December 30, 2013 Forecast Discussion

000
FXUS61 KALY 301428
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
928 AM EST MON DEC 30 2013

.SYNOPSIS…
WE WILL HAVE AN ACTIVE WEATHER PATTERN THIS WEEK AND IT WILL TURN
MUCH COLDER. TEMPERATURES WILL FALL TODAY IN THE WAKE OF AN ARCTIC
FRONT AND HIGH PRESSURE WILL BRIEFLY BUILD IN TONIGHT. A QUICK
MOVING LOW PRESSURE SYSTEM WILL APPROACH AND PASS OVER THE REGION ON
TUESDAY RESULTING IN SNOW SHOWERS…ESPECIALLY TO THE NORTH AND WEST
THE CAPITAL DISTRICT. LAKE EFFECT SNOWS WILL FOLLOW AS MORE HIGH
PRESSURE BUILDS TUESDAY NIGHT. A WIDESPREAD MODERATE TO SIGNIFICANT
SNOWFALL IS POSSIBLE TO CLOSE OUT THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 915 AM EST…ARCTIC BOUNDARY CONTINUES TO SLIDE EAST OF THE
REGION WITH BRISK CONDITIONS AND TEMPERATURES FALLING A FEW
DEGREES PER HOUR THIS MORNING. SURFACE RIDGE WILL BUILD IN DURING
THE AFTERNOON WHICH WILL RELAX THE GRADIENT AND WIND MAGNITUDES
ACROSS THE REGION.

PREV DISC…
TURNING COLDER TODAY…WITH TEMPERATURES FALLING IN THE WAKE
AN ARCTIC BOUNDARY. THE BOUNDARY IS WORKING ITS WAY ACROSS THE
FORECAST AREA AT THIS TIME. TEMPERATURES HAVE RISEN A COUPLE
DEGREES AHEAD OF IT…WITH READINGS DROPPING ACROSS CENTRAL AND
NORTHERN NEW YORK. KSLK DROPPED 14 DEGREES IN 2 HOURS WITH THE
FRONT`S PASSAGE. HAVE MADE ADJUSTMENTS BASED ON OBSERVATIONAL
DATA. CONTINUE TO HAVE CHANCES POPS MAINLY ACROSS THE HIGHER
TERRAIN FOR EARLY THIS MORNING AS THE BOUNDARY MOVES THROUGH WITH
POPS DECREASING AS THE DAY PROGRESSES AND HIGHER PRESSURE BUILDS
IN FROM THE WEST. WINDS WILL BECOME BRISK AND GUSTY THIS MORNING
AS THE PRESSURE GRADIENT TIGHTENS USHERING IN THE COLDER AIRMASS.
THE GRADIENT WILL BEGIN TO WEAKEN THIS AFTERNOON AS THE HIGH
BUILDS IN.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/…
SURFACE HIGH PRESSURE WILL MOVE EASTWARD AND WEAKEN AS IT CROSSES
THE REGION TONIGHT. EXPECTING A PERIOD OF MOSTLY CLEAR SKIES ALONG
WITH WINDS BECOMING LIGHT/VARIABLE TO CALM WHICH WILL ALLOW
TEMPERATURES TO TUMBLE. LOWS ARE EXPECTED TO RANGED FROM AROUND 10
DEGREES BELOW ZERO ACROSS THE SOUTHERN ADIRONDACKS TO ABOUT 10
DEGREES IN THE MID HUDSON VALLEY. WIND CHILL ARE NOT ANTICIPATED TO
BE AN ISSUE TONIGHT AS THE WINDS DIMINISH.

THE REGION WILL REMAIN UNDER THE LONGWAVE TROUGH HOWEVER THE FLOW
IS EXPECTED TO FLATTEN BECOMING NEARLY ZONAL BY WEDNESDAY. A QUICK
MOVING CLIPPER SYSTEM WILL APPROACH AND CROSS THE REGION ON TUESDAY.
THE SURFACE LOW IS EXPECTED TO CROSS ACROSS NORTHERN NEW YORK DURING
AFTERNOON WITH THE BEST CHANCES FOR SNOW SHOWERS ACROSS THE SOUTHERN
ADIRONDACKS INTO THE LAKE GEORGE REGION WHERE 1 TO 3 INCHES IS
EXPECTED. TEMPERATURES WILL BE BELOW NORMAL BY 5 TO 10 DEGREES.

IN THE WAKE OF THE CLIPPER…THE LOW LEVEL FLOW WILL BE FAVORABLE
FOR A PERIOD OF LAKE EFFECT SNOWS TUESDAY NIGHT. INITIALLY
IMPACTING THE WESTERN ADIRONDACKS. THIS WILL BE SHORT LIVED AS
MORE HIGH PRESSURE BUILDS IN.

VIGOROUS SHORT WAVE ENERGY ENTERING THE CONUS OVER THE PACIFIC
NORTHWEST WILL DIG A TROUGH OVER THE PLAINS AND THIS WILL BRING US
OUR NEXT STORM SYSTEM AS WE HEAD INTO THE LATER PART OF THE WEEK.
ON WEDNESDAY/NEW YEARS DAY…HIGH PRESSURE OVER EASTERN CANADA
SHOULD DOMINATE. LINGERING LAKE EFFECT SHOULD DIMINISH DURING THE
MORNING. IN THE AFTERNOON THERE ARE LOW CHANCES THAT SOME LIGHT
OVERRUNNING SNOW COULD DEVELOP IN ADVANCE OF THE NEXT LOW PRESSURE
SYSTEM.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
CONFIDENCE IS INCREASING IN A SIGNIFICANT WINTER STORM EVENT
IMPACTING THE REGION DURING THE WED NIGHT THROUGH FRIDAY TIME
PERIOD. HOWEVER…MANY QUESTIONS REMAIN REGARDING THE EXACT STORM
TRACK AND AMOUNT OF PRECIPITATION…WHICH WILL DETERMINE EXACTLY HOW
BIG OF AN IMPACT THIS STORM HAS ON OUR REGION.

AT THE START OF THE EXTENDED PERIOD…THE MODELS AGREE ON AN AREA OF
LOW PRESSURE MOVING FROM THE OHIO VALLEY ON WED NIGHT TOWARDS
WESTERN PA FOR THURSDAY. AHEAD OF THIS STORM SYSTEM…ISENTROPIC
LIFT ALONG THE STORM/S WARM FRONT WILL BRING A STEADY LIGHT SNOW TO
THE AREA…ESP WESTERN PARTS OF THE REGION…FOR WED NIGHT INTO
THURSDAY. WITH A COLD AIR MASS IN PLACE…ALL PRECIP WILL BE IN THE
FORM OF A FLUFFY SNOW…WITH MIN TEMPS ON WED NIGHT RANGING FROM
AROUND A FEW DEGREES BELOW ZERO IN THE WESTERN ADIRONDACKS TO AROUND
15 IN THE MID HUDSON VALLEY. MAX TEMPS ON THURSDAY WILL GENERALLY BE
IN THE TEENS /SINGLE DIGITS OVER THE ADIRONDACKS AND LOW 20S OVER
THE MID HUDSON VALLEY/.

AT THE SOME POINT…ANOTHER AREA OF LOW PRESSURE WILL FORM OFF THE
MID ATLANTIC COAST AND RAPIDLY STRENGTHEN AS IT MOVES NORTHEAST.
THIS COULD BRING SOME ADDITIONAL SNOWFALL TO THE REGION FOR LATE IN
THE DAY THURSDAY….INTO THURSDAY NIGHT…AND POTENTIALLY EVEN
FRIDAY…ALTHOUGH JUST CLOSELY THIS STORM TRACKS TO THE CLOSE AND
HOW QUICKLY IT MOVES WILL DETERMINE HOW MUCH EXTRA PRECIP WE
RECEIVE.

THERE ARE TIMING DIFFERENCES IN THE VARIOUS MODELS…AS THE 00Z
GFS/NAM/GGEM/GEFS MEAN ARE QUICKER AND MORE PROGRESSIVE THAN BOTH
THE 12Z ECMWF/00Z ECMWF. THE NAM/GFS SEEM A LITTLE TOO
PROGRESSIVE…WHILE THE 00Z ECMWF IS A LITTLE TOO AMPLIFIED. THE 00Z
ECMWF ENSEMBLE MEAN IS A LITTLE WEAKER/FASTER THAN THE OPERATIONAL
00Z ECMWF…BUT STILL SLOWER/MORE AMPED UP THAN THE LATEST GFS. FOR
NOW…WE WILL FOLLOW THE LEAD OF WPC AND FAVOR THE 29/12Z
ECMWF…WHICH STILL SHOWS A SIGNIFICANT STORM SYSTEM FOR OUR ENTIRE
AREA…AND LOOKS TO BE A GOOD COMPROMISE. WE WILL GO WITH LIKELY
POPS FOR THURSDAY/THURS NIGHT…WITH POPS TAPERING DOWN THROUGH THE
DAY ON FRIDAY. TEMPS LOOK VERY COLD…WITH MINS BELOW ZERO OVER THE
HIGH TERRAIN AND SINGLE DIGITS IN VALLEY AREAS FOR THURSDAY NIGHT.
DURING THE DAY FRIDAY…HIGHS WILL ONLY BE IN THE SINGLE DIGITS TO
LOW TEENS OVER MUCH OF THE AREA.

TOTAL PRECIP AMOUNTS ARE STILL UNKNOWN…AS QPF AMOUNTS VARY
SIGNIFICANT IN THE MODELS AND IN THE ENSEMBLES AS WELL. THE 00Z
ECMWF HAS A WORST-CASE SCENARIO OF NEARLY 2.00 INCHES LIQUID
EQUIVALENT…AND THIS LOOKS TO BE AN OUTLIER AT THIS POINT. THE 00Z
GFS/GGEM HAVE AROUND 0.75 INCHES…AND THIS IS SUPPORTED BY THE 12Z
GEFS. THE 00Z EURO HAD AROUND AN INCH…AND THIS SEEMS MOST
REASONABLE CONSIDERING THE EXPECTED TRACK. WITH THE COLD AIR MASS
IN PLACE…THIS WOULD BE A SIGNIFICANT SNOWFALL DUE TO HIGH SNOW TO
LIQUID RATIOS…AND THIS STORM THREAT WILL BE HIGHLIGHTED IN THE
HWO.

WITH A FRESH SNOW PACK IN PLACE…CLEARING SKIES…AND A VERY COLD
ARCTIC HIGH PRESSURE AREA JUST NORTH OF THE AREA…FRI NIGHT WILL BE
THE COLDEST NIGHT OF THE SEASON. WE ARE CURRENTLY FORECASTING MIN
TEMPS BELOW ZERO OVER MUCH OF THE REGION…WITH TEMPS AS COLD AS -20
DEGREES. ALTHOUGH WINDS WILL LIGHTEN UP OVERNIGHT…WIND CHILL
VALUES STILL LOOK EXTREMELY COLD…WITH WIND CHILL VALUES OF -10 TO
-35 POSSIBLE…WITH THE COLDEST VALUES OVER THE HIGH TERRAIN OF THE
ADIRONDACKS. THIS WILL ALSO BE HIGHLIGHTED IN OUR HWO STATEMENT.

MAINLY DRY BUT CONTINUED COLD CONDITIONS WILL BE IN PLACE FOR
SATURDAY WITH HIGHS IN THE TEENS. TEMPS WILL START TO MODERATE FOR
SAT NIGHT INTO SUNDAY…AS WE GET INTO A SOUTHERLY FLOW AHEAD OF AN
APPROACHING CLIPPER SYSTEM. TEMPS SAT NIGHT WILL ONLY DROP A LITTLE
FOR SAT/S HIGHS…WITH SINGLE DIGITS TO LOW TEENS FOR LOWS. MAX
TEMPS ON SUNDAY WILL BE MUCH WARMER…WITH MID 20S TO MID 30S ACROSS
THE REGION. THERE MAY BE SOME SNOW SHOWERS ALONG THE CLIPPER/S COLD
FRONT BY SUN AFTN…ALTHOUGH THIS SYSTEM WILL BE MOISTURE STARVED
AND WON/T HAVE MUCH ACTIVITY ALONG IT.

THE MODELS ARE HINTING AT YET ANOTHER STORM FOR SOMETIME SUNDAY
NIGHT INTO MONDAY…ALTHOUGH THIS TRACK LOOKS FURTHER INLAND AND
WARMER. THE 00Z ECMWF SUGGESTED MAINLY SNOW FOR THE CAPITAL REGION
NORTH AND WEST…ALTHOUGH THE GFS AND GEFS HAD MUCH DIFFERENT AND
VARIED SOLUTIONS. CONSIDERING WE DONT EVEN KNOW HOW THE LATE WEEK
STORM WILL PLAY OUT…WILL ONLY GO WITH CHC POPS FOR THAT SYSTEM FOR
NOW…BUT WILL NEED TO WATCH IT OVER THE WEEKEND.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/…
AN ARCTIC FRONTAL BOUNDARY IS CROSSING THE REGION THIS MORNING. THE
FRONT WILL BE CROSSING THROUGH THE TAF SITES OVER THE NEXT 1-2
HOURS. WINDS ARE S-SW AHEAD OF THE BOUNDARY…AND WILL QUICKLY
SWITCH TO A W-NW DIRECTION BEHIND THE FRONT AT SPEEDS OF 10-15 KTS.
THERE WILL BE A FEW HIGHER GUSTS AT KALB/KPSF…ESP DURING THE LATE
MORNING AND INTO THE AFTN…AS SFC HEATING ALLOWS FOR BETTER MIXING.

ALTHOUGH SOME LINGERING LOW LEVEL MOISTURE IS ALLOWING FOR MVFR
FLYING CONDITIONS EARLY THIS MORNING DUE TO MIST AND LOW
STRATUS…FLYING CONDITIONS LOOKS TO IMPROVE TO VFR BY THE MID
MORNING HOURS AS THE WESTERLY FLOW BEHIND THE FRONT BRINGS IN MUCH
DRIER AIR. DURING THE LATE MORNING AND THROUGH THE AFTN…THERE WILL
BE JUST FEW-SCT DIURNALLY DRIVEN STRATOCU CLOUDS AND PASSING HIGH
CIRRUS.

WINDS WILL DIMINISH FOR THIS EVENING AT UNDER 10 KTS…WITH JUST
FEW-SCT CIRRUS CLOUDS FOR TONIGHT AND CONTINUED VFR CONDITIONS.

OUTLOOK…
TUE NIGHT: MODERATE OPERATIONAL IMPACT. BREEZY. CHANCE OF SHSN.
NEW YEARS DAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
WED NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.
THU-THU NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SN.
FRI: MODERATE OPERATIONAL IMPACT. CHANCE OF SN.

&&

.HYDROLOGY…
NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THIS WEEK. RIVERS AND
STREAMS ARE CRESTING FROM SUNDAY`S PRECIPITATION. WILL BE GETTING
MUCH COLDER THIS WEEK…STARTING TODAY WITH THE PASSAGE OF ARCTIC
BOUNDARY. TEMPERATURES ARE EXPECTED TO TURN MUCH COLDER BY LATE IN
THE WEEK. ICE FORMATION WILL RESUME AND THICKEN THIS WEEK. THE
WEATHER PATTERN WILL BE ACTIVE WITH ALL THE PRECIPITATION EXPECTED
TO BE IN THE FORM OF SNOW.

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…IAA
NEAR TERM…IAA/BGM
SHORT TERM…IAA
LONG TERM…FRUGIS
AVIATION…FRUGIS
HYDROLOGY…IAA

FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY

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