FXUS61 KALY 120242
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
942 PM EST FRI DEC 11 2009
.SYNOPSIS...
A DEEP LOW PRESSURE SYSTEM WILL CONTINUE MOVING NORTHEAST ACROSS
EASTERN CANADA TONIGHT...AS A LARGE ARCTIC HIGH PRESSURE SYSTEM
SETTLES IN TO THE SOUTH OF THE REGION. THIS WILL RESULT IN THE
CONTINUATION OF GUSTY WESTERLY WINDS THROUGH TONIGHT. AS THE COLDER
AIR MOVES ACROSS THE RELATIVELY WARMER WATER OF LAKE ONTARIO...LAKE
EFFECT SNOW WILL CONTINUE INTO EARLY SATURDAY ACROSS AREAS OF THE
WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WITH SIGNIFICANT
SNOWFALL. LATER IN THE WEEKEND...A WEAK LOW PRESSURE SYSTEM WILL
BRING SOME SNOW AND RAIN TO THE REGION ON SUNDAY AND SUNDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 940 PM...LARGE SINGLE LAKE EFFECT BAND HAS BEEN SOMEWHAT
DISRUPTED DURING THE LAST FEW HOURS AND HAS SHOWN SIGNS OF
WEAKENING AND ERODING ALONG THE EASTERN EDGE. EXTREMELY DRY
ENVIRONMENT OUTSIDE THE BAND AS WELL AS SIGNIFICANT DIRECTIONAL
WIND SHEAR MAY BE RESPONSIBLE FOR THE DISORGANIZATION. THE 00Z ALB
AND BUF SOUNDINGS REVEAL PWATS OF ONLY 0.09...WHICH IS VERY DRY.
IN TERMS OF THE SENSIBLE FORECAST...THIS IS HAVING IMPLICATIONS
FOR SOUTHERN HERKIMER/NORTHERN FULTON COUNTY WHERE CURRENT
HEADLINES RESIDE. AT LEAST LIGHT SNOW IS FALLING ACROSS SOUTHERN
HERKIMER NEAR ROUTE 8 AND NORTH OF I-90. THERE ARE STILL SOME
SIGNIFICANT REFLECTIVITIES ACROSS THE TUG HILL...SO IT IS POSSIBLE
SOME RE-ORGANIZATION TAKES PLACE AS LAKE-TEMP DIFFERENCES STILL
VERY LARGE AND CAPPING INVERSION HEIGHTS ARE ABOVE 3 KM.
SO...WHILE CONFIDENCE IN 7+ INCHES IN SOUTHERN HERKIMER HAS
DIMINISHED...IT STILL IS POSSIBLE FOR AREAS NEAR ROUTE 8 SO WILL
NOT DROP CURRENT WARNING THERE...OR THE ADVISORY ACROSS NORTHERN
FULTON. THE BAND IS STILL AFFECTING CENTRAL HERKIMER/SOUTHWEST
HAMILTON IN A WEAKENED STATE...BUT A FEW TO SEVERAL MORE INCHES
MAY FALL OVERNIGHT SO WILL JUST KEEP THE WARNING GOING THERE AND
DECREASE SNOWFALL AMOUNTS SOMEWHAT. OUTSIDE OF THE LAKE EFFECT
ONLY A FEW LIGHT SNOW SHOWERS OR FLURRIES WILL OCCUR...MAINLY
ACROSS THE HIGHER TERRAIN.
PREVIOUS NEAR TERM DISCUSSION...
COLD WESTERLY FLOW CONTINUES THROUGH TONIGHT WITH THE HEAVY LAKE
EFFECT SNOW BAND CONTINUING OFF LAKE ONTARIO. THE SNOW BAND IS A
LITTLE FURTHER SOUTH...SO HAVE EXPANDED THE LAKE EFFECT SNOW
WARNING INTO SOUTHERN HERKIMER COUNTY. THE LAKE SNOW BAND WILL NOT
SHIFT MUCH FURTHER SOUTH OVERNIGHT. SO THE HEAVY LAKE EFFECT SNOW
BAND WILL BE CONFINED TO AREAS NORTH OF THE MOHAWK VALLEY AND
THRUWAY. WITH THE MORE SOUTHERN POSITION OF THE LAKE SNOW
BAND...HAVE ALSO ISSUED A LAKE EFFECT SNOW ADVISORY FOR NORTHERN
FULTON COUNTY.
FOR THE REST OF THE REGION...EXPECT PARTLY CLOUDY CONDITIONS WITH
SCT SNOW SHOWERS IN MOST AREAS. LAKE ERIE LAKE EFFECT SNOW BAND WAS
EXTENDING AS FAR EAST AS THE CATSKILLS AND PRODUCING SCT SNOW
SHOWERS THERE.
WESTERLY SURFACE WINDS WILL CONTINUE QUITE GUSTY...BUT BELOW
ADVISORY CRITERIA. LOWS WILL BE IN THE SINGLE NUMBERS AND TEENS...
WITH WIND CHILL READINGS BELOW ZERO AT TIMES.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
ON SATURDAY...THE MEAN LOW LEVEL WIND FLOW WEAKENS CONSIDERABLY
THROUGH THE DAY...AND THE DEPTH OF THE INSTABILITY AND MOISTURE
BECOMES TOO SHALLOW BY AFTERNOON TO SUPPORT AN ORGANIZED LAKE EFFECT
SNOW BAND. SOME WEAK WARM ADVECTION BEGINS BY AFTERNOON AS THE LOW
LEVEL RIDGE AXIS BUILDS OVER OUR REGION...AND BEGINS TO BUILD EAST.
HIGHS SATURDAY IN THE 20S TO LOWER 30S. WEAK WARM ADVECTION WILL
CONTINUE SATURDAY NIGHT...BUT LOW LEVEL RIDGING STILL CLOSE ENOUGH
FOR LIGHT WINDS AND MOSTLY CLEAR SKIES EARLY IN THE NIGHT. WITH SNOW
COVER...TEMPERATURES WILL ONCE AGAIN FALL INTO THE SINGLE NUMBERS
AND TEENS. HIGH CLOUDS WILL SPREAD OVER THE REGION TOWARD SUNRISE
AHEAD OF THE NEXT SYSTEM.
THERE IS INCREASING CONSENSUS FROM GUIDANCE THAT OUR REGION WILL SEE
PCPN FROM A WEAK LOW MOVING OFF THE VIRGINIA COAST SUNDAY AND SUNDAY
NIGHT. EXPECT QPF IN THE QUARTER TO HALF INCH RANGE WITH THIS
SYSTEM. HOWEVER...MODELS HAVE BEEN TRENDING WARMER WITH THIS SYSTEM
ESPECIALLY THE GFS AND NAM...SO ALL SNOW IS UNLIKELY WITH THIS
EVENT...EVEN ACROSS NORTHERN AREAS. HAVE GENERALLY FORECAST A SNOW
MIXING WITH OR CHANGING TO RAIN SCENARIO FOR THE ENTIRE FORECAST
AREA...WITH THE MILDER TEMPS AND LIQUID OR MIXED PCPN REMAINING WELL
INTO SUNDAY NIGHT. IN GENERAL ONE TO THREE INCHES OF SNOW HAVE BEEN
FORECAST IN THE GRIDS. HIGHS SUNDAY WILL BE IN THE 30S TO AROUND
40...BUT THESE HIGHS WILL OCCUR LATE IN THE DAY WITH THE TEMP
REMAINING STEADY INTO THE EVENING. LATER ON SUNDAY NIGHT...THE TEMPS
WILL SLOWLY DIP TO BETWEEN 25 AND 35.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE PERIOD WILL START WITH A WEAK HIGH PRESSURE RIDGE MOVING
EASTWARD OVER THE NORTHEAST BEHIND THE COLD FRONT WHICH PASSES
THROUGH SUNDAY INTO SUNDAY NIGHT. THIS HIGH PRESSURE WILL RESULT IN
DRYING CONDITIONS DURING THE DAY ON MONDAY BEFORE ANOTHER LOW
APPROACHES FROM THE WEST MONDAY NIGHT INTO TUESDAY. AT THIS
TIME...WILL INDICATE CHC FOR SNOW SHOWERS FOR MONDAY NIGHT...BUT
ENOUGH WARMING BETWEEN 925-850 MB COULD ALLOW FOR SOME POCKETS OF
RAIN OR EVEN FREEZING RAIN...SO WE WILL NEED TO MONITOR AS EVENT
NEARS.
GFS AND ECMWF INDICATE SFC LOW TRACKING NORTH OF NY ON TUESDAY WITH
SECONDARY TROUGH REINFORCED BY UPPER LEVEL TROUGH BEHIND THE COLD
FRONT. THIS WILL KEEP PRECIP IN THE FA THROUGH LATE TUESDAY/EARLY
WEDNESDAY BEFORE HIGH PRESSURE STARTS TO SLOWLY BUILD WITH
NORTHWESTERLY FLOW PRODUCING LAKE AFFECT SNOW ACROSS THE ADIRONDACKS
AND WESTERN MOHAWK VALLEY THROUGH THURSDAY. DURING THE DAY
TUESDAY...TEMPERATURES IN THE VALLEYS WILL BE WARM ENOUGH FOR SNOW
SHOWERS TO TRANSITION TO RAIN SHOWERS BEFORE COLDER TEMPERATURES
FILTER IN TUESDAY NIGHT. THE COLDER AIR IN THE WAKE OF THE
FRONT/STORM SYSTEM SHOULD ALLOW LAKE EFFECT SNOWBANDS TO IMPACT NW
PORTIONS OF THE REGION. HOWEVER...LOW LEVEL FLOW MAY BE MORE NW THAN
CURRENT EVENT...WITH POTENTIALLY SHORTER OVER LAKE TRAJECTORY...
WHICH COULD REDUCE THE INTENSITY SOMEWHAT.
FOR FRIDAY...GFS AND ECMWF DIFFER WITH ECMWF BRINGING HIGH PRESSURE
ACROSS THE MID-ATLANTIC STATES AND GFS BRINGING A CLIPPER TYPE LOW
QUICKLY THROUGH ON FRIDAY. ECMWF BRINGS A SIMILAR LOW IN ABOUT A DAY
LATER. WILL HAVE TO KEEP AN EYE ON THIS TO SEE IF TIMING ISSUES
RESOLVE AS WE GET CLOSER.
TEMPERATURES WILL START ABOVE NORMAL THROUGH TUESDAY NIGHT WHEN
COLDER TEMPERATURES FILTER IN BEHIND THE FIRST STORM. MAX
TEMPERATURES WILL BE AROUND NORMAL THROUGH THE REST OF THE PERIOD
WITH MIN TEMPS ABOUT 5 DEGREES BELOW NORMAL.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS. THE ONLY
EXCEPTION WILL BE SOME BRIEF REDUCTION TO MVFR WITHIN A FEW LIGHT
LAKE EFFECT SNOW SHOWERS OR FLURRIES NEAR KGFL THIS EVENING.
OTHERWISE...A FEW FLURRIES POSSIBLE AT KALB OVERNIGHT SO WILL
MENTION VCSH...BUT VFR EXPECTED TO PREVAIL.
WINDS WILL REMAIN WEST BUT SPEEDS DECREASING TO 10-15 KT OVERNIGHT
WITH SOME OCCASIONAL GUSTS TO AROUND 20 KT.
OUTLOOK...
SAT NGT...VFR...NO SIG WX.
SUN-SUN NGT...MVFR/IFR -RA/-SN LIKELY.
MON...VFR...NO SIG WX.
MON NGT-WED...VFR/MVFR. CHC -SHRASN.
&&
.HYDROLOGY...
WE WILL STAY COLD ENOUGH FOR LITTLE OR NO SNOW MELT. SOME LIGHT SNOW
OR RAIN IS LIKELY SUNDAY AND SUNDAY NIGHT. TEMPS WILL NOT GET WARM
ENOUGH TO CAUSE ANY SIGNIFICANT SNOW MELT...AND RAIN WILL NOT BE
HEAVY ENOUGH FOR SIGNIFICANT RUNOFF TO OCCUR...SO NO HYDRO PROBLEMS
ARE FORESEEN FOR THE NEXT WEEK.
SOME RIVER ICE WILL BEGIN TO FORM EARLY THIS WEEKEND ACROSS THE
NORTHERN SECTIONS OF OUR HYDRO AREA.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR NYZ032-
033-038.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SATURDAY FOR NYZ082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM/JPV
SHORT TERM...GJM
LONG TERM...KGS
AVIATION...JPV
HYDROLOGY...GJM
