000
FXUS61 KBGM 201437
AFDBGM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
937 AM EST THU NOV 20 2008
.SYNOPSIS...
A COLD FRONT MOVING SOUTH THROUGH NY INTO PA WILL KEEP SNOW
SHOWERS IN THE FORECAST TODAY. LAKE EFFECT SNOWS WILL SET UP BY
EARLY FRIDAY MORNING OVER UPSTATE NY, WITH POSSIBLE SIGNIFICANT
ACCUMULATIONS EXPECTED THROUGH SATURDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 930AM...SHSN ASSOCIATED WITH WEAKENING WAVE ARE CONFINED
PRIMARILY TO AREAS WEST OF INTERSTATE 81...BUT ARE WEAKENING AND
DIMINISHING IN COVERAGE. AT THE SAME TIME...LAKE EFFECT SHSN ARE
ORGANIZING OVER LAKE ONTARIO...WITH SIGNIFICANT LAKE ENHANCED
SHSN SOUTHEAST OF LAKE ERIE. AS THE DECAYING WAVE DROPS SOUTH AND
EAST...THE FLOW OVER LAKE ONTARIO WILL BEGIN TO GAIN A NORTHERLY
COMPONENT...WITH CONVECTION NOW SEEN OVER THE SOUTHERN SHORE OF
THE LAKE DROPPING SOUTH TOWARDS MY NORTHERN COUNTIES. SO...EXPECT
SHSN COVERAGE ALONG THE LAKE PLAIN TO INCREASE THIS AFTERNOON...
WHILE DIMINISHING SOMEWHAT FURTHER SOUTH AND EAST. DON/T SEE MUCH
MORE THAN AN INCH OF SNOW ACCUMS TODAY AS FLOW ORIENTATION BEHIND
THE DEPARTING SYSTEM IS PRIMARILY FROM THE NORTH /SEE THE CWMW
SOUNDING/...WHICH WOULD FAVOR MORE OF A MULTIBAND SCENARIO LATE
TODAY.
REMAINING GRIDS ARE IN GOOD SHAPE AND HAVE MADE ONLY MINOR TWEAKS
TO ACCOUNT FOR CURRENT OBS.
UPDATED GRIDS/PRODUCTS ARE ON THE STREET.
PREVIOUS DISCUSSION FOLLOWS...
CLIPPER SYSTEM WILL BRING RELATIVELY MINOR AMOUNTS OF SNOW TO
UPSTATE NY AND THE NORTHERN TIER OF PA THROUGH EARLY EVENING. THE
COLD SHOT POURING DOWN ACROSS LAKE ONTARIO WILL RELOAD THE POLAR
AIRMASS OVER OUR REGION, AND SET THE STAGE FOR FUTURE LAKE EFFECT
SNOWS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
VERY COLD THIS PERIOD WITH TEMPERATURES TYPICAL OF MIDDLE JANUARY.
THE COLD AIRMASS FROM THE BL UP TO 850MB GENERATES SOME IMPRESSIVE
LL LAPSE RATES. ONCE WINDS ALIGN OFF THE LAKES, IT SHOULD BE AN
POTENT EARLY SEASON LAKE EFFECT EVENT.
310-320 FLOW ALIGNS THROUGH THE LOWER ATMOSPHERE EARLY FRIDAY.
COMBINATION OF LOW SHEAR AND HIGH LAPSE RATES SHOULD LEAD TO LAKE
BANDS FORMING DOWN WIND. IT APPEARS THE MOST LIKELY BAND POSITION
WILL BE FROM NORTHERN ONONDAGA INTO WESTERN MADISON COUNTY, BUT
CANNOT RULE OUT PORTIONS OF WESTERN ONEIDA AND CAYUGA.
BY FRIDAY NIGHT, THE LAPSE RATES INDICATE EVEN GREATER
INSTABILITY. AND THIS IS WHEN WE SHOULD SEE OUR HIGHEST SNOW
RATES. WILL FORECAST 3 TO 6 INCHES OF NEW SNOW OVER THIS TIME
PERIOD AS A STARTING POINT.
LAKE SNOWS WILL CONTINUE INTO SATURDAY, THOUGH THE FLOW SHIFTS
ENOUGH TO SUGGEST THERE MAY BE SIGNIFICANT BANDS THROUGH THE
FINGER LAKES COUNTIES INTO CORTLAND AND TOMPKINS.
WILL BE ISSUING LAKE EFFECT SNOW WATCH FOR ONONDAGA AND MADISON
COUNTIES. DUE TO THE CURRENT UNCERTAINTY, WILL LEAVE IT TO NEXT
SHIFT TO MAKE A CALL ON ONEIDA/CAYUGA AND POTENTIALLY ANY AREAS TO
BE AFFECTED ON SATURDAY.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
UPDATED AT 110 AM...NO CHGS TO THE MED RNG FCST. SOME DIFFS ARISE
BY DAY 6-7 W/RESPECT TO THE DVLPMNT OF A CUTOFF LOW OVER THE NE
U.S. AND PSBL CSTL DVLPMNT. SO MAIN EMPHASIS ATTM WILL BE ON THE FNTL
PSSG MONDAY FOLLOWED BY ANOTHER SHOT OF COLD AIR AND POTNL LES
INTO MIDWEEK. PREV BLO...
AN UNSETTLED PERIOD...WITH BELOW NORMAL TEMPERATURES...IS EXPECTED
TO CONTINUE THROUGH AT LEAST MUCH OF NEXT WEEK.
GENERAL MODEL AGREEMENT ABOUT AN ANCHORED EASTERN U.S. TROUGH THROUGHOUT
THE PERIOD. DETAIL DIFFERENCES IN EXACTLY HOW THIS TROUGH
AMPLIFIES/RE-LOADS EARLY NEXT WEEK LEAD TO OBVIOUS MODEL TO MODEL
DISCREPANCIES IN HOW MUCH PRECIPITATION OCCURS FROM MONDAY ONWARD.
FOR NOW...WE`LL CONTINUE WITH THE IDEA THAT LAKE-EFFECT SNOWS WILL
WIND DOWN DURING THE LATTER PART OF THE WEEKEND. AFTER THIS BRIEF
LULL...THINGS GET MORE ACTIVE AGAIN FROM LATER MONDAY THROUGH THE
MIDDLE OF NEXT WEEK...AS A STORM SYSTEM MAY TRY TO ORGANIZE NEAR
THE EAST COAST. DUE TO MUCH UNCERTAINTY THIS FAR OUT...WE`LL
RETAIN OUR CHANCES FOR AT LEAST SOME LIGHT SNOWFALL/SNOW SHOWERS
WELL INTO NEXT WEEK.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
AREAS OF MVFR TDA AS CLIPPER-TYPE SYSTEM AND ASSCD -SN/LOWER CIGS
AFFECT THE FCST AREA. TNGT THE CDFNT WILL DROP SWD AND INTO CNTRL
NY WITH MORE -SHSN AND MVFR CONDITIONS. LIGHT WINDS THIS MRNG
BECMG W TO NW 5-10 KTS TDA AND THEN NWLY 5-10 TNGT.
OUTLOOK...
LATE THURSDAY NIGHT THROUGH SATURDAY...LOCALIZED MVFR/IFR
POSSIBLE...AS LAKE-EFFECT SNOW BANDS DEVELOP OVER THE REGION.
SUNDAY INTO MONDAY...IMPROVEMENT BACK TO VFR FORESEEN.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...LAKE EFFECT SNOW WATCH FROM FRIDAY MORNING THROUGH SATURDAY
MORNING FOR NYZ018-036.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP/JMA
SHORT TERM...DJP
LONG TERM...MLJ
AVIATION...
