000
FXUS61 KALY 162058
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
358 PM EST THU FEB 16 2012
.SYNOPSIS…
A FAST MOVING FRONTAL BOUNDARY WILL BRING A ROUND OF WET WEATHER
TO THE REGION THIS EVENING. AS COLDER AIR FILTERS ACROSS THE OPEN
WATERS OF THE GREAT LAKES…SOME LAKE EFFECT SNOW MAY IMPACT
PORTIONS OF THE ADIRONDACKS AND WESTERN MOHAWK VALLEY. ANOTHER
FAST MOVING SYSTEM IS EXPECTED TO IMPACT THE REGION SATURDAY NIGHT
WITH A CHANCE FOR LIGHT SNOW.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/…
A VERY CHALLENGING NEAR TERM AS THE COMBINATION OF COOLING CLOUD
TOPS AND ISENTROPIC LIFT WILL RESULT IN A SHIELD OF PRECIPITATION
MOVING ACROSS THE REGION. PRECIPITATION INTENSITY IS ALSO
RESULTING IN WAVES OF RAIN/SNOW AND PERHAPS SOME SLEET MIXING IN
FROM TIME TO TIME. CURRENT SURFACE TEMPERATURES FROM MESONETS AND
RTMA ANALYSIS REVEALS TEMPERATURES ARE ABOVE FREEZING.
HOWEVER…THESE TEMPERATURES ARE OSCILLATING DEPENDING ON PRECIP
INTENSITY WHICH WILL BE A VERY CHALLENGING FOR THE HOURLY
GRIDS/FORECAST.
AFTER SUNSET…MOST OF THE PRECIPITATION WILL TRANSITION BACK TO
MAINLY SNOW. BACKEDGE OF THE PRECIP SHIELD WAS TRACKING ACROSS
WESTERN NY/PA. EXTRAPOLATION OF THIS WOULD PLACE THE PRECIP ENDING
TIME CLOSE TO 00Z FRIDAY FOR OUR WESTERN ZONES AND SHORTLY AFTER
03Z FOR OUR ADJACENT WESTERN NEW ENGLAND COUNTIES. BASED ON THE
TIMING OF CHANGEOVER TO SNOW AND THE ENDING OF THE PRECIP…THIS
SEEMS THE WINDOW FOR SNOW ACCUMULATIONS WILL BE RATHER LIMITED.
THEREFORE…WE WILL HOLD ACCUMULATIONS TO GENERALLY AROUND 1
INCH…MAINLY FOR THE HIGHER TERRAIN.
COLD ADVECTION EVOLVES OVERNIGHT AS 850MB FRONT TRACKS TOWARD THE
HUDSON RIVER VALLEY CLOSE TO 12Z FRIDAY. MEANWHILE A DRY SLOT IS
EXPECTED TO MOVE INTO NY/PA AS 1001MB SURFACE LOW TRACKS NORTHWARD
ACROSS ONTARIO/QUEBEC. OVERNIGHT LOWS WILL RANGE FROM THE UPPER
20S ACROSS THE TERRAIN AND LOW-MID 30S FOR THE VALLEY LOCATIONS.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/…
THE AFOREMENTIONED DRY SLOT MOVES ACROSS THE CWA DURING FRIDAY
MORNING WHERE AMPLE BREAKS IN THE CLOUDS ARE EXPECTED. WIND
TRAJECTORIES BECOME WESTERLY AS 850MB TEMPS DROP BACK TOWARD -10C.
THIS WOULD SET THE STAGE FOR A MARGINAL LAKE EFFECT EVENT DOWNWIND
OF LAKE ONTARIO AS INVERSION HEIGHTS ARE FORECAST TO BE BETWEEN
5-6K FEET /C0ULD BE A LITTLE HIGHER AS CYCLONIC FLOW INCREASES
OVER THE LAKE/. LOW LEVEL CONVERGENT SIGNALS REMAIN SUB-PAR AS
BANDS DO NOT LOOK TO BE TOO ORGANIZED. AT THIS TIME…WE WILL
PLACE 1-3 INCHES FOR PORTIONS OF HERKIMER COUNTY AND CLOSELY
MONITOR TRENDS.
OTHERWISE…MIXING LAYER HEIGHTS AND MOMENTUM TRANSFER SUGGESTS
WINDS WILL OCCASIONALLY GUST OVER 20KTS WITH SOME POTENTIAL
FUNNELING DOWN THE MOHAWK WITH GUSTS TO 30KTS IN THE CAPITAL
REGION. BASED ON CURRENT UPSTREAM TEMPERATURES IN THE WAKE OF THE
FROPA…WE WILL FORECAST HIGHS IN THE VALLEYS INTO THE 40S WITH
30S FOR THE WESTERN MOHAWK VALLEY AND HIGHER TERRAIN ABOVE 1000
FEET.
A SHORT WAVE RIDGE AXIS QUICKLY MOVES ACROSS NY STATE OVERNIGHT
FRIDAY WHICH WILL LOWER THE INVERSION HEIGHTS AND DIMINISH LAKE
EFFECT. STILL COULD SEE SOME CLOUD COVER ACROSS THE TERRAIN AS
THIS MOISTURE BECOMES TRAPPED UNDER THE SUBSIDENCE INVERSION.
LOOKING UPSTREAM…NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE
SUGGESTS A FAST MOVING CLIPPER SYSTEM DURING SATURDAY AND SATURDAY
EVENING. THIS WAVE WILL WEAKEN AS IT BECOMES ENTRAINED WITHIN THE
CONFLUENT FLOW. NEVERTHELESS…SEEMS A BAND OF PRECIP WILL MOVE
ACROSS THE REGION. AT THIS TIME…THERMAL PROFILES SUGGEST MAINLY
SNOW YET BOUNDARY LAYER TEMPS COULD BE A LITTLE WARMER FOR A
RAIN/SNOW MIXTURE WITH CURRENT QPF FIELDS AROUND ONE TENTH OF AN
INCH.
THIS SYSTEM QUICKLY DEPARTS TOWARD MIDNIGHT WITH IMPROVING
CONDITIONS AS HIGH PRESSURE RETURNS AND NEAR SEASONABLE
TEMPERATURES.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/…
THE NORTH ATLANTIC OSCILLATION (NAO) LOOKS TO REMAIN WEAKLY
POSITIVE THROUGHOUT THE EXTENDED PERIOD. THIS HAS BEEN THE
PREVAILING PATTERN ALL WINTER LONG AND AGAIN WHEN THE NAO IS
POSITIVE…THIS FEATURES A PERSISTENT LOW PRESSURE ANCHORED NEAR
ICELAND AND HIGH PRESSURE NEAR THE AZORES…WHICH WILL BE THE CASE
GOING INTO THE EXTENDED PERIOD. IN THIS MODE…THE POLAR JETSTREAM
USUALLY IS DISPLACED FURTHER NORTH THAN NORMAL AND
ZONAL…ALLOWING FOR LITTLE OR NO PHASING WITH THE SOUTHERN
JETSTREAM AND THEREFORE LIMITED OPPORTUNITY FOR COASTAL STORMS (IE
NOR`EASTERS). ALSO…THIS PATTERN KEEPS MOST OF THE REALLY ARCTIC
AIR TO OUR NORTH.
WE WILL START THE PERIOD WITH A STORM IN THE SOUTHERN STREAM WORKING
INTO THE MID ATLANTIC REGION SUNDAY. A FEW PAST MODEL RUNS OF THE
GFS…AND ENSEMBLE MEMBERS OF THE GFS…SUGGESTED THIS STORM WOULD
PHASE WITH THE NORTHERN JETSTREAM AND PRODUCE A SIGNIFICANT
SNOWSTORM. HOWEVER…THIS IS LOOKING LESS AND LESS LIKELY TO BE THE
CASE…AND MOST…IF NOT ALL MODEL GUIDANCE (INCLUDING THE MOST
RECENT 12ZGFS) HAS THIS SYSTEM SLIDING OFF TO OUR SOUTH…POSSIBLY
GRAZING OUR EXTREME SOUTHERN AREAS WITH A LITTLE SNOW OR RAIN SUNDAY
BUT EVEN HERE…THE ODDS FAVOR IT EVEN MISSING THESE AREAS. WE WILL
KEEP SLIGHT CHANCES IN ON SUNDAY INTO SUNDAY EVENING BUT THAT AS FAR
AS IT GOES.
AS THIS STORM SLIDES PRESUMABLY SLIPS TO OUR BY MONDAY…HIGH
PRESSURE BUILDS INTO THE REGION. MONDAY LOOKS SEASONABLY CHILLY AND
DRY WITH A GOOD DEAL OF SUNSHINE. AS THIS HIGH SLIDES TO OUR
EAST…TEMPERATURES WILL MODERATE ONCE MORE TO ABOVE NORMAL LEVELS
WHERE THEY HAVE BEEN MOST OF THE WINTER.
BY WEDNESDAY…A WEAK SYSTEM LOOKS TO MOVE ACROSS THE NORTHERN TIER
WITH POLAR JETSTREAM AND SHOULD BRING US A LITTLE RAIN (POSSIBLY
MIXED WITH WINTRY PRECIPITATION). FROM THIS VANTAGE POINT…THIS
SYSTEM LOOKS TO BRING ONLY LIGHT AMOUNTS OF QPF AS IT TOO WILL BE
MOVING QUICKLY IN THE PROGRESSIVE FLOW PATTERN WITH LITTLE
OPPORTUNITY TO REALLY STRENGTHEN.
ANOTHER COLD FRONT APPROACHES THURSDAY AND PERHAPS ANOTHER ONE FOR
FRIDAY…KEEP OUR WEATHER SOMEWHAT UNSETTLED WITH SLIGHT CHANCES OF
SHOWERS. HOWEVER…MUCH OF THIS TIME WILL LIKELY BE DRY TEMPERATURES
REMAINING A BIT ABOVE NORMAL.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/…
EVEN WITH A 5 TO 10 TEMP- DEWPT SPREAD…SNOW AND SLEET HAVE MADE
IT INTO THE VALLEYS. HEAVIEST PRECIP WILL BE IN THE FORM OF SNOW
LATER THIS AFTERNOON
…21Z-22Z ONSET…DETERIORATING CONDITIONS TO IFR FOR 3 TO 6
HOURS LATE THIS AFTERNOON INTO EARLY EVENING.
TEMPS ABV FREEZING WITH WETBULBS NEAR FREEZING WILL ALLOW FOR
RAIN TO MIX WITH SNOW AND SLEET…CHANGING TO ALL SNOW. TEMPS
WILL CONTINUE THEIR GRADUAL DROP WITH EVAPORATIVE COOLING..ESP
WITHIN HEAVIER PRECIP…ALLOWING FOR PRECIP TO CHANGE TO ALL SNOW
AROUND 21Z. UPSTREAM OBS SHOW IFR CONDITIONS IN HEAVIER PRECIP
AND MODELS SHOW BEST ISENTROPIC LIFT TO COME THIS AFTERNOON AND
EVENING. HAVE IFR VSBYS AND CIGS IN -SN ABOUT 21Z-02Z AT KALB AND
KPOU. KGFL COULD SEE HEAVIER PRECIP FOR A FEW HOURS LONGER.
AROUND 09Z-10Z…VSBYS WILL IMPROVE TO VFR AS -SN CHANGES OVER TO
MORE SHOWERY ACTIVITY…WITH CIGS CONTINUING TO GRADUALLY
IMPROVE IN THE EARLY MORNING.
WINDS OUT OF THE SOUTH WILL SHIFT SW AFTER MIDNIGHT…FURTHER
SHIFTING W-NW IN THE EARLY MORNING HOURS OF FRIDAY. WIND SPEEDS
GENERALLY 5-10 KTS THIS AFTERNOON THROUGH THE OVERNIGHT. WIND
SPEEDS WILL INCREASE LATE FRIDAY MORNING TO 8-13 KTS.
OUTLOOK…
FRI-SAT…VFR…NO SIG WX.
SAT NGT-SUN…VFR/MVFR. CHC -SN POSS MIX WITH -RA.
MON-TUE…VFR…NO SIG WX.
&&
.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED OVER THE NEXT SEVERAL DAYS. SOME
GAGES WILL CONTINUE TO HAVE ICE EFFECTS NORTH OF THE MOHAWK RIVER
VALLEY IN THE ALBANY HYDRO SERVICE AREA.
A LOW PRESSURE SYSTEM AND ITS ASSOCIATED COLD FRONT WILL BRING SOME
RAIN AND/OR SNOW TO THE REGION FROM THIS AFTERNOON THROUGH TONIGHT.
QPF AMOUNTS GENERALLY EXPECTED TO BE AROUND ONE-TWO TENTHS OF AN INCH TO
ONE THIRD OF AN INCH ACROSS THE HSA.
SOME LAKE ENHANCED OR UPSLOPE SNOWFALL IS POSSIBLE FOR THE WESTERN
ADIRONDACKS FRIDAY INTO SATURDAY WITH LIGHT ACCUMULATIONS EXPECTED.
THE WINTER SPRING FLOOD POTENTIAL OUTLOOK HAS BEEN ISSUED FOR
EASTERN NEW YORK AND WESTERN NEW ENGLAND. PLEASE REFER TO
ALBESFALY /FGUS71 KALY/ FOR FURTHER DETAILS.
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…BGM
NEAR TERM…BGM
SHORT TERM…BGM
LONG TERM…HWJIV
AVIATION…KGM
HYDROLOGY…BGM
FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
