FXUS61 KALY 120905
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
405 AM EST SAT DEC 12 2009

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE SOUTH TODAY AND 
OFF THE MID ATLANTIC COAST TONIGHT. WEAK LOW PRESSURE WILL ORGANIZE 
OVER THE MID ATLANTIC SUNDAY AFTERNOON AND SLIDE SOUTH OF LONG 
ISLAND SUNDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION ON 
MONDAY.

&&

.NEAR TERM /THROUGH TODAY/...
LAKE EFFECT SNOW BAND ACROSS HERKIMER AND HAMILTON COUNTIES THAT HAS 
BEEN IN THE PICTURE SINCE THURSDAY WILL RELAX ITS GRIP TODAY. 
THROUGH THE EARLY MORNING HOURS...THE BAND HAS STRUGGLED TO MAKE 
PENETRATION INTO HERKIMER COUNTY. AREAL EXTENT OF COLDER CLOUD TOPS 
HAS BEEN SHRINKING AND WARMING THROUGH THE NIGHT AS WELL. VERY DRY 
AIR IN PLACE ACROSS NY OUTSIDE OF LAKE EFFECT REGION WITH 00Z ALY 
PWAT OF 0.09 NOTED AND CURRENT 2 AM TD AT ALB OF 2F. GOING FORWARD 
MODEL SOUNDINGS IN HERKIMER COUNTY INDICATE THE INVERSION HEIGHTS 
CURRENTLY RUNNING AROUND 10K FEET WILL BE DOWN TO 6K FEET BY 18Z AND 
DROPPING THROUGH THE AFTERNOON. ALSO INDICATIONS OF SOME INCREASING 
SHEAR THROUGH THE MORNING AS BOUNDARY LAYER WINDS BACK TO SOUTHWEST 
WHILE WINDS ALOFT REMAIN NORTHWEST. BOUNDARY LAYER FLOW IS NOW 
TURNING ANTICYCLONIC AS HIGH PRESSURE BUILDS IN. COULD SEE ANOTHER 
INCH OR TWO IN ISOLATED LOCALES IN HERKIMER COUNTY. BUT WITH NO REAL 
ORGANIZED BAND IMPACTING COUNTY...PLAN TO DROP ALL LAKE EFFECT 
HEADLINES WITH ZONE ISSUANCE.

ELSEWHERE TODAY...TEMPERATURES WILL MODERATE ABOUT 5 DEGREES FROM 
YESTERDAY. IN ADDITION WINDS NOT NEARLY BE AS STRONG AS YESTERDAY. 
STILL COULD SEE SOME FLURRIES AROUND...WITH SOME SNOW SHOWERS 
POSSIBLE IN UPSLOPE REGIONS OF THE SOUTHERN GREEN MOUNTAINS AND 
BERKSHIRES...BUT LITTLE IF ANY ACCUMULATION EXPECTED. 

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
HIGH PRESSURE CRESTS ACROSS THE AREA AROUND 7 PM TONIGHT...THEN 
DRIFTS EAST. WITH CLEARING SKIES AND LIGHT TO CALM WINDS...SHOULD BE 
IDEAL FOR RADIATIONAL COOLING...AT LEAST TO START THE EVENING. WITH 
THE HIGH SLIDING EAST OVERNIGHT...SOME WEAK WARM ADVECTION MAY SLOW 
DOWN THE TEMPERATURE DECLINE. HAVE GREATEST TEMPERATURE DROP 
OCCURRING FOR FIRST HALF OF THE NIGHT...THEN LEVELING OFF FOR 
OVERNIGHT HOURS. MAV AND MET IN GOOD AGREEMENT SO BLEND USED FOR LOW 
TEMPS.

MAIN STORY FOR THIS PERIOD WILL BE LOW PRESSURE TRACKING FROM THE 
MID ATLANTIC OFF THE NORTHEAST COAST. NAM/GFS/ECMWF IN GOOD 
AGREEMENT ON TRACK AND INTENSITY OF LOW PRESSURE SYSTEM. THIS IS NOT 
A STRONG SYSTEM...BUT WITH A STRONG 850MB JET /60-70 KNOTS/ CROSSING 
THE REGION ON SUNDAY AFTERNOON AND EVENING...LOW LEVEL CONVERGENCE 
AT THE NOSE OF THE JET ALONG WITH UPSLOPE FLOW INTO THE SOUTHERN 
ADIRONDACKS AND SOUTHERN VERMONT AND A BOUT OF MODEST FGEN FORCING 
ENOUGH DYNAMICS IN PLACE TO YIELD SOME RESPECTABLE PRECIPITATION. AS 
FOR HOW MUCH...AROUND ONE THIRD TO ONE HALF INCH WITH PERHAPS SOME 
ENHANCEMENT IN THOSE AFOREMENTIONED UPSLOPE ZONES. A LOOK AT MODEL 
SOUNDINGS SHOWS THE GFS WARMER THAN THE NAM. THE NAM THERMAL FIELD 
PERFORMED QUITE WELL ON WEDNESDAY WITH OUR LAST BOUT OF MIXED PRECIP 
AND WAS FAVORED TO INITIALIZE P-TYPE CONSIDERATIONS WITH THIS EVENT. 
FOR THE MOST PART...VALLEY LOCATIONS SHOULD SEE LIMITED SNOWFALL 
ACCUMULATION...UP TO AN INCH OR TWO. IN THOSE FAVORED UPSLOPE 
LOCALES...COMBINATION OF COLDER NAM PROFILES AND HIGHER QPF ARGUE 
FOR SNOWFALL TOTALS REACHING ADVISORY CRITERIA...SAY 3 TO 6 INCHES. 
CONFIDENCE IS NOT HIGH ENOUGH /GIVEN LURKING GFS WARMER SOUNDINGS/ 
FOR ANYTHING MORE THAN AN HWO MENTION AT THIS POINT. 

TEMPERATURES ON SUNDAY WILL FOLLOW A NON-DIURNAL TREND WARMING INTO 
THE EVENING BEFORE COOLING SOME OVERNIGHT.

REGARDING STRONG JET CROSSING AREA SUNDAY AFTERNOON AND EVENING...IT 
LOOKS LIKE LOW LEVEL INVERSION WILL PRECLUDE GUSTS FROM REACHING THE 
SURFACE. HIGHER ELEVATIONS OF THE CATSKILLS AND WESTERN NEW ENGLAND 
COULD SEE STRONGER GUSTS /AND THIS IS REFLECTING IN GRID 
FORECAST/...BUT NOT EXPECTING ANY WIND HEADLINES AT THIS TIME.

HIGH PRESSURE BUILDS IN FOR MONDAY. LITTLE IN THE WAY OF COOLING 
BEHIND THIS SYSTEM. SO TEMPERATURES ON MONDAY LOOK TO BE ABOUT 5 
DEGREES ABOVE NORMAL.  

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A SURFACE LOW IS FORECAST TO MOVE FROM SOUTHERN LAKE MICHIGAN ON 
MONDAY EVENING TO WESTERN LAKE ONTARIO BY TUESDAY MORNING...BRINGING 
THE POSSIBILITY OF OVERRUNNING PRECIP INTO THE REGION AHEAD OF THE 
FRONT FOLLOWED BY PRECIP ASSOCIATED WITH THE FRONTAL PASSAGE ITSELF. 
THE FRONTAL PASSAGE ON TUESDAY IS FOLLOWED BY AN UPPER TROF MOVING 
ACROSS THE REGION TUESDAY NIGHT WHICH CONTINUES THE CHANCE OF 
PRECIP. AS FOR P-TYPE IT WOULD LIKELY BE SNOW JUST ABOUT EVERYWHERE 
MONDAY NIGHT...THEN MIX WITH AND CHANGE TO RAIN FROM THE MOHAWK 
VALLEY SOUTH DURING THE DAY TUESDAY AS TEMPERATURES WARM INTO THE 
UPPER 30S AND LOW 40S...THEN MIX AGAIN AND CHANGE BACK TO ALL SNOW 
TUESDAY EVENING AS TEMPERATURES DROP TO NEAR/BELOW FREEZING. LOWS 
TUESDAY NIGHT WILL RANGE FROM THE TEENS IN THE ADIRONDACKS TO THE 
20S IN THE HUDSON VALLEY. 

HIGH PRESSURE MOVES IN FROM THE WEST ON WEDNESDAY WITH BRISK 
NORTHWESTERLY WINDS WHICH WILL RESULT IN COLD AIR ADVECTION INTO THE 
REGION OVER TWO TO THREE OF THE GREAT LAKES...SUGGESTING SOME LAKE 
EFFECT SNOW FOR OUR NORTHWESTERN AREAS AND A SLIGHT CHANCE OF SNOW 
SHOWERS ELSEWHERE FOR WEDNESDAY. HIGHS WEDNESDAY ARE FORECAST TO 
RANGE FROM NEAR 20 NORTH TO THE THE UPPER 30S IN THE LOWER HUDSON 
VALLEY. TEMPERATURES ARE EXPECTED TO REALLY PLUMMET WEDNESDAY NIGHT 
WITH LOWS NEAR ZERO ACROSS THE ADIRONDACKS AND HIGHER ELEVATIONS OF 
SOUTHERN VERMONT...AND IN THE TEENS IN THE HUDSON AND MOHAWK 
VALLEYS. AS THE HIGH AND LOW CENTERS MIGRATE FARTHER EASTWARD THE 
PRESSURE GRADIENT...AND THE RESULTING WINDS...SLACKEN SOME AND THE 
AREA OF LAKE EFFECT SNOW SHOWERS SHOULD SHRINK TO JUST THE 
ADIRONDACKS AND THE UPPER MOHAWK VALLEY...WITH NO PRECIP FARTHER 
EAST ON WEDNESDAY NIGHT. 

THURSDAY AND THURSDAY NIGHT SHOULD SEE EVEN LESS OF A LIKELIHOOD OF 
PRECIP...AGAIN CONFINED TO THE ADIRONDACKS AND THE UPPER MOHAWK 
VALLEY...WITH TEMPERATURES RISING ONLY INTO THE 20S AND LOW 
30S...WITH PARTLY SUNNY SKIES IN THE HUDSON VALLEY AND MOSTLY CLOUDY 
SKIES OVER THE ADIRONDACKS AND GREEN MOUNTAINS. IT WILL BE EVEN 
COLDER THURSDAY NIGHT...LOWS NEAR AND BELOW ZERO ACROSS THE 
ADIRONDACKS AND SOUTHERN VERMONT...AND IN THE TEENS OVER THE HUDSON 
VALLEY. 

FRIDAY WILL SEE INCREASED CLOUDINESS AS THE NEXT WEATHER MAKER 
BEGINS TO CROSS THE GREAT LAKES TO WESTERN PA BY FRIDAY EVENING. 
HIGHS FRIDAY WILL BE A BIT WARMER...IN THE 20S AND LOW 30S. IT WILL 
NOT BE QUITE AS COLD FRIDAY NIGHT...AS A LOW IS FORECAST TO MOVE 
EASTWARD FROM THE GREAT LAKES STATES INTO THE MID ATLANTIC REGION. 
THE LOW WILL BRING A CHANCE OF SNOW TO THE REGION SATURDAY AS IT 
STARTS TO TAP ATLANTIC MOISTURE BUT THE PRECIP SHOULD NOT LAST LONG 
AS THE SYSTEM MOVES OUT TO SEA. 

FOR THE MOST PART...WE USED GMOS TO INITIALIZE THE GRIDS 
FOR THIS PERIOD. TEMPERATURES WILL GENERALLY AVERAGE ABOUT
5 DEGREES BELOW NORMALS FOR THIS TIME OF THE YEAR. 
&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL ACROSS THE REGION THE NEXT 24 HOURS. 
HOWEVER THERE WILL BE SOME LOCAL AREAS OF MVFR/IFR CONDITIONS IN
LAKE EFFECT SNOW BANDS EXTENDING EAST FROM LAKE ONTARIO INTO THE
ADIRONDACKS. THERE MAY ALSO BE A FEW UPSLOPE ENHANCED BANDS OVER
THE WESTERN CATSKILLS...THE NORTHERN BERKSHIRES...AND THE GREEN 
MOUNTAINS OF SOUTHERN VERMONT. 

WESTERLY WINDS HAVE DIMINISHED DURING THE EVENING AND WILL BE 
5 TO 10 KNOTS DURING THE PREDAWN HOURS. AFTER SUNRISE THEY WILL
INCREASE TO BETWEEN 10 AND 15 KNOTS WITH GUSTS TO 20 KNOTS DOWN
THE MOHAWK VALLEY TO THE ALBANY AREA DUE TO THE TERRAIN. THEY 
WILL THEN DIMINISH TO LESS THAN 5 KNOTS TONIGHT. 

OUTLOOK...
SUN-SUN NGT...MVFR/IFR -RA/-SN LIKELY. 
MON...VFR...NO SIG WX. 
MON NGT-WED...VFR/MVFR. CHC -SHRASN.

&&

.HYDROLOGY...
FOR THE MOST PART...RIVER LEVELS AND FLOWS HAVE BEEN DROPPING WITH 
TEMPERATURES WELL BELOW FREEZING ACROSS THE REGION. THERE IS SOME 
INDICATIONS FROM THE GAGE ON THE MOOSE RIVER AT MCKEEVER THAT AN ICE 
JAM FORMED EARLY FRIDAY...THEN BROKE FRIDAY EVENING RESULTING IN A 
FOUR FOOT DROP IN THE WATER LEVEL. MCKEEVER IS ONE OF OUR COLDER 
LOCATIONS AND THERE IS A GOOD LIKELIHOOD THAT ICE HAS FORMED ON MANY 
WATER SURFACES ACROSS THE REGION...ESPECIALLY ACROSS THE ADIRONDACKS 
WHERE TEMPERATURES HAVE BEEN AVERAGING TEN TO TWENTY DEGREES BELOW 
FREEZING. HIGHS FRIDAY ONLY MADE IT INTO THE TEENS AT SEVERAL SITES 
IN THE ADIRONDACKS...INCLUDING STILLWATER RESERVOIR...OLD 
FORGE...AND LAKE PLEASANT. WHILE THE SNOW MAY MIX OR TURN TO RAIN 
SUNDAY AFTERNOON...IT WILL NOT GET WARM ENOUGH FOR THE COLD SNOWPACK 
TO MELT. THE SAME WILL BE TRUE WITH THE SYSTEM EXPECTED TO AFFECT 
THE REGION MONDAY NIGHT INTO TUESDAY. ASIDE FROM THE POSSIBILITY OF 
ICE MOVEMENT BLOCKING THE CHANNEL...WATER LEVELS WILL REMAIN LOW. 

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...NONE.
MA...NONE.
VT...NONE.

&&

$$
SYNOPSIS...OKEEFE
NEAR TERM...OKEEFE
SHORT TERM...OKEEFE
LONG TERM...RCK
AVIATION...RCK
HYDROLOGY...RCK