FXUS61 KBUF 141953
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
253 PM EST MON DEC 14 2009
.SYNOPSIS...
A WEAK LOW WILL LIFT ACROSS SOUTHERN ONTARIO TONIGHT WITH A FEW
SHOWERS ACROSS OUR REGION. COLDER AIR WILL BEGIN TO FILTER INTO
WESTERN AND CENTRAL NEW YORK IN THE WAKE OF THIS LOW ON TUESDAY
ALONG WITH SOME RAIN AND SNOW SHOWERS. A NORTHWEST FLOW OF COLDER
AIR WILL THEN PREVAIL THROUGH THE MIDDLE AND LATTER PART OF THE WEEK
WITH SOME LIMITED LAKE SNOWS SOUTHEAST OF THE LAKES.
&&
.NEAR TERM /THROUGH TUESDAY/...
SURFACE LOW TRACKS FROM NEAR CHICAGO TO LAKE ONTARIO TONIGHT AND
NORTHERN NEW YORK TUESDAY MORNING. FOR MOST OF THE REGION THIS WILL
RESULT IN PATCHY LIGHT RAIN AND DRIZZLE. NORTH OF THE ASSOCIATED
WARM FRONT...OVER THE EASTERN LAKE ONTARIO REGION....A MIX OF
RAIN/SNOW IS LIKELY OVERNIGHT. TEMPERATURES WILL NOT SEE TOO MUCH OF
A DIP OVERNIGHT LOWS WITH THE HIGHER ELEVATIONS OF THE TUG HILL
LIKELY TO BE THE ONLY AREAS SEEING TEMPS FALL TO FREEZING OR BELOW.
ON TUESDAY WITH THE REGION ON THE BACK SIDE OF THE LOW...COLDER AIR
WILL BEGIN TO FILTER IN RESULTING IN SLOWLY FALLING TEMPERATURES
DURING THE AFTERNOON HOURS. SOME LINGERING SCATTERED LIGHT RAIN OR
SNOW SHOWERS IN THE MORNING WILL TAPER OFF AND CHANGE TO ALL SNOW
DURING THE AFTERNOON. THE COLD WEST TO NORTHWEST FLOW WILL BEGIN TO
INITIATE SOME LAKE EFFECT SNOW SHOWERS TO THE LEE OF THE LAKES WITH
ONLY MINOR ACCUMULATIONS EXPECTED BY SUNSET.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
THIS PERIOD WILL FEATURE A NORTHWEST FLOW OF COLD AIR WITH THE
TYPICAL LAKE RESPONSE SOUTHEAST OF THE LAKES. ALTHOUGH AIRMASS
TEMPERATURES WILL BE PLENTY COLD ENOUGH FOR GOOD INSTABILITY (850T
IN -14C RANGE OVER LAKE TEMPS OF +5C) FLOW WILL BE NORTHWEST...IN
300-310 RANGE...LESSENING LAKE FETCH AND AIRMASS WILL BE QUITE DRY SO
A MAJOR LAKE EVENT IS NOT EXPECTED. STILL...SEVERAL INCHES ARE
POSSIBLE IN FAVORED LOCATIONS.
WE WILL START WITH FAIRLY STRONG COLD ADVECTION AND A SUBTLE
SECONDARY SHORT WAVE...EVIDENT ON NAM12...DURING TUES EVENING.
THIS MAY SUPPORT A MORE GENERAL SNOW SHOWER THREAT EARLY IN THE
EVENING BEFORE THE NORTHWEST FLOW LAKE EFFECT TAKES OVER AND
CONTINUES INTO WED. COULD SEE INCH OR SO ACCUM...MAYBE 1-3 SOUTHEAST
OF LAKES AND IN UPSLOPE AREAS. BOTH WED AND THURS WILL SEE 850 MB TEMPS
IN -14C RANGE...SUPPORTING MAXES ONLY IN M-U 20S...SOME TEN DEG
BELOW NORMAL. WILL CARRY LIKELY POPS WED IN AREAS SE OF LAKES FROM
ORLEANS TO OSWEGO OFF LK ONTARIO AND FROM SRN ERIE TO CHAUT/CATT OFF
ERIE...CHC POPS ELSEWHERE AS CAN ALWAYS SEE SOME LK HURON/GGN BAY
ACTIVITY SNEAKING DOWN INTO NIAG FRONTIER FROM TIME TO TIME. COULD
SEE A FEW INCHES IN FAVORED LOCALES. AS WEAK SYSTEM SLIDES BY TO
OUR SOUTH ON THURSDAY AS A STRONGER SFC RIDGE BUILDS SOUTH TOWARD
OUR AREA WITH DRIER AIR...SUPPRESSING CAP...SO WILL LOWER POPS TO
40-50 SE OF LKS AND 20 ELSEWHERE....WITH SAME PLACEMENT AS WED'S
ACTIVITY. LESSER ACCUMS IF ANY ON THURS.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
...COLD BUT RELATIVELY TAME WX IN STORE...
MODELS CONTINUE TO DIVERGE DURING THIS PERIOD BUT DO HAVE SOME
SIMILARITIES. THEY AGREE ON BUILDING A STRONG SFC RIDGE DOWN
ACROSS ONTARIO AND THE LAKES INTO OUR AREA ON FRIDAY. STILL QUITE
COLD WITH 850MB TEMPS IN -15C RANGE...SUPPORTING MAXES IN M20S.
FLOW ALMOST NIL...LIGHT NORTHERLY IF ANYTHING...SO REDUCED POPS TO
SLGT CHC AS AS ANY LAKE RESPONSE SHOULD BE MINIMAL. REST OF PERIOD
IN DOUBT...GFS SHOWS RETROGRADING UPPER LOW ACROSS QUEBEC INTO
ONTARIO AND THEN SOUTH ACROSS THE LAKES TO OUR WEST. THIS WOULD
PLACE OUR ARE IN A COLD BUT RATHER DRY REGIME AS FLOW WILL BE
BACKING FROM SOUTH TO EAST TO NORTH. ECMWF AND CAN GEM ON OTHER
HAND KEEP UPPER LOW OVER QUEBEC WITH SOUTHERN STREAM SENDING A LOW
UP AND OFF THE COAST. THIS SOLUTION WOULD STILL KEEP US COLD WITH
LIMITED LAKE RESPONSE AS OUR WINDS WOULD BE GENERALLY NORTHERLY.
FOR NOW...WILL GO WITH 20-30 POPS NORTH TO SOUTH ON SAT AS SYSTEM
SLIDES WELL TO OUR SOUTH...THEN BROADBRUSH TOWARDS CLIMO WITH 30
POPS FOR CHC LGT SNOW BOTH SUN AND MON. TEMPS STILL BELOW NORMAL
AS 850 MB TEMPS REMAIN IN -12 TO -14C RANGE...U20S MAXES AND M-U
TEENS MINS...COLDER NORTH COUNTRY.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
MVFR CONDITIONS ACROSS THE REGION THIS AFTERNOON MAY BRIEFLY LIFT
TO VFR FOR A SHORT WHILE BEFORE CONDITIONS DETERIORATE TO IFR/LIFR
WITH APPROACHING LOW. PRECIP EXPECTED TO REMAIN AS LIGHT RAIN AND
DRIZZLE FOR MOST OF THE AREA WITH THE EXCEPTION OF AREAS EAST OF
LAKE ONTARIO WHERE A MIX OF RAIN AND SNOW WILL OCCUR.
CONDS WILL REMAIN IFR THROUGH TUESDAY MORNING BEFORE A GRADUAL
IMPROVEMENT DURING THE AFTERNOON TO VFR CONDITIONS.
OUTLOOK...
WEDNESDAY AND THURSDAY...VFR/MVFR IN SNOW SHOWERS...ESP SE OF
LAKES.
FRIDAY...MAINLY VFR.
&&
.MARINE...
WEAK LOW PRESSURE WILL MOVE ACROSS SOUTHERN ONTARIO TONIGHT.
FOLLOWING THE PASSAGE OF THE LOW ON TUESDAY...A STRENGTHENING WEST
TO NORTHWESTERLY FLOW OF MUCH COLDER WILL OVERSPREAD THE REGION
TUESDAY AFTERNOON AND TUESDAY NIGHT. THE COMBINATION OF THE
TIGHTENING PRESSURE GRADIENT AND GOOD DOWNWARD MOMENTUM TRANSPORT IN
THE COLD ADVECTION REGIME WILL RESULT IN WINDS AND WAVES INCREASING
TO ABOVE SMALL CRAFT CRITERIA TUESDAY AFTERNOON AND TUESDAY
NIGHT. SMALL CRAFT ADVISORIES WILL THUS EVENTUALLY BE NEEDED
BEGINNING TUESDAY AFTERNOON ON LAKE ERIE AND BY EARLY TUESDAY
EVENING ON LAKE ONTARIO. THESE WILL BE ISSUED ON FUTURE SHIFTS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SFM
NEAR TERM...LEVAN
SHORT TERM...SFM
LONG TERM...SFM
AVIATION...LEVAN
MARINE...LEVAN/SFM
