February 7, 2013 Forecast Discussion

000
FXUS61 KALY 080003
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
703 PM EST THU FEB 7 2013

.SYNOPSIS…
CLOUDS WILL CONTINUE TO INCREASE THIS EVENING WITH SOME
LIGHT SNOW DEVELOPING…ESPECIALLY AFTER MIDNIGHT. SNOW WILL BECOME
STEADY BY TOMORROW AFTERNOON AND HEAVY BY THE EVENING HOURS AS A
STRONG LOW PRESSURE SYSTEM MOVES NORTHEAST ALONG THE EASTERN
SEABOARD. THE STORM WILL DEPART OUT TO SEA ON SATURDAY
MORNING…LEAVING COLD AND BLUSTERY CONDITIONS IN ITS WAKE.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/…
AS OF 7 PM EST…VISIBLE AND SATELLITE IMAGERY IS IMPRESSIVE
THIS EVENING…SHOWING A RAPIDLY DEVELOPING CYCLONE OVER THE
DEEP SOUTH. LOTS OF CLOUD TO GROUND LIGHTNING IS EVIDENT ACROSS
THE EASTERN GULF OF MEXICO AND WESTERN ATLANTIC. THE NORTHERN
STREAM SYSTEM IS ALSO QUITE POTENT…AND EVEN WAS SHOWING SOME LTG
OF IT/S OWN EARLIER TODAY. YET A THIRD POTENT DISTURBANCE WAS
TRANSLATING EAST ACROSS THE SOUTHERN PLAINS. THESE THREE SYSTEMS
WILL CONTINUE TO INTERACT AND EVENTUALLY AFFECT OUR REGION.

MID AND HIGH LEVEL CLOUDS ARE INCREASING OVER OUR REGION. VERY
DRY AIR IS IN PLACE…WITH DEWPOINTS AROUND ZERO IN MOST PLACES.
IT LOOKS TO REMAIN DRY DURING THE EVENING HOURS FOR MOST AREAS.
HOWEVER…ONCE THE COLUMN MOISTENS UP ENOUGH…SOME LIGHT SNOW
WILL DEVELOP ACROSS THE ADIRONDACKS BY ABOUT MIDNIGHT OR SO. THE
CHC FOR LIGHT SNOW WILL INCREASE ACROSS THE ENTIRE REGION DURING
THE REMAINDER OF THE OVERNIGHT HOURS…BUT ANY ACCUMULATIONS
OVERNIGHT LOOK LIGHT…WITH JUST A COATING ACROSS MOST AREAS
/PERHAPS AN INCH OR TWO ACROSS THE ADIRONDACKS/.

OVERNIGHT LOWS WILL RANGE FROM THE SINGLE DIGITS IN THE
ADIRONDACKS TO THE LOW 20S IN THE MID HUDSON VALLEY. TEMPS LOOK TO
DROP OFF MOST THIS EVENING BEFORE CLOUDS THICKEN UP.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/…
…POWERFUL WINTER STORM TO IMPACT THE REGION FRIDAY INTO FRIDAY
NIGHT…

A WINTER STORM WARNING HAS BEEN ISSUED FOR THE MAJORITY OF THE
REGION. THE EXCEPTION IS LITCHFIELD COUNTY CONNECTICUT…WHERE A
BLIZZARD WARNING HAS BEEN ISSUED.

DESPITE THIS STORM BEING IN THE SHORT-TERM PERIOD…THE MODELS ARE
STILL NOT IN TOTAL AGREEMENT ON THE EXACT TRACK OF THE UPCOMING
STORM. THIS WILL HAVE AN IMPACT ON JUST HOW MUCH PRECIPITATION
OCCURS ACROSS OUR AREA. EVEN WITH THIS UNCERTAINTY…THERE STILL
IS ENOUGH OF A SIGNAL IN THE GUIDANCE TO HAVE THE CONFIDENCE TO
ISSUE WINTER STORM WARNINGS/BLIZZARD WARNINGS ACROSS THE FORECAST
AREA. SNOW RATIOS SHOULD BE AT LEAST CLIMO /12.5:1/ OR
GREATER…AS OPTIMAL SNOW CRYSTAL GROWTH IS EXPECTED…MAINLY
DURING FRIDAY NIGHT.

DURING THE DAYTIME ON FRIDAY…LIGHT SNOW WILL DEVELOP ACROSS MUCH
OF THE REGION DUE TO WARM AIR ADVECTION WELL OUT AHEAD OF THE
STORM THAT BEGINS TO RAPIDLY DEEPEN OFF THE MID ATLANTIC COAST.
SNOWFALL WILL BECOME MORE STEADY AND HEAVIER IN INTENSITY BY
LATE FRIDAY AFTERNOON…AS SOME ATLANTIC MOISTURE GETS INVOLVED.
JUST A FEW INCHES WILL LIKELY OCCUR THROUGH FRIDAY AFTERNOON…BUT
THE MAIN SHOW IS STILL YET TO COME.

AS THE LOW BOMBS OUT OFF THE JERSEY SHORE FRIDAY EVENING…FRONTOGENESIS
WILL LEAD TO A PERIOD OF MODERATE TO HEAVY SNOW ACROSS OUR
AREA…ESPECIALLY OUR NEW ENGLAND ZONES…WHERE MESOSCALE BANDING
WILL LIKELY TAKE PLACE. SNOW RATES ON FRIDAY EVENING WILL EXCEED
ONE INCH PER HOUR IN MANY AREAS…AND PARTS OF
BERKSHIRE/LITCHFIELD COUNTY MAY EVEN SEE SNOW RATES OF UP TO THREE
INCHES PER HOUR AT TIMES.

850 HPA U WIND ANOMALIES WILL BE ABOUT 2 TO 5 STD BELOW NORMAL.
THIS WILL ALLOW FOR A STRONG FETCH OF EASTERN FLOW ACROSS OUR
REGION…TRANSPORTING PLENTY OF ATLANTIC MOISTURE INTO THE AREA.

WITH THE DEVELOPING LOW…NE WINDS WILL BECOME STRONG DURING THE
OVERNIGHT HOURS…ESP ACROSS LITCHFIELD COUNTY. A SEVERAL HOUR
PERIOD OF WIND GUSTS OF 30-35 MPH…ALONG WITH HEAVY
SNOWFALL…LOOKS OT OCCUR ACROSS LITCHFIELD…WHICH IS WHY A
BLIZZARD WARNING HAS BEEN ISSUED. ELSEWHERE…WIND GUSTS OF 15 TO
30 MPH ARE POSSIBLE…WHICH MAY ALLOW FOR SOME BLOWING AND
DRIFTING OF THE SNOW ACROSS THE REMAINDER OF OUR AREA AS WELL.

SNOWFALL WILL WIND DOWN AROUND SUNRISE ON SATURDAY…ALTHOUGH
LINGERING SNOW SHOWERS COULD KEEP UP UNTIL NEARLY NOON ACROSS OUR
FAR EASTERN AREAS.

THE BIGGEST QUESTION IS HOW MUCH TOTAL SNOW WILL OCCUR. WE HAVE
SIDED GENERALLY WITH THE 00Z/12Z ECMWF QPF…AS THE ECMWF HAS BEEN
FAIRLY CONSISTENT FROM RUN TO RUN. THE ECMWF HAS ALSO BEEN
GENERALLY IN THE MIDDLE REGARDING THE STORM TRACK BETWEEN THE 12Z
GFS MODEL…WHICH IS TOO FAR EAST…AND THE 12Z NAM…WHICH IS
MUCH TOO FAR WEST. THE 12Z NAM IS CERTAINLY WELL OVERDONE WITH
IT/S QPF ACROSS OUR AREA. THE 09Z SREF GUIDANCE WOULD SUGGEST THAT
THE 00Z/12Z ECMWF LOOKS ON TRACK WITH BOTH IT/S TRACK AND EXPECTED
QPF AS WELL.

OUR CURRENT FORECAST CALLS FOR 8-12 INCHES OUR NORTHERN/NORTHWESTERN
ZONES…AROUND 10-12 INCHES ACROSS THE CAPITAL REGION/SCHOHARIE
VALLEY…10-16 INCHES ACROSS THE EASTERN CATSKILLS/MID HUDSON
VALLEY…12-16 INCHES ACROSS THE TACONICS AND SRN VT…12-18
INCHES ACROSS THE BERKSHIRES…AND 15-25 INCHES ACROSS LITCHFIELD
COUNTY.

IT WILL REMAIN COLD AND BLUSTERY IN THE WAKE OF THE STORM. HIGH
PRESSURE WILL START TO APPROACH BY SAT AFTN…ALLOWING FOR SKIES
TO CLEAR OUT. MAX TEMPS ON SATURDAY WILL BE IN THE 20S WITH A
COLD NW WIND. WITH THE EXPECTED CLEAR SKIES AND SNOWPACK IN
PLACE…TEMPS ON SATURDAY NIGHT WILL BE COLD…WITH SINGLE DIGITS
IN MANY AREAS /SOME BELOW ZERO READINGS ACROSS THE HIGH TERRAIN/.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/…
THE PERIODS STARTS OFF DRY…WITH DEEP LOW PRESSURE TRACKING ACROSS
THE UPPER GREAT LAKES THROUGH MONDAY. THIS WILL BRING A WINTRY MIX
ACROSS THE FORECAST AREA MONDAY. THE PRECIPITATION WILL BECOME SNOW
SHOWERS BEHIND A STRONG COLD FRONT MONDAY NIGHT. THE SNOW WILL WIND
DOWN ON TUESDAY…WITH A CHANCE OF LAKE EFFECT SNOW SHOWERS FOR THE
BALANCE OF THE PERIOD. IN ADDITION…A WEAK TROF ACROSS THE
MID-ATLANTIC ON WEDNESDAY WILL BRING A CHANCE OF SNOW SOUTH OF THE
CAPITAL REGION. WITH WEAK HIGH PRESSURE ON THURSDAY…ANY WEAK
DISTURBANCES COULD PRODUCE SOME ADDITIONAL SNOW SHOWERS OR FLURRIES
MAINLY ACROSS UPSLOPE REGIONS OF THE TACONICS/WESTERN NEW ENGLAND
CHAINS.

HIGH TEMPERATURES FROM THE UPPER 20S TO MID 30S ON SUNDAY WILL
MODERATE TO FROM AROUND 30 DEGREES IN THE ADIRONDACKS…TO AROUND 40
DEGREES IN THE MID HUDSON VALLEY. BY THURSDAY…HIGHS WILL HAVE
LEVELED OFF BACK NEAR THE SUNDAY HIGHS. LOWS WILL BE IN THE SINGLE
DIGITS AND TEENS SUNDAY NIGHT…THE 20S TO AROUND 30 DEGREES MONDAY
NIGHT…THE TEENS AND 20S TUESDAY NIGHT…AND FROM AROUND 10 TO
AROUND 20 DEGREES WEDNESDAY NIGHT.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/…
POWERFUL WINTER STORM WILL IMPACT THE REGION FRIDAY INTO SATURDAY.

VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST MIDNIGHT.
THEN…PATCHY LIGHT SNOW WILL DEVELOP AFTER MIDNIGHT…FIRST AT
KGFL…THEN EXPANDING TO KALB/KPOU AND KPSF AFTER 08Z.
INITIALLY…THE SNOW SHOULD BE LIGHT ENOUGH TO ONLY DROP VSBYS
INTO THE MVFR RANGE.

THE PERIODS OF MAINLY LIGHT SNOW SHOULD EVENTUALLY CAUSE IFR VSBYS
AND CIGS TO DEVELOP DURING THE MID TO LATE MORNING HOURS…WITH
SOLID IFR/LIFR CONDITIONS EXPECTED FOR FRIDAY AFTERNOON. THE SNOW
WILL BECOME STEADIER…AND INCREASE IN INTENSITY DURING THE MID TO
LATE AFTERNOON HOURS…WITH MODERATE SNOWFALL INTENSITY DEVELOPING.

WINDS WILL REMAIN LIGHT OVERNIGHT FROM THE NORTH TO NORTHEAST AT
GENERALLY LESS THAN 7 KT. NORTH TO NORTHEAST WINDS WILL INCREASE
TO 5-10 KT FRI MORNING…AND 10-15 KT BY LATE AFTERNOON.

OUTLOOK…
FRI NIGHT. IFR/LIFR WITH SNOW HEAVY AT TIMES.
SAT…MVFR/VFR…CHC -SN.
SAT NIGHT-SUN NIGHT…VFR…NO SIG WX.
MON-MON NIGHT…MVFR/IFR. CHC -SN/-PL/-FZRA CHANGING TO -RA.
TUE…VFR/MVFR. SLIGHT CHC -SHRA/-SHSN.

&&

.HYDROLOGY…
WIDESPREAD HYDRO PROBLEMS ARE NOT ANTICIPATED OVER THE NEXT FEW
DAYS AS OUR COLD WEATHER CONTINUES WITH ALL PRECIPITATION TOMORROW
INTO TOMORROW NIGHT IN THE FORM OF SNOW.

SOME RIVER AND STREAM GAGES ARE EXPERIENCING ICE EFFECTS. ICE
WILL CONTINUE TO FORM AND THICKEN ON ALL BODIES OF WATER THROUGH
THE WEEKEND.

EARLY NEXT WEEK…DAYTIME TEMPERATURES MAY RISE ABOVE
FREEZING…ALONG WITH THE POSSIBILITY FOR A LIGHT WINTRY MIX ON
MONDAY. THESE TEMPERATURES MAY ALLOW FOR SOME SNOW MELT…AND A SLOW DOWN ON
THE DEVELOPMENT OF ICE…BUT NO HYDRO ISSUES ARE ANTICIPATED 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…BLIZZARD WARNING FROM 6 AM FRIDAY TO NOON EST SATURDAY FOR
CTZ001-013.
NY…WINTER STORM WARNING FROM 6 AM FRIDAY TO NOON EST SATURDAY FOR
NYZ032-033-038>043-047>054-058>061-063>066-082>084.
MA…WINTER STORM WARNING FROM 6 AM FRIDAY TO NOON EST SATURDAY FOR
MAZ001-025.
VT…WINTER STORM WARNING FROM 6 AM FRIDAY TO NOON EST SATURDAY FOR
VTZ013>015.

&&

$$
SYNOPSIS…FRUGIS
NEAR TERM…KL/FRUGIS
SHORT TERM…FRUGIS
LONG TERM…ELH
AVIATION…KL/IRL/NAS
HYDROLOGY…FRUGIS/GJM

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