Winter Storm Watch for western NY (Buffalo CWA):
...WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY EVENING
THROUGH MONDAY EVENING...
* LOCATIONS...SOUTHERN ERIE AND WYOMING COUNTIES AND THE WESTERN
SOUTHERN TIER
* TIMING...LATE SUNDAY EVENING THROUGH EARLY MONDAY EVENING.
* HAZARDS...ACCUMULATING HEAVY WET SNOW.
* ACCUMULATIONS...3 TO 6 INCHES SUNDAY NIGHT...5 TO 10 INCHES
MONDAY...AND AN INCH OR LESS MONDAY EVENING...LEADING TO STORM
TOTALS OF 8 TO 16 INCHES.
* WINDS...NORTH TO NORTHEAST GUSTING AS HIGH AS 40 MPH.
* VISIBILITIES BELOW A HALF MILE AT TIMES.
* IMPACTS...WIDESPREAD DOWNED TREES AND POWER LINES CAUSING
POWER OUTAGES. HAZARDOUS DRIVING CONDITIONS DEVELOPING.
* FORECASTER CONFIDENCE...HIGH.
Buffalo NWS AFD on this event:
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
THE MOST INTERESTING PORTION OF THE FORECAST OCCURS DURING THIS
TIMEFRAME. DEEPENING LOW PRESSURE MOVES UP THE MID ATLANTIC COAST
AND PROGRESSES ACROSS NEW YORK STATE ON MONDAY. GFS AND ECMWF ARE
CLOSEST WITH THEIR RESPECTIVE TRACKS SEPARATES BY ONLY 50 MILES OR
SO...THE GFS IS FARTHER TO THE WEST...AND EACH MODEL TRACK IF
SLIGHTLY WESTWARD OF THE PREVIOUS COUPLE OF MODEL RUNS. 12Z NAM IS
MUCH FARTHER WEST THEN GFS/EC AND PLACES MOST OF THE WINTRY PRECIP
OVER THE FAR WESTERN EDGE OF THE FORECAST AREA. WILL OPT TO USE
GFS/ECMWF AS MODELS OF CHOICE FOR PERSISTENCE...USING SOME OF THE
FINER FEATURES OF THE 12Z NAM12 FOR THERMAL/ISENTROPIC GRADIENTS.
THIS PATTERN IS ALMOST A FRAME BY FRAME REPLAY OF AN EVENT WHICH
OCCURRED ON THE 2ND AND 3RD OF APRIL 2005. THERE WAS AN 8 INCH
SNOWFALL AT KBUF WITH MORE THAN A FOOT OF SNOW ALONG THE CHAUTAUQUA
RIDGE...AND MORE THAN TWO FEET OF SNOW ACROSS NORTHWESTERN PA AND
NORTHEAST OHIO.
THE DEFINING FACTOR FOR THIS STORM WILL BE THE THERMAL GRADIENT
ALONG THE TRACK OF THE SURFACE LOW. HIGH PRESSURE TO THE NORTH WILL
SUPPLY A CONTINUED SUPPLY OF COOLER/COLDER BOUNDARY LAYER AIR...
OVERLAIN BY A WEDGE OF WARMER AIR ALOFT. THE AIRMASS WILL BE NEARLY
SATURATED TO 15KFT...WELL WITHIN THE COLD LAYER OF DENDRITIC CRYSTAL
GROWTH...AND AS THE HEAVIER SNOW FALLS THROUGH THAT WARMER LAYER IT
SHOULD BE ABLE TO OVERWHELM THE WARMTH AND COOL IT TO BELOW
FREEZING...REFERRED TO AS DYNAMIC COOLING.
THERE WILL BE A REGION OF SNOW AND SLEET AND RAIN ALONG THE NARROW
TRANSITION ZONES FROM EAST TO WEST. THIS LINE WILL BE NORTH/SOUTH
AND ALONG THE FINGER LAKES. THE HEAVIER SNOW WILL BE TO THE WEST OF
THIS LINE AND OVER THE HIGHER ELEVATIONS OF THE ALLEGANY
PLATEAU...GENERALLY FROM WESTERN LIVINGSTON AND ACROSS WYOMING
COUNTY...TO SOUTHERN ERIE COUNTY AND ACROSS THE HILLS OF THE WESTERN
SOUTHERN TIER. WARMER AIR IN THE LOWER LAYERS TO THE SOUTH OF LAKE
ONTARIO MAY BE JUST WARM ENOUGH TO MELT THE SNOW TO RAIN FOR
NIAGARA/ORLEANS/MONROE COUNTIES...BUT JUST UP TO THE NIAGARA
ESCARPMENT THEN THE PRECIP WILL MIX WITH AND TRANSITION OVER THE
SNOW ALONG THE SOUTHERN EDGES OF THESE COUNTIES.
WARMER AIR OVER CENTRAL AND NORTHERN NEW YORK SHOULD KEEP ALL PRECIP
IN THE FORM OF RAIN DURING SUNDAY NIGHT THROUGH MONDAY...CHANGING
OVER TO A MIX OF RAIN AND SNOW ON MONDAY NIGHT...THEN BACK TO RAIN
ON TUESDAY BEFORE TAPERING OFF ALTOGETHER.
IN TERMS OF HOW POTENTIALLY UNUSUAL THIS WHOLE EVENT COULD BE (ESP
THE SNOW ASPECT OF IT)...NEARLY ALL OF THE MAJOR FORECAST PARAMETERS
(500MB AND 700MB HEIGHTS...MSLP...850MB TEMPS...AND WIND COMPONENTS)
ARE 4 TO 5 STANDARD DEVIATIONS FROM NORMAL. IT IS CERTAINLY
SIGNIFICANT WHEN A COUPLE FORECAST PARAMETERS ARE THAT ANOMALOUS...
BUT WHEN NEARLY ALL OF THE MAIN FACTORS ARE THIS FAR FROM
NORMAL...THEN THE EVENT STARTS TO RISE TO THAT OF A MEMORABLE OR
EVEN HISTORIC STATURE...IF ALL OF THESE FACTORS REMAIN IN PERFECT
ALIGNMENT.
Great soaking rain that we really needed.