December 8, 2013

000
FXUS61 KALY 082344
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
644 PM EST SUN DEC 8 2013

.SYNOPSIS…
AS A WEAK STORM SYSTEM APPROACHES…SNOW WILL OVERSPREAD THE AREA
TONIGHT. WARMER AIR WILL WORK IN AND THE SNOW WILL MIX WITH THEN
CHANGE TO SLEET AND FREEZING RAIN DURING THE MORNING…MAKING FOR
A HAZARDOUS MORNING COMMUTE. EVENTUALLY…A CHANGEOVER TO PLAIN
RAIN IS EXPECTED ACROSS MOST OF THE LOCAL AREA BY
AFTERNOON…ESPECIALLY FOR VALLEY LOCATIONS. MUCH OF THE REMAINDER
OF THE UPCOMING WEEK WILL BE COLD AND DRY…WITH SOME LAKE EFFECT
SNOW SHOWERS ACROSS THE ADIRONDACKS.

&&

.NEAR TERM /THROUGH MONDAY/…
AS OF 643 PM EST…WINTER WEATHER ADVISORIES CONTINUE ACROSS THE
ENTIRE FORECAST AREA…BEGINNING AT 10 PM.

THE FORECAST REMAINS ON TARGET WITH SNOW NOW REACHING AS FAR NORTH
AS THE LOWER HUDSON VALLEY REGION. THE SURFACE HIGH CONTINUES TO
SHIFT NORTHEASTWARD ACROSS NEW ENGLAND TONIGHT. COLD AIR DAMMING
IS OCCURRING DOWN THE APPALACHIANS. AREAS OF LOW PRESSURE BOTH
ACROSS THE GREAT LAKES AND MID ATLANTIC COAST WILL BE WEAK AS THEY
SLOW MOVE NORTHEAST THROUGH THE OVERNIGHT HOURS.

ONCE THE COLUMN MOISTENS UP…SNOW WILL OVERSPREAD THE AREA LATER
THIS EVENING AND OVERNIGHT. SNOW LOOKS TO REACH THE MID HUDSON
VALLEY BY 10PM OR SO…THE CAPITAL REGION BY MIDNIGHT…AND THE
ADIRONDACKS BY 2 AM. SNOW WILL BE RATHER LIGHT THROUGH THE
OVERNIGHT HOURS…BUT ALL AREAS LOOK TO HAVE ENOUGH ACCUMULATION
TO AT LEAST COAT THE GROUND.

BY 5-7 AM…ENOUGH WARMER AIR WILL HAVE WORKED INTO THE SOUTHERN
MOST PORTION OF THE FORECAST FOR SLEET AND FREEZING RAIN. THE
THREAT FOR MIXED PRECIPITATION…SLEET AND FREEZING RAIN…WILL
WORK NORTHWARD UP THROUGH THE CAPITAL DISTRICT…MOHAWK VALLEY AND
SOUTHERN VERMONT…THROUGH THE MORNING HOURS. IT SHOULD NOT BE
UNTIL THE EARLY AFTERNOON FARTHER NORTH.

TEMPS WILL BE WARM ENOUGH TO ALLOW ANY PRECIP TO CHANGEOVER TO
RAIN BY AFTERNOON UP THE HUDSON VALLEY INTO THE CAPITAL DISTRICT
AND ACROSS LITCHFIELD COUNTY. IT WILL TAKE LONGER ACROSS THE HIGHER
TERRAIN OF THE EASTERN CATSKILLS…TACONICS…BERKSHIRES INTO
SOUTHERN VERMONT. AREAS FURTHER NORTH MAY NEVER CHANGE TO PLAIN
RAIN. HIGHS MONDAY ARE ONLY EXPECTED TO TOP OUT IN THE 30S.

PRECIP WILL BE RATHER SPOTTY DURING THE AFTN HOURS. THE CHC FOR
PRECIP DECREASES AS THE AFTN GOES ON. THERE WILL BE A LOSS OF ICE
IN THE CLOUDS BY THE AFTN HOURS AS WELL…SO PRECIP MAY JUST BE
DRIZZLE OR FREEZING DRIZZLE BY THAT POINT.

SNOWFALL AMOUNTS WILL BE LIGHT DUE TO THE LIMITED AMOUNT OF QPF
/GENERALLY TWO TO FOUR TENTH OF AN INCH OF LIQUID EQUIVALENT/. TOTAL
SNOW TOTALS WILL RANGE FROM 1 TO 4 INCHES…HIGHEST IN THE
ADIRONDACKS. VALLEY LOCATIONS…SUCH AS THE MID HUDSON VALLEY AND
CAPITAL REGION…WILL LIKELY BE ON THE LOWER END OF THIS RANGE. ICE
ACCRETION UP TO A TENTH OF AN INCH IS POSSIBLE AS WELL…ESP FOR
THE SOUTHERN HALF OF THE REGION.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/…
COLDER AIR WILL FILTER BACK IN MONDAY NIGHT AS THE LOWS MOVE AWAY
FROM THE REGION. THE REGION WILL REMAIN UNDER THE LONGWAVE TROUGH
AND A SHORT WAVE TROUGH WILL MOVE THROUGH IT APPROACHING THE
GREAT LAKES REGION TUESDAY. THIS FEATURE WILL BRING CHANCES FOR
SNOW SHOWERS TO THE WESTERN ADIRONDACKS. MODEL GUIDANCE SHOWS A
WAVE OF LOW PRESSURE WILL FORM ALONG A FRONTAL BOUNDARY STALLED
WELL TO OUR SOUTH AND MOVE OFF THE SOUTHEAST COAST TUESDAY IN
RESPONSE TO SOUTHERN STREAM ENERGY. THERE ARE SOME INDICATES THE
NORTHERN EDGE OF THE PRECIPITATION COULD REACH THE SOUTHERN
PORTIONS OF THE FORECAST AREA. SO IN COLLABORATION WITH NEIGHBORING
OFFICES HAVE CHANCE POPS IN FOR TUESDAY DURING THE DAY.

TEMPERATURES WILL RUN ABOUT 5 DEGREES BELOW NORMAL.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/…
THE LONG TERM PERIOD WILL BE CHARACTERIZED BY FRIGID TEMPERATURES
AND OCCASIONAL LAKE EFFECT SNOW.

A MEAN LONGWAVE TROUGH AND SUBSEQUENT CYCLONIC FLOW ALOFT WILL
PREVAIL ACROSS MUCH OF THE NORTHEAST FOR THE LONG TERM
PERIOD…ALLOWING FOR BELOW NORMAL TEMPERATURES. THESE COLD
TEMPERATURES WILL BE HELD IN PLACE AS FAST-MOVING UPPER-LEVEL
IMPULSES MOVE THROUGH THE FLOW ALOFT…BRINGING REINFORCING SHOTS OF
COLD AIR WITH THEM. AT THE SURFACE…A STRONG AREA OF HIGH PRESSURE
WILL REMAIN ANCHORED TO THE SOUTH OF THE REGION.

THE QUESTION STILL REMAINS EXACTLY HOW COLD IT WILL GET ACROSS THE
REGION…ESPECIALLY REGARDING LOW TEMPERATURES. MODEL GUIDANCE
DIVERGES SIGNIFICANTLY DUE TO THE PROGRESSIVE UPPER-LEVEL FLOW…SO
HAVE USED A HEAVILY-BLENDED HPC APPROACH. THIS BLENDED APPROACH MAY
RESULT IN A SMOOTHING FACTOR IN THE EVENTUAL TEMPERATURES…BUT
REGARDLESS IT WILL BE DOWNRIGHT FRIGID ACROSS THE REGION.

HIGH TEMPERATURES WILL STRUGGLE TO REACH INTO THE MID 20S ACROSS
VALLEY LOCATIONS…WHILE FAILING TO GET OUT OF THE TEENS IN HIGHER
ELEVATIONS. LOW TEMPERATURES WILL BE THE COLDEST OF THE SEASON THUS
FAR…DIPPING WELL INTO THE SINGLE DIGITS ACROSS MOST OF THE
REGION…AND BELOW ZERO ACROSS PORTIONS OF THE ADIRONDACKS.

THE COMBINATION OF COLD TEMPERATURES AND A BRISK NORTHWEST WIND
THROUGHOUT MUCH OF THE LONG TERM PERIOD WILL BRING WIND CHILL VALUES
CLOSE TO…IF NOT REACHING…ADVISORY LEVELS OF -20F AND BELOW
WEDNESDAY THROUGH SATURDAY…ESPECIALLY DURING THE NIGHTTIME HOURS
ACROSS PORTIONS OF HERKIMER AND HAMILTON COUNTIES. ELSEWHERE…WIND
CHILL VALUES WILL STILL BE FRIGID BUT LOOK TO REMAIN ABOVE ADVISORY
CRITERIA. WILL CONTINUE TO MENTION THE POSSIBILITY OF WIND CHILL
HEADLINES FOR PORTIONS OF THE ADIRONDACKS IN THE HWO.

BESIDES THE COLD…THE ANCHORED SURFACE HIGH PRESSURE TO THE SOUTH
AND THE WEST/NORTHWEST FLOW ALOFT WILL HELP SET THE STAGE FOR A
POTENTIALLY SIGNIFICANT LAKE EFFECT SNOW EVENT ACROSS PORTIONS OF
THE WESTERN ADIRONDACKS AND POSSIBLY THE WESTERN MOHAWK RIVER
VALLEY. A LONG AND LIKELY MULTI-LAKE FETCH OFF BOTH LAKES ERIE AND
ONTARIO COINCIDENT WITH LIKELY MODERATE TO STRONG LAKE-ENHANCED
INSTABILITY GIVEN LARGE DELTA-T DIFFERENCES WILL RESULT IN A
PROLONGED LAKE EFFECT SNOW EVENT TUESDAY NIGHT THROUGH
THURSDAY…WITH SEVERAL INCHES OF SNOW POSSIBLE ACROSS PORTIONS OF
HERKIMER AND HAMILTON COUNTIES. FOR NOW…WILL CONTINUE MENTION IN
HWO…BUT LAKE EFFECT SNOW HEADLINES WILL LIKELY BE NEEDED AS THE
EVENT DRAWS CLOSER IN TIME.

ANOTHER STORM SYSTEM MAY GRAZE THE REGION FOR THE WEEKEND…BUT
CONFIDENCE IN THIS SCENARIO REMAINS LOW GIVEN THE LARGE SPREAD
AMONGST THE MODEL GUIDANCE AS THE UPPER LEVEL FLOW TRANSITIONS TO
MORE OF A ZONAL PATTERN. WILL CONTINUE TO MENTION SLIGHT CHANCE POPS
FOR THE FIRST HALF OF THE WEEKEND BEFORE HIGH PRESSURE BUILDS ACROSS
THE REGION TO END THE WEEKEND.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/…
ALTHOUGH FLYING CONDITIONS ARE CURRENTLY VFR…THEY WILL BE LOWERING
THROUGH THE OVERNIGHT HOURS FROM SOUTH TO NORTH AS PRECIPITATION
ASSOCIATED WITH A STORM SYSTEM MOVES INTO THE REGION.

LIGHT SNOW WILL IMPACT KPOU BY 03Z…WITH A TEMPO FOR IFR
CONDITIONS DUE TO VSBYS BETWEEN 03Z-06Z. FURTHER NORTH…KPSF
COULD SEE IFR SNOW AS SOON AS 04Z. PRECIP SHOULD BE LIGHT ONCE IT
BEGINS AT KGFL/KALB AROUND MIDNIGHT…WITH FLYING CONDITIONS MVFR.
IFR VSBYS/CIGS LOOK TO OCCUR AT KGFL/KALB BY LATE TONIGHT.

AS TEMPS WARM ALOFT…SNOW WILL MIX WITH SLEET/FREEZING RAIN TOWARDS
MONDAY MORNING…ESP FOR THE SOUTHERN TERMINALS. FLYING CONDITIONS
LOOK TO REMAIN GENERALLY IFR THROUGH THE ENTIRE DAY ON MONDAY WITH
LOW CIGS IN PLACE. THE PRECIP WILL CHANGE OVER TO RAIN BY THE LATE
MORNING…TAKING LONGEST TO CHANGEOVER AT KPSF. PRECIP WILL BE
RATHER LIGHT AND SPOTTY THROUGH THE DAY ON MONDAY…AND BY
AFTN…THERE MAY BE BE POCKETS OF DRIZZLE OR MIST…AS WIDESPREAD
PRECIP SHOULD HAVE ENDED.

SFC WINDS WILL BE LIGHT OR NEARLY CALM OVERNIGHT. THEY WILL BECOME
EASTERLY AT AROUND 5 KTS BY LATE TONIGHT…AND EVENTUALLY BECOME
OUT OF S-SW DURING THE DAY MONDAY AT LIGHT SPEEDS.

OUTLOOK…
MON NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF RA…SN.
TUE: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUES NIGHT: LOW OPERATIONAL IMPACT. BREEZY.
WED: LOW OPERATIONAL IMPACT. BREEZY. SLIGHT CHANCE OF SHSN.
WED NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
THU: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
THU NIGHT-FRI: NO OPERATIONAL IMPACT. NO SIG WX.

&&

.HYDROLOGY…
NO HYDRO RELATED CONCERNS ARE EXPECTED OVER THE NEXT 5 DAYS.

ANOTHER ROUND OF PRECIPITATION TONIGHT AND MONDAY. THE QPF WILL BE
LIGHT WITH THREE TO FOUR TENTHS OF AN INCH EXPECTED. IN ADDITION
MOST WILL BE IN THE FORM SNOW. OTHERWISE…MAINLY LAKE EFFECT
SNOWS ARE EXPECTED DURING THE WEEK.

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…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON EST
MONDAY FOR CTZ001-013.
NY…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON EST
MONDAY FOR NYZ038>040-047>054-058>061-063>066.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
MONDAY FOR NYZ032-033-041>043-082>084.
MA…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON EST
MONDAY FOR MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST
MONDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…IAA/FRUGIS
NEAR TERM…IAA/FRUGIS
SHORT TERM…IAA
LONG TERM…IRL
AVIATION…FRUGIS
HYDROLOGY…IAA

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