February 25, 2012 Forecast Discussion

000
FXUS61 KALY 252045
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
345 PM EST SAT FEB 25 2012

.SYNOPSIS…
HIGH PRESSURE EXTENDING FROM THE WESTERN GREAT LAKES THROUGH THE
OHIO AND TENNESSEE VALLEYS WILL BUILD INTO THE EASTERN UNITED
STATES THROUGH TOMORROW NIGHT AND OFFSHORE MONDAY. LOW PRESSURE
WILL APPROACH FROM THE GREAT LAKES MONDAY AND TRACK ALONG THE
UNITED STATES…CANADA BORDER AND NORTHERN NEW ENGLAND…TRACKING
OFFSHORE TUESDAY MORNING.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/…
SNOW SHOWERS CONTINUE OVER THE REGION WITH THE HIGHEST INTENSITY
IN NORTHERN HERKIMER COUNTY WHERE THE SNOW HEADLINE WILL CONTINUE.
IT SEEMS SOME TRAILING UPPER ENERGY NORTHWEST BOUNDARY LAYER FLOW
AND SOME SURFACE BASED LAKE EFFECT MOISTURE IN WEST SURFACE FLOW
ARE ACTING TOGETHER TO PRODUCE THE SNOW SHOWER ACTIVITY. THERE IS
SOME ENHANCEMENT IN HIGHER ELEVATIONS INCLUDING AREAS AS FAR SOUTH
AS THE EASTERN CATSKILLS AND AS FAR EAST AS THE BERKSHIRES AND
SOUTHERN GREENS OF VERMONT. ACCUMULATIONS HAVE MOSTLY BEEN
CONFINED TO THESE HIGHER ELEVATIONS WHERE TEMPERATURES ARE NEAR
FREEZING. SCATTERED SNOW SHOWERS AND SQUALLS IN VALLEY AREAS HAVE
NOT RESULTED IN MUCH MORE THAN SOME DUSTINGS TO ISOLATED AMOUNTS
JUST UNDER AN INCH.

TRENDS IN DATA AND CURRENT GUIDANCE SUGGESTS THE UPPER ENERGY
EXITS THIS EVENING…AS DOES THE SURFACE LOW OUT OF SE CANADA.
SURFACE AND BOUNDARY LAYER FLOW WILL TURN MORE NORTH TO NORTHWEST
AND THE INVERSION SHOULD BECOME MORE SHALLOW THIS EVENING.
SO…SNOW SHOWER ACTIVITY…AND THE WIND ADVISORY WINDS SHOULD
DIMINISH BY EARLY THIS EVENING. SO…AGAIN…LAKE EFFECT SNOW AND
WIND ADVISORY HEADLINES WILL CONTINUE TO EXPIRATION.

SOME CLEARING SHOULD TAKE PLACE…ESPECIALLY OUTSIDE OF HIGHER
ELEVATIONS WHERE UPSLOPE WINDS COULD MAKE CLOUD COVER LINGER
LONGER. EVEN WITH WINDS DIMINISHING…WINDS SHOULD STAY STEADY
ENOUGH THAT FEW AREAS IF ANY WILL BE ABLE TO GO CALM. SO…LOW
TEMPERATURES TONIGHT SHOULD BE ON THE WARMER SIDE OF GUIDANCE AND
IN SOME CASES A DEGREE OR TWO WARMER THAN THE WARMEST GUIDANCE.
LIGHTEST WINDS AND COLDEST TEMPERATURES SHOULD BE IN THE SOUTHERN
ADIRONDACKS WHERE THE MOST SNOW HAS FALLEN.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/…
TOMORROW AND TOMORROW NIGHT…WEAK HIGH PRESSURE BUILDS IN…BUT
BY LATER SUNDAY NIGHT…ANOTHER WEAK MOISTURE STARVED NORTHERN
STREAM SYSTEM APPROACHES THE REGION FROM THE GREAT LAKES. A BRIEF
PERIOD OF COLD ADVECTION SHOULD OCCUR SUNDAY…WITH BREEZY WEST TO
NORTHWEST WINDS. MOST AREAS SHOULD BE PARTLY TO MOSTLY SUNNY. SO
WITH THE INCREASING SUN ANGLE AND SOME BREEZY WINDS…MIXING
SHOULD HELP TEMPERATURES TO REACH THE LOWER TO MID 30S IN MANY
AREAS. SOME MID 20S IN THE SOUTHERN ADIRONDACKS AND SOUTHERN
GREENS…AND SOME UPPER 30S MID HUDSON VALLEY AND NW CT. SOME MID
CLOUDS SHOULD TRACK THROUGH THE REGION TOMORROW NIGHT…WITH THE
BEST COVERAGE IN NORTHERN AREAS. STILL…WINDS SHOULD BE NEARLY
CALM…MAYBE BECOMING LIGHT SOUTH TOWARD DAYBREAK. LOWS IN THE
UPPER TEENS TO LOWER 20S. SOME SINGLE NUMBERS IN THE SOUTHERN
ADIRONDACKS.

ON MONDAY AND MONDAY EVENING…A WEAK UPPER IMPULSE TRACKS THROUGH
THE REGION…BUT WITH WEST TO WEST SOUTHWEST FLOW…AND LITTLE
MOISTURE ASSOCIATED WITH IT…JUST SOME SCATTERED TO ISOLATED SNOW
SHOWER ACTIVITY IN PARTS OF THE WESTERN MOHAWK VALLEY AND SOUTHERN
ADIRONDACKS. STRONG BOUNDARY LAYER FLOW FROM THE WEST AND
SOUTHWEST AND BREEZY SURFACE WINDS…ALONG WITH WARMING BOUNDARY
LAYER TEMPERATURES SHOULD RESULT IN HIGHS IN THE 40S…NEAR 50
CAPITAL DISTRICT AND LOWER TO MID 50S MID HUDSON VALLEY AND NW
CT…WITH AROUND 40 SOUTHERN ADIRONDACKS. COLD FRONT SHOULD TRACK
THROUGH MONDAY EVENING…AND COLD ADVECTION SHOULD SPREAD ACROSS
THE REGION THROUGH THE NIGHT. SOME CLEARING IS LIKELY…BUT WINDS
MAY STAY UP AS BOUNDARY LAYER FLOW STAYS STRONG. LOWS IN THE MID
TO UPPER 20S…UPPER TEENS TO LOWER 20S HIGHER ELEVATIONS.

COLD ADVECTION CONTINUES TUESDAY WITH INTERVALS OF CLOUDS AND
SUN…BUT SOME LAKE EFFECT MOISTURE COULD KEEP THE WESTERN MOHAWK
VALLEY AND SOUTHERN ADIRONDACKS MOSTLY CLOUDY. HIGHS IN THE LOW TO
MID 40S…AROUND 30 TO MID 30S HIGHER ELEVATIONS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/…
COMING SOON…

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/…
AS OF 1230 PM…A NARROW BAND OF LIFR LAKE EFFECT SNOW SHOWERS WAS
JUST SOUTH OF KALB. IT HAD LIFTED NORTH AND HAD ALREADY BEGUN TO
SLIP BACK TO THE SOUTH. THIS BAND IS EXPECTED TO MEANDER ABOUT
DURING THE DAYLIGHT HOURS UNTIL INCREASING DIRECTIONAL SHEAR AND
DRIER AIR PUTS THE KIBOSH ON THE ACTIVITY. THUS FOR KALB…HAVE A
4-HR PERIOD TEMPO FOR IFR VSBY IN -SHSN.

SECONDARY BANDS TO THE SOUTH ARE EXPECTED TO GET NEAR KPOU…BUT
BASED ON THE WIND FLOW SHOULD BARELY NUDGE AGAINST THEM WITH
UNDULATIONS. HAVE A 4-HOUR PERIOD IN MVFR VSBY -SHSN FOR THEM TILL
AROUND SUNDOWN. LIGHTER…LESS SIGNIFICANT BANDING ACROSS THE
SOUTHERN DACKS CERTAINLY WARRANTS A VCSH FOR KGFL.

VERTICAL SHEAR INCREASES IN BOTH SPEED AND DIRECTION TOWARD EVENING
AND BEYOND. WIND SHEAR GROUPS ENTER THE PICTURE BY THE 00Z TO 06Z
TIME FRAME…WITH SIGNIFICANT SPEEDS AT 2000 FEET PEAKING IN THE 40
TO 50 KT RANGE. THIS IS THE MAXIMA OF A LOW-LEVEL JET…AS SPEEDS
BEYOND 2000 FEET STEADY OFF OR DROP. THE JET MOVES OUT OVERNIGHT…
WITH 2000-FOOT SPEEDS REDUCED BY ALMOST HALF BY 12Z.

WINDS HAD MIXED DOWN AS EXPECTED THIS MORNING…AND WE CAN EXPECT
VELOCITIES IN THE 15 TO 25 KTS RANGE THIS AFTERNOON…WITH GUSTS
FROM ABOUT 25 TO 40 KTS. AS IS TYPICAL WITH A WNW FLOW…KALB WILL
BE FAVORED FOR THE HIGHER END OF THESE VALUES. THE SHEAR CONCERNS
WILL BE GONE DURING THE DAY ON SUNDAY…AND MIXING ON SUNDAY WILL
PRODUCE OCCASIONALLY GUSTY SURFACE WINDS AGAIN…THOUGH ONLY HALF AS
STRONG AS TODAY.

SUNDAY WILL BE VFR GALORE WITH BASICALLY CLEAR…SUNNY SKIES.

OUTLOOK….
SUN PM-SUN NGT…VFR…NO WX…DECREASING WINDS.
MON-TUE…VFR…NO SIG WX.
TUE NGT-WED…VFR…CHC MVFR/IFR IN -SN…TRANSITIONING TO -RA WED.

&&

.HYDROLOGY…
NO RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS…DESPITE
SOME MINOR RISES TONIGHT FROM RAINFALL ACROSS SOUTHERN AREAS.

SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA.

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…WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-013.
NY…WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR
NYZ032.
MA…WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-025.
VT…WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR VTZ013>015.

&&

$$
SYNOPSIS…NAS
NEAR TERM…NAS
SHORT TERM…NAS
LONG TERM…KL
AVIATION…ELH
HYDROLOGY…NAS

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License