FXUS61 KBUF 060232
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
932 PM EST SAT DEC 5 2009
.SYNOPSIS...
HIGH PRESSURE BUILDING FROM THE OHIO VALLEY WILL BRING AN END TO ANY
LAKE EFFECT SNOW THAT LINGERS SOUTHEAST OF THE LAKES TONIGHT INTO
SUNDAY MORNING. AS THE HIGH SLIDES OFF THE EAST COAST MONDAY...A
WEAK LOW WILL TRACK EAST FROM THE CENTRAL GREAT LAKES AND BRING A
GENERAL LIGHT SNOW TO THE AREA. A STRONGER WINTER STORM IS POSSIBLE
FOR MID WEEK WITH MUCH COLDER CONDITIONS FOR THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
BASED ON BUF RADAR, ISSUED A QUICK UPDATE TO INCREASE POPS OFF LAKE
ERIE TO THE SOUTH OF BUFFALO, ESPECIALLY ACROSS CHAU/CATT COUNTIES
AN ADD A COUPLE OF INCHES OF ACCUMULATION. ALSO INCREASED POPS TO
HIGH CHC RANGE OVER SOUTHERN ERIE. COULD GET UP TO AN INCH IN SOME
SOUTHERN PORTIONS OF COUNTY NEAR CATTARAUGUS CREEK.
ALSO ADDED CHC POPS TO SOUTHERN LEWIS COUNTY FROM BACK EDGE OF
COASTAL SYS POSSIBLY BRUSHING THAT REGION.
AS OF 20Z A LOW PRESSURE SYSTEM OFF THE VIRGINIA COAST WAS PRODUCING
A PRECIPITATION FIELD THAT WAS JUST MISSING OUR FORECAST AREA TO THE
EAST. IT WAS SNOWING LIGHTLY AS FAR WEST AS A ROME TO ITHACA LINE.
AS THE SYSTEM CONTINUES NORTHEAST OVERNIGHT WE DO NOT EXPECT THE
SHIELD TO GET ANY FURTHER WEST. THIS DOES NOT MEAN THE WHOLE AREA
WILL BE SNOW FREE HOWEVER. AS THE EVENING WEARS ON A NORTHWEST FLOW
IN THE LOWER LEVELS WILL BECOME A LITTLE STRONGER. PARAMETERS WILL
BECOME MORE FAVORABLE FOR LAKE EFFECT SNOW SOUTHEAST OF BOTH LAKES.
AT THIS TIME WE WILL GO WITH JUST CHANCE POPS AND ONLY MINOR
ACCUMULATIONS IF ANY. ELSEWHERE THERE WILL BE A CLEARING TREND
OVERNIGHT.
HIGH PRESSURE WILL BUILD TO THE SOUTH OF US SUNDAY. WE WILL GET AN
INCREASING WEST TO SOUTHWEST FLOW. PARTLY TO MOST SUNNY SKIES ARE
EXPECTED OVER MOST OF THE CWA WITH HIGHS ONLY IN THE 30S. IT WILL BE
CLOUDIER EAST OF LAKE ONTARIO WHERE LAKE EFFECT PARAMETERS REMAIN
FAVORABLE FOR SCATTERED LAKE EFFECT SNOW SHOWERS. THE BACKING
STEERING WINDS WILL PUSH IT FARTHER NORTHWARD INTO JEFFERSON AND
LEWIS COUNTIES AND THE CHANCE WILL ALSO CONTINUE TO OSWEGO COUNTY.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
THE SURFACE RIDGE WILL SLIDE OFF THE EAST SUNDAY NIGHT AND ALLOW ANY
LINGERING LAKE EFFECT SNOW TO END AS SUBSIDENCE AND INCREASING LOW
LEVEL SHEAR TAKE OVER.
LOW PRESSURE APPROACHING FROM THE CENTRAL GREAT LAKES WILL THEN
BRING A CHANCE OF LIGHT SNOW ON MONDAY AS WEAK ISENTROPIC LIFT
DEVELOPS AHEAD OF THIS SYSTEM. AFTER THE WEAK LOW DRIFTS OFF THE NEW
ENGLAND COAST MONDAY NIGHT...A NORTHWEST FLOW WILL SET UP ACROSS THE
LAKES AND GENERATE LIMITED LAKE EFFECT SNOW SHOWERS. ANY LINGERING
LAKE SNOWS WILL END BY TUESDAY TUESDAY AFTERNOON AS HIGH PRESSURE
BUILDS ACROSS NEW YORK STATE AND BRINGS SOME SUNSHINE TO THE AREA.
CLOUDS WILL INCREASE FROM WEST TO EAST TUESDAY NIGHT AS THE
INTENSIFYING LOW LIFTS OUT OF THE SOUTHERN ROCKIES AND MOVES INTO
THE MIDWEST. A POWERFUL LOW LEVEL JET SURGING AHEAD OF THE LOW WILL
ADVECT MOISTURE INTO PARTS OF WESTERN NEW YORK BEFORE DAYBREAK
WEDNESDAY. THE TEMPERATURES WILL BE COLD ENOUGH FOR MAINLY SNOW.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THE INTENSE SURFACE LOW THAT IS FORECAST TO MOVE INTO THE MIDWEST
TUESDAY NIGHT IS STILL LOOKS LIKE IT WILL HAVE A SIGNIFICANT IMPACT
ON OUR AREA WEDNESDAY AND THURSDAY. THE GFS AND AND ECMWF TRACK THE
MAIN CENTER OF THE LOW JUST WEST OF NEW YORK STATE WEDNESDAY...WHILE
A COASTAL LOW DEVELOPS NEAR CHESAPEAKE BAY DURING THE AFTERNOON.
THE DEVELOPMENT OF THE COASTAL LOW WILL KEEP THE WARMEST LOW LEVEL
AIR TO OUR SOUTHEAST...BUT ENOUGH WARM AIR SHOULD MAY SURGE NORTH
WITH THE LOW LEVEL JET WEDNESDAY AFTERNOON TO ALLOW FOR A POSSIBLE
CHANGEOVER TO RAIN ALONG THE LAKE PLAINS. DEPENDING UPON HOW MUCH OF
A MIX OF RAIN AND SNOW THERE IS...OR IF CHANGEOVER TO RAIN DOES
OCCUR...IT LOOKS LIKE WE COULD SEE SIGNIFICANT ACCUMULATIONS OF SNOW
ON WEDNESDAY. STAY TUNED FOR LATER DETAILS.
THE OTHER FACTOR TO TAKE INTO ACCOUNT WILL BE THE WINDS ASSOCIATED
WITH THIS PATTERN. A LOOK AT THE 1.5 PVU FIELD SHOWS A DEEP
INTRUSION ASSOCIATED WITH THE MAIN SURFACE LOW AT 12Z WEDNESDAY
TRACKING OVER WESTERN TO CENTRAL NY BETWEEN 12Z AND 18Z. I LIKE TO
USE THE LEADING GRADIENT OF THIS PV INTRUSION TO TIME THE ONSET OF
GUSTY WINDS AND THE POTENTIAL FOR CONVECTION. THIS PV INTRUSION IS
ALSO COINCIDENT WITH A 6-HOUR DROP OF 13-16 MILLIBARS DURING THE
SAME TIMEFRAME...BOTH PARAMETERS POINTING TO A VERY WINDY DAY FOR
WEDNESDAY.
AS THE LOW TRACKS 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.
THE MAIN CENTER OF THE LOW IS FORECAST TO MOVE TO THE GULF OF SAINT
LAWRENCE DURING THURSDAY NIGHT AND ONWARD TO LABRADOR ON
FRIDAY...WHILE HIGH PRESSURE BUILDS INTO THE MIDDLE ATLANTIC STATES.
THE COLD NORTHWEST FLOW BETWEEN THESE TWO SYSTEMS WILL GENERATE
LAKE EFFECT SNOW THURSDAY THROUGH FRIDAY.
ANOTHER...MUCH WEAKER LOW WILL BRING A CHANCE OF SNOW ON SATURDAY.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
BUF/IAG/ROC...LARGELY WESTERLY SURFACE WINDS ACROSS LAKE ERIE IS
DEVELOPING SOME LAKE EFFECT ACTIVITY SOUTH OF THESE SITES.
HOWEVER...A PESKY SW 850 MB FLOW IS LIFTING SOME OF THIS MOISTURE
TOWARDS BUF/IAG. WITH A DRY NW FLOW AT THESE SITES...THIS MOISTURE
IS JUST RESULTING IN A CLOUD DECK. MOST MODEL GUIDANCE FORECASTS A
MORE WESTERLY FLOW DEVELOPING AT 850 MB...WHICH SHOULD CLEAR OUT
THESE SITES BETWEEN 06Z AND 09Z. UNTIL THEN...CAN/T RULE OUT A
BRIEF PERIOD OF MVFR CIGS. FOR SUNDAY...WINDS SHIFT MORE
SOUTHWESTERLY...BRINGING CLOUDS IN LATE IN THE DAY. FOR NOW...KEEP
CIGS VFR...BUT MAY SNEAK IN AT MFR.
JHW...LIGHT LAKE EFFECT SNOW HAS MOVED INTO THE REGION. RUC/WRF
COMBO SEEMS TO HANDLE FAIRLY WELL...MOVING A BAND THROUGH 07Z OR
SO. AFTERWARDS...850 MB WINDS BECOME MORE WESTERLY...LINING UP
BETTER WITH SURFACE WINDS. THIS WILL LIKELY RESULT IN A MORE
ORGANIZED BAND...BUT ONE WHICH WILL BE SOUTH OF JHW. EXPECT
CONDITIONS TO SLOWLY IMPROVE SUNDAY...THOUGH THERE IS LOW
CONFIDENCE IN TIMING WHEN THE MFVR CIG WILL FINALLY MIX/LIFT.
ART...CLOUDS ASSOCIATED WITH THE EXITING LOW WILL MOVE OFF TO THE
EAST THIS EVENING. EXPECT VFR CONDITIONS TO PREVAIL AS WINDS REMAIN
W OR NW...BUT EXPECT LAKE EFFECT ACTIVITY TO MOVE CLOSER LATE IN
THE DAY SUNDAY AS WINDS SHIFT MORE SW. VARIABLE CONDITIONS
EXPECTED SUNDAY AFTERNOON. PERIODS OF IFR OR LOWER ARE POSSIBLE IN
LAKE EFFECT BANDS...BUT SHOULD NOT BE PREDOMINANT.
OUTLOOK...
SUNDAY NIGHT...VFR WITH A CHANCE OF SNOW SHOWERS EAST OF LK
ONTARIO.
MONDAY...VFR/MVFR WITH A CHANCE OF SNOW.
TUESDAY...VFR.
WEDNESDAY...MVFR/IFR WITH RAIN/SNOW. PSBL LOW LEVEL WIND SHEAR.
THURSDAY...MVFR/IFR SNOW SHOWERS. STRONG SURFACE WINDS LIKELY.
&&
.MARINE...
SOUTHWEST TO WESTERLY WINDS WILL INCREASE AGAIN ON SUNDAY WITH
SMALL CRAFT ADVISORIES. DURING MIDWEEK...A STRONG WINTER STORM WILL
LIKELY GENERATE GALES ON THE LAKES WEDNESDAY AND THURSDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 1 AM EST MONDAY FOR
LOZ042-043.
SMALL CRAFT ADVISORY FROM 1 PM SUNDAY TO 6 AM EST MONDAY
FOR LOZ045.
SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 5 AM EST MONDAY
FOR LOZ044.
&&
$$
SYNOPSIS...TJP
NEAR TERM...JJP/SAGE
SHORT TERM...TJP
LONG TERM...TJP/WCH
AVIATION...APFFEL
MARINE...TJP
