November 25, 2013 Forecast Discussion

000
FXUS61 KALY 252127
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
427 PM EST MON NOV 25 2013

.SYNOPSIS…
LOW PRESSURE DEVELOPING IN THE GULF STATES…LOOKS TO TRACK UP THE
EASTERN SEABOARD LATE TUESDAY THROUGH EARLY THANKSGIVING DAY…
RIGHT THROUGH THE HUDSON VALLEY. THIS TRACK WILL LIKELY BRING MOST
AREAS MORE RAIN THAN SNOW…BUT SIGNIFICANT AMOUNTS OF WINTRY
PRECIPITATION ARE POSSIBLE OVER THE ADIRONDACKS.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/…
MID AND HIGH CLOUDS CONTINUING TO STREAM INTO THE REGION. PERIOD
OF PARTLY CLOUDY TO MOSTLY CLEAR SKY THIS EVENING WILL ALLOW
TEMPERATURES TO DROP INTO THE LOWER TO MID 20S. ONCE CLOUDS
THICKEN…TEMPERATURES SHOULD HOLD STEADY..AND PERHAPS RISE A
DEGREE OR TWO TOWARD SUNRISE AS WARM ADVECTION BEGINS TO
INCREASE.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/…
…WINTER STORM WATCH REMAINS IN EFFECT FOR THE SOUTHERN
ADIRONDACKS…

STORM SYSTEM STILL EXPECTED TO AFFECT THE REGION TOMORROW THROUGH
WEDNESDAY NIGHT. BASED ON THE SOUTHERN STREAM DOMINANCE OF THE
SYSTEM…THE ASSOCIATED CONVECTION AND DOWNSTREAM UPPER
RIDGING…SIDING WITH MOE WESTERN TRACK OF THE SURFACE FEATURE
AND WARMER GUIDANCE IN TERMS OF TEMPERATURES ALOFT. THIS WOULD
SUGGEST SOME PERIODS OF LIGHT SNOW TOMORROW ALONG THE FORWARD
SURGE OF THE MID LEVEL JET…MOISTURE AND ISENTROPIC LIFT WITH
TEMPERATURES REACHING THE 30S IN THE AFTERNOON…PERHAPS AROUND 40
HUDSON VALLEY TOWARD AND AFTER SUNSET ONCE THE WARM ADVECTION
INCREASES RAPIDLY. SNOW SHOULD CHANGE TO A MIX AND RAIN IN VALLEY
AREAS AND SOUTHERN AREAS AROUND OR JUST AFTER SUNSET. ANY SNOW
ACCUMULATIONS DURING THE DAY WOULD BE LITTLE IF ANYTHING.

LOW LEVEL JET ENERGY SURGES NORTH TUESDAY NIGHT WITH VERY HIGH
PWAT…FORCING AND UPPER DYNAMICS. BASED ON THE LOW LEVEL RIDGING
BEING OFFSHORE THE MID ATLANTIC COAST…AGEOSTROPHIC WINDS NOT
SUGGESTING ANY COLD ADVECTION TO ANCHOR COLD AIR AT LOW LEVELS…
SO WARM AIR SHOULD BE ABLE TO SPREAD NORTH THROUGH THE NIGHT.
STILL…AREAS OF THE WESTERN MOHAWK VALLEY…LAKE GEORGE SARATOGA
REGION AND SOUTHERN ADIRONDACKS WILL BE THE SLOWEST TO WARM WHERE
ACCUMULATING SNOW…FREEZING RAIN AND SLEET WILL OCCUR.
TEMPERATURES MAY FALL A DEGREE OR TWO TOMORROW EVENING BUT THEN
RISE AFTER MIDNIGHT AND THROUGH SUNRISE…AGAIN…WITH THE MOST
WARMING OUTSIDE OF NORTHERN AND NORTHWESTERN AREAS.

THE COMBINATION OF SNOW…FREEZING RAIN AND SLEET COULD BE ENOUGH
FOR WINTER STORM WARNINGS…BUT JUST KEEPING THE WATCHES UP UNTIL
THE ACTUAL STORM TRACK PRECIPITATION TRANSITION ZONE IS MORE
CLEAR. AREAS THAT SEE MOSTLY RAIN WILL SEE RAIN HEAVY AT TIMES…
WHICH WILL CONTINUE THROUGH WEDNESDAY MORNING. ENSEMBLE
PROBABILITIES FOR 2 OR MORE INCHES OF RAIN EXIST OVER SOUTHERN NY
AND WESTERN NEW ENGLAND WHERE FLOOD WATCHES MAY BE CONSIDERED
AFTER THE NEXT SET OF GUIDANCE IS CONSULTED TONIGHT. HIGHS
WEDNESDAY WITH THE WARM ADVECTION IN THE 40S…AROUND 40
SOUTHERN ADIRONDACKS…AND SOME 50S MID HUDSON VALLEY AND NW CT.

SYSTEM EXITS LATER WEDNESDAY AND WEDNESDAY NIGHT…WITH
INDICATIONS OF A DRY SLOT AND VERY LITTLE IN THE WAY OF UPPER
DEFORMATION…SUGGESTING ONLY SCATTERED SNOW SHOWER OR SNOW FLURRY
ACTIVITY AS THE PRECIPITATION EXITS. LAKE EFFECT SNOW SHOWER
ACTIVITY SHOULD QUICKLY EVOLVE TO NORTHWEST/SOUTHEAST ORIENTED
MULTI BANDS AS NORTHWEST LOW LEVEL FLOW SETS UP AND COLD ADVECTION
DEEPENS. HIGHS THURSDAY IN THE MID 20S TO LOWER 30S…SOME UPPER
TEENS SOUTHERN ADIRONDACKS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/…
THU NT-FRI NT…AS THE STORM SYSTEM CONTINUES TO DEPART TO OUR NORTH
AND NORTHEAST…HIGH PRESSURE BUILDS IN FROM THE SOUTHWEST THU NT
AND EARLY FRI…WITH REINFORCING HIGH PRESSURE BUILDING ACROSS SOUTH
CENTRAL CANADA. A WEAK SFC TROUGH WILL SEPARATE THESE TWO
HIGHS…AND WILL SLOWLY PASS SOUTHWARD ACROSS OUR REGION ON FRIDAY.
AT THIS TIME…HAVE KEPT CONDITIONS DRY…BUT WILL HAVE TO WATCH FOR
THE POSSIBILITY OF SOME LIGHT SNOW SHOWERS OR FLURRIES ACCOMPANYING
THIS BOUNDARY…ESPECIALLY FOR CENTRAL AND SOUTHERN PORTIONS OF THE
REGION. TEMPS SHOULD REMAIN BELOW SEASONAL LEVELS…WITH DAYTIME
MAXES MAINLY IN THE 20S TO LOWER 30S…AND OVERNIGHT MINS FALLING
INTO THE SINGLE DIGITS AND TEENS FOR MOST AREAS…EXCEPT FOR 15-20
ACROSS PORTIONS OF THE MID HUDSON VALLEY.

SAT-SUN NT…HIGH PRESSURE INITIALLY BUILDS ACROSS FROM SOUTHEAST
CANADA…WITH MAINLY FAIR CONDITIONS…AND CHILLY TEMPS FOR SAT.
HOWEVER…AS THE HIGH MOVES FURTHER EAST…A VEERING LIGHT EAST TO
SOUTHEAST FLOW ABOVE THE BOUNDARY LAYER MAY ALLOW FOR SOME LOW LEVEL
MOISTURE TO BUILD NORTHWARD…WHICH THE 12Z/25 SHOWS MOST
AGGRESSIVELY. AT THIS TIME…WILL ONLY ADD SOME SLIGHT CHC POPS FOR
SUNDAY…AND LOW CHC POPS FOR SUN NT…MAINLY FOR LIGHT SNOW
SHOWERS…GIVEN COLD THERMAL PROFILES. FOR TEMPS…EXPECT SAT MAXES
TO REACH MID 20S TO LOWER 30S …ALTHOUGH PERHAPS SOME UPPER
TEENS/LOWER 20S ACROSS SOME HIGHER ELEVATIONS. ON SUNDAY…EXPECT
MAX TEMPS TO REACH THE MID 30S TO NEAR 40 IN VALLEY AREAS…AND
GENERALLY 20S TO LOWER 30S ACROSS HIGHER ELEVATIONS. SAT NT/SUN AM
MINS SHOULD FALL INTO THE TEENS TO LOWER 20S IN MOST AREAS…WHILE
SUN NT/MON AM MINS SHOULD FALL INTO THE 20S.

MONDAY…UNCERTAINTY INCREASES AMONG SOURCES OF
GUIDANCE…ESPECIALLY WITH REGARD TO THE HANDLING OF A PV MAX
OFF THE CALIFORNIA COAST…AND THE POSSIBLE INTERACTION WITH A
NORTHERN STREAM PV MAX. THE 12Z/25 ECMWF HINTS AT A STRONGER PIECE
OF THE SOUTHWEST PV EJECTING OUT AND ALLOWS FOR GREATER INTERACTION
WITH THE NORTHERN STREAM ENERGY…AND SUBSEQUENT STRONGER SFC
DEVELOPMENT CLOSER TO THE EAST COAST EARLY NEXT WEEK. AT THIS
TIME…DUE TO OVERALL LOW CONFIDENCE…HAVE INDICATED CHC POPS…FOR
RAIN/SNOW SHOWERS…WITH SNOW SHOWERS DOMINANT DURING NIGHTTIME

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/…
SURFACE HIGH PRESSURE CONTINUES TO MOVE OFF THE MID ATLANTIC COAST
THIS AFTERNOON INTO TONIGHT. LOW PRESSURE WILL BE ORGANIZING OVER
THE DEEP SOUTHEAST TOMORROW MORNING…AS AN UPPER LEVEL
DISTURBANCE MAY PRODUCE SOME SCT SNOW SHOWERS OR FLURRIES AFTER
DAY BREAK TO PARTS OF THE REGION.

VFR CONDITIONS ARE EXPECTED TO PREVAIL THE NEXT 24 HOURS ENDING
18Z TUESDAY WITH MID AND HIGH CLOUDS INCREASING EARLY THIS
EVENING. A WEAK DISTURBANCE IN THE MID LEVEL SW FLOW MAY TRIGGER A
FEW SNOW SHOWERS OR FLURRIES TOWARDS 12Z FROM KALB-KPSF NORTHWARD.
A VCSH GROUP WAS USED TO ADDRESS THIS POSSIBILITY. CIGS WILL BE
LOWERING TO 3.5-6 KFT AGL BTWN 12Z-16Z/TUE. OVER RUNNING PCPN WELL
IN ADVANCE OF THE CYCLONE WILL START TO GET CLOSE TO THE ERN NY
TERMINALS AFTER 21Z/TUE.

THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT LESS THAN 10 KTS
THIS AFTERNOON INTO THIS EVENING. EXPECT THE SFC WINDS TO CONTINUE
FROM THE S/SW AT 5-11 KTS LATE TOMORROW MORNING.

OUTLOOK…
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF WINTRY MIX.
TUESDAY NIGHT AND WEDNESDAY: HIGH OPERATIONAL IMPACT. DEFINITE RA.
WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT.BREEZY LIKELY SHSN…SN.
THANKSGIVING DAY: LOW OPERATIONAL IMPACT.BREEZY SLIGHT CHANCE OF
SHSN.
THURSDAY NIGHT THROUGH SATURDAY: NO OPERATIONAL IMPACT. NO
SIG WX.

&&

.HYDROLOGY…
A POTENT COASTAL STORM WILL IMPACT THE REGION WITH MODERATE TO
POTENTIALLY SIGNIFICANT AMOUNTS OF WATER EQUIVALENT.

IT WILL BE MAINLY DRY THROUGH EARLY TUESDAY.

THE TIME FRAME WILL BE FROM LATE TUESDAY AFTERNOON INTO WEDNESDAY
EVENING AS A COASTAL STORM COULD BRING 1.5 TO 3+ INCHES OF LIQUID
EQUIVALENT PRECIPITATION TO THE REGION /LOCALLY HIGHER AMOUNTS ARE
POSSIBLE/. IT WILL BEGIN AS SNOW AND COULD LINGER AS SNOW AND
SLEET IN THE NORTHERN MOUNTAINS. HOWEVER IN MUCH OF THE REGION IT
IS EXPECTED TO CHANGE TO RAIN…RESULTING IN SIGNIFICANT WITHIN
BANK RISES. IN THIS STORMS WAKE IT WILL TURN SHARPLY COLDER AGAIN
WEDNESDAY NIGHT…WITH ICE FORMATION LIKELY TO BEGIN ANEW.

RAIN…POSSIBLY HEAVY AT TIMES…COULD CAUSE SOME PONDING OF SOME
ROADWAYS WHERE LEFTOVER LEAVES COULD CLOG STORM DRAINS. A FLOOD
WATCH MAY BE NEEDED FOR PARTS OF THE REGION IF THE POTENTIAL FOR
MINOR FLOODING INCREASES.

THE GOOD NEWS IS THAT FLOW WERE RUNNING A BIT BELOW NORMAL DUE TO
PERSISTENT DRY WEATHER OF LATE. HOWEVER…ONE TO TWO PLUS INCHES
OF RAINFALL IN LESS THAN 12 HRS COULD CAUSE SOME PROBLEMS.

AFTER THE STORM BLASTS THROUGH ANOTHER MAINLY DRY SPELL IS EXPECTED
WITH CONTINUED BELOW NORMAL TEMPERATURES.

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…WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR NYZ032-033-038-042-082.
MA…NONE.
VT…NONE.

&&

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

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