FXUS61 KBUF 152329
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
629 PM EST TUE DEC 15 2009
.SYNOPSIS...
LOW PRESSURE MOVING INTO THE CANADIAN MARITIMES THIS EVENING WILL
DRAW PROGRESSIVELY COLDER AIR SOUTHWARD ACROSS OUR REGION OVERNIGHT
AND WEDNESDAY. THIS WILL PRODUCE BANDS OF LAKE EFFECT SNOW SOUTHEAST
OF LAKES ERIE AND ONTARIO...ESPECIALLY LATE TONIGHT THROUGH
WEDNESDAY NIGHT. THE COLDER THAN NORMAL WEATHER WILL PERSIST THROUGH
THE REST OF THE WEEK AS THE LOW CONTINUES SLOWLY TO THE NORTHEAST
AND HIGHER PRESSURE BUILDS IN FROM THE UPPER GREAT LAKES.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
WHILE THE INFLUENCE FROM THE DEPARTING NEW ENGLAND LOW HAS
ENDED...THE LIFT FROM THE APPROACHING UPPER LEVEL TROUGH AND
ACCOMPANYING SHORT WAVE IS GENERATING SOME LIGHT SNOW OVER WESTERN
NEW YORK AND THE GENESEE VALLEY THIS AFTERNOON...WITH LITTLE OR NO
ACCUMULATION SO FAR. EXPECT THE SNOW TO PICK UP A BIT AND IMPACT THE
ENTIRE CWA WITH AN INCH OR TWO ACCUMULATION...GENERALLY BETWEEN 00Z
AND 06Z AS THE SHORT WAVE TRACKS EAST ACROSS THE AREA.
THE SYNOPTIC SNOW WILL BE ENHANCED SOUTHEAST OF THE LAKES AS 850 MB
TEMPERATURES COOL TO ABOUT -13C BY 06Z. WHILE THERE WILL BE DECENT
LOW LEVEL MOISTURE AND FAVORABLE ICE CRYSTAL GROWTH WITHIN THE CLOUD
LAYER...THE PASSING SHORT WAVE WILL TEND TO INCREASE THE WIND SHEAR
WITHIN THE STEERING LAYER. AFTER THE SHORT WAVE CLEARS THE
AREA...THE LOW LEVEL MOISTURE IS FORECAST TO DECREASE WHILE THE
INVERSION LOWERS. THUS...IT DOES NOT APPEAR THAT THE FAVORABLE
PARAMETERS FOR LAKE EFFECT SNOW WILL COME TOGETHER AT THE RIGHT TIME
TO GENERATE WELL ORGANIZED BANDS OF SNOW TONIGHT. BASED ON
THIS...STILL PLANT TO KEEP ACCUMULATIONS BELOW ADVISORY CRITERIA
TONIGHT...BUT THIS SITUATION WILL HAVE TO MONITORED CLOSELY THIS
EVENING.
ON WEDNESDAY...THE LAKE SNOWS WILL HAVE THE GREATEST IMPACT EAST OF
LAKE ONTARIO...ESPECIALLY DURING THE AFTERNOON AS THE BOUNDARY LAYER
WINDS LINE UP MORE FROM THE WEST...THEREBY INCREASING THE FETCH
ACROSS THE LAKE. WITH GOOD SNOW GROWTH FORECAST WITHIN THE MOIST
LOWER LEVELS...BELIEVE SNOWFALL TOTALS WILL REACH ADVISORY CRITERIA
ACROSS MUCH OF OSWEGO AND SOUTHERN LEWIS COUNTIES. RIGHT NOW...IT
LOOKS LIKE THE STEADIEST SNOW WILL STAY JUST SOUTH OF JEFFERSON
COUNTY.
OFF LAKE ERIE...EXPECT LAKE SNOWS TO BE ONGOING ACROSS THE SOUTHERN
TIER...BUT THE SUBSIDENCE INVERSION WILL BE LOWER AND THE FAVORABLE
SNOW GROWTH IS NOT FORECAST TO EXTEND AS DEEPLY INTO THE MOIST LOW
LEVEL AIR. THEREFORE...ADDITIONAL ACCUMULATIONS SHOULD REMAIN UNDER
ADVISORY CRITERIA.
ELSEWHERE ACROSS THE AREA...EXPECT MAINLY DRY...BUT COLD CONDITIONS
WEDNESDAY AS AREA TEMPERATURES HOVER IN LOWER TO MIDDLE 20S.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
THE EARLY PART OF THIS FORECAST PERIOD IS A LITTLE TRICKY AS A SHORT
WAVE AND A SURFACE TROUGH WILL BE SLIDING SOUTH ACROSS THE FORECAST
AREA DURING THE EARLY TO MID EVENING HOURS. MOST AREAS WILL SEE SOME
MEASURABLE SNOW AS THE TROUGH SWINGS THROUGH AND THE LAKE EFFECT
ACTIVITY OFF LAKE ONTARIO THAT IS EXPECTED TO BE FOCUSED ACROSS
OSWEGO AND SOUTHERN LEWIS COUNTIES WEDNESDAY SHOULD MIGRATE
SOUTHWARD. AFTER THE SHIFT WE EXPECT LIGHTER ACTIVITY WITH MULTIPLE
SMALLER BANDS WHICH WILL EXTEND BACK WESTWARD ALL THE WAY INTO THE
NIAGARA FRONTIER. THE LAKE EFFECT SNOW ADVISORY FOR OSWEGO AND
SOUTHERN LEWIS COUNTY THROUGH 23Z WILL NOT LIKELY HAVE TO BE
EXTENDED BUT WE WILL KEEP AN EYE ON THIS.
ACTIVITY WILL CONTINUE TO WIND DOWN DURING THE DAY THURSDAY AS HIGH
PRESSURE BEGINS TO BUILD IN FROM THE CENTRAL GREAT LAKES. EVEN
THOUGH THE AIR WILL BE VERY COLD...THE MODEL SOUNDINGS INDICATE A
LOWERING CAP WITH A SHORT FETCH. STILL ENOUGH MOISTURE IN THE
CRYSTAL GROWTH REGION THOUGH FOR THE FIRST PART OF THE DAY.
THURSDAY NIGHT WILL LIKELY BE THE COLDEST NIGHT OF THE YOUNG SEASON
BECAUSE OF A COLD AIR MASS AND GOOD RADIATIONAL COOLING CONDITIONS.
WE EXPECT TEENS IN THE WARMEST AREAS...SINGLE NUMBERS IN THE
SOUTHERN TIER INLAND AREAS AND EVEN ZERO OR COLDER IN THE NORTH
COUNTRY.
MAINLY DRY AND COLD WEATHER WILL PREVAIL FRIDAY AND FRIDAY NIGHT AS
HIGH PRESSURE CONTINUES TO BUILD OVER THE AREA.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
SOME FAIRLY SIGNIFICANT MODEL DIFFERENCES THROUGH THIS PERIOD SO
CONFIDENCE IS NOT VERY HIGH AS FAR AS TIMING ANY PRECIPITATION.
HOWEVER ALL MODEL SOLUTIONS ARE PAINTING SLIGHTLY BELOW NORMAL
TEMPERATURES AS AN UPPER TROUGH PERSISTS ACROSS EASTERN CANADA. WE
WILL BE BASING THIS PART OF THE FORECAST MAINLY ON HPC GUIDANCE
WHICH IS FAIRLY CLOSE TO THE 00Z ECMWF.
FOR THE DETAILS...
SATURDAY AND SATURDAY NIGHT LOOK DRY AT THIS POINT AS A SURFACE HIGH
NOSES IN ACROSS THE LOWER LAKES AND LOW PRESSURE ORGANIZES ACROSS
THE SOUTHERN ATLANTIC STATES. SUNDAY WILL MOSTLY LIKELY BE DRY AS
WELL AS THE LOW STRENGTHENS ALONG THE CAROLINA COAST BUT WE WILL
INCLUDE CHANCE POPS DUE TO MODEL UNCERTAINTY AND CYCLONIC FLOW WITH
AN UPPER TROUGH REMAINING ACROSS EASTERN CANADA.
THE AFOREMENTIONED LOW IS FORECAST TO MOVE TO NEAR THE CANADIAN
MARITIMES MONDAY AND TUESDAY. TEMPERATURES SHOULD STAY SLIGHTLY
BELOW NORMAL IN THE NORTHWEST FLOW ON THE WEST SIDE OF THIS SYSTEM
BUT NO IMPORTANT WEATHER APPEARS TO BE ON THE HORIZON. WE WILL CARRY
CHANCE POPS FOR BOTH DAYS BECAUSE OF THE NORTHWEST CYCLONIC FLOW.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
PLENTY OF LOW LEVEL MOISTURE WILL REMAIN ACROSS THE AREA
THROUGH THE 00Z TAF PERIOD...WITH IFR TO LOW MVFR CIGS THE
GENERAL RULE. SOME LIFR CIGS ARE ALSO POSSIBLE AT TIMES IN LAKE
EFFECT SNOW SHOWERS SOUTHEAST OF THE GREAT LAKES. UPPER
TROUGHING AND COLD AIR ALOFT WILL CONTINUE TO WORK INTO THE REGION
TONIGHT. THIS WILL BRING PERIODS OF LAKE EFFECT SNOW SOUTHEAST OF
THE GREAT LAKES. IFR/LIFR VSBYS WILL BE LIKELY IN THE AFFECTED
AREAS.
OUTLOOK...
WEDNESDAY AND THURSDAY...VFR/MVFR IN SNOW SHOWERS...ESP ESE OF LAKES
WHERE SOME IFR IS POSSIBLE IN LAKE SNOWS WED/WED NT.
FRIDAY AND SATURDAY...MAINLY VFR.
SUNDAY...MAINLY VFR.
&&
.MARINE...
SMALL CRAFT ADVISORIES WILL BE CONTINUED AND EXTENDED INTO AT LEAST
WEDNESDAY NIGHT AS A COLD NORTHWEST FLOW PERSISTS ACROSS THE LOWER
LAKES REGION IN THE WAKE OF LOW PRESSURE MOVING INTO THE CANADIAN
MARITIMES. HIGHER PRESSURE WILL BEGIN TO BUILD IN THURSDAY. THIS
WILL ALLOW THE WINDS AND WAVES TO SUBSIDE SOMEWHAT AS THE PRESSURE
GRADIENT WEAKENS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY FROM 7 AM TO 6 PM EST WEDNESDAY FOR
NYZ006-008.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 AM EST THURSDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 3 AM EST THURSDAY FOR
LOZ042>045.
&&
$$
SYNOPSIS...SAGE
NEAR TERM...TJP
SHORT TERM...SAGE
LONG TERM...SAGE
AVIATION...TJP/TMA
MARINE...SAGE
