY SEE A BIT OF SUNSHINE IN THE WEST DURING
THE AFTERNOON.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
CONTINUING TO FOLLOW THE NAM12 LOW LEVEL OMEGA AND WIND CHARTS
THROUGH THE SHORT TERM. IMPRESSIVE LIFT ALONG WITH MODEL CAPE WILL
CONTINUE ACROSS WARNING AREA TONIGHT THROUGH FRIDAY. 850MB TEMPS
IN THE GENERATION AREA ACROSS THE CENTRAL PORTION OF THE LAKE
WILL DROP TO -18C THROUGH THE NIGHT BUT WILL RISE A FEW DEGREES
FRIDAY. STILL HOWEVER...EXPECT SNOW BAND WITH HEAVY SNOW AND MOST
LIKELY THUNDER/LIGHTNING AT TIMES TO CONTINUE TONIGHT THROUGH
FRIDAY AND INTO FRIDAY NIGHT. ANOTHER POSITIVE IS THAT BEST OMEGA
CONTINUES TO RESIDE WITHIN THE FAVORABLE AREA FOR SNOW GROWTH INTO
FRIDAY NIGHT. FOR NOW...WARNING LOCATION LOOKS FINE. BY 12Z
FRIDAY MODEL SHOWS MORE OF A WNW FLOW AT 850MB HOWEVER...WILL
HOLD OFF ON ADDING GEAUGA AND CRAWFORD TO THE WARNING AT THIS TIME
HOWEVER SINCE THE LAKE TENDS TO HOLD ONTO A TROF WHICH WOULD BACK
WINDS FROM THE FORECAST. NOT MUCH CHANGE TO THE FORECAST SATURDAY
THROUGH SUNDAY NIGHT. DID ALLOW FOR MORE SUNSHINE SATURDAY WITH
THE BUILDING HIGH PRESSURE. MODEL DIFFERENCES SHOWING UP IN THE RH
FIELDS SUNDAY NIGHT WITH THE GFS 6 TO 8 HOURS FASTER WITH THE
MOISTURE. AT THIS TIMES WILL USE A BLEND OF THE
MODELS...TRANSITIONING TO THE GFS FOR LATE SUNDAY AND SUNDAY
NIGHT.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
LOW PRESSURE SYSTEM IS PROGGED TO MOVE EAST ACROSS THE AREA MONDAY 
INTO MONDAY NIGHT.  MODELS AGREE IN BRINGING WARM AIR ADVECTION TO 
THE REGION DURING THE DAY IN ADVANCE OF THE COLD FRONT. GRADIENT 
PICKS UP ENOUGH TO INCREASE WINDS OUT OF THE SOUTH DURING THE DAY 
AND I DECIDED TO BUMP TEMPERATURES INTO THE 40S FOR HIGHS. AS 
TEMPERATURES WARM UP DURING THE DAY MONDAY...WARM AIR ADVECTION 
SHOULD BE STRONG ENOUGH TO KEEP PRECIPITATION ALL RAIN DURING THE 
DAY. 

COLD FRONT IS EXPECTED TO SWEEP EAST ACROSS THE AREA MONDAY EVENING 
AND THIS WILL BRING ANOTHER SHOT OF COLD AIR TO THE REGION.  MODELS 
GRADUALLY BRING THE MORE INTENSE COLD AIR INTO THE REGION DURING THE 
END 48 HOURS OF THE EXTENDED PERIOD. THE COLDER AIR WILL TRANSITION 
PRECIPITATION TO A CHANCE OF SNOW SHOWERS MONDAY NIGHT. THE SYNOPTIC 
SNOW WILL GRADUALLY TRANSITION INTO LAKE EFFECT SNOW THROUGH THE 
LATTER PERIODS AS COLD AIR ADVECTION TAKES PLACE ONCE AGAIN.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
STRONG LOW PRESSURE MOVING NORTHEAST OVER SOUTHEAST ONTARIO AND
WILL BE LOCATED OVER QUEBEC BY THURSDAY EVENING. GUSTY WINDS WILL
CONTINUE THROUGH MUCH OF PERIOD FOR MOST TAF SITES...BUT THERE
WILL BE A GRADUAL DIMINISHING TREND. 

MAINLY MVFR CEILINGS ACROSS THE AREA WILL CONTINUE THROUGH AT
LEAST THE MORNING HOURS. SCATTERED SNOW SHOWERS ACROSS THE AREA
WILL BRING VIS DOWN TO IFR PERIODICALLY OVERNIGHT. ACROSS WESTERN
ZONES DURING THE AFTERNOON AND EVENING HOURS EXPECTING A TREND
TOWARD VFR WHILE REMAINDER OF SITES WILL IMPROVE TO VFR BETWEEN
18Z AND 03Z FRIDAY. 

ERI WILL BE MOST IMPACTED BY LAKE EFFECT SNOW AFTER 18Z AND
CONTINUE BEYOND TAF PERIOD INTO FRIDAY MORNING WITH LAKE EFFECT
SNOW. MODELS SHOWING GOOD SET UP FOR LAKE EFFECT SNOW BANDS TO
IMPACT ERI BY THE EVENING. GIVEN THE POTENTIAL...MENTIONED SNOW
SHOWERS WITH IFR VIS AND NEAR IFR CEILINGS AT TOWARDS END OF THE
PD.

.OUTLOOK...NON VFR THURSDAY NIGHT MAINLY ERI. NON VFR CONTINUING
ALONG LAKESHORE EAST OF CLEVELAND INTO SATURDAY MORNING...THEN VFR
ALL SITES SATURDAY AFTERNOON AND EVENING. NON VFR SUNDAY AND
MONDAY.

&&

.MARINE...
WILL GO AHEAD AND DROP THE STORM WARNINGS ON LAKE ERIE AS WINDS HAVE 
DROPPED BELOW THE 50 KNOT THRESHOLD. LONG POINT STILL HAD WINDS 
SUSTAINED AT ABOUT 48 KNOTS AT 03Z BUT I ANTICIPATE THEY TOO WILL 
DROP FURTHER DURING THE MORNING. WINDS AT ALL OF THE LAND SITES HAVE 
DROPPED DOWN TO BELOW GALES BUT I TILL THINK WE ARE SEEING GALE 
FORCE WINDS ON THE LAKE AT THIS TIME.  SO WILL GO WITH THE GALE 
WARNINGS FOR THE TIME BEING. WINDS ARE GOING TO TAKE THEIR TIME 
DECREASING OVER THE NEXT FEW DAYS. IT WILL TAKE UNTIL AT LEAST 
SATURDAY TO SEE REASONABLE DECREASES IN THE WIND SPEED. 

STRONG SOUTHWEST WINDS CAUSED WATER LEVELS ON THE WESTERN END OF 
LAKE ERIE TO DROP TO AT OR NEAR RECORD LEVELS LIKELY EXPOSING A LOT 
OF THE MUD BOTTOM ALONG THE WESTERN SHORE.  WATER LEVELS APPROACHED 
70 INCHES BELOW THE CRITICAL MARK FOR SAFE NAVIGATION ON THE WESTERN 
BASIN.  WILL CONTINUE WITH LOW WATER ADVISORY THROUGH THE MORNING.  
WATER LEVELS ARE QUICKLY STARTING TO GO BACK UP AGAIN AND WE HAVE 
RECOVERED ABOUT HALF THE DISTANCE BETWEEN WHERE IT BOTTOMED OUT AND 
THE CRITICAL MARK.  PROBABLY A WALL OF WATER RETURNING BACK TO THE 
WEST END.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...LAKE EFFECT SNOW WARNING UNTIL 4 AM EST SATURDAY FOR OHZ012-
     014-089.
     LAKE EFFECT SNOW WATCH FROM 3 PM EST THIS AFTERNOON THROUGH 
     LATE FRIDAY NIGHT FOR OHZ013.
PA...LAKE EFFECT SNOW WARNING UNTIL 4 AM EST SATURDAY FOR PAZ001-
     002.
     LAKE EFFECT SNOW WATCH FROM 3 PM EST THIS AFTERNOON THROUGH 
     LATE FRIDAY NIGHT FOR PAZ003.
MARINE...STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LEZ061-149-169.
     LOW WATER ADVISORY UNTIL 4 PM EST FRIDAY FOR LEZ142-143-162-
     163.
     GALE WARNING UNTIL 4 AM EST FRIDAY FOR LEZ142>148-162>168.

&&

$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...LOMBARDY
AVIATION...ABE
MARINE...LOMBARDY