000
FXUS61 KALY 052213
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
510 PM EST TUE FEB 5 2013
.SYNOPSIS…
A CLIPPER SYSTEM WILL APPROACH AND MOVE ACROSS THE REGION
TONIGHT…BRINGING SOME VERY LIGHT SNOW TO THE AREA. FAIR WEATHER
IS EXPECTED MID WEEK AS HIGH PRESSURE BUILDS IN. A WIDESPREAD
SNOWFALL IS ANTICIPATED FOR THE LATER HALF OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/…
AS OF 505 PM…RADAR AND SURFACE OBSERVATIONS ARE INDICATING SOME
LIGHT SNOW SHOWERS DEVELOPING ACROSS THE MID HUDSON
VALLEY…SOUTHEAST CATSKILLS AND NW CT. IT APPEARS TO BE A
SEEDER-FEEDER AS THE HIGH AND MID CLOUDS ARE SEEDING THE LOWER
CLOUDS ALREADY IN PLACE. SO WE WILL RAISE THOSE SOUTHERN THREE
COUNTIES TO LIKELY POPS FOR THE REMAINDER OF TONIGHT.
OTHERWISE…UPSTREAM RADARS CONTINUE TO SHOW A BAND OF PRECIP ACROSS
SOUTHERN LOWER MICHIGAN AND TRACKING SOUTHEAST TOWARD OHIO. LATEST
HRRR REFLECTIVITY CONTINUES TO FAVOR MORE SCATTERED ACTIVITY
EVOLVING TONIGHT SO WE WILL KEEP THE CURRENT POPS IN PLACE AT THIS
TIME.
PREV DISC…
PER THE H2O VAPOR LOOP ANALYSIS…A FAST MOVING SHORT WAVE WAS
CROSSING THE LOWER GREAT LAKES REGION THIS AFTERNOON. REGIONAL
RADARS SHOW A SCT-BKN LINE OF PRECIPITATION THAT WAS ASSOCIATED
WITH WEAK FORCING. THIS FORCING IS EXPECTED TO REMAIN QUASI-
FOCUSED AS IT MIGRATES ACROSS THE CWFA. EXPERIENTIAL FORECAST
REFLECTIVITIES LEAD BY THE HRRR ALL SUGGEST A SCATTERED NATURE TO
THE SNOWFALL TONIGHT. ALONG WITH THE MOS GUIDANCE…WE WILL DROP
BACK POPS TO THE HIGH CHC-SCT CATEGORY WITH ACCUMULATIONS LESS
THAN 1 INCH FOR MOST LOCATIONS. THE CLOUD COVER WILL LIKELY REMAIN
EXTENSIVE OVERNIGHT WHICH SHOULD KEEP TEMPS A LITTLE MILDER THAN
THIS MORNINGS VALUES.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/…
WEDNESDAY…
MINOR LAKE EFFECT SNOW EVENT WILL BE POSSIBLE FOR PORTIONS OF THE
MOHAWK VALLEY AND ADIRONDACKS IN THE MORNING BEFORE THOSE
INVERSION HEIGHTS COLLAPSE TOWARD NOON. OTHERWISE…VARIABLE CLOUD
COVER WILL BEGIN TO SLOWLY IMPROVE THROUGH THE DAY AS TEMPERATURES
CLIMB INTO THE LOW-MID 30S FOR VALLEY LOCATIONS AND 20S ELSEWHERE.
WINDS WILL BE RATHER GUSTY THROUGH THE DAY AS WE MIX UP TO 30KT
MAGNITUDES. FURTHERMORE…THOSE WINDS MAY GET FUNNELED DOWN THE
MOHAWK RIVER FOR A SLIGHT ENHANCEMENT TO THOSE WESTERLY WINDS
THROUGH THE DAY.
WEDNESDAY NIGHT…
RIDGE OF HIGH PRESSURE WILL CREST OVER THE REGION. THIS WILL ALLOW
FOR…INITIALLY…CLEAR SKIES THROUGH THE EVENING HOURS WHICH WILL
SEND TEMPS QUICKLY DOWNWARD WITH NEAR IDEAL RADIATIONAL COOLING
/CLEAR SKIES AND LIGHT WINDS WITH A FROZEN AND PARTIAL SNOW
COVERED GROUND/. THEN WE WILL WATCH UPSTREAM CONDITIONS CLOSELY AS
STRONG PACIFIC ENERGY COMES ASHORE AND TRACKS ACROSS THE CENTER OF
THE NATION. NCEP MODEL SUITE ALONG WITH INTERNATIONAL GUIDANCE ARE
IN RATHER GOOD AGREEMENT WITH BROAD WARM ADVECTION ALOFT TO
COMMENCE OVERNIGHT WEDNESDAY INTO SUNRISE THURSDAY MORNING.
ISENTROPIC ANALYSIS ON THE 285-290K SURFACE SUPPORTS BROAD
ISENTROPIC LIFT AND SLOWLY LOWERING CPD/S TO RESULT WITH AN
INCREASE OF CLOUD COVER. THESE CLOUDS SHOULD LIMIT FURTHER
DECLINES IN THE TEMPERATURES OVERNIGHT AND MAY EVEN SEE A SLOW
REBOUND TOWARD SUNRISE.
THURSDAY…
THE AFOREMENTIONED ISENTROPIC LIFT CONTINUES THROUGH THE DAY
THURSDAY WITH A CONTINUE DECREASE IN THOSE CPD/S. THIS SHOULD
RESULT IN THE THICKENING AND LOWERING OF THE CLOUD DECK AND THE
CHANCE FOR OVERRUNNING LIGHT SNOW TO DEVELOP. WHILE MODEL QPF
SIGNALS ARE NOT SHOWING THIS ACROSS OUR REGION /THEY DO SO FURTHER
UPSTREAM/…THE COMBINATION OF CONTINUED ISENTROPIC LIFT AND LESS
THAN 30MB CPD/S…WE WILL PLACE CHC POPS ACROSS THE NORTHERN 1/2
OF THE CWFA BEGINNING BY LATE MORNING. THE BEST CHANCE FOR AN
ACCUMULATING SNOWFALL WILL LIKELY REMAIN ALONG AND NORTH OF I90
WHERE THE BEST LIFT AND MOISTURE PROFILES ARE EXPECTED AND VALUES
UP TO 1 INCH POSSIBLE. AS FOR TEMPERATURES…THE LOW LEVEL
AGEOSTROPHIC FLOW DOES INCREASE FROM THE NORTH AND THIS TOO SHOULD
LIMIT TEMPERATURES FROM GETTING OUT OF THE 20S.
THURSDAY NIGHT…
THIS WILL BE THE PERIOD OF TRANSITION TO A POTENTIAL STORM
IMPACTING THE REGION. GLOBAL MODEL TRENDS AND THE PERSISTENT ECMWF
FOR THE PAST 5 RUNS WANT TO PHASE THE NORTHERN STREAM PACIFIC
ENERGY WITH SOUTHERN STREAM WAVE/S/ ACROSS BAJA AND NORTHERN
MEXICO. LOW LEVEL SOUTHERLY JET AND MOISTURE TRANSPORT VECTORS
INCREASE RATHER RAPIDLY THURSDAY NIGHT WHERE THE CHANCE FOR LIGHT
SNOW TO INCREASE ACROSS THE REGION. GIVEN THE FORECAST WIND
TRAJECTORY AND MAGNITUDES…WE WILL FAVOR THE HIGHER TERRAIN WITH
LIKELY POPS AND HIGH CHANCE FOR THE VALLEY LOCATIONS. AS FOR
NOW…SNOWFALL AMOUNTS OF 1-2 INCHES WITH THE POSSIBILITY OF SOME
HIGHER TOTALS IN THE MOUNTAINS. GUIDANCE NUMBERS ARE FAIRLY CLOSE
AS WE LEANED MORE TOWARD THE GFS/ECMWF MOS NUMBERS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/…
HPC GUIDANCE. MOST MODELS NOW ON BOARD WITH A MAJOR WINTER EVENT
FOR THE END OF THE WEEK. LOW PRESSURE WILL BE NEAR VIRGINIA BEACH
AT THE START OF THE PERIOD…WITH SNOW ALREADY OVERSPREADING OUR
FORECAST AREA. THE LOW WILL TRACK TO SOUTH OF WESTERN NOVA SCOTIA
BY SATURDAY MORNING…INTENSIFYING RAPIDLY. A PERIOD OF RAIN OR A
SNOW MIX IS A POSSIBILITY BRIEFLY DURING THE DAY ON FRIDAY IN THE
LOWER SECTION OF THE MID HUDSON VALLEY…BUT FOR NOW WILL SAY IT IS
ALL SNOW. OTHERWISE…AN ALL-SNOW EVENT IS ANTICIPATED WITH
CONFIDENCE…WITH ACTIVITY WINDING DOWN SWIFTLY DURING THE DAY ON
FRIDAY. A FLOW TURNING NORTHERLY ENHANCED BY STRONG HIGH PRESSURE
MOVING IN BY SUNDAY ENSURES THAT WE HAVE AN ALL-SNOW EVENT BEYOND
FRIDAY AFTERNOON.
AS IT LOOKS RIGHT NOW…THE LOW IS EXPECTED TO STAY WELL ENOUGH TO
THE SOUTH…SUCH THAT 6 TO 10 INCHES OF TOTAL SNOW ACCUMULATION
LOOKS MOST REASONABLE…WITH THE GREATER AMOUNTS…OF COURSE…TO
THE SOUTH AND EAST IN OUR FORECAST AREA. MORE IS POSSIBLE…BUT SO
IS LESS…DEPENDING ON HOW THE SYSTEM EVOLVES. THIS LOOKS TO BE A
BROAD-AREA SNOW-PRODUCER.
BY SATURDAY NIGHT…SKIES WILL BE MOSTLY ON THE PARTLY CLOUDY
SIDE…WITH WINDS RAPIDLY DIMINISHING TO MAKE THE NIGHT A COLD ONE.
BUT THE REPRIEVE WILL BE BRIEF AS ANOTHER SYSTEM THREATENS THE
REGION WITH A WINTRY MIX OF PRECIPITATION FOR MONDAY/MONDAY NIGHT.
A COLD FRONT SLIDES THROUGH THE REGION…WITH TUESDAY BEGINNING A
PERIOD OF LAKE EFFECT SNOW SHOWERS…MAINLY WEST OF THE CAPITAL
REGION.
HIGH TEMPERATURES WILL RANGE FROM THE MID 20S IN THE ADIRONDACKS AND
GREENS…TO THE UPPER 30S IN THE LOWER MID HUDSON VALLEY. ON
SATURDAY…ALMOST ALL AREAS WILL FAIL TO CRACK THE FREEZING MARK.
ON SUNDAY…HOWEVER…ALMOST ALL LOCATIONS WILL MAKE IT TO AT LEAST
JUST ABOVE FREEZING. HIGHS ON MONDAY WILL RANGE FROM THE MID AND
UPPER 30S IN THE ADIRONDACKS AND GREENS…TO THE UPPER 40S IN THE
MID HUDSON VALLEY. THE COLD FRONT WILL BACK OFF TUESDAY HIGH
TEMPERATURES FROM AROUND 30 DEGREES IN THE ADIRONDACKS…TO THE MID
40S IN THE MID HUDSON VALLEY.
LOW TEMPERATURES BOTH FRIDAY AND SATURDAY NIGHTS WILL RANGE FROM
AROUND ZERO IN THE ADIRONDACKS…TO THE MID TEENS IN THE LOWER MID
HUDSON VALLEY. SUNDAY NIGHT LOWS WILL RANGE FROM THE UPPER TEENS IN
THE ADIRONDACKS…TO THE UPPER 20S IN THE LOWER MID HUDSON VALLEY.
A FURTHER MODERATION WILL TAKE PLACE FOR MONDAY NIGHT.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/…
WEAK HIGH PRESSURE WILL MOVE EAST OF THE REGION THIS EVENING…AS A
WEAK CLIPPER LOW MOVES INTO THE GREAT LAKES. SOME LIGHT SNOW IS
EXPECTED AT THE KALB/KPOU/KGFL/KPSF TERMINALS AS THIS SYSTEM TRACKS
ACROSS THE AREA TONIGHT. ACCUMULATIONS ARE EXPECTED TO BE VERY
LIGHT…ALTHOUGH IT IS LIKELY THAT IFR CONDITIONS MAINLY DUE TO VSBY
WITHIN THE LIGHT SNOW WILL OCCUR. THE LIGHT SNOW WILL END WEDNESDAY
MORNING AROUND OR SHORTLY AFTER SUNRISE…WITH CONDITIONS IMPROVING
TO VFR.
WINDS WILL BE NEAR CALM THROUGH AROUND SUNRISE WEDNESDAY…THEN
BECOMING WESTERLY WEDNESDAY MORNING AND INCREASING TO AROUND 5-10 KT.
OUTLOOK…
WED-THU…VFR. NO SIG WX.
THU NGT-FRI NIGHT. MVFR/IFR WITH SNOW LIKELY.
SAT…VFR…NO SIG WX.
&&
.HYDROLOGY…
WIDESPREAD 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…NONE.
MA…NONE.
VT…NONE.
&&
$$
SYNOPSIS…BGM
NEAR TERM…BGM
SHORT TERM…BGM
LONG TERM…ELH
AVIATION…JPV
HYDROLOGY…IAA/BGM
FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY
