February 24, 2012 Forecast Discussion

000
FXUS61 KALY 241034
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
535 AM EST FRI FEB 24 2012

.SYNOPSIS…
A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH TONIGHT
WITH SNOW AND RAIN. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY. FAIR AND
CHILLY CONDITIONS WILL RETURN FOR SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM TODAY/…
AS OF 500 AM…RADAR SHOWS THAT THE RUC SHORT TERM MODEL APPEARS TO
BE CORRECT THAT THE HEAVY BAND OF SNOW OVER THE SOUTHERN PART OF THE
FORECAST AREA WILL EXIT THE REGION TO THE EAST EARLY THIS MORNING…
AND ONLY RELATIVELY LIGHT SNOW WILL LIFT NORTH ACROSS THE REST OF
THE REGION. THIS WILL RESULT IN A LULL IN THE PCPN FOR MUCH OF THE
MORNING AND INTO EARLY THIS AFTERNOON…BEFORE ANOTHER ROUND OF
SIGNIFICANT PCPN MOVES IN LATER THIS AFTERNOON AHEAD OF THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVING THROUGH THE EASTERN GREAT
LAKES.

AS A RESULT…WITH NO WIDESPREAD SIGNIFICANT SNOW EXPECTED TO MAKE
IT NORTH OF GREENE…COLUMBIA AND BERKSHIRE COUNTY EARLY THIS
MORNING…DECIDED TO DROP THE WINTER WEATHER ADVISORY FOR THE
SCHOHARIE AND MOHAWK VALLEYS…THE HELDERBERGS AND THE NORTHERN
TACONICS. FURTHER NORTH SNOW WILL BE LIGHT THIS MORNING…BUT IT MAY
STILL BE COLD ENOUGH FOR ACCUMULATING SNOW THIS AFTERNOON WHEN THE
NEXT ROUND OF PCPN ARRIVES…SO THE WINTER WEATHER ADVISORY
CONTINUES ACROSS NORTHERN AREAS.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/…
COMING SOON.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/…
DETERMINISTIC…BOTH 00Z EURO AND 00Z GFS SHOW WEAK UPPER IMPULSE
MOVING NORTH OF THE AREA ON MONDAY. SOME TIMING DIFFERENCES BUT
OVERALL IMPACT WILL BE FOR CLOUDS/CHANCE POPS OVER NORTHERN THIRD OF
AREA. REST OF AREA SHOULD REMAIN PARTLY SUNNY AND DRY. AFTER
IMPULSE PASSES BY A WEAK COLD FRONT CROSSES AREA MONDAY NIGHT. COLD
ADVECTION MAY LEAD TO SOME SCATTERED LAKE EFFECT SNOW SHOWERS SO
SLT/CHC POPS NORTHWEST EARLY TUESDAY BUT RIDGING SHOULD LEAD TO
MAINLY FAIR WEATHER ACROSS AREA. BY WEDNESDAY ANOTHER STORM SYSTEM
MOVES INTO GREAT LAKES REGION AND UP SAINT LAWRENCE AND LIKE PRESENT
STORM…THIS ONE BRINGS WINTRY MIX CHANGING TO RAIN AND BACK TO SNOW
DOWNWIND OF LAKE ONTARIO AND OVER HIGHER TERRAIN. EURO A LITTLE
SLOWER BUT BY LATE THURSDAY ALL BUT FAR NORTHWEST SHOULD BE DRY WITH
LINGERING LAKE EFFECT AND UPSLOPE SNOW SHOWERS. BOTH MODELS SHOW
RIDGING BUILDING INTO THE AREA ON FRIDAY WITH FAIR WEATHER.

PROBABILISTIC…00Z GEFS ENSEMBLES SHOW HIGHEST PROBABILITY OF
PRECIP ON WEDNESDAY INTO THURSDAY. EXTENDED STATISTICAL GUIDANCE
SHOWS TEMPS AVERAGING ABOVE NORMAL ALTHOUGH SATURDAY THROUGH MONDAY
WILL BE NEAR NORMAL.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/…
A LOW PRESSURE SYSTEM WILL APPROACH FROM THE OHIO VALLEY TONIGHT
BRINGING A WINTRY MIX WITH VFR CONDITIONS GIVING WAY TO MVFR/IFR
CONDITIONS BETWEEN 08Z AND 13Z FROM SOUTH TO NORTH. THE WINTRY MIX
IS THEN EXPECTED TO GRADUALLY CHANGE TO ALL RAIN AT THE TAF SITES
BTWN 13Z AND 18Z WITH KGFL BEING THE SLOWEST TO CHANGE TO RAIN.
MVFR/IFR CONDITIONS ARE EXPECTED AT THE TAF SITES FROM 16Z-18Z
THROUGH MOST OF THE REST OF THE TAF PERIOD EXCEPT AT KPOU WHICH
COULD BECOME VFR FOR THE LAST FEW HOURS.

WINDS WILL BE LIGHT AND VARIABLE THROUGH THE REST OF THE OVERNIGHT
AND THEN BECOME EAST NORTHEAST AT 6 KTS OR LESS FRIDAY MORNING AND
EAST TO SOUTHEAST AROUND 10 KTS OR LESS FRIDAY AFTERNOON. DEPENDING
ON THE TIMING OF A COLD FRONT PASSAGE WINDS MAY SWITCH TO SOUTHWEST
TO WEST NEAR THE END OF THE TAF PERIOD AND BECOME GUSTY.

OUTLOOK….
FRI…MVFR/IFR CIGS/VSBYS…TRANSITION TO RA FROM KPOU TO KGFL IN
THE MORNING.
FRI NGT…VFR/MVFR…CHC -SHSN. BECOMING WINDY.
SAT…VFR…SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN…VFR…DECREASING WINDS.
MON…VFR SLIGHT CHC -SHRA/-SHSN.
TUE…VFR.

&&

.HYDROLOGY…
SOME MODERATE RIVER RISES ARE POSSIBLE OVER THE SOUTHERN THIRD OF
OUR AREA TONIGHT AS RUNOFF FROM MELTING SNOW COMBINES WITH RUNOFF
FROM SOME HEAVIER DOWNPOURS AHEAD OF A COLD FRONT. SOME PONDING OF
WATER IN LOW LYING AND POOR DRAINAGE AREAS MAY SLOW THE EVENING
COMMUTE. NO LARGER RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS.

SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA. PERSISTENT COLD TEMPERATURES THIS
WEEKEND MAY ALLOW ADDITIONAL ICE FORMATION TO OCCUR LATE SATURDAY
INTO EARLY MONDAY IN BASINS NORTH OF THE MOHAWK RIVER VALLEY.

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…WINTER WEATHER ADVISORY UNTIL 2 PM EST FRIDAY FOR NYZ058-063.
WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
NYZ032-033-042-043-061-082-083.
MA…WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
MAZ001-025.
VT…WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
VTZ013>015.

&&

$$
SYNOPSIS…GJM
NEAR TERM…GJM
SHORT TERM…GJM
LONG TERM…SND
AVIATION…SND
HYDROLOGY…SND

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