FXUS61 KALY 072329
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
629 PM EST MON DEC 7 2009
.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM WILL EXIT THE REGION EARLY TONIGHT. AFTER
THAT...A WEAK RIDGE OF HIGH PRESSURE WILL BUILD EASTWARD ACROSS THE
REGION LATER TONIGHT AND TUESDAY...ACCOMPANIED BY GENERALLY FAIR AND
SEASONABLY COLD CONDITIONS. A STRONG STORM SYSTEM WILL APPROACH FROM
THE GREAT LAKES FOR WEDNESDAY...BRINGING SNOW TO THE REGION VERY
LATE TUESDAY NIGHT...WHICH WILL LIKELY CHANGE TO MIXED PRECIPITATION
AND EVENTUALLY TO RAIN ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
A SHORTWAVE TROF AND WEAK ASSOCIATED SURFACE LOW WILL TRACK ACROSS
NORTHERN NEW YORK AND NORTHERN NEW ENGLAND EARLY TONIGHT AND EXIT
THE REGION. NORTHERN PART OF THE FORECAST AREA WILL HAVE THE HIGHEST
CHANCE OF SNOW SHOWERS WITH LIKELY POPS FORECAST THERE...AND
DECREASING POPS FURTHER TO THE SOUTHEAST. AFTER MIDNIGHT THE
FORECAST IS DRY FOR AREAS FROM ALBANY SOUTH AND EAST. EVEN WITH THE
SNOW SHOWERS TAPERING OFF...EXPECT CLOUDS TO LINGER SO TEMPS WILL
NOT DROP THAT MUC FROM CURRENT READINGS. HAVE ONLY FORECAST LOWS IN
THE LOW OR MID 20S THROUGHOUT THE REGION...EVEN THOUGH CURRENT TEMPS
(AS OF 500 PM) ARE IN THE UPPER 20S OR LOWER 30S.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
TUE...EXCEPT FOR POSSIBLE LINGERING SNOW SHOWERS/FLURRIES ACROSS THE
NORTHWESTERN PART OF THE FORECAST AREA...EXPECT FAIR AND DRY WEATHER
OVER MOST OF THE TREGION AS WEAK HIGH PRESSURE SYSTEM BUILDS IN.
SOME CLOUDS WILL STILL LINGER HOWEVER WITH THE FORECAST FOR MOST
AREA BEING MOSTLY CLOUDY IN THE MORNING AND PARTLY SUNNY DURING THE
AFTERNOON.
TUE NT/WED...COMPLEX STORM SYSTEM WILL INTENSIFY AND HEAD INTO THE
CENTRAL GREAT LAKES ON WED...WHILE A WEAK SECONDARY LOW MAY DEVELOP
ALONG THE WARM FRONT AND HEAD TOWARD THE GULF OF MAINE. GIVEN THAT
THE PRIMARY LOW IS EXPECTED TO REMAIN QUITE STRONG...ENOUGH WARM AIR
IS EXPECTED TO BECOME ENTRAINED IN THE MID/UPPER LEVELS OF THE
ATMOSPHERE TO PREVENT AN ALL SNOW SCENARIO FOR OUR REGION.
THERMAL PROFILES FROM THE LATEST MODEL RUNS INDICATE THAT THIS COULD
BE A SIMPLE SNOW CHANGING TO RAIN EVENT FOR MOST OF THE FORECAST
AREA WITH ANY FREEZING RAIN LIMITED TO SPOTTY LOCATIONS ACROSS THE
NORTHERN PART OF THE FORECAST AREA. HAVE REMOVED THE MENTION OF
FREEZING RAIN FROM THE GRIDS FOR NOW DUE TO THE LOW LIKELIHOOD BASED
ON THE 12Z MODELS...BUT LATER MODEL RUNS MAY REQUIRE THAT FREEZING
RAIN BE INCLUDED AGAIN.
IT/LL BE DRY THROUGH THE FIRST HALF OF TUESDAY NIGHT...WITH SNOW
RAPIDLY OVERSPREADING THE ENTIRE FORECAST DURING THE PREDAWN HOURS.
BY 12Z WEDNESDAY EXPECT SNOW TO BE FALLING THROUGHOUT THE FORECAST
AREA. CURRENT GRIDDED FORECASTS SHOW 3 TO 6 INCHES MAY FALL ACROSS
THE FORECAST AREA BEFORE A CHANGEOVER BEGINS DURING THE MID MORNING
TO EARLY AFTERNOON PERIOD. TOO EARLY TO ISSUE A WINTER WEATHER
ADVISORY FOR THIS EVENT...AND DON/T THINK IT WILL REACH WINTER STORM
CRITERIA...SO NO WINTER STORM WATCH WILL BE ISSUED AT THIS TIME.
STEADY PCPN WILL TAPER OFF TO SCT SHOWERY PCPN LATE WEDNESDAY
AFTERNOON AND WEDNESDAY EVENING. THE COLD FRONT WILL MOVE THROUGH
WEDNESDAY EVENING WITH A RAPID DROP OF MID LEVEL TEMPS...BUT A MUCH
SLOWER DROP AT THE SURFACE. SCT RAIN SHOWERS WILL CHANGE TO SNOW
SHOWERS WEDNESDAY NIGHT...BUT LITTLE ADDITIONAL ACCUMULATION IS
EXPECTED SINCE SIGNIFICANT LAKE EFFECT SNOW IS NOT EXPECTED TO GET
GOING UNTIL THURSDAY.
STRONG SOUTHEAST WINDS MAY BE AN ISSUE ON WEDNESDAY...ESPECIALLY
DURING THE MORNING. AT THIS POINT IS APPEARS WIND ADVISORY LEVEL
WINDS ARE POSSIBLE FOR HIGH TERRAIN AREAS...AND AREAS WHICH ARE
PRONE TO CHANNELING OF A SOUTHEAST FLOW.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AN EXTENDED PERIOD OF COLD WEATHER IS ANTICIPATED ACROSS MUCH OF
THE LONG TERM PERIOD. THIS MAKES SENSE BASED ON ENSEMBLE FORECASTS
WHICH SHOWS A NEGATIVE NAO ALONG WITH RIDGING ACROSS PORTIONS OF
ALASKA...AND AN MJO AROUND PHASE 8 OR NEUTRAL....WHICH FAVORS COLD
AND POTENTIALLY STORMY WEATHER ACROSS THE EASTERN CONUS.
THE START OF THE EXTENDED PERIOD WILL FEATURE A PERIOD OF LAKE
EFFECT FOR PARTS OF HERKIMER AND HAMILTON COUNTIES. LAKE TEMPS ARE
STILL AROUND 5-8 DEGREES C...AND EXPECTED 850 HPA TEMPS OF -16 TO
-18 DEGREES C /BASED OFF THE 12 UTC GFS/...SHOULD LEAD TO A LONG
DURATION PERIOD OF MODERATE TO EXTREME INSTABILITY BASED ON THE
NIZIOL LAKE EFFECT SCALE. WITH A LONG FETCH ACROSS LAKE
ONTARIO...AND A POSSIBILITY OF SOME MULTI-LAKE ENHANCEMENT OFF THE
UPSTREAM LAKES SUPERIOR AND HURON...HAVE FORECASTED LIKELY POPS
ACROSS THE WESTERN DACKS FOR THURSDAY INTO FRIDAY. THE INLAND EXTENT
OF THE LAKE BANDS IS STILL YET TO BE DETERMINED...ALTHOUGH THE
MUTLI-LAKE CONNECTION AND LOW DIRECTIONAL SHEAR IN THE LOWEST FEW
THOUSAND METERS OF THE COLUMN COULD FAVOR THE SIGNIFICANT LAKE
EFFECT ENTERING OUR AREA...BASED ON CURRENT ONGOING CSTAR RESEARCH.
MEANWHILE...THE REMAINDER OF THE CWA WILL BE MAINLY CLOUDY
WITH SOME LINGERING FLURRIES DUE TO THE LARGE SCALE TROUGH SITUATED
OVER THE NORTHEAST...ALTHOUGH SOME MORE SUNNY BREAKS ARE POSSIBLE
ACROSS THE MID HUDSON VALLEY WHERE DOWNSLOPING SHOULD HELP KEEP
SKIES PARTLY SUNNY DOWN THERE. THE OTHER ISSUE WILL BE THE WIND FOR
THURSDAY INTO EARLY FRIDAY WHICH WILL BE QUITE GUSTY AS THE PRESSURE
GRADIENT BETWEEN THE BUILDING HIGH AND DEPARTING LOW REMAINS STRONG.
TEMPS WILL SOMEWHAT SEASONABLE ON THURSDAY DUE TO DECENT
MIXING...BUT WILL BE HELD QUITE CHILLY FOR FRIDAY AS THE COLD AIR
REALLY SETTLES IN AND MOST AREAS WILL LIKELY NOT REACH FREEZING.
THE LAKE EFFECT WILL DIE DOWN ON SATURDAY AS A STRONG /1034 HPA/
HIGH PRESSURE MOVES JUST SOUTH OF THE REGION. THIS SHOULD HELP LOWER
THE INVERSION HEIGHT AND PUT AN END TO THE LAKE RESPONSE BY THE AFTN
HOURS. STILL...TEMPS WILL REMAIN COLD ON SATURDAY AND SUNDAY AS 850
HPA REMAINS IN THE -14 TO -18 DEGREES C RANGE...KEEPING MAX TEMPS
BELOW FREEZING FOR MUCH OF THE AREA.
MEANWHILE...LOW PRESSURE WILL BE ORGANIZING ACROSS THE CAROLINA
COAST FOR SAT NIGHT AND MOVING NORTHEASTWARD FOR SUNDAY. AT THIS
POINT...BOTH THE 12 UTC GFS/ECMWF SHOW THIS SYSTEM STAYING TO OUR
SOUTH...ALTHOUGH HAVE INCLUDED CHC POPS FOR SOUTHERN AREAS IN CASE
THIS SYSTEM BEGINS TO TREND NORTHWARD. WITH TEMPS SUFFICIENTLY
COLD...THIS SYSTEM WOULD BE ALL SNOW FOR OUR AREA IF IT WHERE TO
COME FURTHER NORTH THAN CURRENTLY PROGGED.
ANOTHER REINFORCING SURGE OF BITTER AIR WILL HEAD TOWARDS OUR AREA
ON SUNDAY NIGHT AS AN ARCTIC FRONT MOVES TOWARDS THE REGION. COULD
EVEN HAVE SOME SQUALLS ALONG THIS BOUNDARY AS IT CROSSES THE LAKES
AND PASSES THROUGH THE REGION. SINCE THIS IS DAY 7 TO 8...WILL NOT
GO MORE THAN LOW CHC/SLIGHT CHC POPS FOR NOW...BUT WILL CONTINUE TO
WATCH THE EVOLUTION OF THE FRONT. THE COLDEST AIR /850 HPA TEMPS TO
-20 TO -30 DEGREES C/ REMAIN ACROSS QUEBEC WITH THE UPPER LEVEL
LOW...ALTHOUGH CONTINUED COLD AIR OF -12 TO -16 DEGREE C AIR AT 850
HPA WILL KEEP MAX/MIN TEMPS BELOW NORMAL RIGHT INTO EARLY NEXT WEEK.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
DUE TO SCATTERED SNOW SHOWER ACTIVITY HAVE INCLUDED VCSH AT ALL
TERMINALS. MAINLY VFR CONDITIONS ARE EXPECTED OVERNIGHT. LIGHT
FOG MAY DEVELOP AT KGFL AROUND 6Z REDUCING VSBYS TO MVFR FOR A
BRIEF PERIOD. BY MORNING CEILINGS WILL INCREASE AS HIGH PRESSURE
MOVES IN. A BKN DECK OF HIGH CLOUDS WILL MOVE IN LATER IN THE
AFTERNOON TOMORROW AHEAD OF THE APPROACHING STORM.
WINDS WILL BE LIGHT AND OUT OF THE WEST OVERNIGHT INTO TOMORROW
AT ALL TERMINALS.
OUTLOOK...
WED...MVFR/IFR. SN/RA LIKELY.
THUR...VFR/MVFR...CHC -SHSN. WINDY.
FRI...VFR. NO SIG WX.
SAT...VFR. NO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS EXPECTED THROUGH EARLY WEDNESDAY AS ANY
PRECIPITATION UP TO THAT TIME WILL COME IN THE FORM OF SNOW AND THUS
HAVE NO DIRECT IMPACT ON THE RIVERS.
ON WEDNESDAY...SNOW MIXING WITH OR CHANGING TO RAIN COULD PRODUCE
SOME HYDRO PROBLEMS...ESPECIALLY FROM ALBANY SOUTH AND EAST WHERE
THE GREATEST AMOUNT OF RAIN IS EXPECTED TO FALL AND TEMPERATURES
WARM UP THE MOST.
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...GJM
NEAR TERM...GJM
SHORT TERM...GJM
LONG TERM...BJF
AVIATION...KREKELER
HYDROLOGY...GJM
