March 18, 2013 Forecast Discussion

000
FXUS61 KALY 181116
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
716 AM EDT MON MAR 18 2013

.SYNOPSIS…
A SIGNIFICANT STORM SYSTEM WILL APPROACH AND MOVE ACROSS THE
REGION TONIGHT AND TUESDAY. IN THE WAKE OF THIS STORM SYSTEM…WE
REMAIN WITHIN AN UNSETTLED PATTERN WITH BRISK WESTERLY WINDS AND
THE CHANCE FOR ADDITIONAL WINTRY PRECIPITATION FOR THE REMAINDER
OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
ALL IS QUIET THIS MORNING AND CHILLY AS 1030MB SURFACE HIGH WAS
ANCHORED ACROSS EASTERN NEW YORK AND INTO WESTERN NEW ENGLAND.
HOWEVER…UPSTREAM CONDITIONS ARE NOT AS QUIET AS CONVECTION AND
OVERRUNNING PRECIPITATION WERE EVOLVING. TODAY WILL BE MARKED BY
INCREASING CLOUD COVER FROM SOUTHWEST TO NORTHEAST AND THE CHANCE
FOR LIGHT SNOW DEVELOPING ACROSS THE CATSKILLS AND PERHAPS INTO
PORTIONS OF THE WESTERN MOHAWK VALLEY PER TIMING FROM THE LATEST
HOURLY RAP/HRRR. TEMPERATURES THIS MORNING ARE STARTING OUT COLD
AND WITH THE CLOUD COVER INCREASING…HIGHS TODAY WILL AVERAGE
INTO THE LOWER AND MIDDLE 30S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/…
…POTENT LATE WINTER STORM TO IMPACT THE REGION WITH WARNINGS
BEING ISSUED…

RATHER IMPRESSIVE ISENTROPIC LIFT ON THE 295K SURFACE SUGGESTS A
RAPID DETERIORATING CONDITIONS THIS EVENING FROM SOUTHWEST TO
NORTHEAST. PRECIPITATION WILL BE IN THE FORM OF SNOW THIS EVENING
AS COMBINATION OF WET BULB PROCESSES AND NOCTURNAL TIMING.
HOWEVER…ONE MAIN CHANGE THIS RUN OF THE NCEP MODEL SUITE AND
INTERNATIONAL GUIDANCE IS THE EVIDENCE OF A MID LEVEL DRY SLOT
CENTERED AROUND H500 AFTER 06Z TUESDAY. THIS WOULD ALLOW FOR A
PRONOUNCED DECREASE IN PRECIP INTENSITY AND LOSS OF THE ICE NUCLEI
FOR A PERIOD OF EITHER SLEET OR FREEZING RAIN/DRIZZLE APPROACHING
THE CAPITAL REGION. FURTHERMORE…THE STRENGTH OF THE WARM
ADVECTION ALOFT OVERNIGHT MAY RESULT IN A PERIOD OF ACCUMULATING
ICE ACROSS THE CATSKILLS…MID HUDSON VALLEY…NW CT AND THE
BERKS AS THE LOW LEVEL AGEOSTROPHIC LOW REMAINS FROM THE NORTHEAST
KEEPING THE SUB FREEZING TEMPS IN PLACE. THE COMBINATION OF
ACCUMULATING SNOW THEN A TRANSITION TO SLEET AND/OR FREEZING RAIN
ARE THE REASONS WHY THE WARNING WAS ISSUED FOR THESE AREAS. NORTH
AND WEST OF THESE AREAS…MAINLY SNOW IS EXPECTED. FOLLOWING THE
WPC WWD AND ECMWF WHICH WAS FAVORED BY REGIONAL AND NATIONAL
DISCUSSIONS…MANY LOCATIONS OVERNIGHT WILL ACCUMULATE 4-8 INCHES
WITH SOME HIGHER TOTALS ACROSS THE HIGHER TERRAIN OF THE DACKS AND
SOUTHERN GREENS INCLUDING THE LAKE GEORGE SARATOGA REGION.
ENSEMBLES OF THE U/V H925 WIND COMPONENTS SUGGEST -4 TO -5
STANDARD DEVIATIONS OF THE U COMPONENT AND +2 TO +3 STANDARD
DEVIATIONS OF THE V COMPONENT WITH PWAT ANOMALIES 1-2 STANDARD
DEVIATIONS ABOVE NORMAL. SO THERE IS NO LACK OF MOISTURE NOR WIND
CONTRIBUTIONS INTO PORTIONS OF THE CATSKILLS…BERKSHIRES AND
SOUTHERN VT FOR ENHANCED UPSLOPE CONDITIONS WHERE ACCUMULATIONS OF
FEW MORE INCHES ARE EXPECTED.

AS THE COASTAL LOW DEVELOPS OFF THE COAST OF NJ…DEFORMATION AXIS
WILL LINE UP ACROSS MOST OF EASTERN NY AND MIGRATING INTO WESTERN
NEW ENGLAND TUESDAY MORNING WITH ADDITIONAL ACCUMULATING
PRECIPITATION. CHALLENGING PRECIP TYPES DEVELOP ALONG AND SOUTH OF
I90 TUESDAY AS BOUNDARY LAYER TEMPS WARM ABOVE FREEZING WHICH WILL
HAVE AN IMPACT ON ACCUMULATIONS AND SOME RAIN MIXING IN. TROWAL
SETS UP NORTH OF I90 BY TUESDAY AFTERNOON YET THE MID LEVEL DRY
SLOT MAY CUT OFF THE BEST POTENTIAL FOR ICE NUCLEI AND MORE
SIGNIFICANT ACCUMULATING SNOWFALL.

TUESDAY NIGHT INTO WEDNESDAY…WE SHIFT OUR ATTENTION TOWARD LAKE
EFFECT/ENHANCEMENT WHERE PORTIONS OF THE ADIRONDACKS MAY
EXPERIENCE ADDITIONAL ACCUMULATIONS OF SNOW WHERE ADDITIONAL
HEADLINES MAY BE NEEDED. WE WILL EVALUATE THIS FURTHER ONCE THIS
MAIN STORM IMPACTS ARE EAST OF THE REGION.

IN CASE YOU WERE WONDERING…SPRING ARRIVES THIS WEDNESDAY MARCH
20TH AT 702 AM EDT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
THE EXTENDED PERIOD WILL BE DOMINATED BY A LARGE CUTOFF TROUGH
SITUATED OVER THE NORTHEASTERN US AND SOUTHEASTERN CANADA.
CYCLONIC FLOW AROUND THIS LARGE STALLED UPPER LOW WILL ALLOW FOR
PLENTY OF CLOUDS AND SOME SNOW SHOWERS AND FLURRIES…ESP FOR THE
HIGH TERRAIN AND FOR AREAS NORTH AND WEST OF THE CAPITAL
REGION…WHERE SOME LAKE ENHANCEMENT WILL OCCUR. WE HAVE INCLUDED
SLIGHT CHC/CHC POPS FOR THESE AREAS TO ACCOUNT FOR THIS
POSSIBILITY OF SOME LIGHT SNOW SHOWERS.

VORTICITY SWINGING AROUND THIS LARGE UPPER LOW MAY ALLOW FOR
SOME ADDITIONAL SFC CYCLOGENESIS ALONG THE MID ATLANTIC COAST FOR
THURS INTO THURSDAY NIGHT…BUT ANY DEVELOPMENT LOOKS WELL TO FAR
SOUTH AND EAST TO HAVE ANY IMPACT ON OUR REGION.

MAX TEMPS THURS/FRI WILL BE HELD IN THE 30S FOR MOST AREAS /SOME
UPPER 20S ACROSS THE HIGH TERRAIN/ WITH MINS IN THE TEENS TO LOW
20S.

THE CUTOFF TROUGH MAY FINALLY BEGIN TO MOVE EAST OF THE REGION FOR
THE WEEKEND…BUT A LARGE SCALE TROUGH WILL REMAIN SITUATED OVER THE
NORTH CENTRAL AND NORTHEASTERN PORTION OF THE CONUS. TEMPS WILL
MODERATE SOMEWHAT FOR THE WEEKEND…ALTHOUGH IT WILL STILL BE A
LITTLE BELOW NORMAL…WITH MAX TEMPS RANGING FROM THE MID 30S TO MID
40S…AND MINS MAINLY IN THE 20S.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/…
A SIGNIFICANT WINTER STORM WILL AFFECT THE AREA THIS EVENING THROUGH
THE OVERNIGHT HOURS AND INTO TOMORROW.

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE AFTERNOON HOURS
TODAY. HIGH LEVEL AND EVENTUALLY MID LEVEL CLOUDS WILL INCREASE
DURING THE MORNING AND AFTN HOURS…WITH BKN-OVC CIGS BY EARLY
EVENING AT ALL TAF SITES.

SNOW SHOULD DEVELOP AT KALB/KPSF/KGFL AROUND OR SHORTLY AFTER 00Z
TUESDAY. CONDITIONS WILL RAPIDLY DECREASE TO IFR ONCE SNOW COMMENCES
AND WILL BE HEAVY AT TIMES BY LATE THIS EVENING AT ALL SITES.

SLEET AND FREEZING RAIN WILL BEGIN TO MIX IN AFTER ABOUT 06Z AT
KPOU. SOME SLEET IS POSSIBLE AT KPSF LATE TONIGHT AS WELL. THE
PRECIP WILL DECREASE IN INTENSITY LATE TONIGHT…WHICH MAY ALLOW FOR
VSBYS AND PERHAPS CIGS AS WELL TO TEMPORARILY GO TO MVFR CONDITIONS
TOWARDS SUNRISE TUESDAY. HOWEVER…HEAVIER PRECIPITATION WILL
RETURN DURING THE DAY ON TUESDAY FOR ALL SITES.

CALM WINDS WILL BE IN PLACE THIS MORNING. E-SE WINDS AT LIGHT SPEEDS
WILL DEVELOP BY AFTERNOON TODAY. WINDS WILL BECOME E-NE AT 5-10 KTS
TONIGHT.

OUTLOOK…
TUE…LIFR/IFR. SNOW AT KALB/KGFL AND SNOW…SLEET AND FREEZING
RAIN POSSIBLE AT KPSF/KPOU.
TUE NIGHT-FRI…VFR/MVFR. BREEZY. CHC -SHSN.

&&

.FIRE WEATHER…
NO CRITICAL FIRE WEATHER CONCERNS THE NEXT FIVE DAYS.

A LATE WINTER STORM WILL IMPACT THE REGION WITH SNOW OR MIXED
PRECIPITATION BEGINNING LATE MONDAY AND LASTING INTO TUESDAY.
LIQUID PRECIPITATION AMOUNTS WILL BE WELL OVER HALF AN INCH
EVERYWHERE WITH ACCUMULATING SNOW LIKELY FROM ALBANY
NORTHWARD…AND SNOW OR MIXED PRECIPITATION SOUTH OF ALBANY.

THE REST OF THE WEEK WILL BE BLUSTERY AND COLD WITH LIMITED AMOUNTS
OF SUNSHINE AND SCATTERED SNOW SNOW SHOWERS…ESPECIALLY IN THE
MOUNTAINS.

&&

.HYDROLOGY…
NO HYDROLOGICAL PROBLEMS EXPECTED THROUGH THE NEW WEEK.

A MORE SIGNIFICANT PRECIPITATION EVENT WILL OCCUR LATE MONDAY
THROUGH TUESDAY. THERE IS A HIGH CHANCE FOR HALF AN INCH TO OVER ONE
INCH OF LIQUID EQUIVALENTS ACROSS THE ENTIRE REGION…BUT MUCH OF
IT WILL FALL AS SNOW OR MIXED PRECIPITATION. PER THE LATEST RIVER
ENSEMBLES…IMPACTS ARE EXPECTED TO BE MINIMAL 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…WINTER STORM WARNING FROM 6 PM THIS EVENING TO 8 PM EDT
TUESDAY FOR CTZ001-013.
NY…WINTER STORM WARNING FROM 6 PM THIS EVENING TO 8 PM EDT
TUESDAY FOR NYZ032-033-038>043-047>054-058>061-063>066-
082>084.
MA…WINTER STORM WARNING FROM 6 PM THIS EVENING TO 8 PM EDT
TUESDAY FOR MAZ001-025.
VT…WINTER STORM WARNING FROM 6 PM THIS EVENING TO 8 PM EDT
TUESDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…BGM
NEAR TERM…BGM
SHORT TERM…BGM
LONG TERM…FRUGIS
AVIATION…KL/FRUGIS
FIRE WEATHER…BGM
HYDROLOGY…BGM

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