000
FXUS61 KALY 042130
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
430 PM EST WED FEB 4 2015
.SYNOPSIS…
A FAST MOVING LOW PRESSURE SYSTEM WILL MOVE ACROSS
SOUTHERN QUEBEC INTO NORTHERN NEW ENGLAND TONIGHT. AN ARCTIC
FRONT WILL SLOWLY MOVE SOUTHEAST ACROSS THE REGION PRODUCING A
PERIOD OF ACCUMULATING SNOWFALL. A BITTERLY COLD AIR MASS WILL
BUILD BACK INTO THE REGION THURSDAY NIGHT INTO FRIDAY…AS SOME LAKE
EFFECT SNOW SHOWERS WILL IMPACT LOCATIONS NORTH AND WEST OF THE
CAPITAL REGION TO CLOSE THE WORK WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/…
AS OF 430 PM EST…LOW PRESSURE EAST OF GEORGIAN BAY WILL MOVE
ACROSS NRN NY/SRN QUEBEC AROUND MIDNIGHT…THEN EAST OF NRN NEW
ENGLAND BY DAYBREAK TOMORROW. AN ARCTIC COLD FRONT WILL SLOWLY
SAG S/SE ACROSS THE REGION. STRONG LOW-LEVEL CONVERGENCE ALONG THE
BOUNDARY WILL PRODUCE A PERIOD OF SNOW ACROSS THE FCST AREA FROM
N/NW TO S/SE ACROSS THE REGION.
THE ARCTIC FRONT SHOWS SIGNS OF BEING AN ANA COLD FRONT…AND NOT
A KATA COLD FRONT WITH THE BRUNT OF THE PCPN BEHIND THE WINDSHIFT
ON THE LEADING EDGE OF FRONTAL BOUNDARY. ALSO SOME UPPER LEVEL
SHORT-WAVE ENERGY WILL HELP INCREASE THE LIFT FOR AN EXTENDED OF
LIGHT TO POSSIBLY MODERATE SNOW. THERE ARE ALSO SIGNS THAT THE
LOW-LEVEL FGEN INCREASES IN THE WAKE OF THE FRONTAL WIND SHIFT TOO.
SNOWFALL AMOUNTS ARE TRICKY…AND WE USED A 12-15:1 RATIO FOR THE
EVENT. ALSO…THE BETTER QG LIFT LOOKS LIKE IT WILL BE FROM THE
ERN CATSKILLS…CAPITAL REGION…BERKSHIRES NORTH AND WEST. IT
LOOKS LIKE IT WILL BE A GENERAL 1-3" OR 2-4" SNOWFALL. IT WILL
PROMOTE A SLIPPERY MORNING COMMUTE. OUR WINTER WEATHER ADVISORY
CRITERIA IS A 4 INCH MID POINT OVER 12 HOURS. SOME LOCATIONS ALONG
THE WRN SPINE OF THE SRN GREENS…AND IN THE BERKSHIRES COULD GET
5 INCHES OR SO…ALSO THE BEST BET FOR 4 INCHES WILL BE OVER THE
WRN DACKS. IF THE COVERAGE AREA INCREASES FOR 4 OR MORE INCHES OF
SNOWFALL…THEN A WINTER WEATHER ADVISORY WILL BE NEEDED.
LOWS TONIGHT WILL BE DUE TO WET BULB COOLING EFFECTS AND THE
PLACEMENT OF THE LOW-LEVEL COLD ADVECTION WITH THE FRONTAL
PASSAGE. EXPECT LOWS A COUPLE DEGREES BELOW ZERO…TO SINGLE
DIGITS NORTH AND WEST OF THE CAPITAL DISTRICT…AND TEENS TO L20S
FROM ROUGHLY THE CAPITAL REGION…AND SRN VT SOUTH AND EAST.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/…
TOMORROW…THE SNOWFALL IN THE WAKE OF THE FRONT WILL STILL BE
PIVOTING FROM THE NRN CATSKILLS…CAPITAL REGION…AND SRN VT
SOUTH AND EAST AT 6 AM. AGAIN A GENERAL 1-4" IS EXPECTED WITH
ISOLATED HIGHER AMOUNTS OVER THE SRN GREENS AND BERKS. TEMPS
SHOULD CONTINUE TO FALL THROUGH THE DAY INTO THE TEENS AND SINGLE
DIGITS WITH BELOW ZERO READINGS OVER THE SRN DACKS.
EXPECT THE SNOW TO TAPER TO SCT FLURRIES AND SNOW SHOWERS BY
LUNCHTIME WITH THE ARCTIC AIR MASS BUILDING. H850 TEMPS CRASH TO
-20C TO -25C FROM ROUGHLY THE CAPITAL REGION NORTH AND WEST…AND
-18C TO -20C TO THE SOUTH AND EAST. BLUSTERY NW WINDS OF 10 TO 20
MPH WITH SOME GUST TO 30-35 MPH WILL YIELD SOME WIND CHILL VALUES
OF 15 BELOW TO 10 ABOVE DURING THE DAYTIME. A QUICK CHECK OF THE
MIN APPARENT TEMP VALUES SHOWS THAT WE DO NOT REACH WIND CHILL
ADVISORY CRITERIA PRIOR TO 6 PM IN THE 2ND PERIOD.
TOMORROW NIGHT…WIND CHILL ADVISORY CRITERIA MAY BE MET IN THE
THIRD PERIOD EARLY ON…ESPECIALLY OVER THE HIGHER TERRAIN. THE
BIG QUESTION IS WHETHER THE WINDS GO LIGHT TO CALM BETWEEN 06Z-
12Z. THIS WOULD NOT BE A WIND CHILL SITUATION THEN. A SPRAWLING
ANTICYCLONE OVER THE OHIO AND MS RIVER VALLEYS BUILDS INTO THE
REGION. THE RIDGE AXIS SETTLES OVER UPSTATE NY AND PA. SOME VERY
COLD TEMPS MAY BE REALIZED WITH THE FRESH 1-4" OF SNOW COVER ON
THE DEEP SNOW PACK. OUR FCST IS ABOUT 3-5 DEGREES COLDER THAN A
MAV/MET BLEND WITH LOWS 10 TO 20 BELOW ZERO NORTH AND WEST OF THE
CAPITAL REGION…AND ZERO TO 10 BELOW TO THE SOUTH AND EAST. IF
THE WINDS HOLD UP AT 5-10 MPH THEN WIND CHILLS OF 10 TO 30 BELOW
COULD BE POSSIBLE. OVERALL…ANOTHER FRIGID NIGHT.
FRI-FRI NIGHT…A CLIPPER LOW WILL BE PASSING S/SE OF JAMES BAY
FRIDAY MORNING. SOME WARM ADVECTION OCCURS OVER THE FCST AREA.
SOME LAKE EFFECT SNOW SHOWERS INDUCED BY THE ISENTROPIC LIFT AHEAD
OF THE CLIPPER WILL PRODUCE SOME LIGHT SNOWFALL OVER THE W-CNTRL
MOHAWK VALLEY…SRN DACKS AND THE SRN GREENS. MOST OF THE FCST
AREA WILL STAY DRY WITH HIGHS MAINLY IN THE TEENS…EXCEPT FOR
SOME LOWER 20S OVER THE MID HUDSON VALLEY. IN THE W/NW FLOW IN THE
WAKE OF THE CLIPPER SOME LAKE EFFECT SNOW FIRE UP. THE WRN
DACKS…NRN CATSKILLS…AND W-CNTRL MOHAWK VALLEY COULD RECEIVE A
FEW INCHES. ALSO SOME WESTERLY UPSLOPE SNOWFALL IS POSSIBLE ALONG
THE SRN GREENS AND NRN TACONICS. IT LOOKS LIKE A MULTI-LAKE
CONNECTION ALONG THE FRONTAL BOUNDARY TRAILING THE CLIPPER. THIS
BOUNDARY COULD BE THE FOCUS FOR SEVERAL BOUTS OF SNOWFALL THROUGH
THE WEEKEND INTO EARLY NEXT WEEK. LOWS FRI NIGHT WILL BE IN THE
SINGLE DIGITS AND LOWER TEENS.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/…
AS WE START THE LONG TERM
PERIOD EXTENDING OUT THROUGH EARLY NEXT WEEK…A PROLONGED PERIOD OF
LIGHT TO AT TIMES MODERATE SNOW IS IN THE FORECAST WITH TEMPERATURES
REMAINING BELOW NORMAL THROUGHOUT THE ENTIRE EXTENDED PERIOD.
AS WE START ON SATURDAY…LATEST 04/12Z MODEL AND PROBABILISTIC
GUIDANCE SUPPORTS AN ACTIVE SYNOPTIC PATTERN WITH OUR REGION BEING
UPSTREAM OF AN UPPER LEVEL TROUGH AXIS OVER THE NORTHERN ATLANTIC.
THIS IN RETURN IN CONJUNCTION WITH A 100-110 KT NORTHERN STREAM JET
WITH ASSOCIATED PERTURBATIONS FROM THE MAIN FLOW AT 500 HPA WILL
CAUSE LOCAL AREAS OF POSITIVE VORTICITY TO ENHANCE VERTICAL LIFT.
THIS WILL ALL BE FURTHER ASSOCIATED WITH A STATIONARY FRONT
EXTENDING FROM THE UPPER MIDWEST INTO PENNSYLVANIA AS WE GO INTO
SATURDAY EVENING. WITH OUR REGION BEING ON THE NORTH SIDE OF THE
STATIONARY BOUNDARY…A GOOD CAA WILL BE ESTABLISHED ACROSS THE
REGION. LATEST CROSS SECTION COMPOSITES SHOW GOOD VALUES OF 850-700
HPA FRONTOGENESIS NORTH OF THE STATIONARY FRONT BOUNDARY ALONG WITH
GOOD 700 HPA OMEGA VALUES. THIS WILL HELP TO FURTHER INCREASE OUR
CHANCES FOR SOME SNOWFALL ACROSS THE REGION. WITH THE CURRENT 12Z
GUIDANCE AND NUMERICAL DATA…THE QUASI STATIONARY FRONT OVER THE
REGIONS PREVIOUSLY INDICATED WILL STAY ACROSS THAT DOMAIN OVER THE
WEEKEND. IF THIS SOLUTION PANS OUT…OUR REGION CAN EXPERIENCE SOME
PERSISTENT LIGHT TO MODERATE SNOWFALL OVER THE COURSE OF THE WEEKEND
INTO EARLY NEXT WEEK. EXACT TIMING AND AMOUNTS WILL BE UPDATED IN
FUTURE FORECASTS.
AS WE GO TOWARD MONDAY NIGHT…12Z MODEL DATA SHOW SOME ACCORD WITH
AN UPPER LEVEL TROUGH DIVING SOUTH FROM THE MIDWEST INTO THE
SOUTHEAST AND WILL HELP TO PUSH EASTWARD THE BAROCLINIC ZONE OVER
THE MID ATLANTIC EASTWARD AS A SURFACE LOW DEVELOPS DOWNSTREAM OF
THE TROUGH AXIS OVER THE SOUTHEAST COASTLINE BY TUESDAY MORNING. AS
THIS IS OCCURRING…AN ENERGY TRANSFER LOOKS TO BE TAKING PLACE TO
THE COASTAL SYSTEM AS IT MOVES UP THE COASTLINE TUESDAY NIGHT INTO
WEDNESDAY MORNING. POPS DROP OFF ACROSS THE REGION TUESDAY AFTERNOON
AS OUR REGION AT THIS TIME IS FAR OFF COURSE FROM HAVING A WESTERLY
IMPACT BY THIS COASTAL SYSTEM. UPDATES TO FUTURE FORECAST WILL BE
MADE AS WE GET CLOSER TO THIS EVENT. HIGH TEMPERATURES MONDAY
THROUGH WEDNESDAY WILL RANGE FROM THE UPPER TEENS IN THE HIGH
COUNTRY TO MID 20S IN VALLEY LOCATIONS.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/…
THE FIRST ROUND OF SNOW
SHOWERS/FLURRIES HAS JUST ABOUT ENDED ACROSS THE KALB/KGFL/KPSF/KPOU
TAF SITES. EXPECT VFR CONDITIONS AT THE TAF SITES INTO THIS
EVENING…WITH JUST A TEMPO GROUP INCLUDED FOR MVFR VSBYS AT
KGFL/KALB/KPSF DUE TO LINGERING SNOW SHOWERS.
LATER THIS EVENING…A MORE STEADY SNOW WILL SPREAD ACROSS THE
REGION AS AN ARCTIC COLD FRONT MOVES IN FROM THE NORTHWESY. THE
FRONT WILL MOVE ACROSS THE TAF SITES BETWEEN 06Z AND 09Z. EXPECT
MVFR/IFR CIGS/VSBYS DUE TO SNOW A FEW HOURS BEFORE AND A FEW HOURS
AFTER THE FRONTAL PASSAGE. AROUND AND AFTER 12Z ON TUESDAY…
CONDITIONS WILL RAPIDLY IMPROVE TO VFR AT ALL THE TAF SITES.
EXPECT SOUTH TO SOUTHWEST WINDS AT THE TAF SITES AHEAD OF THE COLD
FRONT AT 5 TO 10 KTS…WITH SOME GUSTS AROUND 15-18 KTS AT KALB.
BEHIND THE FRONT THE WINDS WILL SHIFT TO NORTH OR NORTHWEST AT 8 TO
12 KTS…AND INCREASE TO 10 TO 14 KTS WITH GUSTS OF 16 TO 22 KTS BY
MID MORNING ON THURSDAY.
&&
.HYDROLOGY…
NO SIGNIFICANT HYDROLOGIC PROBLEMS ARE EXPECTED THE NEXT 5 DAYS.
BELOW NORMAL TEMPERATURES WILL BE THE GENERAL RULE WHICH WILL
ALLOW ICE TO THICKEN ON RIVERS…STREAMS CREEKS…LAKES AND OTHER
BODIES OF WATER.
A LIGHT SNOWFALL OF 1 TO 4 INCHES WILL BE COMMON TONIGHT INTO
TOMORROW. PERIODS OF LIGHT TO MODERATE SNOW WILL BE INTERMITTENT
FROM THE WEEKEND INTO EARLY NEXT WEEK ALONG A FRONTAL BOUNDARY.
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…WASULA
NEAR TERM…WASULA
SHORT TERM…WASULA
LONG TERM…LFM
AVIATION…GJM
FIRE WEATHER…
HYDROLOGY…KL/WASULA
