November 25, 2013 Forecast Discussion

000
FXUS61 KALY 251144
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
645 AM EST MON NOV 25 2013

.SYNOPSIS…
ARCTIC HIGH PRESSURE WILL SLOWLY RETREAT OFFSHORE TODAY ALLOWING THE
AIR MASS TO MODERATE A LITTLE. 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 /THROUGH TONIGHT/…
AS OF 645 AM EST…STILL COULD BE A FEW FLURRIES OVER EXTREME
WESTERN SCHOHARIE COUNTY AS WELL AS NORTHERN HERKIMER COUNTY. THE
REMAINDER OF THE REGION WAS DRY WITH JUST A FEW CIRRUS CLOUDS.

NO REAL CHANGES WITH THIS UPDATE.

THE 06Z RUN CYCLE OF THE NAM AND GFS HAVE ACTUALLY TRENDED A LITTLE
EAST WITH THE TRACK OF THE STORM WITH BOTH MODELS NOW TRACKING THE
LOW MORE THROUGH TOWARDS THE CONNECTICUT VALLEY AS OPPOSED TO THE
HUDSON VALLEY. THAT SAID…THE COLUMN CONTINUES TO BE TOO WARM FOR
ANYTHING FROM RAIN FROM THE CAPITAL REGION AND POINTS SOUTH AND
EAST…AFTER A POSSIBLE START AS A WINTRY MIX. FURTHER NORTH AND
WEST OF THE CAPITAL REGION…IT STILL LOOK TO BE MORE LIKE A PROLONG
PERIOD OF WINTRY MIX.

BOTH MODELS HAVE SLOWED THE PRECIPITATION A LITTLE…NOW DELAYING IT
UNTIL TUESDAY NIGHT. HOWEVER FOR NOW…WE HAVE NO MADE ANY CHANGES
TO OUR GRIDDED DATA BASE…BUT THE BULK OF THE PRECIPITATION WILL
NOT HAPPEN UNTIL PROBABLY AFTER THE EVENING RUSH HOUR.

PRECIPITATION AMOUNTS LOOKED PRETTY SIMILAR TO THE PREVIOUS RUNS.
THE GFS CONTINUES TO BE A LITTLE FAST LIFTING PRECIPITATION OUT ON
WEDNESDAY.

TEMPERATURES HAVE BOTTOMED OUT AT THEIR COLDEST LEVELS SINCE LAST
MARCH. UNDER A CLEAR TO PARTLY SKY…LOWS HAVE RANGED FROM 10 TO 15
DEGREES ACROSS THE HUDSON VALLEY FROM ALBANY SOUTHWARD…SINGLE
NUMBERS NORTH AND WEST OF ALBANY WITH A FEW SPOTS IN THE MORE SNOW
COVERED REGIONS OF THE ADIRONDACKS BOTTOMING OUT AROUND OR A LITTLE
BIT BELOW ZERO DEGREES.

THE WIND IS LIGHT OR CALM AND SHOULD STAY THAT WAY MUCH OF THAT
MORNING.

ANY FLURRIES WELL TO THE WEST OF THE HUDSON VALLEY WILL BE
INSIGNIFICANT.

LATER TODAY…AS HIGH PRESSURE MOVES OFFSHORE…THE WEST WIND WILL
TURN LIGHT SOUTHERLY. SOME HIGH CLOUDS WILL MAR A DEEP AZURE.
TEMPERATURES WILL MODERATE A LITTLE COMPARED TO YESTERDAY…REACHING
25 TO 30 ACROSS MUCH OF THE HIGHER TERRAIN AND AREAS NORTH AND WEST
OF THE CAPITAL DISTRICT…30 TO 35 CAPITAL DISTRICT SOUTH AND
EAST.

TONIGHT WILL SHOULD REMAIN MAINLY DRY WITH VARYING AMOUNT OF CLOUDS.
A WEAK SHORT WAVE IN THE NORTHERN STREAM…APPROACHING FROM THE WEST
COULD TRIGGER A FEW FLURRIES OR A TOUCH OF LIGHT SNOW ANYWHERE
ACROSS THE REGION BY DAYBREAK…BUT AT MOST…WE ARE LOOKING FOR A
DUSTING TO MAYBE HALF OF AN INCH DOWNWIND OF LAKE ONTARIO. THE
CLOUDS AND A LIGHT SOUTHERLY BREEZE WILL KEEP TEMPERATURES IN THE
TEENS NORTH OF ALBANY…LOWER TO MID 20S FROM ALBANY SOUTHWARD.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/…
POTENT STORM IS EXPECTED TO IMPACT THE REGION LATE TUESDAY INTO
EARLY THURSDAY…

A WINTER STORM WATCH HAS BEEN POSTED OF THE SOUTHERN ADIRONDACKS AND
WESTERN MOHAWK VALLEY FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
EVENING.

THE AFOREMENTIONED SHORT WAVE LOOKS TO PHASE WITH ENERGY FROM THE
SOUTHERN STREAM…CURRENTLY OVER NEW MEXICO…TO DEVELOP A DEEP MID
LONGITUDE TROUGH WHICH WILL CARVE OUT THIS EARLY WINTER STORM.

MODEL CONSENSUS POINTS TO TRACK THAT WILL TAKE THIS STORM TO THE
WEST OF THE INTERSTATE-95…TRACKING UP INTO THE HUDSON VALLEY LATE
TUESDAY NIGHT INTO WEDNESDAY MORNING. PRECIPITATION FROM THE STORM
LOOKS TO REACH OUR CATSKILL AREAS EARLY TUESDAY AFTERNOON AND
SOUTHERN VERMONT BY TUESDAY EVENING.

THIS STORM LOOKS TO REMAIN AN OPEN WAVE…THAT IS THE UPPER LEVEL
TROUGH IS NOT FORECAST BY ANY MODEL TO CLOSE OFF. PER PREVIOUS CSTAR
RESEARCH THIS SHOULD LIMIT "BANDED" PRECIPITATION. HOWEVER…THERE
WILL A TIGHT BAROCLINIC ZONE OVER OUR REGION. PWATS LOOK TO RAPIDLY
INCREASE TO ABOUT 1.5 INCHES IN OUR EASTERN AREAS LATE TUESDAY
NIGHT…WHICH IS 4 STANDARD DEVIATIONS ABOVE NORMAL. GOOD SURFACE
CONVERGENCE COUPLED WITH STRONG DIVERGENCE ALOFT ALONG WITH THIS
MOISTURE POOLING WILL NEARLY GUARANTEE THE HEAVIEST PRECIPITATION
EVENT IN MONTHS OVER OUR REGION.

THIS TRACK SHOULD DRIVE IN ENOUGH WARM AIR FROM THE OCEAN TO INSURE
A PRIMARILY RAIN EVENT FROM THE CAPITAL DISTRICT AND AREAS SOUTH AND
EAST OF ALBANY.

HOWEVER…ENOUGH COLD AIR COULD REMAIN IN PLACE TO PRODUCE MORE
SIGNIFICANT AMOUNTS OF FROZEN AND FREEZING PRECIPITATION ACROSS OUR
SOUTHERN ADIRONDACKS AS WELL AS WESTERN MOHAWK VALLEY.
THEREFORE…WE ISSUED A WINTER STORM WATCH STARTING MID TUESDAY
AFTERNOON…LASTING UNTIL MIDNIGHT WEDNESDAY HEADING INTO
THANKSGIVING DAY FOR THESE AREAS ONLY.

H850 TEMPERATURES AND MOST OF THE MODELS RISE WELL ABOVE
FREEZING…IN SOME CASES UP TO ABOUT +10 IN SOUTHERN ZONES. MORE
ABOUT THE POTENTIAL IMPLICATIONS OF THE RAINFALL CAN BE FOUND IN OUR
HYDROLOGY SECTION. HOWEVER…EVEN THOUGH H850 TEMPERATURES LOOK TO
RISE TO EVEN ABOUT +5C IN NORTHWESTERN ZONES…INITIALLY SNOW LOOKS
TO DEVELOP IN THIS AREA…MIXING WITH SLEET AND FREEZING RAIN WHICH
MIGHT BE PROLONGED AS SHALLOW COLD AIR REMAINS TRAPPED NEAR THE
SURFACE. EVEN THOUGH A PERIOD OF PLAIN RAIN IS LIKELY LATE TUESDAY
NIGHT INTO EARLY WEDNESDAY AS SURFACE TEMPERATURES MUSCLE THEIR WAY
JUST ABOVE THE FREEZING MARK…COLD AIR WILL PUSH BACK INTO THE AREA
AS THE STORM BEGINS TO SLOWLY PULL AWAY ON WEDNESDAY. AT THAT
POINT…THE UPPER LEVEL TROUGH HAS TO SWING THROUGH INDUCING
CONTINUED ASCENT AND THE STRONG LIKELIHOOD OF RAIN CHANGING BACK TO
SLEET AND SNOW.

THE POTENTIAL IS THERE FOR UP TO 7 INCHES OF SNOW…MIXED WITH SLEET
AND PERHAPS ICE ACCRETIONS UP TO HALF AN INCH THICK. THE THREAT IS
ABOUT 50 PERCENT…NOT ETCHED IN STONE YET.

COLD AIR INITIALLY IN PLACE…ESPECIALLY AT THE SURFACE…COULD LEAD
TO A LITTLE SNOW OR SLEET ELSEWHERE LATE TUESDAY BUT AGAIN ANY
FROZEN PRECIPITATION SHOULD QUICKLY TRANSITION TO LIQUID RAIN ALBANY
SOUTH AND EAST. IF NEEDED…WINTER WEATHER ADVISORIES WILL BE ISSUED
AT LATER TIME. THERE IS EVEN A CHANCE OF A LITTLE SNOW OR SLEET AT
THE TAIL END OF THE STORM WEDNESDAY NIGHT.

THE LATEST TRENDS OF THE GEFS STILL INDICATE A VERY STRONG V
COMPONENT UP TO FOUR STANDARD DEVIATIONS INDICATIVE OF A VERY STRONG
SOUTHERLY COMPONENT WHICH WILL SERVE TO RAPIDLY INCREASE THOSE PWAT
VALUES AND WARM THE MID LAYERS OF THE ATMOSPHERE.

HIGH TEMPERATURES ON TUESDAY LOOK TO RISE INTO THE MID 30S TO
LOWER 40S…EXCEPT CLOSER TO FREEZING ACROSS THE WATCH AREA. THEY
MIGHT BRIEFLY DROP A FEW DEGREES EARLY TUESDAY NIGHT DUE TO
EVAPORATIVE COOLING. HOWEVER…THEY LOOK TO RISE SLOWLY FROM THE
CAPITAL DISTRICT SOUTH AND EASTWARD…STAYING SAFELY ABOVE FREEZING.
IN FACT…THEY WILL LIKELY BE IN THE LOWER 40S NEAR ALBANY…MID TO
40S TO NEAR 50 FURTHER SOUTH AS WE HEAD INTO EARLY WEDNESDAY.
FURTHER NORTH AND WEST…AGAIN…TEMPERATURES WILL BE SLOWER TO RISE
ABOVE FREEZING…BUT SHOULD BRIEFLY REACH THE MID TO UPPER 30S LATER
TUESDAY NIGHT INTO EARLY WEDNESDAY BEFORE FALLING BACK TO FREEZING
OR LATER LATER ON WEDNESDAY AS THE WIND TURNS NORTH OR NORTHWESTERLY.

ELSEWHERE TEMPERATURES TOO WILL FALL DURING THE AFTERNOON WITH MOST
SPOTS REACHING DOWN TO NEAR FREEZING BY WEDNESDAY NIGHT.

SPEAKING OF WIND…WE ARE NOT LOOKING FOR ANY REAL WIND RELATED
PROBLEMS…ALTHOUGH AN EAST OR SOUTHEASTERLY WIND WILL INCREASE TO
10 TO 15 MPH…GUSTING UP TO 30-35 MPH ACROSS MAINLY THE HIGHER
TERRAIN TO THE EAST OF THE HUDSON VALLEY TUESDAY NIGHT INTO EARLY
WEDNESDAY. BY LATE WEDNESDAY…THE WIND WILL SHIFT TO THE NORTH OR
NORTHWEST WILL BE 15 TO 25 MPH IN MOST AREAS WITH SOME HIGHER
GUSTS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
EVEN THOUGH THE STORM SYSTEM WILL BE OVER EASTERN CANADA…MOISTURE
IN THE CYCLONIC FLOW AROUND THE STORM WILL STILL BE WRAPPING ALL THE
WAY BACK INTO OUR REGION THROUGH EARLY WEDNESDAY NIGHT…AND WILL
ONLY SLOWLY DECREASE DURING THE LATE NIGHT AND INTO WEDNESDAY. POPS
ARE FORECAST TO BE IN THE LIKELY RANGE EARLY WEDNESDAY NIGHT WITH
MAINLY LIGHT SNOW AS THE PCPN TYPE SINCE MOST AREAS WILL HAVE
ALREADY COOLED OFF ENOUGH FOR PCPN TO FALL AS SNOW. AFTER MIDNIGHT
POPS DECREASE TO CHANCE LEVELS IN MOST AREAS WITH SOME LIKELY POPS
REMAINING OVER THE ADIRONDACKS. FOR THE AFTER MIDNIGHT PERIOD WILL
USE SNOW SHOWERS AS THE PCPN TYPE. LOWS WILL DIP INTO THE TEENS AND
LOWER 20S AS WEST TO NORTHWEST WINDS PICK UP TO 15 TO 25 MPH WITH
GUSTS OVER 35 MPH.

JUST SOME SCATTERED OR ISOLATED SNOW SHOWERS THANKSGIVING DAY…BUT
IT WILL REMAIN WINDY AND COLD WITH HIGHS IN THE UPPER TEENS AND 20S.

HIGH PRESSURE WILL FINALLY BUILD INTO THE REGION THURSDAY NIGHT AND
MAINTAIN CONTROL OF OUR WEATHER THROUGH SATURDAY NIGHT WITH MAINLY
CLEAR TO PARTLY CLOUDY SKIES AND COLD TEMPS. HOWEVER…CLOUDS WILL
BE ON THE INCREASE SATURDAY NIGHT AS THE NEXT LOW PRESSURE SYSTEM
APPROACHES FROM THE WEST. LOWS THURSDAY NIGHT WILL BE IN THE SINGLE
NUMBERS AND TEENS…IN THE 10 TO 20 DEGREE RANGE FRIDAY NIGHT…AND
THE MID TEENS TO MID 20S SATURDAY NIGHT. HIGHS FRIDAY WILL BE IN THE
20S TO LOWER 30S…AND THE 20S TO MID 30S SATURDAY.

ON SUNDAY MOISTURE WILL CONTINUE TO INCREASE AND HAVE INCLUDED
SLIGHT CHANCE POPS IN ALL AREAS WITH LOW CHANCE POPS OVER THE
ADIRONDACKS. HIGHS SUNDAY WILL BE IN THE UPPER 20S AND 30S.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/…
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE 24 HOUR PERIOD
ENDING 12Z TUESDAY AS THE LARGE SURFACE HIGH CENTERED OVER THE OHIO
VALLEY PASSES BY TO OUR SOUTH AND MOVES OFF THE MID ATLANTIC COAST
TODAY. GENERALLY CLEAR SKIES TO AREAS OF SCT/BKN SC AS THE LAKE
EFFECT BAND SHIFTS NORTH AND AFFECTS THE TAF SITES TODAY. NO PCPN
EXPECTED FROM THE LAKE BAND AT THIS TIME. AFTER 00Z TUESDAY EXPECT
OVERUNNING MID/HIGH CLOUDS TO SPREAD ACROSS THE REGION.

SURFACE WINDS WILL GENERALLY BE LIGHT WESTERLY EARLY THIS MORNING…
THEN SHIFT TO SOUTHWEST AND THEN SOUTHERLY DURING THE DAY.
SOUTHERLY WINDS OF 5 TO 10 KTS WILL CONTINUE INTO MONDAY NIGHT.

OUTLOOK…
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF WINTERY 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 2.5 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.

THE GOOD NEWS IS THAT FLOW WERE RUNNING A BIT BELOW NORMAL DUE TO
PERSISTENT DRY WEATHER OF LATE. AT THIS TIME…NO FLOOD WATCHES HAVE
BEEN ISSUED BASED ON THE RAINFALL AMOUNTS.

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…HWJIV
NEAR TERM…HWJIV
SHORT TERM…HWJIV
LONG TERM…GJM
AVIATION…HWJIV/GJM
HYDROLOGY…HWJIV

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