February 24, 2014 Forecast Discussion

000
FXUS61 KALY 242350
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
650 PM EST MON FEB 24 2014

.SYNOPSIS…
AN ARCTIC AIR MASS WILL BE IN PLACE THIS WEEK WITH BELOW NORMAL
TEMPERATURES. A SERIES OF DISTURBANCES ASSOCIATED WITH AN UPPER
LEVEL LOW WILL PRODUCE SCATTERED SNOW SHOWERS AND FLURRIES INTO THE
MID WEEK. A CLIPPER LOW ON WEDNESDAY WILL PRODUCE MORE WIDESPREAD
SNOW SHOWERS…AS IT PASSES ACROSS THE SOUTHERN QUEBEC AND NORTHERN
NEW YORK BORDER…WITH A REINFORCING SHOT OF ARCTIC AIR.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/…
AS OF 650 PM EST…NOT MANY CHANGES NEEDED WITH THIS FORECAST
UPDATE. CELLULAR SNOW SHOWER ACTIVITY HAS BEEN DECREASING IN
COVERAGE AND INTENSITY THIS EVENING AFTER SUNSET. THIS TREND
SHOULD CONTINUE OVERNIGHT..EXCEPT FOR THE CONTINUED THREAT FOR
LAKE EFFECT SNOW SHOWERS TO IMPACT AREAS FROM THE SOUTHWEST
ADIRONDACKS SOUTHWARD TO THE MOHAWK VALLEY. THE MOST CONCENTRATED
ACTIVITY IS EXPECTED TO BE ACROSS SOUTHERN HERKIMER COUNTY…WHERE
A LAKE EFFECT SNOW ADVISORY REMAINS IN EFFECT. WE DID LOWER
EXPECTED SNOWFALL TOTALS SLIGHTLY TO 3 TO 6 INCHES…SINCE
ACTIVITY HAS BEEN RATHER DISORGANIZED THUS FAR.

INVERSION HEIGHTS ARE MARGINAL UPSTREAM AT KSYR/KRME/KUCA AT 6-7
KFT AGL WITH A 280-290 DEG LOW-LEVEL TRAJ. THE INSTABILITY CLASS
IS CONDITIONAL TO MODERATE WITH THE POSSIBILITY OF NARROW
FRAGMENTED LAKE BANDS EXTENDING DOWNSTREAM INTO SRN HERKIMER
SUPPORTED BY THE LOCAL HIRESWRF COLUMNAR REF PRODUCT BTWN 00Z-03Z.
THE LATEST HRRR 3-KM REF PRODUCT ALSO KEYS INTO THIS AREA.
GENERALLY…SLIGHT TO LOW CHC POPS HAVE BEEN FORECAST TONIGHT WEST
OF THE HUDSON RIVER VALLEY…EXCEPT HIGH CHANCE TO LIKELY POPS FOR
THE WESTERN MOHAWK VALLEY AND A PORTION OF THE SOUTHWEST
ADIRONDACKS WHERE LAKE EFFECT ACTIVITY WILL BE MORE PRONOUNCED.

H850 TEMPS WILL BE IN THE -17C TO -20C RANGE WITH THE COLD
ADVECTION IN THE WAKE OF THE SFC TROUGH. EXPECT LOWS TO BE IN THE
UPPER SINGLE DIGITS AND TEENS FROM THE CAPITAL DISTRICT SOUTH AND
EAST…WITH SINGLE DIGITS TO A FEW BELOW ZERO READINGS /SRN DACKS/ OVER
THE NRN TIER. BRISK W/NW WINDS WILL GENERATE WIND CHILLS 10 TO 15
BELOW ZERO OVER THE SRN DACKS…AND GENERALLY 5 BELOW TO 5 ABOVE
IN MOST OTHER LOCATIONS.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/…
TUESDAY…ANY ORGANIZED LAKE EFFECT ACTIVITY DIMINISHES DUE TO THE
LOWERING INVERSION. HOWEVER…LAKE MOISTURE WILL STILL BE
UTILIZED…AS A WEAK MID LEVEL DISTURBANCE MAY FOCUS ISOLATED TO
SCATTERED SNOW SHOWERS AGAIN DURING DURING THE MORNING INTO THE
AFTERNOON…WITH THE BETTER CHANCE OF SNOWFALL IN THE AFTERNOON
ALONG THE WRN SPINE OF THE WRN DACKS…SRN GREENS…NRN-CNTRL
TACONICS AND BERKSHIRES. THE WESTERLY UPSLOPE SNOW SHOWERS AND
FLURRIES MAY PRODUCE LIGHT SNOW AMOUNTS OF A COATING TO AN INCH OR
TWO. H850 TEMPS WILL BE RUNNING 1 TO 2 STANDARD DEVIATIONS BELOW
NORMAL ACCORDING TO THE LATEST GEFS. TEMPS WILL STILL RUN ABOUT 10
DEGREES OR SO BELOW NORMAL. OUR FORECAST FAVORS THE COLD NAM MOS
MAX TEMPS WITH TEENS OVER THE SRN DACKS. LOWER TO M20S OVER THE
REST OF THE FCST AREA…EXCEPT U20S OVER THE MID HUDSON
VALLEY…SRN TACONICS…AND NW CT.

TUE NIGHT…A CLIPPER LOW APPROACHES FROM THE NRN GREAT LAKES
REGION…AND SE ONTARIO. THIS CLIPPER WILL TAP SOME LAKE EFFECT
MOISTURE…AS THE FLOW BACKS TO SOUTHWEST. THERE IS SOME SYNOPTIC
LIFT WITH THIS SYSTEM. OROGRAPHIC AND LOW-LEVEL CONVERGENCE MAY
PROMOTE A PERIOD OF LIGHT SNOW ESPECIALLY NORTH AND WEST OF THE
CAPITAL REGION. A BURST OF LAKE EFFECT OR LAKE ENHANCED SNOWFALL
MAY OCCUR OVER THE WRN DACKS/WRN MOHAWK VALLEY AROUND MIDNIGHT AND
THEREAFTER. 1-4 INCHES OF SNOWFALL MAY BE POSSIBLE…ESPECIALLY
OVER THE WRN DACKS BY WED MORNING. WITH THE WEAK THERMAL
ADVECTION…SLIGHT OR LOW CHANCES OF SNOW SHOWERS SPREAD EASTWARD
ACROSS THE FCST AREA AFTER MIDNIGHT. LOWS WILL RANGE FROM THE
SINGLE DIGITS OVER THE NW PORTION OF THE FCST AREA TO TEENS FROM
THE MOHAWK VALLEY/CAPITAL REGION SOUTH AND EAST.

WED-WED NIGHT…THE CLIPPER MOVES N/NE OF NRN NY OVER SRN QUEBEC
BY NOON. ANOTHER LOW PRESSURE SYSTEM FORMS WELL OFF THE MID
ATLANTIC COAST. A PERIOD OF SNOW SHOWERS OR LIGHT SNOW WILL IMPACT
THE REGION DURING THE MORNING INTO THE EARLY PM AHEAD OF THE
ARCTIC FRONT. CHC POPS WERE USED FOR THE ENTIRE AREA. SNOW ACCUMS
OF A COATING TO AN INCH WILL BE POSSIBLE. ARCTIC AIR POURS BACK
INTO THE REGION WITH H850 TEMPS FALLING TO -19C TO -23C OVER THE
FCST AREA…AND THE GEFS INDICATE THESE VALUES WILL BE 2 TO 3
STANDARD DEVIATIONS BELOW NORMAL. THE STRONG COLD ADVECTION SWEEPS
THROUGH BEFORE NIGHTFALL. AFTER HIGHS IN THE TEENS AND 20S WITH
BLUSTERY CONDITIONS…LOWS WILL BE ZERO TO 5 BELOW OVER THE SRN
DACKS AND PARTS OF THE LAKE GEORGE REGION….AND SINGLE DIGITS
ELSEWHERE. UPSLOPE AND LAKE EFFECT SNOW SHOWERS WILL CONTINUE IN
THE AFTERNOON…AND THEN TAPER SNOW SHOWERS NORTH AND WEST OF THE
TRI CITIES WITH ANOTHER DISTURBANCE APPROACHING FROM THE UPPER
GREAT LAKES REGION. WIND CHILLS VALUES MAY NOT HIT ADVISORY LEVELS
WED NIGHT DUE TO A WEAKENING WIND FIELD…BUT MAY HIT ADVISORY
LEVELS OVER SOME OF THE MTN ZONES THU NIGHT/FRI MORNING.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/…
A SERIES OF EMBEDDED SHORTWAVES WILL MOVE ABOUT THE BASE OF A LARGE
UPPER LEVEL TROUGH THAT WILL PROVIDE CHANCES OF SOME PRECIPITATION
THROUGHOUT THE EXTENDED PERIOD. THE UPPER LEVEL FLOW PATTERN WILL
BEGIN TO SLOWLY TRANSITION INTO A ZONAL PATTERN WITH COLD AIR STILL
IN PLACE AS WE GO THE THE END OF THE EXTENDED PERIOD.

THURSDAY INTO FRIDAY…COLD NORTHWESTERLY FLOW WITH BELOW AVERAGE
TEMPERATURES WITH T850 BETWEEN -20C TO -24C AND T925 TEMPS BETWEEN
-16C AND -20C WILL BE LOCKED INTO THE REGION. A NEGATIVE TILTED
SHORTWAVE TROUGH WITHIN THE UPPER LEVEL FLOW WITH THE AXIS OVER THE
NY/CANADA BORDER WILL PROVIDE THE CHANCE OF SNOW SHOWERS ESPECIALLY
AREAS NORTH AND WEST OF THE IMMEDIATE CAPITAL REGION NEAR THE UPPER
LEVEL TROUGH AS WE GO THURSDAY NIGHT INTO FRIDAY MORNING. A STEEP
GRADIENT IN ISOBARS WILL ALSO PRODUCE GUSTY NORTHWEST WINDS
WITH GUSTS NEAR 30 MPH POSSIBLE ESPECIALLY IN THE HIGHEST TERRAIN.
TEMPERATURES ON THURSDAY WILL RANGE FROM THE LOWER 20S TO UPPER 20S
WHICH WILL FALL TO LOWER TEENS IN THE HIGH TERRAIN TO NEAR 20 IN
VALLEY LOCATIONS ON FRIDAY. LOW TEMPERATURES ON THURSDAY WILL BE
VERY COLD WITH VALUES RANGING FROM 10 BELOW TO NEAR ZERO IN THE HIGH
TERRAIN TO AROUND ZERO TO 5 ABOVE FOR THE VALLEY AREAS.

FRIDAY NIGHT THROUGH MONDAY…COLD AIR FROM CANADA WITH
NORTHWESTERLY WINDS WILL CONTINUE WITH SERIES OF UPPER LEVEL TROUGHS
CONTINUING TO MOVE WEST TO EAST ACROSS OUR AREA WITH AREAS OF WEAK
HIGH PRESSURE IN BETWEEN THE PASSING DISTURBANCES AS THE UPPER LEVEL
WAVE OSCILLATES AROUND THE LARGE UPPER LEVEL LOW IN NORTHERN QUEBEC.
THE NEXT CHANCE OF SNOW SHOWERS ACCORDING TO THE LATEST 12Z MODELS
AND NUMERICAL GUIDANCE WILL BE DURING THE DAY ON SATURDAY AS ANOTHER
WAVE OF LOW PRESSURE MOVES RIGHT OVER OUR REGION ACCORDING TO THE
LATEST TRENDS. CHANCE OF SNOW SHOWERS WILL BE IN THE FORECAST AT
THIS TIME AS THE TRACK AND INTENSITY AGREEMENT BETWEEN THE MODELS
SHOW LOW CONFIDENCE AT THIS TIME. A SURFACE HIGH PRESSURE WILL WORK
INTO THE AREA ON SUNDAY GIVING TRANQUIL WEATHER CONDITIONS. AS WE GO
INTO MONDAY…THE MODELS DO DIFFER IN OUR NEXT WEATHER SYSTEM WITH
ITS TRACK AND INTENSITY. THIS WILL HAVE TO BE MONITORED WITH FUTURE
UPDATES TO THE FORECAST. HIGH TEMPERATURES FROM SATURDAY INTO MONDAY
WILL REMAIN BELOW AVERAGE WITH TEMPERATURES RANGING FROM THE MID
TEENS TO MID 20S. LOW TEMPERATURES WILL ALSO BE VERY COLD FOR THIS
TIME OF YEAR WITH TEMPERATURE 10 BELOW ZERO TO NEAR ZERO FOR THE
LAKE GEORGE SARATOGA REGION POINTS NORTH AND WEST AND ALSO IN THE
HIGH TERRAIN OF NEW ENGLAND AND WITH LOW TEMPERATURES OF 0 TO 5 IN
THE IMMEDIATE CAPITAL REGION AND VALLEY LOCATIONS.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/…
MAINLY VFR CONDITIONS WITH CIGS AROUND 3500-5000 FEET ARE
EXPECTED AT THE TERMINALS THROUGH THE 24 HOUR PERIOD ENDING 00Z
WEDNESDAY. THE ONLY EXCEPTION WILL BE A LOW PROBABILITY FOR A
PASSING SNOW SHOWER OR TWO. SNOW SHOWERS HAVE BEEN DIMINISHING IN
COVERAGE THIS EVENING WITH LOSS OF DAYTIME HEATING.
HOWEVER…THERE IS STILL A CHANCE FOR A FEW LAKE ENHANCED SNOW
SHOWERS TONIGHT INTO EARLY TUESDAY MORNING. WILL MENTION VCSH AT
THE ALB/KPSF/KGFL TERMINALS TO ACCOUNT FOR THIS CHANCE. ANY SNOW
SHOWER COULD BRIEFLY RESULT IN MVFR/IFR CONDITIONS…BUT
PROBABILITY OF OCCURRENCE IS TOO LOW TO MENTION EXPLICITLY IN
TAFS.

WEST-NORTHWEST WINDS WILL INITIALLY BE AROUND 10-15 KT WITH GUSTS
TO 25 KT ESPECIALLY AT KALB/KPSF…WITH WIND SPEEDS DECREASING TO
AROUND 5-10 KT AFTER MIDNIGHT. WIND SPEEDS WILL INCREASE AGAIN BY
MID MORNING TUESDAY TO AROUND 10-15 KT WITH SOME GUSTS NEAR 20 KT.

OUTLOOK…
TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.
WEDNESDAY: MODERATE OPERATIONAL IMPACT. WINDY. CHANCE OF SHSN.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: MODERATE OPERATIONAL IMPACT. BREEZY. CHANCE OF SHSN.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
FRIDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.

&&

.HYDROLOGY…
AN ARCTIC AIR MASS WILL REMAIN ACROSS THE HYDRO SERVICE AREA FOR
THE ENTIRE WEEK WHICH WILL ALLOW ICE TO REFORM…THICKEN…AND
STRENGTHEN ON AREA RIVERS AND LAKES THROUGH THE WEEK. LIGHT
PRECIPITATION IS EXPECTED DURING THE WEEK…AND ANY THAT DOES
OCCUR WILL BE IN THE FORM OF SNOW SHOWERS OR LIGHT SNOW. NO HYDRO
IMPACTS ARE EXPECTED ON THE MAIN STEM RIVERS THE NEXT 5 DAYS.

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…LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST TUESDAY FOR NYZ038.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…11/WASULA
NEAR TERM…JPV/WASULA
SHORT TERM…WASULA
LONG TERM…LFM
AVIATION…JPV
HYDROLOGY…11/WASULA

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