February 4, 2013 Forecast Discussion

000
FXUS61 KALY 042059
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
359 PM EST MON FEB 4 2013

.SYNOPSIS…
A FAST MOVING WEATHER DISTURBANCE WILL TRACK ALONG THE INTERSTATE
80 CORRIDOR TONIGHT. THIS WILL BRING SOME CLOUDS AND THE CHANCE
FOR A PERIOD OF LIGHT SNOW SOUTH OF THE CAPITAL REGION OVERNIGHT.
A WEAK AREA OF HIGH PRESSURE WILL INFLUENCE OUR WEATHER ON TUESDAY
BEFORE THE NEXT CLIPPER ARRIVES TUESDAY NIGHT. THIS WILL PROVIDE
THE REGION WITH A PERIOD OF LIGHT SNOW THAT IS EXPECTED TO END
WEDNESDAY MORNING.

&&

.NEAR TERM /THROUGH TONIGHT/…
LAKE EFFECT SNOW BAND REMAINS RATHER DISORGANIZED /DIURNAL CYCLE/
AS THE BAND EXTENDS ACROSS SOUTHERN LAKE ONTARIO…INTO THE
SYRACUSE AREA…THEN INTO THE CAPITAL REGION WITH UPSLOPE
CONDITIONS ACROSS THE BERKSHIRES. PER THE LATEST RUC/RAP…THE LOW
LEVEL CONVERGENT SIGNATURE REMAINS IN PLACE WITH A SLIGHT
SOUTHWARD SHIFT TO SHORTLY AFTER SUNSET. SO WE WILL RETAIN POPS
THROUGH AT LEAST EARLY EVENING WITH A GRADUAL DECREASE AS SURFACE
HIGH BUILDS OVER THE LAKE AND THE RESULT OF SUBSIDENCE SHOULD
DIMINISH ADDITIONAL LAKE EFFECT ACTIVITY. WE WILL KEEP THE LAKE
EFFECT SNOW ADVISORY FOR SOUTHERN HERKIMER COUNTY UNTIL 7 PM EST.

AS SEEN IN THE H2O VAPOR IMAGERY…A RATHER FAST MOVING SHORT
WAVE WAS TRACKING BETWEEN THE I80/I70 CORRIDOR ACROSS THE MID
WEST. LATEST PROJECTIONS FROM THE NCEP MODEL SUITE SUGGEST ALONG
WITH UPSTREAM RADAR MOSAIC SUGGEST THE POTENTIAL FOR SOME LIGHT
SNOW SOUTH OF I90 OVERNIGHT. THERE ARE HINTS OF A WEAK BANDED
STRUCTURE ACROSS THE SOUTHERN THREE COUNTIES AS THE H850-700 2D
FGEN LAYER INCREASES TOWARD AND AFTER MIDNIGHT. AT THIS TIME…PER
COLLABORATION WITH NERFC…WE WILL KEEP THE QPF LOW WHICH WILL
HOLD ACCUMULATIONS TO ONE INCH OR LESS.

CLOUD COVER WILL BE PROBLEMATIC ALONG AND SOUTH OF I90 WITH
PARTIAL CLEARING TO THE NORTH. THIS WILL ALLOW FOR A DIVERSE
TEMPERATURES ACROSS THE REGION WITH BELOW ZERO READINGS ACROSS
THE DACKS TO MIDDLE TEENS FOR THE SOUTHERN CATSKILLS…MID HUDSON
VALLEY…NW CT.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/…
THE SYSTEM WILL BE DEPARTING OFF THE MIDDLE ATLANTIC COAST TUESDAY
MORNING AS A WEAK AREA OF HIGH PRESSURE CRESTS OVER THE REGION.
HOWEVER…LOW LEVEL MOISTURE REMAINS RATHER HIGH AND WITH DAYTIME
HEATING APPROACHING AND EXCEEDING THE CONVECTIVE
TEMPERATURE…ADDITIONAL CLOUD COVER IS EXPECTED. SO BREAKS OF
SUNSHINE WILL FADE BEHIND AN INCREASING CANOPY OF CLOUDS THROUGH
THE DAY. THIS WILL KEEP TEMPERATURES MAINLY IN THE TEENS AND 20S.

THE NEXT CLIPPER WILL BE FAST APPROACHING AS IT WAS CURRENTLY
TRACKING THROUGH ALBERTA. THIS ALBERTA CLIPPER WILL TRACK ACROSS
THE REGION TUESDAY NIGHT WITH AMPLE MOISTURE AND SOME ASSISTANCE
FROM THE GREAT LAKES FOR PERIOD OF LIGHT SNOW. A BROAD AREA OF QG
FORCING WILL BECOME MAXIMIZED FROM AROUND MIDNIGHT TIL NEAR
SUNRISE WEDNESDAY. ACCUMULATIONS ARE EXPECTED TO REMAIN BELOW
ADVISORY CRITERIA WITH 1-2 INCHES EXPECTED ON AVERAGE.

WEDNESDAY INTO WEDNESDAY NIGHT…SURFACE HIGH REESTABLISHES ITSELF
FOR A TRANQUIL PERIOD OF WEATHER. THERMAL PROFILES WILL BE A BIT
MILDER WEDNESDAY ALONG WITH A STRENGTHENING WET-NORTHWEST WIND FOR
DOWNSLOPING TO COMMENCE AND RAISE TEMPERATURES IN THE HUDSON RIVER
VALLEY AND NW CT INTO THE LOWER AND MIDDLE 30S AND 20S ELSEWHERE.
OVERNIGHT LOWS WILL DIP BACK BELOW FREEZING FOR THE DACKS AND
SINGLE DIGITS TO TEENS FOR THE REMAINDER OF THE CWFA.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/…
THE EXTENDED FEATURES QUITE OF BIT OF UNCERTAINTY FOR THE CLOSE OF
THE WORK WEEK WITH A POTENTIAL COASTAL LOW BASED ON THE ECMWF…AND
TEMPERATURES POTENTIALLY MODERATING BACK ABOVE NORMAL AFTER THE
WEEKEND…AS THE PERSISTENT LONGWAVE TROUGH OVER THE NORTHEAST
BEGINS TO WEAKEN.

THURSDAY…THE LATEST GFS…ECMWF…GLOBAL ENSEMBLES…CANADIAN
GLOBAL GEM ALL HAVE HIGH PRESSURE BUILDING IN FROM SRN QUEBEC OVER
THE FCST AREA. A SEASONABLY COLD AND DRY DAY IS ANTICIPATED WITH
TEMPS NEAR OR SLIGHTLY BELOW NORMAL. UPSTREAM OF NY AND NEW ENGLAND
A CLIPPER LOW WILL BE APPROACHING FROM THE UPPER MIDWEST AND THE WRN
GREAT LAKES REGION.

THURSDAY NIGHT INTO FRIDAY…CLOUD COVERAGE WILL INCREASE AS WE GO
INTO FRIDAY MORNING AS AN APPROACHING GREAT LAKES WEAK LOW PRESSURE
WORKS ITS WAY INTO OUR AREA ESPECIALLY ACROSS THE ADIRONDACKS. THE
TIMING OF THIS LOW PRESSURE INTO THE REGION IS VERY IMPORTANT FOR
WHAT COULD HAPPEN AS A DEVELOPING LOW PRESSURE SYSTEM OFF THE NORTH
CAROLINA COAST LINE MAY PHASE TOGETHER WITH THE LOW PRESSURE SYSTEM
MOVING INTO OUR NORTHERN AREAS AFTER 12Z FRIDAY.

FRIDAY TO FRIDAY NIGHT…12Z MODEL RUNS STILL SHOW DIFFERENT
SOLUTIONS WITH THE GFS AND CMC MODELS SHOWING NO PHASING OF THE TWO
UPPER LEVEL PATTERNS AND THE EURO SHOWING A STRONG DEVELOPING
CYCLOGENESIS WITH FAVORABLE UPPER LEVEL DYNAMIC CONDITIONS FOR THE
TWO PHASING UPPER LEVEL JETSTREAM. IT IS STILL TOO EARLY TO
DETERMINE QPF AMOUNTS BUT FURTHER UPDATES TO THE FORECAST WILL BE
MADE AS WE GET CLOSER TO THE EVENT.

FRIDAY NIGHT INTO TUESDAY…PRECIPITATION SHOULD BE EXITING THE
REGION BY 12Z SATURDAY AS WE RETURN TO FAIR WEATHER CONDITIONS AS A
HIGH PRESSURE BUILDS IN FROM THE SOUTHWEST UNDER A BROAD AREA OF
SURFACE DIVERGENCE UPSTREAM FROM THE DEPARTING UPPER LEVEL TROUGH.
THIS BROAD TROUGH BUILDING IN WITH A SOUTHERLY WIND FLOW WILL ALLOWS
TEMPERATURES TO BE PERHAPS SLIGHTLY ABOVE NORMAL DURING THE SECOND
HALF OF THE WEEKEND INTO EARLY NEXT WEEK. A COLD FRONT ASSOCIATED
WITH A LOW PRESSURE IN CANADA MAY WORK INTO THE AREA AT THE END OF
THE EXTENDED PERIOD. POPS ARE LOW AT THIS TIME WITH THE BEST CHANCE
OF PRECIP IN OUR NORTHERN AND WESTERN AREAS AS THE COLD FRONT
PROGRESSES THROUGH THE GREAT LAKES AREA EARLY NEXT WEEK. BUT THE
TIMING OF THIS FRONT WILL BE ONE TO WATCH AS WE GO INTO THE MIDDLE
OF NEXT WEEK.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/…
LOW PRESSURE WILL DEEPEN AND INTENSIFY OVER THE CANADIAN MARITIMES
WITH BLUSTERY CONDITIONS TODAY…AND SOME LAKE EFFECT SNOW SHOWERS
MAINLY SOUTH AND WEST OF KALB WILL CONTINUE. ANOTHER WEAK
DISTURBANCE WILL PASS SOUTH OF LONG ISLAND TONIGHT WITH PERHAPS
SOME LIGHT SNOW SHOWERS NEAR KPOU.

LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO MOVE ACROSS THE KALB-
KPSF CORRIDOR. OCCASIONAL BRIEF PERIODS OF IFR HAVE BEEN OCCURRING
AND WILL MENTION IN TEMPO GROUPS FOR THESE TWO TERMINALS THROUGH
19Z AT KALB AND 20Z AT KPSF. WILL KEEP MENTION OF VCSH AS MAIN
ACTIVITY SLOWLY SHIFTS SOUTHWARD.

OTHERWISE…VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE 24
HOURS PERIOD ENDING 18Z TUESDAY. AT LEAST BKN CLOUD COVER IN VFR
RANGE WILL LIKELY WILL LIKELY REMAIN OVERNIGHT…ASSOCIATED
WITH THE WEAK DISTURBANCE TO OUR SOUTH. ONLY TERMINAL WHERE THERE
IS A LOW PROBABILITY FOR A LIGHT SNOW SHOWER IS KPOU…WHERE A
VCSH HAS BEEN INDICATED FROM 06Z ONWARD.

WINDS WILL WEST-NORTHWEST AT 12-16 KTS WITH SOME GUSTS UP TO 25
KT…ESPECIALLY AT KALB AND KPSF. WIND SPEEDS WILL DECREASE TO 10
KT OR LESS AFTER SUNSET…BECOMING LIGHT AND VARIABLE AFTER
MIDNIGHT.

OUTLOOK…
TUE AFTN…VFR. NO SIG WX.
TUE NIGHT-WED MRNG. MVFR. CHC -SN AND ASSOC IFR.
WED AFTN…VFR/MVFR. CHC -SHSN. BREEZY.
WED NIGHT-THU…VFR. NO SIG WX.
THU NGT-FRI. MVFR/IFR. CHC OF SNOW.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE NOT ANTICIPATED OVER THE NEXT FEW DAYS AS OUR
COLD WEATHER CONTINUES WITH ANY PRECIPITATION 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.

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…LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ038.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…BGM
NEAR TERM…BGM
SHORT TERM…BGM
LONG TERM…LFM
AVIATION…JPV
HYDROLOGY…IAA/BGM

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

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