Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 311203
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
703 AM EST SAT JAN 31 2015

.SYNOPSIS...
COLD AIR WILL REMAIN ENTRENCHED ACROSS THE REGION THIS WEEKEND WITH
A FEW LINGERING SNOW SHOWERS. THEN LOW PRESSURE WILL TRACK ACROSS
PENNSYLVANIA SUNDAY NIGHT INTO MONDAY WHICH WILL BRING STEADY SNOW
TO MOST AREAS WITH THE GREATEST AMOUNTS ACROSS SOUTHERN PORTIONS.
THEN ANOTHER ROUND OF BITTERLY COLD AIR WILL BUILD INTO THE REGION
THROUGH TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY WILL GET OFF TO A VERY COLD START WITH EARLY MORNING
TEMPERATURES IN THE SINGLE DIGITS IN MOST AREAS...EXCEPT WELL
BELOW ZERO IN THE NORTH COUNTRY.

A NW FLOW ACROSS LAKE ONTARIO IS CAUSING SOME LIGHT LAKE EFFECT SNOW
SHOWERS OR FLURRIES SOUTH OF THE LAKE WHICH ARE LIMITED BY DRY
AIR UPSTREAM AND LOW EQUILIBRIUM LEVELS. IR SATELLITE SHOWS THE
LEADING EDGE OF WARMER AIR ALOFT TRACKING SLOWLY EAST AS IT ENTERS
WESTERN LAKE ONTARIO. THIS SHOULD BRIEFLY ENHANCE LIGHT LAKE
EFFECT SNOW SHOWERS AS IT MOVES ACROSS THE LAKE...BUT SNOW SHOWERS
SHOULD END BEHIND IT WHEN EQUILIBRIUM LEVEL LOWER EVEN FURTHER.
THIS WILL ALSO BRING WARMER (BUT STILL QUITE COLD) AIR...WITH
HIGHS IN THE LOWER 20S ACROSS MUCH OF WESTERN NEW YORK WHILE EAST
OF LAKE ONTARIO STAYS IN THE COLDER AIR MASS WITH HIGHS IN THE
SINGLE DIGITS.

A REINFORCING COLD FRONT WILL APPROACH FROM THE NORTH TONIGHT AND
REACH THE NY/PA STATE LINE EARLY SUNDAY MORNING. EVEN AHEAD OF THIS
TEMPERATURES ALOFT WILL BE AROUND -13C AT 850MB WHICH IS MARGINALLY
COLD ENOUGH FOR LAKE ENHANCEMENT AHEAD OF THE FRONT. THE 00Z
NAM/RGEM BRIEFLY SHOW A WELL ALIGNED WNW FLOW DOWN LAKE ONTARIO
AROUND 06Z WHICH IS LIKELY TO BRING SOME LAKE EFFECT SNOW SHOWERS SE
OF LAKE ONTARIO. OTHER HIGH RESOLUTION GUIDANCE (WRF/ARW) ALSO
HINT AT THIS IN QPF FIELDS. THIS MAY BRING AN INCH OR TWO TO
WAYNE/N CAYUGA/OSWEGO COUNTIES. ELSEWHERE...EXPECT MODEST LAKE
ENHANCEMENT AND UPSLOPING BUT JUST LIGHT PRECIPITATION WITH LITTLE
ACCUMULATION TONIGHT.

00Z BUFKIT PROFILES CONTINUE TO SHOW LIMITED (BUT SOME) MID-LEVEL
MOISTURE BEHIND THIS FRONT. IF THIS MOISTURE IS NOT AMPLE TO PRODUCE
CLOUDS AND SOME SEEDING...THEN FREEZING DRIZZLE IS POSSIBLE ACROSS
SOUTHERN AREAS. THERMAL PROFILES ARE COLDER NORTH. MID-LEVEL CLOUDS
WILL MOVE IN LATE TONIGHT WHICH SHOULD END THE RISK FOR FREEZING
DRIZZLE. CONFIDENCE IN PRECIPITATION AND PRECIPITATION TYPE REMAINS
TOO LOW FOR ANY HEADLINES...WITH LIGHT SNOW EXPECTED TO BE THE
PRIMARY PRECIPITATION TYPE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
...WINTER STORM WATCH ISSUED SUNDAY INTO MONDAY FOR NY WESTERN
SOUTHERN TIER AND WESTERN FINGER LAKES...

LATEST 31/00Z GLOBAL MODELS ARE IN GOOD AGREEMENT WITH THE NEXT
WINTER STORM TO BRING ACCUMULATING SNOW TO WESTERN AND NORTH-CENTRAL
NEW YORK. IN THE MID-LEVELS A SIGNIFICANT SHORTWAVE TROUGH AND
EMBEDDED VORT MAX WILL SHIFT FROM THE CENTRAL PLAINS ACROSS THE
MIDWEST AND OHIO VALLEY SUNDAY INTO MONDAY. MODELS TRACK THE CENTER
OF THE ASSOCIATED SURFACE LOW ALONG THE OHIO RIVER SUNDAY AND SUNDAY
NIGHT THEN ALONG THE PA/MD BORDER ON MONDAY. THIS IS A FAVORABLE
TRACK FROM ACCUMULATING SNOW ACROSS OUR FORECAST AREA AS SYNOPTIC
MOISTURE AND LIFT ASSOCIATED WITH THE SURFACE LOW WILL COMBINE WITH
AN ARCTIC AIRMASS IN PLACE.

A BLEND OF 00Z WPC AND GLOBAL MODEL QPF WAS USED IN THIS LATEST
FORECAST PACKAGE TO PRODUCE FORECAST SNOW AMOUNTS. THE QPF BLEND
WAS COMBINED WITH SMOOTHED HOURLY COBB METHOD SLR VALUES TO YIELD
AVERAGE SNOW RATIOS OF ABOUT 10:1 SUNDAY INCREASING TO ABOUT 14:1
SUNDAY NIGHT THEN CLOSE TO 16:1 ON MONDAY ALL AS A COLDER AIRMASS
LOWERS THE DENDRITIC SNOW GROWTH ZONE TO THE SURFACE PRODUCING
MORE EFFICIENT SNOW GROWTH PROCESS. STORM TOTAL FORECAST SNOW
AMOUNTS RANGE FROM 8-10 INCHES ALONG THE NY-PA BORDER TO 2-4 ALONG
THE SOUTHERN SHORE OF LAKE ONTARIO SO EXPECTING A FAIRLY SHARP
GRADIENT WITH THIS STORM.

THE STORM WILL SHIFT OFF THE NEW JERSEY COAST MONDAY WITH SNOWFALL
TAPERING OFF INTO THE AFTERNOON. THE NORTHERLY FLOW ACROSS LAKE
ONTARIO WILL BRING AT LEAST A LOW CHANCE OF SOME LAKE ENHANCED SNOWS
MONDAY NIGHT BUT EQUILIBRIUM LEVELS OF 5KFT OR LESS WILL KEEP THE
MULTI-BANDED SNOWS VERY SHALLOW.

COLLABORATION WITH SURROUNDING OFFICES AND AN INCREASE IN FORECAST
CONFIDENCE WITH 00Z MODELS RUNS HAS LED TO ISSUANCE OF A WINTER
STORM WATCH BEGINNING 7AM SUNDAY FOR THE WESTERN SOUTHERN TIER AND
WESTERN FINGER LAKES WHERE THE HIGHER CONFIDENCE FOR WARNING
CRITERIA SNOW AMOUNTS EXISTS. FOR THE BUFFALO AND ROCHESTER METRO
AREAS AND SURROUNDING COUNTIES STORM TOTAL SNOW AMOUNTS ARE CLOSER
TO ADVISORY LEVEL SO HAVE NOT ISSUED A WINTER STORM WARNING. IF
LATER MODEL RUNS CONTINUE TO SHIFT THE TRACK OF THIS STORM NORTH
HIGHER SNOW TOTALS BY BE ADDED TO THE FORECAST FOR BUFFALO AND
ROCHESTER WHICH MAY REQUIRE A WATCH OR WARNING WITH LATER UPDATES.
PLEASE STAY TUNED TO FUTURE UPDATES AT THE STORM EVOLVES.

A COLD NORTHEAST FLOW WILL CAUSE TEMPERATURES TO FALL THROUGH THE
TEENS SUNDAY TO THE SINGLE DIGITS EVEN BELOW ZERO EAST OF LAKE
ONTARIO SUNDAY NIGHT. INCREASING WINDS AS THE STORM DEEPENS WILL
LIKELY BRING BITTERLY COLD WIND CHILL TEMPERATURES SUNDAY NIGHT
THROUGH MONDAY FROM THE -TEENS ACROSS WESTERN NEW YORK TO THE
-TWENTIES FOR THE NORTH COUNTY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
IN THE EXTENDED...WEAK LAKE SNOWS OFF LAKE ONTARIO SHOULD LIFT
NORTHWARD AND EVENTUALLY FALL APART ALTOGETHER ON TUESDAY AS THE
FLOW BACKS TO SOUTHWESTERLY AND WARM ADVECTION DEVELOPS IN ADVANCE
OF A CLIPPER SYSTEM...WITH THE LATTER THEN BRINGING A BRIEF PUSH OF
"MILDER" AIR AND A CHANCE OF SNOW SHOWERS ON WEDNESDAY. IN THE WAKE
OF THIS SYSTEM...RENEWED ARCTIC COLD AND AT LEAST SOME LAKE ONTARIO
LAKE SNOWS SHOULD RETURN FOR THURSDAY AND FRIDAY.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A NORTHWEST FLOW IS PRODUCING SOME LIGHT LAKE EFFECT SNOW SHOWERS
SOUTH OF LAKE ONTARIO. THE LEADING EDGE OF WARMER AIR ALOFT WILL
CONTINUE TO MOVE FROM W-E. THIS WILL INITIALLY BRING SOME LIGHT
LAKE EFFECT SNOW SHOWERS AND MVFR CIGS...BUT EXPECT SNOW TO AND
AND CIGS TO RISE BEHIND IT. BY THIS AFTERNOON...EXPECT MOSTLY VFR
CONDITIONS. THESE SHOULD LAST INTO THIS EVENING UNTIL A COLD FRONT
DROPS FROM N-S AND BRINGS SOME SNOW SHOWERS AND MVFR/IFR CIGS.

OUTLOOK...
SUNDAY...VFR/MVFR. A CHANCE OF SNOW SHOWERS.
SUNDAY NIGHT AND MONDAY...IFR IN SNOW IN MOST AREAS...VFR/MVFR
WITH A CHANCE OF SNOW AT ART.
TUESDAY...VFR/MVFR. A CHANCE OF SNOW SHOWERS EAST OF LAKE ONTARIO.
WEDNESDAY...VFR/MVFR. A CHANCE OF SNOW SHOWERS.

&&

.MARINE...
HIGH PRESSURE WILL RIDGE NORTHEASTWARD FROM THE OHIO VALLEY AND
BRING A BRIEF PERIOD OF NON SCA CONDITIONS TODAY. A COLD FRONT
WILL DROP ACROSS THE LAKES TONIGHT WITH AN INCREASING WESTERLY
FLOW BEHIND IT. THEN LOW PRESSURE WILL TRACK TO THE SOUTH OF THE
LAKES SUNDAY NIGHT WITH AN INCREASING NORTHEASTERLY FLOW. EACH OF
THESE SYSTEMS MAY PRODUCE SCA CONDITIONS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WIND CHILL ADVISORY UNTIL 9 AM EST THIS MORNING FOR NYZ006>008-
     012-019>021-085.
     WINTER STORM WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING
     FOR NYZ012>014-019>021-085.
MARINE...NONE.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...SMITH
LONG TERM...JJR
AVIATION...APFFEL
MARINE...APFFEL



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