Lake Effect Snow Advisory 5, NWS Buffalo, NY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
321 AM EST THU FEB 9 2006

.SHORT TERM (TODAY THROUGH SATURDAY)...

WATER VAPOR LOOP THIS MORNING SHOWING A WELL DEFINED UPPER SHORTWAVE
DROPPING SOUTH FROM JAMES BAY. THIS UPPER SHORTWAVE AND ASSOCIATED
COLD FRONT WILL CROSS THE AREA THIS AFTERNOON. BOTH THE NAM AND GFS
SUGGESTING AN IMPRESSIVE AMOUNT OF VERTICAL MOTION ASSOCIATED WITH
FRONTAL PASSAGE...THEREFORE EXPECT BURST OF MODERATE TO HEAVY SNOW
WITH FRONTAL PASSAGE FOR ALL AREAS THIS AFTERNOON. FRONT MOVING
THROUGH QUICK ENOUGH TO LIMIT SNOWFALL AMOUNTS...GENERALLY TWO
INCHES OR LESS. TIMING OF THIS SNOW BURST COULD BECOME A PROBLEM
AS FAR AS PUBLIC IMPACT IS CONCERN WITH IT POTENTIALLY COMING RIGHT
AROUND THE LATE AFTERNOON RUSH HOUR.

AS PREVIOUS DISCUSSIONS ELUDED TO...AREAS EAST OF LAKE ONTARIO WILL
BE PRIMED FOR LAKE EFFECT SNOWS THIS AFTERNOON AND TONIGHT. VERY
FAVORABLE LAKE EFFECT PARAMETERS SETTING UP FROM 18Z THIS AFTERNOON
THROUGH 12Z FRIDAY. A WELL ALIGNED WEST SOUTHWEST FLOW DEVELOPS
AHEAD OF THE FRONT WITH SHARPLY RISING INVERSION HEIGHTS AND
SUFFICIENTLY COLD AIR SHOULD BE ABLE TO ESTABLISH A SIGNIFICANT BAND
OF LAKE EFFECT SNOW...LIKELY STARTING NORTH OF THE TUG HILL THEN
GRADUALLY SHIFTING TO THE SOUTH AS A WESTERLY FLOW DEVELOPS
IMMEDIATELY BEHIND THE FRONT...THEN EVENTUALLY A WEST NORTHWEST FLOW
AFTER 00Z TONIGHT. LOCALIZED SNOWFALL AMOUNTS ON THE TUG HILL COULD
EXCEED A FOOT...THEREFORE HAVE ISSUED A LAKE EFFECT SNOW WARNING FOR
JEFFERSON/LEWIS AND OSWEGO COUNTIES THIS AFTERNOON AND TONIGHT.

THE WEST NORTHWEST FLOW AFTER 00Z TONIGHT SHOULD SHIFT THE LAKE
BAND ACROSS NORTHERN WAYNE AND NORTHERN CAYUGA COUNTIES...THEREFORE
HAVE ISSUED A LAKE EFFECT SNOW ADVISORY WITH AMOUNTS SLIGHTLY LESS
THAN AREAS TO THE NORTH. THESE AREAS WILL HAVE TO BE MONITORED AS
ADVISORY MAY NEED TO BE UPGRADED TO A WARNING BY LATER SHIFTS.

OFF OF LAKE ERIE...LAKE ENHANCEMENT WILL ALSO OCCUR THIS AFTERNOON
AND EARLY TONIGHT...BUT LAKE PARAMETERS NOT QUITE AS FAVORABLE AS
OFF OF LAKE ONTARIO. WELL ALIGNED WEST NORTHWEST FLOW SHOULD BE ABLE
TO GENERATE ADVISORY TYPE SNOWFALL AMOUNTS.

ALL LAKE EFFECT ACTIVITY SHOULD WIND DOWN BY FRIDAY MORNING AS
SURFACE
RIDGE MOVES INTO THE AREA ALONG WITH INCREASING SHEAR.

SREF ENSEMBLE MEMBERS ARE IN NEAR AGREEMENT THAT NEXT SURFACE WAVE
WILL WORK EAST ACROSS THE AREA...PRODUCING A GENERAL SNOWFALL...
ESPECIALLY FROM THE FINGER LAKES WESTWARD. AMOUNTS AT THIS POINT
LOOK TO BE IN THE 1-3/2-4 INCH RANGE PER MODEL QPF (COULD BE LOCALLY
HEAVIER IF SOME LAKE ENHANCEMENT OCCURS).

NAM AND GFS STILL IN DISAGREEMENT WITH SURFACE LOW WORKING UP FROM
THE SOUTHERN STATES SATURDAY INTO EARLY SUNDAY.

NAM IS MUCH WEAKER WITH LOW AND MOVES IT FURTHER OFF THE EAST
COAST... WHILE THE GFS IS MUCH STRONGER WITH LOW AND MOVES IT
FARTHER TO THE WEST. THE GFS SCENARIO COULD RESULT IN SOME HEAVIER
SNOWFALL FOR SOUTHEAST PORTIONS OF THE AREA. AT THIS POINT...WILL
LEAN TOWARD SREF ENSEMBLE SOLUTIONS AND FOLLOW THE WEAKER NAM
SOLUTION.

&&

.LONG TERM (SATURDAY NIGHT THROUGH WEDNESDAY)...

THE BEGINNING OF THIS PERIOD WILL FEATURE A DEEPLY STACKED LOW OFF
THE NEW JERSEY COAST WITH A NORTHERLY FLOW OF COLD AIR ACROSS OUR
FORECAST AREA. IT WILL BE COLD ENOUGH FOR LAKE EFFECT. THIS COMBINED
WITH A CYCLONIC CIRCULATION WILL LEAD US TO GO WITH LIKELY POPS FOR
MOST AREAS RIGHT THROUGH SUNDAY NIGHT AND FOR AREAS SOUTHEAST OF
BOTH LAKES MONDAY AS ANOTHER SHORT WAVE TRACKS SOUTHEAST FROM THE
UPPER LAKES REINFORCING OUR COLD REGIME.

BY TUESDAY THE FLOW BECOMES A LITTLE MORE ZONAL ALOFT BUT THERE IS
NOT MUCH WARM ADVECTION INDICATED ALOFT UNTIL TUESDAY NIGHT. BY
WEDNESDAY A FAIRLY DEEP LOW IS EXPECTED TO TRACK WELL TO OUR NORTH
WHICH FINALLY BRINGING TEMPERATURES BACK A LITTLE ABOVE NORMAL. THE
BEST LIFTING DYNAMICS FOR THE TUESDAY THROUGH WEDNESDAY PERIOD WILL
BE TO OUR NORTH SO WE WILL GO NO MORE THAN CHANCE POPS AT THIS
TIME.

LOOKING FURTHER OUT...THE 00Z GFS ENSEMBLES AND 12Z MEDIUM RANGE GFS
MODEL CONTINUED TO SHOW THAT A +PNA PATTERN WILL REMAIN IN PLACE
ACROSS THE UNITED STATES THROUGH THE NEXT TWO WEEKS. WHILE THE
COLDEST AIR IN THE NORTHERN HEMISPHERE WILL BE OVER EASTERN
SIBERIA...H8 TEMPS WILL GENERALLY REMAIN BELOW -10C ACROSS OUR
REGION. ONLY BRIEF WARM UPS CAN BE EXPECTED DURING THE TWO WEEK
PERIOD WHEN H8 TEMPS WILL OCCASIONALLY REACH UP TO BETWEEN -5 AND
-10C. THIS WILL KEEP THE OVERALL TEMPERATURES BELOW NORMAL INTO THE
THIRD WEEKEND OF THE MONTH WITH FAIRLY HIGH FREQUENCY LAKE SNOWS.

CLIMATOLOGICALLY...THE +PNA PATTERN WILL BE GETTING LONG IN THE
TOOTH BY THIS POINT SO A TRANSITION TO A MILDER PATTERN WILL BECOME
MORE LIKELY AS WE HEAD INTO THE SECOND HALF OF THE MONTH. THE LONG
WAVE PATTERNS SUCH AS THE PNA AND NAO TEND TO FOLLOW 10 DAY TO TWO
WEEK CYCLES ON AVERAGE.

&&

.AVIATION...

A PERSISTENT NORTHWEST ALOFT IS STILL GENERATING A SC DECK...
...AVERAGING BETWEEN 2500 TO 3500 FEET...SOUTHEAST OF THE LAKES.
WIDELY SCATTERED SNOW SHOWERS WILL OCCASIONALLY LOWER VSBYS TO MVFR
AT KROC AND KIAG THROUGH 09Z.

A DEEP UPPER LEVEL TROUGH AND ITS ASSOCIATED COLD FRONT WILL PUSH
SOUTH ACROSS THE AREA BETWEEN 18Z AND 00Z. EXPECT MAINLY VFR
CONDITIONS TO LOWER MVFR AS SNOW SHOWERS BREAK OUT AHEAD OF THE
APPROACHING FRONT. STRENGTHENING WEST TO SOUTHWEST WINDS AHEAD OF
THE FRONT WILL PICK UP ADDITIONAL MOISTURE FROM THE LAKES AND
OCCASIONALLY LOWER CIGS/VSBYS TO IFR VCNTY KBUF AND KART DURING THE
AFTERNOON. THE LAKES BANDS WILL BECOMING ORIENTED SOUTHEAST OF THE
LAKES AS THE WINDS SHIFT TO THE NORTHWEST AFTER 00Z. MVFR TO IFR
CONDITIONS WILL PERSIST THROUGH 06Z FRIDAY AS SNOW SHOWERS CONTINUE
IN THE NORTHWEST FLOW BEHIND THE DEPARTING FRONT.

&&

.MARINE...

LIGHT NORTHWEST WINDS WILL BACK TO THE WEST AND INCREASE TO ABOUT 30
KNOTS LATER THIS MORNING AND DURING THE AFTERNOON AS A COLD FRONT
APPROACHES THE LAKE. THE WINDS WILL SHIFT TO THE NORTHWEST AND
DIMINISH TONIGHT.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING NYZ006>008 1 PM THIS AFTERNOON TO 7 AM
     FRIDAY.
     LAKE EFFECT SNOW ADVISORY NYZ012-019-020-085 1 PM THIS
     AFTERNOON TO 1 AM FRIDAY.
     LAKE EFFECT SNOW ADVISORY NYZ004-005 7 PM THIS EVENING TO 7 AM
     FRIDAY.

MARINE...NONE.

&&

SHORT TERM...TMA
LONG TERM...SAGE/RSH
AVIATION/MARINE...TJP