Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 211724
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1224 PM EST SUN DEC 21 2014

.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL TRACK THROUGH THE REGION TODAY...
BRINGING SOME FLURRIES OR LIGHT SNOW TO PARTS OF EASTERN NEW YORK
AND WESTERN NEW ENGLAND. MOSTLY CLOUDY AND UNSETTLED CONDITIONS
WILL PERSIST THROUGH MUCH OF THE UPCOMING WEEK...WITH SOME LIGHT
MIXED PRECIPITATION POSSIBLE MONDAY NIGHT...AND A PERIOD OF
LOCALLY HEAVY RAIN AND STRONG WINDS POSSIBLE WEDNESDAY INTO
WEDNESDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1215 PM EST...VERY LIGHT SNOW GRAINS HAVE STARTED TO SLIDE
EAST THROUGH WESTERN NEW ENGLAND AND THIS TREND IS EXPECTED TO
CONTINUE THROUGH THIS AFTERNOON. ACCUMS HAVE BEEN VERY LIGHT DUE
TO THE GRAINY NATURE...GENERALLY ONLY ONE TENTH OF AN INCH OR
LESS.

A WEAK UPPER IMPULSE IN THE EASTERN GREAT LAKES...WITH SOME MID
AND HIGH LEVEL MOISTURE IS TRACKING INTO OUR REGION THROUGH THE
DAY. THIS WILL KEEP FA MOSTLY CLOUDY TO CLOUDY THROUGH THE
AFTERNOON.

HIGH TEMPERATURES SHOULD BE ON THE COOLER SIDE OF GUIDANCE. HIGHS
AROUND 30 TO THE MID 30S...SOME 20S IN HIGHER ELEVATIONS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
CLOUD COVER WILL LIKELY PERSIST ACROSS THE REGION...WITH SOME
BRIEF BREAKS IN THE CLOUDS POSSIBLE IN SOME AREAS...BUT NOT ENOUGH
TO ALLOW TEMPERATURES TO DROP MUCH. WITH THE CLOUD COVER AND LIGHT
WINDS...LOWS IN THE MID TO UPPER 20S...SOME UPPER TEENS IN THE
SOUTHERN ADIRONDACKS. WARM ADVECTION SLOWLY STRENGTHENS THROUGH
MONDAY...WITH BOUNDARY LAYER TEMPERATURES GRADUALLY WARMING. LIGHT
WIND FLOW THROUGH THE BOUNDARY LAYER SHOULD MAKE IT DIFFICULT TO
MIX OUT CLOUD COVER...BUT SOUTHERLY WINDS COULD HELP ANY CLEARING
TO THE SOUTH SPREAD SLOWLY NORTH...UNTIL THE MID AND HIGH CLOUDS
ASSOCIATED WITH THE APPROACHING SYSTEM FROM THE WEST SPREAD OVER
THE REGION. STILL...WITH ALL THE CLOUD COVER...HIGHS MONDAY IN THE
30S.

SOUTHERLY BOUNDARY LAYER FLOW SLOWLY INCREASES MONDAY NIGHT AS
DOES WARM ADVECTION AND ISENTROPIC LIFT. LOW LEVEL RIDGING IS
EXPECTED TO BE ANCHORED IN SE CANADA...SO SURFACE FLOW SHOULD BE
NORTHEAST TO SOUTHEAST. AGEOSTROPHIC LOW LEVEL FLOW FROM THE EAST
AND NORTHEAST SUGGEST THAT ANY LIGHT PRECIPITATION THAT DEVELOPS
IN THE REGION COULD HELP TEMPERATURES FALL TO WET BULB LEVELS...
WHICH WOULD SUPPORT SNOW AND/OR MIXED PRECIPITATION IN SOME
AREAS...INCLUDING A CHANCE FOR FREEZING RAIN AND SLEET. LOWS
MONDAY NIGHT ION THE UPPER 20S TO LOWER 30S...JUST ABOVE FREEZING
IN MUCH OF THE HUDSON VALLEY...BUT POTENTIALLY CLOSE TO FREEZING
IN THE CAPITAL DISTRICT. NO WINTER WEATHER HEADLINES YET...WITH
JUST CHANCES FOR FREEZING RAIN BUT WILL INCLUDE IN THE HAZARDOUS
WEATHER OUTLOOK BECAUSE HEADLINES MAY BE NEEDED IF FREEZING RAIN
BECOMES LIKELY IN SOME AREAS AS THE EVENT NEARS.

ALL PRECIPITATION TRENDS TO ALL RAIN TUESDAY AND SLOWLY INCREASES
IN COVERAGE THROUGH TUESDAY AND TUESDAY NIGHT AS WARM ADVECTION
AND ISENTROPIC LIFT STRENGTHEN. HIGHS TUESDAY IN THE 40S...BUT
AROUND 40 IN THE SOUTHERN ADIRONDACKS. LOWS TUESDAY NIGHT IN THE
MID 30S TO LOWER 40S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
ACTIVE AND CHANGEABLE WEATHER EXPECTED FROM CHRISTMAS EVE TO
CHRISTMAS DAY...AS A STORM STORM SYSTEM WITH POSSIBLE MULTIPLE
HAZARDS AFFECTS THE REGION. THE MAIN IMPACTS ARE EXPECTED TO BE
HEAVY RAINFALL AND STRONG WINDS. WINTRY PRECIPITATION IS NOT
EXPECTED TO BE A MAIN HAZARD WITH THIS SYSTEM.

BY CHRISTMAS EVE DAY OUR REGION SHOULD BE FIRMLY ESTABLISHED IN A
WARM SECTOR ASSOCIATED WITH A HIGHLY AMPLIFIED PATTERN. A DEEP
TROUGH WILL BE ADVANCING EASTWARD ACROSS THE UPPER GREAT
LAKES...MIDWEST AND TENN VALLEY REGIONS...WITH A RIDGE AXIS
POSITIONED ACROSS THE WESTERN ATLANTIC. AN ANOMALOUSLY WARM AND
MOIST SOUTHERLY FLOW BOTH IN THE LOW LEVELS AND ALOFT WILL BE IN
PLACE ALONG THE EASTERN SEABOARD. DESPITE EXPECTED CLOUD
COVER...TEMPERATURES WILL BE WELL ABOVE NORMAL FOR THIS TIME OF
YEAR. HIGH TEMPS SHOULD BE CLOSE TO 20 DEGREES ABOVE NORMAL WITH
LOWER TO MID 50S FROM THE HUDSON VALLEY SOUTH AND EAST.

SOUTHERLY WIND FIELD WILL BE INCREASE THROUGHOUT THE DAY WEDNESDAY.
STRONG WINDS WILL LIKELY DEVELOP ACROSS THE HIGHER TERRAIN AND AREAS
SUSCEPTIBLE TO SOUTH-SOUTHEAST FLOW. HOW STRONG WIND SPEEDS END UP
IN VALLEY LOCATIONS WILL DEPEND ON DEGREE OF MIXING. SURGES OF
MOISTURE INTO THE REGION WILL LEAD TO OCCASIONAL HEAVY
RAINFALL...WITH PWATS FORECAST TO INCREASE TO +4 TO +5 STDEV BY LATE
WEDNESDAY. HEAVY RAINFALL ALONG WITH SNOW MELT IN HIGHER TERRAIN
COULD LEAD TO SOME FLOODING. SEE HYDRO SECTION FOR DETAILS.

THERE ARE MODEL DISCREPANCIES WITH REGARDS TO TIMING...TRACK AND
STRENGTH OF THE PARENT LOW PRESSURE AREA...BUT THERE IS AT LEAST
GENERAL CONSENSUS THAT THAT LOW WILL PASS BY TO OUR NORTH AND WEST
AND DEEPEN IN THE PROCESS. A COLD FRONT TRAILING FROM THE LOW LOOKS
TO CROSS OUR REGION FROM WEST TO EAST SOMETIME EARLY CHRISTMAS
MORNING. THE FRONTAL PASSAGE WILL LIKELY BE ACCOMPANIED BY A BURST
OF HEAVY RAINFALL AND GUSTY WINDS. STEADY RAINFALL WILL TAPER OFF TO
SCATTERED VALLEY RAIN SHOWERS AND MOUNTAIN SNOW SHOWERS CHRISTMAS
MORNING. AS THE LOW DEEPENS FURTHER ACROSS SOUTHERN QUEBEC ON
CHRISTMAS DAY...ANOTHER ROUND OF POTENTIALLY STRONG WINDS COULD BE
MORE WIDESPREAD IN THE WESTERLY FLOW WITH BETTER MIXING. HIGH TEMPS
WILL LIKELY OCCUR EARLY IN THE DAY ON CHRISTMAS...WITH TEMPERATURES
FALLING DURING THE AFTERNOON WITH THE DEVELOPING BRISK WESTERLY WIND.

OTHER THAN A FEW UPSLOPE/LAKE ENHANCED SNOW SHOWERS ACROSS THE
HIGHER TERRAIN OF THE WESTERN ADIRONDACKS...DRY WEATHER IS EXPECTED
FOR THE REST OF THE AREA THURSDAY NIGHT INTO FRIDAY. TEMPERATURES
WILL TURN MUCH COLDER COMPARED TO PREVIOUS DAYS...BUT WILL STILL BE
SLIGHTLY ABOVE NORMAL. A WEAKER DISTURBANCE WITH LIMITED MOISTURE
MAY BRING SOME RAIN/SNOW SHOWERS TO THE REGION FRIDAY NIGHT INTO
SATURDAY WITH LIGHT QPF.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL WILL REMAIN ANCHORED ACROSS SOUTHEAST QUEBEC
AND THE CANADIAN MARITIMES...WITH AN UPPER LEVEL DISTURBANCE PASSING
JUST SOUTH OF THE REGION THIS AFTERNOON. HIGH PRESSURE WILL THEN
BUILD IN BOTH AT THE SURFACE AND ALOFT TONIGHT AND MONDAY.

THE AFOREMENTIONED UPPER LEVEL DISTURBANCE...AND A MOIST FLOW ALOFT
FROM THE ATLANTIC OCEAN...HAS ALLOWED AREAS OF LIGHT SNOW/SNOW
GRAINS TO OCCUR AT THE TAF SITES EARLY THIS AFTERNOON. WE EXPECT
THIS LIGHT SNOW TO GRADUALLY DECREASE IN AREAL COVERAGE FROM NW TO
SE THROUGH THE AFTERNOON. BEFORE IT DOES...MVFR TO OCCASIONAL IFR
CIGS/VSBYS WILL BE POSSIBLE...WITH THE GREATEST THREAT THROUGH
AROUND 20Z/SUN AT KPOU AND KPSF. CIGS/VSBYS SHOULD IMPROVE SLIGHTLY
INTO THE MVFR RANGE AFTER THE SNOW TAPERS OFF.

FOR TONIGHT...A CONTINUED STREAM OF ENHANCED LOW LEVEL MOISTURE WILL
REMAIN ACROSS THE TAF SITES. THIS MAY ALLOW ADDITIONAL PATCHY VERY
LIGHT SNOW OR SNOW GRAINS TO REDEVELOP. THERE IS ALSO A POSSIBILITY
THAT SOME FREEZING DRIZZLE OCCURS...ESP AT KPSF AND KPOU AFTER
03Z-06Z/MON. FOR NOW...HAVE INDICATED SNOW SHOWERS...BUT
AGAIN...OBSERVATIONAL TRENDS WILL NEED TO BE WATCHED CLOSELY AS
THERE IS SOME POTENTIAL FOR PATCHY FREEZING DRIZZLE LATE TONIGHT.
CONDITIONS SHOULD DETERIORATE TO LOW MVFR AND IFR THROUGH THE
NIGHT...WITH THE GREATEST THREAT FOR PERSISTENT IFR/LIFR CONDITIONS
EXPECTED AT KPSF...AND KPOU.

ON MONDAY...LINGERING PATCHY LIGHT SNOW GRAINS AND/OR FREEZING
DRIZZLE/DRIZZLE SHOULD GRADUALLY DIMINISH BETWEEN 15Z-18Z/MON.
IFR/MVFR CONDITIONS MAY IMPROVE SLIGHTLY TOWARD OR AFTER 18Z/MON.

WINDS WILL REMAIN LIGHT...FROM THE N TO NE AT LESS THAN 8 KT THROUGH
18Z/MON.

OUTLOOK...

MONDAY NIGHT: LOW OPERATIONAL IMPACT. CHANCE OF SN.
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
TUESDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY RA.
WEDNESDAY: HIGH OPERATIONAL IMPACT. DEFINITE RA.
WEDNESDAY NIGHT: HIGH OPERATIONAL IMPACT. BREEZY. DEFINITE RA.
CHRISTMAS DAY: MODERATE OPERATIONAL IMPACT. WINDY. CHANCE OF SHRA.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.

&&

.HYDROLOGY...
NO HYDROLOGIC ISSUES ARE ANTICIPATED THROUGH TUESDAY NIGHT. A
WIDESPREAD RAINFALL IS EXPECTED WEDNESDAY INTO WEDNESDAY NIGHT AS
A LARGE LOW PRESSURE SYSTEM MOVES ACROSS THE REGION. RAINFALL
AMOUNTS OF 0.75 INCH TO 1.5 INCHES ARE LIKELY ALONG WITH
SIGNIFICANT SNOWMELT WHICH RAISES THE POTENTIAL FOR MINOR FLOODING
AND SIGNIFICANT WITHIN BANK RISES OF LARGER STEM RIVERS. MMEFS
GUIDANCE SUGGESTS THE BEST CHANCES FOR MINOR FLOODING WOULD BE
FROM THE HUDSON VALLEY THROUGH WESTERN NEW ENGLAND. IT IS TOO
EARLY TO ISSUE ANY FLOOD WATCHES...HOWEVER WILL MENTION IN THE HWO
AT THIS TIME.

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...NAS
NEAR TERM...KL/11/NAS
SHORT TERM...NAS
LONG TERM...JPV
AVIATION...JPV
HYDROLOGY...NAS







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