November 6, 2012 Forecast Discussion

000
FXUS61 KALY 062346
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
645 PM EST TUE NOV 6 2012

.SYNOPSIS…
HIGH PRESSURE WILL ALLOW FOR DRY AND COOL CONDITIONS TONIGHT. A NOR
EASTER WILL DEVELOP OFF THE SOUTHEAST COAST LATE TONIGHT AND MOVE
OFF THE JERSEY SHORE TOMORROW…AND TOWARDS CAPE COD ON THURSDAY.
THIS SYSTEM WILL LIKELY BRING THE SEASON/S FIRST SNOWFALL FROM ABOUT
THE CAPITAL REGION AND POINTS SOUTH AND EAST. BEHIND THIS
STORM…WARMER AND DRY CONDITIONS WILL RETURN FOR THE UPCOMING
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/…
AS OF 630 PM…CLEAR SKIES AND LIGHT WINDS PERSISTS ACROSS THE
REGION AND TEMPS OBS MATCH HOURLY TEMPO GRIDS VERY WELL. NO CHANGES
MADE TO THE CURRENT GRIDDED FORECASTS.

.PREVIOUS DISCUSSION…
AS OF 400 PM EST…STILL ESSENTIALLY CLEAR ACROSS OUR ENTIRE REGION
WITH NOTHING MORE THAN A FEW HIGH CIRRUS CLOUDS (POSSIBLY THE RESULT
CONTRAILS). DESPITE THE WALL TO WALL SUNSHINE…STILL DOWNRIGHT
CHILLY WITH TEMPERATURES WITHIN A FEW DEGREES OF 40…MORE THAN 10
DEGREES BELOW NORMAL FOR THE TIME OF YEAR.

THE SKY LOOKS TO REMAIN CLEAR (OR MOSTLY CLEAR) MUCH OF TONIGHT
ALTHOUGH SOME CIRRUS WILL BEGIN TO ENCROACH ON OUR SOUTHERN
AREAS…THE RESULT OF A DEVELOPING STORM WELL OFF THE CAROLINA
COASTLINE.

THEREFORE IT WILL BE ANOTHER GOOD RADIATIONAL NIGHT WITH
TEMPERATURES COOLING QUICKLY AFTER SUNSET…AND BOTTOMING OUT AT
SIMILAR LEVELS COMPARED TO LAST NIGHT. COLD WITH LOWS RANGING FROM
THE TEENS MOST AREAS OUTSIDE THE HUDSON VALLEY AND EVEN THE HUDSON
VALLEY NORTH OF SARATOGA SPRINGS…20-25 FROM THE CAPITAL
SOUTHWARD.

THE WIND WILL BE LIGHT AND VARIABLE TONIGHT AS PRESSURE SLOWLY
REBUILD TO OUR NORTHEAST.

FYI…THE 18Z NAM NOW GIVES A BIT MORE PRECIPITATION TO THE AREAS
FROM ALBANY SOUTH AND EAST…MORE SO THAN THE 12Z NAM BUT LESS SO
THAN THE 12Z GFS. THE 12Z EUROPEAN MODEL WAS A COMPROMISE BETWEEN
THE 12Z NAM AND 12Z GFS.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/…
MODEL GUIDANCE CONTINUES TO HAVE TROUBLE RESOLVING THE NOR`EASTER
THAT IS FORECAST TO DEVELOP TOMORROW.

ALREADY…LOW PRESSURE IS ALREADY EVIDENT OF THE CAROLINA COAST
LINE…AWAITING ANOTHER PIECE OF ENERGY COMING DOWN AROUND A TROUGH
AND LOCATED OVER THE INTERIOR SOUTHEAST. THIS WILL HELP ENERGIZE THE
STORM BY THURSDAY.

MOST MODELS CONTINUE TO TRACK THIS STORM TRACKING WELL TO THE EAST
OF THE COASTLINE AS IT HEADS TOWARD CAPE COD BY THURSDAY. THIS TRACK
WOULD BE WELL SOUTH AND EAST OF THE CLASSIC BENCHMARK WHICH WOULD
GIVE OUR THE POTENTIAL FOR THE MAXIMUM PRECIPITATION (AND SNOW) THAT
COULD COME OUT OF THIS SYSTEM. THE CLASSICAL TRACK FOR THE CAPITAL
DISTRICT TO RECEIVE THE MAXIMUM SNOWFALL WOULD BE STORM TRACKING TO
ABOUT FIRE ISLAND ON THE SOUTH SHORE OF LONG ISLAND…THEN CROSS THE
CAPE COD CANAL…INTO THE GULF OF MAINE.

MAKE NO MISTAKE…IT WILL BE PLENTY COLD FOR MOSTLY SNOW WITH THIS
SYSTEM. IN FACT…GIVEN THE TRACK AND COLD AIR ENTRAINING INTO THE
SYSTEM…ONE THING WE FEEL CONFIDENT IS ONCE AGAIN THIS WILL BE
MAINLY A SNOW EVENT (OR RAIN CHANGING TO SNOW EARLY AS THE AMBIENT
TEMPERATURE MIGHT DICTATE SO…BUT EVAPORATIVE COOLING WOULD QUICKLY
COOL THE COLUMN TO CHANGE ANY RAIN TO SNOW…EVEN IN THE VALLEYS
LATE WEDNESDAY).

THE SPECIFIC TRACK OF THE STORM WOULD BE OFF THE COASTLINE BY MORE
THAN 100 MILES…OFF THE MID ATLANTIC COAST. HOWEVER…BOTH THE GFS
AND NAM HAVE ADVERTISED THIS STORM TO HOOK BACK TOWARD THE COAST TO
THE SOUTHEAST OF LONG ISLAND BY ABOUT THE 12Z THURSDAY TIME FRAME.
THIS WOULD BE IN RESPONSE TO YET ANOTHER PIECE OF ENERGY (UPPER AIR
LOW SYSTEM) CATCHING UP TO DEVELOPING STORM DURING THE DAY WEDNESDAY.

THE 12Z GFS WAS THE FASTEST AND FURTHEST TRACK TO THE
WEST…BRINGING THE SURFACE STORM JUST OFF CAPE BY THURSDAY
AFTERNOON…WHILE THE EURO WAS A LITTLE FURTHER EAST AND SLOWER
STAYING ABOUT 100 MILES OFF CAPE COD AS THE SYSTEM MAKES A TURN OUT
TO SEA.

THE 18Z NAM CAPTURED THE STORM A LITTLE QUICKER AND TRIED TO HOOK IT
MORE FROM WELL OFFSHORE BACK TOWARD THE LONG ISLAND BUT THEN
TRACKING MORE TO THE SOUTH AND EAST AGAIN.

ALL MODELS INDICATED A LOT OF DRY AIR WRAPPING INTO THE SYSTEM BY
THURSDAY…CUTTING BACK THE PRECIPITATION RATES. THE 12Z GFS WAS THE
MOST AGGRESSIVE BRINGING THE FIRST SHOT OF
PRECIPITATION…ASSOCIATED WITH THE FRONTOGENTIC FORCING INTO OUR
REGION….WELL BEFORE THURSDAY EVENING. OTHER MODELS SUGGEST A LOT
OF DRY AIR…FEEDING SOUTH BY HIGH PRESSURE STILL RESIDING TO OUR
NORTH…MIGHT HOLD PRECIPITATION BACK…AT LEAST FROM THE CAPITAL
REGION NORTHWARD…UNTIL DARK WEDNESDAY. THIS WOULD BE RESULT OF
VIRGA (PRECIPITATION EVAPORATING AS IT FALLS THROUGH VERY DRY
AIR).

THE 18Z NAM STILL KEPT THE REGION DRY NORTHWEST OF ALBANY THROUGH
THE ENTIRE EVENT…BUT ACTUALLY HAS BUMPED PRECIPITATION ACROSS THE
CATSKILLS AND LITCHFIELD COUNTY…TO NEARLY AN INCH FROM WEDNESDAY
AFTERNOON THROUGH THURSDAY AFTERNOON (THE END OF THE STORM).

WE CONTINUE TO GO WITH HPC PRECIPITATION AMOUNT WHICH AT THIS
TIME…HAD LIGHTER AMOUNTS TO AROUND A QUARTER OF AN INCH TO LOCALLY
HALF AN INCH IN OUR SOUTHERN AREAS…A TENTH OF AN INCH
LOCALLY…AND LITTLE TO NO PRECIPITATION NORTHWEST OF ALBANY.

LOOK FOR SNOW…OR RAIN CHANGING TO SNOW…OVERSPREADING OUR
SOUTHERN REGION DURING WEDNESDAY AFTERNOON…THE CAPITAL REGION AND
POINTS EAST A LITTLE AFTER DARK. HOW MUCH ULTIMATELY REMAINS
UNCERTAIN…BUT AT THE VERY LEAST…1-4+ INCHES OF SNOW COULD
ACCUMULATE SOUTH AND EAST OF THE CAPITAL DISTRICT….A DUSTING TO
AROUND AN INCH IN THE CAPITAL REGION…AND VIRTUALLY NONE EXPECTED
NORTH AND WEST OF ALBANY.

OBVIOUSLY EVEN A 50 MILE SHIFT IN THE STORM TRACK COULD CHANGE THESE
AMOUNTS ONE WAY OR ANOTHER. DUE TO STILL HIGH UNCERTAINTY AND THE
FACT THAT OUR DETERMINISTIC FORECAST HAS NO MENTION OF SNOW OVER 7
INCHES…NO WINTER STORM WATCHES WERE ISSUED WITH THIS PACKAGE. ANY
ADVISORIES WOULD BE DEFERRED TO THE MIDNIGHT CREW.

KEEP IN MIND…THERE IS STILL A POTENTIAL FOR SIGNIFICANT SNOWFALL
ACCUMULATION TO THE SOUTH AND EAST OF ALBANY…ALTHOUGH THAT CHANCE
WAS WELL UNDER 50 PERCENT. WE WILL CONTINUE TO HIGHLIGHT IN OUR
HAZARDOUS WEATHER OUTLOOK.

WIND COULD BE A MARGINAL PROBLEM OVER THE HIGHER TERRAIN MAINLY
SOUTH AND EAST OF THE CAPITAL DISTRICT LATE WEDNESDAY INTO THURSDAY.
A NORTH TO NORTHEAST WIND COULD GUST UP TO 45 MPH IN THESE AREAS.
WITH OR WITHOUT SNOW…THESE WIND GUSTS COULD LEAD TO HIGHLY
ISOLATED POWER OUTAGES AT WORST. WE FELL WHILE IT WILL GET BREEZY IN
THE VALLEYS…THE WIND GUSTS SHOULD REMAIN AT OR BELOW 25 MPH. IF
NEEDED…A WIND ADVISORY MIGHT BE ISSUED FOR THE HIGHER TERRAIN IN
THE NEXT COMPLETE PACKAGE.

THE STORM WILL PULL AWAY THURSDAY…LEAVING LIGHT LINGERING RAIN OR
SNOW BEHIND. ANY ADDITIONAL ACCUMULATIONS ON THURSDAY WOULD BE
LIGHT…AN INCH OR LESS. IT WILL STILL BE BREEZY TO WINDY ON
THURSDAY. AFTER THAT…HIGH PRESSURE IS FORECAST TO BUILD BACK IN
FROM OUR WEST…INCREASING SUNSHINE FOR FRIDAY.

TEMPERATURES WILL REMAIN BELOW NORMAL IN THE SHORT TERM…ONLY HIGHS
AROUND 40 ON TUESDAY…LOWS MID 20S TO LOWER 30S TUESDAY NIGHT…AND
ONLY BACK IN THE MID 30S TO MID 40S ON FRIDAY.

IT REMAIN CHILLY AND DRY FRIDAY WITH A MOSTLY CLEAR SKY…AS
TEMPERATURES WILL DROP TO SEASONABLY CHILLY LEVELS…AROUND 30
ALBANY AND POINTS SOUTHWARD…20S OUTLYING REGIONS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/…
UPPER-LEVEL RIDGING AND WARMING TEMPERATURES WILL DOMINATE THE
PERIOD BEFORE A LOW PRESSURE SYSTEM AND ATTENDANT COLD FRONT SWEEP
ACROSS THE AREA NEXT WEEK.

AT THE START OF THE LONG TERM PERIOD…UPPER-LEVEL RIDGING WILL BE
AFFECTING MUCH OF THE EASTERN CONUS…A STARK CONTRAST FROM THE
PROGRESSIVE TROUGH PATTERN THAT HAS OCCURRED OVER THE PAST COUPLE OF
WEEKS. SURFACE HIGH PRESSURE WILL BUILD ACROSS THE AREA SATURDAY AND
PERSIST THROUGH THE WEEKEND BRINGING DRY CONDITIONS ACROSS THE
REGION.

WITH SOUTHWEST FLOW ALOFT…LONG RANGE MODEL GUIDANCE IS IN GOOD
AGREEMENT WITH A WARMUP IN TEMPERATURES…INITIALLY MODERATING TO
SEASONABLE TEMPERATURES DURING THE WEEKEND WITH HIGHS GENERALLY IN
THE 50S. HIGH TEMPERATURES MAY EVEN APPROACH 60 IN VALLEY LOCATIONS
TO START OUT THE WORK WEEK MONDAY AS THE SURFACE HIGH DRIFTS TO THE
EAST ENHANCING SOUTHWEST FLOW IN THE LOW LEVELS.

MODEL GUIDANCE CONTINUES TO HINT AT A DIGGING UPPER-LEVEL TROUGH
EJECTING OUT OF THE PACIFIC NORTHWEST DURING THE WEEKEND INTO THE
CENTRAL PLAINS TO START OUT THE WORK WEEK. AS THIS TROUGH AND
ATTENDANT SURFACE LOW AFFECT THE CENTRAL CONUS…THERE REMAINS
SIGNIFICANT MODEL DIFFERENCES IN TIMING AND PLACEMENT OF THIS SYSTEM
AS IT INTERACTS WITH THE DOWNSTREAM RIDGE. REGARDLESS…INTRODUCED
CHANCE POPS INTO THE FORECAST TO START OUT THE WORK WEEK AS GUIDANCE
SUGGESTS THE SYSTEM IMPACTING THE REGION SOMETIME EARLY NEXT WEEK.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/…
VFR CONDITIONS EXPECTED AT THE KGFL/KALB/KPOU/KPSF TAF SITES
THROUGHT AT LEAST 18Z WEDNESDAY. MAINLY CLEAR TO START THE TAF
PERIOD WITH INCREASING HIGHS CLOUDS LATE TONOGHT AND EARLY WEDNESDAY
AS THE COASTAL STORM BEGINS TO DEVELOP AND MOVE NORTHEAST OFF THE
EAST COAST. AFTER 18Z EXPECT CONDITIONS TO BEGIN DETERIORATING AT
KPOU AND KPSF AS SNOW SPREADS INTO THE REGION…MVFR VSBYS WILL MOVE
INTO KPOU/KPSF BETWEEN 18Z AND 20Z…WITH IFR VSBYS MOVING IN
BETWEEN 21Z AND 23Z. AT KALB MVFR VSBYS WILL BEGIN AFTER 21Z…AND
EXPECT SNOW TO REMAIN SOUTH OF KGFL THROUGH 00Z THURSDAY.

SURFACE WINDS WILL CALM OR LIGHT NORTH/NORTHEAST TONIGHT AND EARLY
WEDNESDAY…THEN PICK UP TO 8 TO 12 KTS WITH GUSTS OF 15 TO 20 KTS
LATE WEDNESDAY MORNING AND AFTERNOON.

OUTLOOK…
WED NT…SUB-VFR WITH SNOW AT KPOU AND KPSF. MAINLY MVFR WITH SNOW
LIKELY AT KALB. MAINLY VFR WITH A CHC SNOW AT KGFL.
THU…BRISK. VFR-MVFR. CHC OF SNOW CHANGING TO RAIN AT KPOU…KPSF
AND KALB. THE BETTER CHANCES WILL BE AT KPOU AND KPSF.
FRI-SAT…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO HYDROLOGIC ISSUES ARE EXPECTED ACROSS THE HSA THROUGH THE WEEK.

A COASTAL STORM WILL BRUSH THE REGION FOR LATE WEDNESDAY INTO
THURSDAY. MODEL GUIDANCE STILL HAS THE STORM TRACKING WELL TO OUR
EAST.

LITTLE OR NO QPF EXPECTED NORTHWEST OF ALBANY…A TENTH TO MAYBE A
QUARTER INCH IN AND AROUND ALBANY…A QUARTER TO LOCALLY HALF INCH
IN OUR SOUTHEAST ZONES.

MOST OF THIS WILL FALL AS SNOW AND SHOULD POSE NO PROBLEM ON OUR
WATER SHEDS.

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

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