FXUS61 KBUF 061142
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
642 AM EST SUN DEC 6 2009
.SYNOPSIS...
HIGH PRESSURE PASSING TO OUR SOUTH WILL PRODUCE FAIR...YET
SEASONABLY CHILLY WEATHER ACROSS OUR REGION TODAY WITH JUST SOME
NUISANCE LAKE EFFECT SNOW SHOWERS EAST OF BOTH LAKES. A WEAK SYSTEM
WILL PASS ACROSS SOUTHERN ONTARIO ON TUESDAY...WITH SOME FAIRLY
STEADY SNOW EXPECTED ACROSS THE NORTH COUNTRY. A POWERFUL EARLY
WINTER STORM WILL THEN TAKE AIM ON OUR REGION FOR WEDNESDAY AND
THURSDAY WITH SNOW AND RAIN GIVING WAY TO STRONG WINDS AND MUCH
COLDER WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK BUT COLD BOUNDARY LAYER FLOW WILL RESULT IN A COUPLE AREAS OF
LAKE EFFECT SNOW TODAY AND TONIGHT. 850MB TEMPS FALL TO AROUND -12C
DURING THE DAY AND EXPECT LIGHT LAKE SNOWS IN THE LEE OF EACH LAKE.
WILL HAVE SMALLISH AREAS OF LIKELY POPS TO ACCOUNT FOR THOSE SMALL
ACCUMULATIONS...GENERALLY AN INCH OF LESS FOR EACH 6 HOUR PERIOD.
THERE WILL BE SOME HIGHER AMOUNTS EAST OF LAKE ONTARIO TONIGHT WITH
2 TO 3 INCHES POSSIBLE OVER THE NORTHERN TUG HILL REGION IN
JEFFERSON AND LEWIS COUNTIES. SKY COVER WILL BE DEPENDENT ON THE
LAKE EFFECT CLOUDS. AREAS WITHIN THE LAKE SNOW SHOWERS WILL OF
COURSE SEE CLOUDY SKIES...BUT REGIONS DOWNWIND OF THE LAKES WILL
ALSO HAVE EXTENSIVE CLOUDINESS. WILL HAVE VARYING SKY CONDITIONS
ACROSS THE FORECAST AREA...SUNNIER AWAY FROM LAKE INFLUENCES AND
CLOUDIER DOWNWIND OF THE LAKES.
HIGH TEMPS TODAY WILL BE IN THE UPPER 20S TO LOWER 30S OVER THE
HIGHER TERRAIN OF THE SOUTHERN TIER AND WYOMING COUNTY...AND ACROSS
THE TUG HILL...WITH LOWER TO MIDDLE 30S IN THE LAKE PLAINS AREAS.
LOWS TONIGHT WILL FALL BACK TO THE LOWER TO MIDDLE 20S WITH SOME
TEENS ON THE TUG HILL AND THE SOUTHERN TIER.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
A SHORTWAVE WILL WEAKEN AND SHEAR OUT ACROSS SOUTHERN ONTARIO AND
THE EASTERN GREAT LAKES ON MONDAY...BUT ENOUGH ISENTROPIC LIFT WILL
BE GENERATED TO PRODUCE AT LEAST THE CHANCE FOR SOME NUISANCE SNOW
SHOWERS. THIS WILL ESPECIALLY BE THE CASE ACROSS THE NORTH COUNTRY
AND THOUSAND ISLANDS REGION WHERE LIFT ACROSS A WEKAENING WARM
FRONTAL BOUNDARY WILL BE GREATEST. WILL USE CAT POPS FOR THE NORTH
COUNTRY WHERE STEADIER LIGHT SNOW IS EXPECTED...AND QUICKLY TAPER
THOSE OFF TO CHC FOR -SHSN MUCH OF THE REMAINDER OF THE REGION.
SNOWFALL FROM THIS EVENT WILL RANGE FROM A COUPLE INCHES NORTH OF
WATERTOWN AND BEAVER FALLS TO A COVERING OR LESS MOST ELSEWHERE.
LOW AMPLITUDE RIDGING WILL THEN BULD EAST ACROSS THE GREAT LAKES
MONDAY NIGHT AS THE SHEARED SHORTWAVE WILL LIFT OUT ACROSS NEW
ENGLAND. WHILE THE BULK OF THE REGION SHOULD ONLY EXPERIENCE SOME
FLURRIES MONDAY NIGHT...A WESTERLY FLOW OF -10C H85 AIR WILL
PRODUCE SOME STEADIER LAKE SNOW SHOWERS EAST OF BOTH LAKES. THE
BUILDING RIDGE AFTER MINDIGHT SHOULD HELP TO KEEP SNOWFALL AMOUNTS
TO A MINIMUM...GENERALLY RANGING FROM 2 INCHES OR LESS.
THE RIDGING OVER THE GREAT LAKES WILL AMPLIFY ON TUESDAY IN RESPONSE
TO A STRONG SHORTWAVE MOVING OUT OF THE ROCKIES ONTO THE HIGH
PLAINS. HIGH PRESSURE AT THE SFC WILL MOVE ACROSS OUR FORECAST AREA
ON TUESDAY AS A RESULT...AND THIS WILL LIKELY PRODUCE THE NICEST DAY
OF THE WEEK FOR A LARGE PORTION OF THE AREA. THIS WILL ESSENTIALLY
BE THE CALM BEFORE THE STORM.
THE STRONG SHORTWAVE WITHIN THE SRN BRANCH WILL MOVE OUT OF THE
CENTRAL PLAINS TUESDAY NIGHT AND FURTHER AMPLIFY THE DOWNSTREAM
RIDGE OVER NEW ENGLAND. AT THE SFC...A DEEPENING LOW WILL MOVE FROM
OKLAHOMA TO NEAR CHICAGO BY DAYBREAK. THIS WILL SET UP A SOUTHERLY
FLOW ACROSS OUR WESTERN COUNTIES DURING THE COURSE OF THE NIGHT WITH
COPIOUS AMOUNTS OF LOW LEVEL MOISTURE ADVECTING NORTHWARDS FROM THE
OHIO VALLEY. THE MOISTURE WILL THEN BE LIFTED BY TWO MAIN
MECHANISMS. THE FIRST AND MOST OBVIOUS...FAIRLY STRONG WARM
ADVECTION. THE SECOND...STRONG JET INDUCED LIFT SUPPLIED BY A PAIR
OF 150KT H25 JETS. OUR REGION WILL BE BETWEEN THESE TWO JETS...
SO THERE WILL BE PLENTY OF UPPER LEVEL LIFT SUPPLIED BY A COUPLED
JET.
IT IS ALSO INTERESTING TO NOTE THAT BOTH THE GFS AND ECMWF POINT
SOUNDINGS SHOW A DEEP LAYER OF NEARLY ISOTHERMAL CONDITIONS BETWEEN
MIDNIGHT TUESDAY NIGHT AND DAYBREAK WEDNESDAY. SNOW MICROPHYSICS
COULD THUS BE MORE IMPORTANT THAN USUAL...AS NEARLY 10K FT OF -3 TO
-5C AIR IN THE LOW LEVELS WILL BE IN PLACE. THESE ARE VERY FAVORABLE
CONDITIONS FOR AGGREGATION AND 'HEALTHY' SNOW PRODUCTION. QPF IS NOT
OVERLY IMPRESSIVE FROM ANY OF THE MODELS WITH ONLY A COUPLE TENTHS
WORTH BEING SHOWN...BUT GIVEN THE DYNAMICS AND SNOW MICROPHYSICS...
WOULD NOT BE SURPRISED IF SEVERAL INCHES (MINIMUM) OF SNOW FALLS
WEST OF ROC BY DAYBREAK WEDNESDAY.
THE STRONG SHORTWAVE WILL LIFT ACROSS THE MID WEST AND LAKE ERIE ON
WEDNESDAY WHILE ITS POWERFUL SURFACE REFLECTION WILL CONTINUE TO
STRENGTHEN AS IT WILL TRACK FROM NEAR CHICAGO TO GEORGIAN BAY. THE
CENTRAL PRESSURE OF THE STRM IS EXPECTED TO DROP BELOW 980 MB...
WHICH IS SOME 3 STD BELOW NORMAL MID DECEMBER STORMS. THAT IS
IMPRESSIVE IN ITSELF WHEN YOU CONSIDER THE FREQUENCY OF STRONG
STORMS ACROSS THE GREAT LAKES AT THAT TIME OF YEAR.
IN ANY CASE...THE STRONG WARM ADVECTION AHEAD OF THIS CUTTER TYPE
STORM WILL CHANGE THE SNOW TO RAIN FROM SOUTHWEST TO NORTHEAST
ACROSS OUR FORECAST AREA...BUT NOT BEFORE SEVERAL MORE INCHES OF
SNOW COULD ACCUMULATE WEDNESDAY MORNING. NEEDLESS TO SAY...THE
TIMING OF THE CHANGEOVER WILL BE VERY IMPORTANT AS TO EXACT
ACCUMULATIONS.
THE SNOW SHOULD MIX WITH AND CHANGE TO RAIN ACROSS THE WESTERN
COUNTIES BY LUNCHTIME ON WEDNESDAY...WITH THE CHANGE OVER EAST OF
LAKE ONTARIO HOLDING OFF UNTIL LATER IN THE AFTERNOON.
THE DYNAMICS FROM THE COUPLED JET THAT WERE DISCUSSED EARLIER WILL
REMAIN IN PLACE DURING THS FIRST HALF OF WEDNESDAY...THEN AS THAT
LIFT MOVES OFF TO THE NORTHEAST...IT WILL BE REPLACED BY LOW LEVEL
FORCING FROM A FAIRLY STRONG COLD FRONTAL PASSAGE. A 65 KT LOW LEVEL
JET JUST AHEAD OF THE FRONT COULD BE MIXED TO THE SFC DURING
FROPA...WITH HIGH GUSTS ALSO LIKELY ACROSS THE HIGHER TERRAIN.
WHILE THE VARIOUS GUIDANCE PACKAGES HAVE BEEN IN VERY CLOSE
AGREEMENT DURING THE PAST SEVERAL MODEL RUNS...ONE IMPORTANT
DIFFERENCE HAS SHOWN UP IN THE 00Z RUN. THE ECMWF IS SOME 10MB
DEEPER THAN THE OPERATIONAL GFS WITH THE CENT PRESSURE OF THE SFC
STORM...AND IT ALSO TRACKS THE STORM MORE NNE RATHER THAN NE. THIS
TYPE OF TRACK WOULD BE A BIT LESS FAVORABLE FOR A SIGNIFICANT WIND
EVENT LATE WEDNESDAY NIGHT AND THURSDAY...BUT IT WILL DEFINITELY BE
VERY WINDY IN EITHER CASE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
TEMPERATURES WILL CLEARLY AVERAGE BELOW NORMAL DURING THIS PERIOD.
AS THE POWERFUL STORM SYSTEM LIFTS NORTH OF LAKE ONTARIO WEDNESDAY
NIGHT AND THURSDAY...MUCH COLDER AIR WILL SURGE IN BEHIND THE LOW
AND GENERATE VERY WINDY CONDITIONS AND MORE SYNOPTIC AND LAKE
ENHANCED SNOW.
WHILE A VERY TIGHT PRESSURE GRADIENT WILL BE IN PLACE THURSDAY WITH
A CLIMATOLOGICALLY FAVORED STORM TRACK FOR DAMAGING WINDS...BUFKIT
NAM/GFS DISPLAYS CONTINUE TO SHOW A LACK OF ANY REAL STRONG WINDS
ALOFT. CLASSIC HIGH WIND EVENTS USUALLY HAVE WINDS OF 70-80 KTS
BETWEEN 3-7K FT...BUT THIS EVENT IS ONLY FORECAST TO HAVE WINDS OF
50-55 KTS. THIS WOULD STILL RESULT IN VERY WINDY CONDITIONS FOR THE
REGION ON THURSDAY...BUT WOULD LIKELY PREVENT US FROM PICKING UP
WINDS MORE TYPICAL OF A CLASSIC HIGH WIND EVENT.
ALONG WITH THE HIGH WINDS...-16C H85 AIR WILL POUR ACROSS THE LOWER
GREAT LAKES. THIS WILL BE THE COLDEST AIRMASS OF THE SEASON BY
FAR...AND WILL PRODUCE FAIRLY WIDESPREAD LAKE EFFECT SNOW SHOWERS TO
THE EAST OF BOTH LAKES. WHILE A SOUTHWESTERLY FKLOW OF THIS VERY
COLD COULD INITIALLY BRING SOME ACCUMULATING LAKE SNOWS TO THE BUF
AND ART METRO AREAS...THE FLOW IS EXPECTED TO BECOME MORE
WESTERLY...THEN NORTHWESTERLY. THIS WILL SEND THE MOST SIGNIFICANT
LAKE SNOWS INTO THE LAKE SNOW BELT AREAS.
THE STRETCH OF BELOW NORMAL TEMPERATURES IS EXPECTED TO LAST THROUGH
NEXT WEEKEND BEFORE THE FLOW FROM THE YUKON WILL BREAK DOWN AND ONCE
AGAIN BECOME MORE PACIFIC IN NATURE.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
SOME LAKE EFFECT SNOW SHOWERS WILL CONTINUE EARLY IN THE TAF PERIOD
EAST OF LAKE ERIE THAT WILL BRING MVFR CONDITIONS ACROSS THE
SOUTHERN TIER THROUGH ABOUT 14Z. MVFR CIGS SHOULD IMPROVE TO VFR
CONDITIONS LATER THIS AFTERNOON ACROSS THIS REGION. ACROSS THE
NIAGARA FRONTIER AND THE GENESEE VALLEY GENERALLY VFR CONDITIONS ARE
EXPECTED THROUGH THE TAF PERIOD.
SOME LAKE EFFECT SNOW SHWRS EARLY THIS MORNING SOUTHEAST OF LAKE
ONTARIO SHOULD BE TO THE EAST OF ROCHESTER TO AROUND THE KFZY
REGION. DURING THE COURSE OF THE DAY THE LAKE SNOWS SHOULD MOVE
NORTH TO AREAS EAST OF LAKE ONTARIO AND MAY REACH WATERTOWN DURING
THE AFTERNOON...BEWTEEN 18Z AND 22Z. MVFR CIGS AREA EXPECTED TO
SETTLE ACROSS THE TUG HILL REGION OVERNIGHT.
OUTLOOK...
MONDAY...VFR/MVFR WITH A CHANCE OF SNOW.
TUESDAY...VFR.
WEDNESDAY...MVFR/IFR WITH RAIN/SNOW. POSSIBLE LOW LEVEL WIND SHEAR.
THURSDAY...MVFR/IFR SNOW SHOWERS. STRONG SURFACE WINDS LIKELY.
&&
.MARINE...
SMALL CRAFT ADVISORIES REMAIN IN PLACE FOR THE NEW YORK NEARSHORE
WATERS OF LK ONTARIO AS A FAIRLY TIGHT SFC PRESSURE GRADIENT WILL BE
FOUND BETWEEN HIGH PRESSURE TO OUR SOYUTH AND A LOW NEAR JAMES BAY.
AS A RESULT...STRONG WEST TO SOUTHWESTERLIES WILL PRODUCE WAVES IN
EXCESS OF 4 FEET ON LAKE ONTARIO THROUGH AT LEAST TONIGHT.
MEANWHILE...MODERATE TO FRESH SOUTHWESTERLIES WILL BE FOUND ON LAKE
ERIE WITH WAVES AVERAGING 2 TO 4 FEET.
ATTENTION WILL THEN TURN TO A POWERFUL EARLY WINTER STORM THAT WILL
LIKELY PRODUCE GALE FORCE WINDS AND WAVES IN EXCESS OF 10 FEET
ACROSS BOTH ALKES WEDNESDAY NIGHT AND THRUSDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
MONDAY FOR LOZ042-043.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 AM EST
MONDAY FOR LOZ045.
SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 9 AM EST
MONDAY FOR LOZ044.
&&
$$
SYNOPSIS...RSH
NEAR TERM...WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...JJP/WCH
MARINE...RSH
