November 25, 2012 Forecast Discussion

000
FXUS61 KALY 252340
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
640 PM EST SUN NOV 25 2012

.SYNOPSIS…
THE PERSISTENT CHILLY PATTERN WILL CONTINUE INTO AT LEAST THE
FIRST HALF OF THE WORK WEEK. A FEW UPPER LEVEL DISTURBANCES WILL
TRANSVERSE THE REGION PROVIDING PERIODS OF CLOUDS AND SOME LIGHT
SNOW OR SNOW SHOWERS. THOSE SNOW SHOWERS WILL BE MORE PROBLEMATIC
DOWNWIND OF THE GREAT LAKES AND IMPACT PORTIONS OF THE ADIRONDACKS
AND WESTERN MOHAWK VALLEY.

&&

.NEAR TERM /THROUGH MONDAY/…
AS OF 600 PM EST…WE HAVE GONE AHEAD AN UPGRADED THE LAKE EFFECT
SNOW ADVISORY TO A LAKE EFFECT SNOW WARNING. THIS WAS DONE BASED ON
THE FACT THAT WE HAD GROUND TRUTH REPORTS THAT ALREADY 4 INCHES OF
SNOW ACCUMULATED JUST SINCE THE AFTERNOON ACROSS PORTIONS OF
NORTHERN HERKIMER COUNTY. THE LATEST RUC AND NAM CONTINUE TO PORTEND
THAT IF ANYTHING…THE LAKE BANDS CURRENTLY FOUND OVER THIS
REGION…WILL GO MORE ROBUST AND AS THE LOW LEVEL LAPSE RATE
ACTUALLY INCREASES…AND THE BAND MIGHT ACTUALLY BECOME MORE
CONCENTRIC WITH TIME THROUGH AROUND MIDNIGHT. THE LIQUID TO SNOW
RATIO LOOKS TO BE ABOUT 20:1 SO IT WON`T TAKE MUCH TO PILE IT UP TO
AROUND 8 INCHES ACROSS LOCALITIES IN NORTHERN HERKIMER COUNTY.

ALSO…SATELLITE PICTURES SUGGEST A TELECONNECTION HAS SETUP
BETWEEN GEORGIAN BAY AND LAKE ONTARIO WHICH WOULD SERVE TO
SIGNIFICANTLY ENHANCE THE LAKE BAND…ALLOWING IT TO MOVE FURTHER
INLAND.

FOR THE REMAINDER OF THE REGION…ONLY MINOR TWEAKS HERE AND THERE.
WE ARE SEEING SOME DBZ VALUES AROUND 20 LOCALLY BUT SO FAR ONLY
FLURRIES WITH THAT…MUCH OF WHAT WE SAW THROUGHOUT THE DAY.

RECENT RADAR TRENDS CONTINUE TO REVEAL AN INTENSIFYING BAND OF SNOW
COMING ASHORE ACROSS OSWEGO COUNTY AND 1KM ENHANCED VISIBLE IMAGERY
SUGGESTS THE CU/STRATOCU EXTENDS APPROX 120 MILES WESTWARD ACROSS
LAKE ONTARIO WITH HINTS OF CONTRIBUTIONS FROM SOUTHERN LAKE HURON.
FORECAST INVERSION HEIGHTS FROM THE BUFKIT PROFILES ACROSS THE
WESTERN MOHAWK VALLEY AND DOWNWIND OF LAKE ONTARIO SUGGEST LEVELS
WILL AVERAGE AROUND 9K FEET WHERE THE TOP OF THE INVERSION TOUCHES
THE -18 TO -20C. THIS WOULD POINT TOWARD THE POTENTIAL FOR SOME
LIGHTNING BUT WILL NOT INCLUDE IN THE GRIDS. HOWEVER…THIS WILL
ENHANCE SNOWFALL RATES AS THESE BANDS PROPAGATE INLAND. PER THE
CSTAR LAKE RESEARCH OF INLAND PENETRATION OF THESE LAKE BANDS
SUGGESTS OVER 100 MILE INLAND ASSUMING WE CONTINUE WITH SOUTHERN
LAKE HURON CONTRIBUTION. IF WE LOSE UPSTREAM CONNECTION…WE CAN CUT
THIS INLAND PENETRATION TO HALF WHICH WILL BE AN ISSUE FOR NORTHERN
HERKIMER COUNTY WITH ACCUMULATING SNOWFALL. FOR NOW…WE WILL FAVOR
THE WETTER SOLUTION AND THUS THE LAKE EFFECT SNOW WARNING FOR
NORTHERN HERKIMER COUNTY AND THE CONTINUATION OF THE LAKE EFFECT
ADVISORY FOR HAMILTON COUNTY. H2O VAPOR IMAGERY DOES SUGGEST A
COUPLE OF SHORT WAVES TRACKING ACROSS THE NORTHERN GREAT LAKES
REGION WHICH MAY DISRUPT THE FLOW AND BACK IT TO TAKE THE BAND A
LITTLE FURTHER NORTH BEFORE RETURNING TO A MORE WEST TO EAST FLOW
OVERNIGHT. REMAINDER OF THE REGION…EXPECTATIONS FOR ADDITIONAL
STRATUS CLOUDS AND PERHAPS SOME FLURRIES OR LIGHT SNOW SHOWERS WHICH
WILL BE MORE AN ISSUE ACROSS THE HIGHER TERRAIN AND ESPECIALLY INTO
THE CATSKILLS WITH LOWS RANGING FROM THE UPPER TEENS TO THE UPPER
20S /HIGHER VALUES ACROSS THE MID HUDSON VALLEY/.

WE HAVE ISSUED A PUBLIC STATEMENT (ALBPNSALY) REGARDING SNOWFALL
TOTALS. PLEASE REFER TO THE STATEMENT FOR ALL THE LATEST SNOWFALL
ACCUMULATIONS.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/…
AS THE AFOREMENTIONED SHORT WAVE/S/ TRACK EAST OF THE REGION BY
SUNRISE MONDAY…LAKE BANDS WILL BEGIN TO SHIFT SOUTHWARD ACROSS
THE MOHAWK VALLEY AND WEAKEN AS DRIER AIR ALOFT AND LOWERING
INVERSION HEIGHTS COMMENCE. HOWEVER…THERE SHOULD REMAIN AN AMPLE
SCT-BKN STRATUS DECK THROUGHOUT THE REGION DESPITE SURFACE
PRESSURES RISING THROUGH THE DAY. HIGH TEMPERATURES MONDAY WILL
NOT BE TOO MUCH DIFFERENT THAN SUNDAYS HIGHS WITH MAINLY 20S FOR
THE HIGHER TERRAIN AND 30S ELSEWHERE.

SHORT WAVE…AS SEEN IN THE H2O VAPOR LOOP IMAGERY…WAS
APPROACHING THE BIG SKY COUNTRY OF MONTANA. THIS WAVE WILL DIVE
INTO THE NORTHERN TIER OF THE CONUS THROUGH MONDAY AND TRACK
SOUTHEAST ALONG THE FOOTHILLS OF THE ROCKIES. THE DOWNSTREAM UPPER
FLOW REMAINS RATHER CONFLUENT WHICH SUGGESTS THIS WAVE WILL NOT
TAP INTO THE SOUTHERN CONUS MOISTURE AND WILL HAVE TO UTILIZE THE
PACIFIC MOISTURE THAT WAS STREAMING ACROSS THE CENTRAL ROCKIES.
EXPECTATION…AS HAS BEEN WELL ADVERTISED IN THE ECMWF THE PAST
SEVERAL DAYS…IS FOR THIS WAVE TO TRACK MAINLY SOUTH OF THE
REGION MONDAY NIGHT INTO TUESDAY. THERE WILL BE ANOTHER
OPPORTUNITY FOR ADDITIONAL CLOUD SEEDING ACROSS THE GREAT LAKES
WITH AN RENEWED ENHANCEMENT OF LAKE ACTIVITY THROUGH THIS PERIOD.
ACCUMULATIONS UP TO A COUPLE OF INCHES ARE POSSIBLE ACROSS
NORTHERN HERKIMER AND HAMILTON COUNTIES WITH THIS LAKE
ENHANCEMENT. OTHERWISE…WITH RESPECT TO THE WAVE PASSING BY TO
OUR SOUTH…GLOBAL AND SHORT TERM MODELS CONTINUE TO SHOW A MORE
DRIER SOLUTION SOUTH OF ALBANY. FOR NOW…WE WILL CONTINUE WITH
THE CURRENT CHC-SCT POPS FOR LIGHT SOUTH SOUTH OF THE CAPITAL
DISTRICT AND FLURRY POTENTIAL ELSEWHERE. AS CLOUDS WILL BE
PREVALENT…HAVE KEPT TEMPS CLOSE TO OR SLIGHTLY COOLER THAN MOS
NUMBERS.

BY TUESDAY NIGHT…WE FIND OURSELVES IN-BETWEEN THE DEPARTING
SYSTEM TO OUR SOUTH AND THE NEXT UPSTREAM WAVE APPROACHING THE
CENTRAL GREAT LAKES REGION. WITH AN BRIEF ANTICYCLONIC SURFACE
FLOW AT THE SURFACE AND LACK OF UPPER LEVEL TRIGGERS…WE WILL
FORGO ANY MENTION OF PRECIP AT THIS TIME. SINCE SEVERAL BREAKS IN
THE OVERCAST ARE EXPECTED…WE WILL FOLLOW A COLDER SOLUTION WITH
RESPECT TO OVERNIGHT LOWS…ESPECIALLY WHERE FRESH SNOW COVER IS
EXPECTED.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/…
THE EXTENDED OR LONG TERM PERIOD WILL BEGIN WITH A FRONTAL BOUNDARY
OR MAYBE TWO OF THEM CROSSING THE REGION ON WEDNESDAY. THE FRONTAL
BOUNDARY(S) COULD BRING SOME INNOCUOUS SNOW SHOWERS MAINLY TO AREAS
NORTH AND WEST OF THE CAPITAL DISTRICT…BUT ANY AMOUNTS SHOULD BE
FAIRLY LIGHT AND SCATTERED.

BEHIND THE FRONT…ANOTHER ROUND OF CHILLY NORTHWESTERLY FLOW WITH
H850 TEMPERATURES AROUND -10C…WILL LIKELY PRODUCE ANOTHER ROUND OF
LAKE EFFECT SNOW SHOWERS. AT THIS VANTAGE POINT…THIS DOES NOT LOOK
LIKE A SIGNIFICANT EVENT AS THE FLOW LOOKS TOO NORTHWESTERLY (AS
OPPOSED TO WESTERLY) AND ANTICYCLONIC. (A NORTHWESTERLY FLOW TENDS
TO BREAK THE BANDS APART MITIGATING HEAVIER AMOUNTS OF SNOWFALL AS
WELL AS KEEPING A LOT OF THE BANDS TO OUR WEST THE ANTICYCLONIC FLOW
SUPPRESSES ASCENT AND THUS LEFT MOISTURE AVAILABLE TO PRECIPITATE
OUT OF THE CLOUDS).

OF COURSE THIS SCENARIO WILL BE CLOSELY MONITORED AS GET CLOSER TO
THIS TIME FRAME TO SEE IF THERE ARE ANY CHANGES TO THIS CURRENT
THINKING.

MOST OF LAKE EFFECT ACTION WILL TAKE PLACE NORTH AND WEST OF ALBANY
(THE USUAL SUSPECTS…ADIRONDACKS/MOHAWK VALLEY…CATSKILLS).

BY THURSDAY…A BACK DOOR COLD FRONT IS FORECAST TO SLIP SOUTH
THROUGH OUR REGION…ENFORCING THE CHILLY AIR MASS…AND PERHAPS
BRINGING A FEW MORE SNOW SHOWERS TO OUR NORTHWESTERN AREAS.

A SMALL CANADIAN HIGH IS FORECAST TO QUICKLY BUILD IN THURSDAY
NIGHT TO BRING PERHAPS THE COLDEST NIGHT OF THE YEAR…ESPECIALLY
THOSE AREAS WHERE A SNOW PACK WILL BE IN PLACE (DOWNWIND OF LAKE
ONTARIO - MOHAWK VALLEY AND ADIRONDACKS). DRY COLD WEATHER LOOKS TO
HOLD INTO FRIDAY.

AFTER THAT…AS THE SURFACE HIGH WILL BEGIN TO SLIP
OFFSHORE…AND A SOUTHERLY FLOW WILL INITIALLY WARM THE MID LAYERS
OF THE ATMOSPHERE. OVERRUNNING OF THIS WARMER SLIGHTLY MORE MOIST
AIR COULD BRING A ROUND OF LIGHT WINTRY PRECIPITATION…BUT THIS
FAR OUT…WE WILL ONLY GO WITH SLIGHT CHANCES FRIDAY NIGHT THROUGH
SATURDAY NIGHT SINCE TIMING ISSUES ARE IMPOSSIBLE TO NAIL DOWN
THIS FAR OUT.

BY SUNDAY…THE SOUTHERLY FLOW SHOULD BRING MILDER TEMPERATURES BUT
STILL THE THREAT OF MAINLY LIQUID RAIN SHOWERS.

TEMPERATURES WILL CONTINUE TO RUN BELOW NORMAL THROUGH FRIDAY…WITH
HIGHS MAINLY IN THE 30S VALLEY LOCATIONS…20S HIGHER TERRAIN.
OVERNIGHT LOWS WILL BE IN THE 20S FROM ALBANY SOUTH AND EAST…TEENS
NORTH AND WEST…AND EVEN SINGLE NUMBERS COME FRIDAY MORNING IN
THOSE COLD SHELTERED SNOW COVERED MOUNTAIN VALLEYS.

SATURDAY/S HIGHS WILL BEGIN TO RETURN TO MORE SEASONABLE
LEVELS…STILL CHILLY IN THE 30S TO LOWER 40S…BUT THEN WARMING TO
HIGHER INTO THE 40S MOST PLACES BY SUNDAY.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/…
MAINLY VFR CONDITIONS WILL LIKELY PREVAIL THROUGH MONDAY.

STILL DEALING WITH PLENTY OF LAKE EFFECT CLOUDS AT ALL BUT KPOU
WHERE OCCASIONALLY THEY FORM A CEILING THERE AS WELL. FOR THE MOST
PART…THESE ARE VFR CLOUDS WITH CLOUD BASES 4-6 KFT. LAKE EFFECT
SNOW SHOWERS HAVE HAPPENED AT KALB…BUT THUS FAR REALLY ONLY
FLURRIES WITH VERY LITTLE RESTRICTION TO VISIBILITY. WE DID INCLUDE
A TEMPO FOR 6 SM -SHSN THERE THROUGH 04Z AND WE DID INCLUDE A TEMPO
FOR A CIG OVC030.

AS THE FLOW BECOMES MORE SW ALOFT…THE LAKE EFFECT BAND WILL LIFT
NORTH POSSIBLY IMPACTING KGFL BUT UNLIKELY.

AT THE OTHER SITES VFR WILL PREVAIL WITH SIMILAR CLOUD BASES EXCEPT
KPOU WHICH LOOKS TO REMAIN MORE SCATTERED AT THE 4-6 KFT LEVEL.

THE CLOUDS AT ALL THE OTHER TAF SITES LOOK TO BECOME SCATTERED
OVERNIGHT.

THE GUSTY WINDS HAVE CEASED AND SHOULD BE WSW UNDER 10KTS THROUGHOUT
THE NIGHT.

A SURFACE TROUGH WILL MOVE THROUGH DURING MONDAY. BEHIND THAT
FEATURE THE WIND WILL VEER TO THE WEST AGAIN AND PICK UP IN SPEED A
BIT BY AFTERNOON…GENERALLY AROUND 12KTS…GUSTING TO AROUND 20KTS
AT MOST OF THE SITES. LOW LEVEL INSTABILITY AND LAKE ENHANCEMENT
WILL TEND TO PRODUCE VFR CIGS AGAIN…GENERALLY IN THE 4-6K FT
RANGE.

OUTLOOK…
MON NITE…VFR. NO SIG WX.
TUE-TUE NIGHT…VFR…CHC -SHSN SOUTH.
WED-FRI…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO HYDROLOGIC PROBLEMS ARE EXPECTED THROUGH THE NEXT 5 DAYS.

LAKE EFFECT SNOWS WILL IMPACT PORTIONS OF THE WESTERN ADIRONDACKS
AND WESTERN MOHAWK VALLEY THROUGH TONIGHT WHERE SEVERAL INCHES OF
NEW SNOW IS EXPECTED. OTHERWISE…A LIGHT ACCUMULATION OF SNOW MAY BE
POSSIBLE TO THE SOUTH AND EAST OF THE CAPITAL DISTRICT TUESDAY
INTO TUESDAY NIGHT AS AN AREA OF LOW PRESSURE PASSES SOUTH OF LONG
ISLAND.

WITH THE COLDER AIRMASS IN PLACE SOME ICE WILL START TO DEVELOP ON
RIVERS AND PONDS ESPECIALLY ACROSS THE NORTH COUNTRY AND THE
HIGHER TERRAIN. SOME ICE EFFECTS COULD BE SEEN ON GAGES BY LATE
IN THE WEEK.

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 WARNING UNTIL NOON EST MONDAY FOR NYZ032.
LAKE EFFECT SNOW ADVISORY UNTIL NOON EST MONDAY FOR NYZ033.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…BGM
NEAR TERM…HWJIV/BGM
SHORT TERM…BGM
LONG TERM…HWJIV
AVIATION…HWJIV
HYDROLOGY…IAA/BGM

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