FXUS63 KAPX 100451
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1151 PM EST WED DEC 9 2009
.SYNOPSIS.../ISSUED AT 342 PM/
A STRONG AREA OF LOW PRESSURE WILL DEPART THE GREAT LAKES TONIGHT
WITH COLD AIR SURGING INTO THE REGION. GUSTY WEST TO NORTHWEST WINDS
WILL LEAD TO MODERATE TO HEAVY LAKE EFFECT SNOW IN THE SNOWBELTS
TONIGHT THROUGH THURSDAY. ADDITIONAL LAKE EFFECT SNOW SHOWERS WILL
CONTINUE FROM THURSDAY NIGHT INTO SATURDAY.
&&
.SHORT TERM.../ISSUED AT 1101 PM/...TONIGHT
IN ALL THE EXCITEMENT OF THE LAKE EFFECT, I FORGOT TO TALK ABOUT
THE NON-EVENTS TO THE EAST. BASED ON THE LIGHTER SNOW IN THE EAST,
WILL DROP THE WINTER HEADLINES FOR THE AREAS EAST OF I-75, THAT
WERE SCHEDULED TO GO DOWN AT 06Z. THIS ALSO INCLUDES MACKINAW
COUNTY. CHIPPEWA COUNTY LOOKS GOOD AS THE LAKE EFFECT IS BEGINNING
TO GET STARTED TONIGHT.
JSL
&&
.LONG TERM.../ISSUED AT 342 PM/...TONIGHT AND BEYOND
DEEP UPPER TROFFING WILL PERSIST ACROSS CENTRAL CANADA INTO THE
START OF THE WEEKEND. HEIGHTS WILL BE STEADILY REBOUNDING ACROSS THE
CONUS...LEADING TO RIDICULOUSLY FAST WESTERLIES (500MB WINDS NEAR
100KT BY FRIDAY EVENING). AT THE SURFACE...CANADIAN HIGH PRESSURE
WILL MOVE ACROSS THE TN VALLEY AND CAROLINAS THRU SATURDAY. THIS
WILL MAINTAIN COLD WESTERLY LOW LEVEL FLOW AS WELL. THE MAIN CONCERN
IS THE RESULTING LAKE EFFECT/LAKE ENHANCED SNOWFALL.
MODELS...IN GOOD AGREEMENT ON THE SHORTWAVE MOVING INTO LOWER MI ON
THURSDAY...AND ON THE SYNOPTIC-SCALE DRYING THAT TAKES PLACE ONCE
THAT WAVE GOES BY. AT THE SURFACE THE MODELS ARE ALSO QUITE CLOSE...
THOUGH THE NAM APPEARS TO BETTER RESOLVE THE NEAR-PERMANENT SURFACE
PRESSURE TROFS OVER EACH OF THE GREAT LAKES.
THURSDAY...THE INCOMING SHORTWAVE WILL KEEP US IN A LAKE-ENHANCED
REGIME UNTIL THURSDAY NIGHT...WHEN WE TURN OVER TO PURE LAKE EFFECT
SNOW (LES). WE WILL START THE MORNING WITH 1000-850MB NW WINDS ON
SUPERIOR...WNW ON LAKES MI/HURON. AS THE SURFACE LOW IN WESTERN
QUEBEC PULLS FURTHER AWAY...WINDS WILL GRADUALLY BACK TO W/WNW ON
SUPERIOR...AND DUE WEST ON LAKES MI/HURON. COLD ADVECTION WILL
MAINTAIN DELTA T/S IN THE LOW 20S ON SUPERIOR...AND INCREASE THEM TO
THE MID 20S ON LAKE MI. INVERSION HEIGHTS WILL INCREASE TO THE 7-8K
FEET RANGE. PLENTY OF DEEP MOISTURE AVAILABLE...WITH 850-700MB RH
LEVELS NEAR 80 PERCENT OVER THE UPSTREAM LAKES.
EARLIER SNOWFALL AMOUNTS LOOK PRETTY GOOD...WITH SOME TWEAKS IN
ORDER...MAINLY IN NORTHERN LOWER. WILL SHIFT MAX SNOWFALL A BIT
FURTHER SOUTH...TO FAR EASTERN CHARLEVOIX CO...AND BOOST MAX AMOUNTS
TO 6-8 INCHES. IN EASTERN UPPER MI...BEST ACCUMS WILL BE ALONG/NORTH
OF M-28...MAXING OUT NEAR 6 INCHES AT PARADISE/WHITEFISH PT. BLOWING
SNOW WILL CONTINUE TO BE AN ISSUE UNDER BRISK TO WINDY CONDITIONS...
BUT IT WON/T BE EXTREMELY WINDY.
GIVEN MARGINAL WINDS...UNSTEADY NATURE OF LAKE EFFECT/ENHANCED
SNOW...AND CLIMATOLOGY...FEEL VERY STRONGLY THAT A BLIZZARD WARNING
IS /NOT/ NEEDED. HOWEVER...WINTER STORM WARNINGS WILL BE EXTENDED
THRU THE DAY ACROSS MUCH OF NW/N CENTRAL LOWER AND CHIPPEWA CO.
MAX TEMPS WILL BE UPPER TEENS TO AROUND 20 AND VERY EARLY IN THE
DAY...WITH TEMPS FALLING INTO THE THRU THE TEENS AS THE DAY
PROGRESSES.
THURSDAY NIGHT...ONLY SLOW AND GRADUAL CHANGES IN THE KEY FIELDS...
AS HIGH PRESSURE MOVES EAST ACROSS THE TN VALLEY. 1000-850MB WINDS
WILL REMAIN FROM THE WEST...A SMIDGE NORTH OF WEST EARLY...A SMIDGE
SOUTH OF WEST LATE. THIS WILL KEEP THE MAIN FOCUS FOR SNOW OVER THE
TIP OF NORTHERN LOWER MI...ESPECIALLY PETOSKEY/INDIAN RIVER. (AT THE
SAME TIME...A DOMINANT SUPERIOR BAND SHOULD BE RAMPAGING JUST NORTH
OF WHITEFISH PT.) DELTA T/S IN THE MID 20S ARE VERY NICE. INVERSION
HEIGHTS DO GO DOWN TO 6K FEET...BUT THAT IS FAR FROM HOSTILE TO LES.
NAM12 QPF OUTPUT IS AS HIGH AS 0.20...WHICH IS IMPRESSIVE. WILL KICK
MAX SNOW AMOUNTS UP TO AROUND 6 INCHES. ELSEWHERE...PARTLY TO MOSTLY
CLOUDY WITH A FEW SNOW SHOWERS...AND IN PLACES VERY CHILLY. MOST
MARITIME AREAS WILL HOLD IN THE LOWER TEENS...BUT SOME INLAND
LOCALES WILL SINK TO NEAR ZERO.
FRIDAY...MORE OF THE SAME. 1000-850MB W TO WSW WINDS AND DELTA T/S
IN THE 22-25 RANGE WILL SUPPORT VIGOROUS LES IN THE TIP OF THE MITT.
INVERSION HEIGHTS ACTUALLY RISE TO 9K FEET...AND THE NAM HAS
CONSIDERABLE OMEGA AT AND JUST ABOVE THE CORE DENDRITIC GROWTH ZONE.
WILL KICK SNOWFALL AMOUNTS TO HIGH-END ADVISORY LEVELS...AND
STRONGLY SUSPECT THAT SOME LOCAL ACCUMS IN EMMET AND CHEBOYGAN
COUNTIES WILL BE HIGHER...PERHAPS CONSIDERABLY SO (BEST CHANCE NEAR
PLN). ELSEWHERE...THERE WILL BE SCT LIGHT SNOW SHOWERS...AND MOSTLY
CLOUDY SKIES...EXCEPT THE FAR SE WILL BE PARTLY SUNNY (AT LEAST IN
THE MORNING). MAX TEMPS MID TEENS (EASTERN UPPER...HIGH TERRAIN OF
NORTHERN LOWER) TO LOWER 20S (SE).
FRIDAY NIGHT/SATURDAY...COLD ADVECTION WILL FINALLY PETER OUT FRIDAY
NIGHT...AS A SURFACE RIDGE AXIS MOVES EAST ACROSS THE STATE EARLY
SATURDAY. SOUTHWEST WINDS AND WARM ADVECTION WILL BECOME ESTABLISHED
DURING THE DAY ON SATURDAY. THAT SHOULD OFFER UP A PERIOD OF
RESPECTABLE LAKE EFFECT INTO THE STRAITS AREA AND MACKINAC COUNTY.
HOWEVER...BY LATE SATURDAY DELTA T/S WILL BE DROPPING TOWARD THE MID
TEENS. MORE SIGNIFICANTLY...THERE IS NO SIGNIFICANT WX SYSTEM SEEN
TO ENHANCE SNOWFALL. SO DON/T SEE ANYTHING GETTING RIDICULOUSLY OUT
OF HAND. MIN TEMPS WILL BE SINGLE DIGITS ABOVE AND BELOW ZERO...
COOLEST IN N CENTRAL AND NE LOWER AND IN PARTS OF EASTERN UPPER. MAX
TEMPS MODERATING A SMIDGE INTO THE 20S.
REST OF THE FORECAST...UPPER FLOW WILL BE FLAT AND FAST EARLY IN THE
EXTENDED...BRIEFLY USHERING IN SOME PACIFIC AIR AND RESULTING IN
SOMEWHAT ABOVE NORMAL TEMPS SUNDAY-MONDAY. THE ASSOCIATED WARM
ADVECTION WILL STILL RESULT IN A CHANCE FOR SNOW. AFTER THAT...THE
POLAR LOW IN CENTRAL CANADA WILL WOBBLE SOUTHEAST TO NORTHERN
ONTARIO...WITH UPPER TROFFING RETURNING TO THE CENTRAL STATES. THAT
WILL RETURN ARCTIC AIR TO THE REGION TUESDAY AND ESPECIALLY
WEDNESDAY...WITH ATTENDANT LAKE EFFECT SNOWS.
REALLY REALLY LONG RANGE PROGS...GFS/ECMWF BOTH SHOW THE POLAR LOW
DIVING INTO THE NORTHERN/EASTERN LAKES REGION LATE NEXT WEEK. THIS
WOULD BRING A BRIEF SHOT OF SUB MINUS 20C AIR AT 850MB. BRRRRR.
JZ
&&
.MARINE.../ISSUED AT 1101 PM/
GALE FORCE WIND GUSTS WILL DEVELOP/PERSIST ACROSS ALL THE NEARSHORE
AREAS TONIGHT...AS POWERFUL WINTER STORM DEPARTS TO THE NORTHEAST.
WINDS MAY DIMINISH A LITTLE ON THURSDAY...BUT GUSTY CONDITIONS
FLIRTING WITH GALE FORCE WILL LIKELY CONTINUE AT LEAST THROUGH
THURSDAY EVENING AND PERHAPS LONGER. SO WILL KEEP CURRENT GALE
WARNINGS INTACT.
ADAM/JSL
&&
.AVIATION.../ISSUED AT 1147 PM/...VALID FOR 06Z TAFS
APN IS NOW VFR IN CIGS AND VSBYS, AND NOT EXPECTED TO SEE MUCH IF
ANYTHING AT THE AIRPORT OVER THE NEXT 24 HOURS. PLN AND TVC,
HOWEVER, ARE ANOTHER STORY AS LOW-LEVEL NORTHWEST FLOW IS FORMING
LAKE EFFECT SNOW BANDS WHICH WILL BE CAUSING THE CIGS AND VSBYS TO
BOUNCE BETWEEN IFR AND MVFR MOST OF THE NIGHT. THE SNOW BANDS NEAR
THE TVC AREA HAVE BEEN DROPPING INTO LIFR TERRITORY AS WELL, SO
HAVE TRIED TO TAKE THAT INTO ACCOUNT AS WELL WITH THE NEXT SNOW
BAND EXPECTED TO GO THROUGH THE REGION OVER THE NEXT COUPLE OF
HOURS.
JSL
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 AM EST THURSDAY FOR MIZ020-025>028-
031>033.
WINTER STORM WARNING UNTIL 7 PM EST THURSDAY FOR MIZ008-016-017-
019-021-022.
LM...GALE WARNING UNTIL 11 PM EST THURSDAY FOR LMZ323-341-342-344>346.
LH...GALE WARNING UNTIL 11 PM EST THURSDAY FOR LHZ345>349.
LS...GALE WARNING UNTIL 11 PM EST THURSDAY FOR LSZ321-322.
&&
$$
