FXUS61 KBUF 160827
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
327 AM EST WED DEC 16 2009

.SYNOPSIS...
LOW PRESSURE IN THE CANADIAN MARITIMES WILL DRAW PROGRESSIVELY 
COLDER AIR SOUTHWARD ACROSS OUR REGION. THIS WILL PRODUCE BANDS OF 
LAKE EFFECT SNOW SOUTHEAST OF LAKES ERIE AND ONTARIO TODAY. A COLD 
FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING A ROUND OF SNOW 
SHOWERS...THEN HIGH PRESSURE BUILDS ACROSS THE REGION LATE 
THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RADAR MOSAICS SHOW MULTIPLE BANDS OF SNOW SETTING UP 
SOUTHEAST OF THE LAKES EARLY THIS MORNING IN RESPONSE TO THE COLD 
NORTHWEST FLOW WHICH HAS SET BEHIND THE DEPARTING MID LEVEL SHORT 
WAVE. 

THE BEST ORGANIZED BANDS ARE LOCATED OVER MONROE AND WAYNE COUNTIES 
WHERE KBUF ONE HOUR SNOW DEPTH ALGORITHM IS INDICATING ONE HALF TO 
ONE INCH ACCUMULATIONS PER HOUR. EXPECT THESE BANDS TO SHIFT A 
LITTLE TO THE NORTH AND EAST EARLY THIS MORNING AS A SECOND MID 
LEVEL SHORT WAVE TRACKS EAST ACROSS THE STATE AND ALLOWS THE 
BOUNDARY LAYER WINDS TO BACK A BIT. 

OFF LAKE ERIE...THE BANDS ARE WEAKER AND LESS ORGANIZED DUE TO THE 
SHORTER FETCH ACROSS THE LAKE AND A LOWER INVERSION. EXPECT THE LAKE 
ERIE BANDS TO REMAIN WEAK...BUT PERSIST THROUGH MOST OF DAY AS THE 
BUFKIT PROFILES FOR KJHW SHOW AMPLE MOISTURE TRAPPED BELOW THE 
SUBSIDENCE INVERSION WITH ADEQUATE SNOW CRYSTAL GROWTH. BASED ON 
THESE TRENDS...WILL JUST INDICATE ANOTHER 1 TO 2 INCHES ACROSS THE 
SOUTHERN TIER. 

FOR LAKE ONTARIO...THE SITUATION IS A LITTLE MORE COMPLICATED. THE 
BAND THAT IS CURRENTLY IN PLACE OVER MONROE AND WAYNE COUNTIES IS 
FORECAST TO SHIFT FARTHER TO THE NORTH LATER THIS MORNING AND DURING 
THE AFTERNOON AS THE BOUNDARY LAYER WINDS BACK A LITTLE MORE IN 
ADVANCE OF A SECONDARY SURFACE TROUGH/ARCTIC FRONT THAT IS FORECAST 
TO DROP SOUTH ACROSS THE LAKE LATE THIS AFTERNOON. THE NAM12 925 
WIND AND OMEGA FIELDS DEPICT THIS NORTHWARD DRIFT VERY 
WELL...ESPECIALLY BETWEEN 15Z AND 18Z. IF THIS TREND VERIFIES...THE 
LONGER FETCH ACROSS THE LAKE WILL COME INTO PLAY AND IMPACT OSWEGO 
AND SOUTHERN LEWIS COUNTIES WITH STEADIER LAKE SNOWS. FOR NOW...WILL 
MAINTAIN THE LAKE EFFECT SNOW ADVISORY THAT IS IN PLACE ACROSS THESE 
TWO COUNTIES...BUT ACCUMULATIONS COULD BE HIGHER IF THE BAND REMAINS 
INTACT OVER THIS AREA LONGER THAN EXPECTED. 

AS THE AFOREMENTIONED FRONT REACHES THE SOUTH SHORE OF LAKE ONTARIO 
DURING THE EARLY EVENING...EXPECT THE SNOW BAND TO SHIFT SOUTH AND 
IMPACT ALL THE COUNTIES BORDERING THE SOUTH OF THE LAKE WITH A QUICK 
1 TO 2 INCHES OF SNOW. SLIGHTLY HIGHER ACCUMULATIONS ARE POSSIBLE 
FROM MONROE TO NORTHERN CAYUGA COUNTIES AS THE WINDS SHIFT TO THE 
WEST NORTHWEST BEHIND THE FRONT. 

AFTER THE FRONT LOOSES ITS CONNECTION TO LAKE ONTARIO...EXPECT THE 
SNOW TO WEAKEN A BIT AS THE FRONT CONTINUES TO DROP SOUTH ACROSS THE 
REST OF THE STATE EARLY TONIGHT. STILL EXPECT MORE LAKE SNOWS TO SET 
UP SOUTHEAST OF LAKE ONTARIO BEHIND THE FRONT...BUT THE SHORTER 
FETCH AND LOWERING SUBSIDENCE INVERSION SHOULD HELP TO KEEP 
ACCUMULATIONS BELOW ADVISORY CRITERIA. 

THE REST OF THE AREA WILL SEE SOME SNOW TONIGHT WITH THE PASSING 
TROUGH...BUT ACCUMULATIONS WILL BE LESS COMPARED TO AREAS CLOSER
TO LAKE ONTARIO.

IN TERMS OF TEMPERATURES DURING THIS PERIOD...READINGS WILL RANGE 
FROM THE LOWER TO MIDDLE 20S TODAY...THEN DIP INTO THE TEENS ACROSS 
MOST LOCATIONS TONIGHT. THE MAIN EXCEPTION TONIGHT WILL BE EAST OF 
LAKE ONTARIO WHERE TEMPERATURES ARE EXPECTED TO DIP INTO THE SINGLE 
DIGITS ACCOMPANIED BY WIND CHILLS IN THE -10F TO -15F RANGE.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ON THURSDAY...THE ARCTIC FRONTAL BOUNDARY WILL STALL ROUGHLY FROM 
BUFFALO SOUTHEASTWARD TO NEW YORK CITY. BY THIS TIME...THE LOW IN 
THE CANADIAN MARITIMES WILL BE WEAKENING...WITH THE FRONT REALLY 
LOOSING ITS PUSH...LEAVING A SHALLOW LAYER OF VERY COLD AIR IN ITS 
WAKE. MOST BUFKIT SOUNDINGS SHOW A SHARP INVERSION FROM 2000 TO 3000 
FT. FOR LAKE EFFECT...THIS WILL LIMIT THE VERTICAL GROWTH...BUT WITH 
-17C AIR AT 925 MB SOUTHEAST OF LAKE ONTARIO...IT WILL BE COLD 
ENOUGH FOR SUFFICIENT SNOW GROWTH. THE SAME CANNOT BE SAID FOR LAKE 
ERIE...WITH TEMPERATURES ONLY AROUND -10C BENEATH THE 
INVERSION...RESULTING IN A MORE MARGINAL CASE. FOCUSING ON LAKE 
ONTARIO...A THICK LAKE-INDUCED CAPE OF AROUND 400 J/KG IS 
EVIDENT...IN A NW FLOW BEHIND THE FRONT. THE MAIN LIMITING FACTOR 
WILL BE THE DRIER ARCTIC AIR WORKING IN AND WEAKENING WINDS. WILL GO WITH 
LIKELY POPS...CENTERED ROUGHLY ON WAYNE COUNTY ON THURSDAY...WITH 
DIMINISHING POPS LATE IN THE DAY. ANY SNOW THAT DOES DEVELOP SHOULD 
HAVE A GOOD FLUFF FACTOR WITH 1 TO 3 INCHES A MIDDLE OF THE ROAD 
FORECAST SOUTHEAST OF ONTARIO. EXPECT THE BAND TO STRUGGLE TO SPREAD 
VERY FAR FROM THE LAKE GIVEN THE LOW INVERSION...WITH LIMITED 
POTENTIAL FOR DEVELOPMENT OFF OF LAKE ERIE AS WELL. THE INVERSION 
WILL LIKELY TRAP LINGERING LOW MOISTURE...WITH MORE CLOUDS THAN SUN 
EXPECTED. WITH THE ARCTIC FRONT STRADDLING THE REGION...EXPECT HIGH 
TEMPERATURES TO RANGE SIGNIFICANTLY FROM THE UPPER 20S IN THE 
SOUTHERN TIER...TO THE TEENS EAST...AND EVEN THE SINGLE DIGITS 
POSSIBLE IN THE COLDEST NORTH COUNTRY LOCATIONS. 

FOR THURSDAY NIGHT AND FRIDAY...SURFACE HIGH PRESSURE WILL BUILD 
ACROSS THE REGION...WITH THE AXIS GRADUALLY DRIFTING TO THE EAST 
FRIDAY NIGHT. WHILE HIGH PRESSURE TYPICALLY BRINGS FAIR WEATHER TO 
THE REGION...THERE IS ONE ISSUE TO CONTEND WITH. THE 
NAM/EUROPEAN/UKMET/GEM ALL PRODUCE LIGHT QPF IN WESTERN PORTIONS OF 
THE STATE. A CLOSER LOOK SHOWS AN AREA OF WEAK WARM AIR ADVECTION 
ALONG THE EXITING FRONTAL BOUNDARY. WHILE DYNAMICS ARE NOT TO 
IMPRESSIVE...THE MODEL CONSENSUS...AND THE FACT THAT ONLY LIGHT QPFS 
CAN PRODUCE SNOW FALL IN THIS VERY COLD ENVIRONMENT...WILL ADD 
CHANCE POPS IN WESTERN SECTIONS. TEMPERATURES WILL AGAIN 
RANGE...COLDEST TO THE EAST. BASICALLY USE A BIAS CORRECTED BLEND 
WEIGHTING THE SREF AND TWEAKING DOWN WHERE ARCTIC AIR IS EXPECTED TO 
BE BEST ENTRENCHED. SKY CONDITIONS WILL VARY...BUT GENERALLY MORE 
OPTIMISTIC EAST...WHERE THE THE HIGH WILL BE MORE FIRMLY IN CONTROL.

THE STALLED FRONTAL BOUNDARY BECOMES MORE EAST-WEST ORIENTED ON THE 
SOUTHERN FRINGE OF THE CWA FRIDAY NIGHT. WILL CONTINUE MINIMAL 
CHANCE POPS...AS MODEL CONSENSUS CONTINUES TO SUGGEST SOME LIGHT 
SNOW SHOWER ACTIVITY ASSOCIATED WITH THE BOUNDARY.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
FOR THIS UPCOMING WEEKEND...WILL INTRODUCE CHANCE POPS FOR 
SATURDAY...MAINTAINING CONTINUITY AS THE STALLED FRONTAL BOUNDARY AND 
UPPER TROF MAY BE ENOUGH TO PRODUCE SNOW SHOWER ACTIVITY FOR SOME. 
BEYOND THIS...THERE REALLY ISN/T MUCH TO HANG YOUR HAT ON OTHER THAN 
AN PERSISTENT UPPER TROF IN EASTERN CANADA. BASICALLY MAINTAIN GOING 
FORECAST WHICH HAS POPS IN THE CHANCE TO SLIGHT CHANCE RANGE THROUGH 
THE PERIOD. 

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 /09Z WEDNESDAY THROUGH SUNDAY/...
PLENTY OF LOW LEVEL MOISTURE WILL REMAIN ACROSS THE AREA 
THROUGH THE 06Z 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 OVERNIGHT.
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...
SCA MAINTAINED ON THE WATERS...WITH THE STRONGEST FLOW ON LAKE 
ONTARIO TODAY...WITH WINDS APPROACHING 30 KTS. EXPECT A BRIEF 
INCREASE AND SHIFT TO THE NORTHWEST IMMEDIATELY BEHIND THE 
PASSAGE AN ARCTIC BOUNDARY ON LAKE ONTARIO THIS EVENING. AFTER 
THIS...WINDS SHOULD DIMINISH...WITH THE A GENERALLY QUIET PERIOD 
EXPECTED ON THE LAKES THROUGH THE WEEKEND.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY FROM 7 AM THIS MORNING TO 6 PM EST 
     THIS EVENING 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...APFFEL
NEAR TERM...TJP
SHORT TERM...APFFEL
LONG TERM...APFFEL/SAGE
AVIATION...TJP/TMA
MARINE...APFFEL