March 20, 2013 Forecast Discussion

000
FXUS61 KALY 202132
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
530 PM EDT WED MAR 20 2013

.SYNOPSIS…
A LARGE AND BROAD UPPER LEVEL DISTURBANCE WILL KEEP TEMPERATURES
BELOW NORMAL AND THE WEATHER SOMEWHAT UNSETTLED THROUGH THE
REMAINDER OF THE WORKWEEK. SCATTERED TO NUMEROUS SNOW SHOWERS WILL
CONTINUE ACROSS THE HILLTOWNS AND MOHAWK VALLEY…WITH ONLY A FEW
FLURRIES OR ISOLATED SNOW SHOWERS ELSEWHERE.
&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/…
AS OF 500 PM EDT…DIURNAL HEATING HAS PRODUCED STEEP LOW LEVEL
LAPSE RATES AND LOTS OF INSTABILITY CLOUDS. THIS PLUS CYCLONIC FLOW
ALOFT CONTINUES TO LEADS TO SNOW SHOWERS…MOST NUMEROUS DOWNWIND OF
LAKE ONTARIO. THE IMPRESSIVE SNOW BAND HAS BEEN DISRUPTED BY HEATING
AND EVEN THERE…THE SNOW BANDS HAVE BECOME QUITE CELLULAR.
HOWEVER…AS THE SUN SETS WE ARE CONFIDENT THIS BAND WILL REGENERATE
ONCE AGAIN TO BRING ANOTHER ROUND OF SIGNIFICANT LAKE EFFECT SNOW TO
HERKIMER AND POSSIBLY EVEN INTO HAMILTON COUNTY. FOR NOW…WILL
LEAVE THE LAKE EFFECT SNOW WARNINGS FOR THESE COUNTIES IN PLACE.

OTHERWISE…AGAIN EXPANDED ISOLATED SNOW SHOWERS INTO THE CAPITAL
REGION AND EVEN A LITTLE SOUTH. OTHERWISE NO BIG CHANGES.

FOR THE REST OF THE DAYLIGHT HOURS…IT WILL BE BRISK WITH THOSE
PESKY SNOW SHOWERS FROM KINGSTON NORTH. OUTSIDE THE
MOUNTAINS…LITTLE OR NO SNOW ACCUMULATIONS IS EXPECTED. ACROSS THE
HIGHER TERRAIN A COATING TO AN INCH IN SPOTS CAN BE EXPECTED BY
DAY/S END. TEMPERATURES WILL GENERALLY HOLD IN THE 30S…EXCEPT 20S
ACROSS THE HIGHER TERRAIN.

A GUSTY NORTHWEST WIND WILL AVERAGE 10-15 MPH…GUSTING TO 25
MPH…EXCEPT AROUND 30 MPH ACROSS PORTIONS OF THE HIGHER
TERRAIN/MOHAWK VALLEY AND GREATER CAPITAL DISTRICT.

WITH THE EXCEPTION OF THE AFOREMENTIONED LAKE EFFECT SITUATION FOR
NORTHERN HERKIMER AND HAMILTON COUNTIES…THE REST OF THE AREA
SHOULD SEE A REDUCTION IN CLOUDS AND SNOW SHOWERS AS WE LOOSE OUR
INSTABILITY. THE BREEZE SHOULD RELAX AS WELL.

WITH THE FRESH SNOW PACK AND REDUCTION IN WIND AND CLOUDS…WENT A
TAD LOWER THE COLD SIDE OF GUIDANCE. LOOK FOR LOWS GENERALLY IN THE
TEENS (NEAR 20 MID HUDSON VALLEY/LOWER LITCHFIELD). A FEW OF THE
COLDEST MOUNTAIN VALLEYS COULD SEE READINGS LOCALLY INTO THE SINGLE
DIGITS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/… BY
EARLY MORNING THURSDAY…THE SUBSIDENCE INVERSION WILL BE
LOWERING…WHICH SHOULD REDUCE THE HEIGHT OF THE LAKE EFFECT
CLOUDS…AND THE INTENSITY OF THE LAKE EFFECT. HOWEVER…THEY WILL
CONTINUE TO PERSIST AS THE HUGE UPPER LEVEL LOW CONTINUES TO
OVERHEAD ADDING CYCLONIC LIFT AND MOISTURE. THIS FEATURE WILL MOVE
VERY LITTLE DURING THE SHORT TERM PERIOD.

HOWEVER…ANOTHER LOBE OF VORTICITY…REINFORCING COLD FRONT…IS
FORECAST BY MOST MODELS TO SWING THROUGH THE ENTIRE AREA LATE
THURSDAY NIGHT INTO EARLY FRIDAY.
THIS MIGHT BRING A BOUT OF WIDESPREAD NUMEROUS SNOW SHOWERS ACROSS
MOST OF THE AREA DURING THIS TIME PERIOD…BUT OUTSIDE OF THE LAKE
BELTS…SHOULD BE LIGHT AND SCATTERED WITH LITTLE OR NO
ACCUMULATION. DOWNWIND OF LAKE ONTARIO AND UPSLOPE AREAS MIGHT SEE
AN INCH OR TWO OF ADDITIONAL SNOWFALL.

BEHIND THE COLD FRONT…THE CHILL AIRMASS WILL BE REINFORCED
INSURING A CONTINUATION OF BELOW NORMAL TEMPERATURES. ON THE BRIGHT
SIDE…BY SATURDAY…IT LOOKS AS THE UPPER AIR LOW FINALLY MOVES OFF
TO OUR EAST. THIS WILL FINALLY MEAN A LITTLE MORE STABILITY OF THE
ATMOSPHERE…A LITTLE MORE SUNSHINE AND LOT LESS SNOW SHOWERS. IT
LOOKS DRY SATURDAY. STRONG MARCH SUN WILL ATTEMPT TO MODERATE
TEMPERATURES BUT THEY WILL STAY REMAIN BELOW NORMAL. IF ANYTHING
THOUGH…SATURDAY WILL ACTUALLY BE BREEZIER THAN FRIDAY AS THE
PRESSURE GRADIENT STEEPENS.

THROUGH THIS PERIOD OVERNIGHT LOWS WILL RANGE FROM THE LOWER TEENS
NORTHWEST TO MID 20S SOUTHEAST. DAYTIME HIGHS FRIDAY WILL ONCE AGAIN
BE MAINLY IN THE 30S (EXCEPT 20S HIGHER TERRAIN) AND CLOSE TO 40 MID
HUDSON VALLEY/LOWER LITCHFIELD COUNTY. SATURDAY…HIGHS WILL
MODERATE TO THE MID 30S NORTHWEST…TO MID 40S SOUTH AND EAST OF THE
CAPITAL DISTRICT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/…
THE LONG TERM PERIOD STARS DRY ON SUNDAY AS A PIECE OF HIGH PRESSURE
BREAKS OFF FROM THE LARGE DOME CENTERED OVER HUDSON BAY. IT WILL
STILL BE BELOW NORMAL TEMPERATURE WISE BUT AT LEAST SOME SUNSHINE
AND ONLY A LITTLE BREEZY.

THEN…WE WILL HAVE TO WATCH A STORM GATHERING IN SOUTHERN STREAM
LATE SUNDAY INTO EARLY NEXT WEEK. IT LOOKS TO BE ANOTHER ONE OF
THESE "STORM SPLITTER" SCENARIOS…WITH THE PRIMARY UPPER LOW
WORKING FROM THE LOWER OHIO VALLEY…AND A SECONDARY LOW DEVELOPING
SOMEWHERE ALONG OR OFF THE SOUTHEAST COAST.

THE CANADIAN MID RANGE FORECAST MODEL (CMC) HAS THIS SYSTEM COMING
STRAIGHT UP ALONG OR EVEN INSIDE THE COAST…AND BRINGING A ROUND OF
SIGNIFICANT SNOW OUR WAY LATER MONDAY.

HOWEVER…THIS MODEL IS NOT SUPPORTED BY THE OPERATIONAL 12Z
EUROPEAN AND GFS MODELS. THE GFS DOES BRING THIS SYSTEM NORTH…BUT
IN WEAKER FORM…WITH MOST OF THE GOOD FORCING REMAINING SOUTH OF
THE REGION. THE GFS ENSEMBLES SUPPORT THIS IDEA…WHICH WOULD BRING
POSSIBLY LIGHT SNOW UP TO THE CAPITAL DISTRICT.

THE 12Z EUROPEAN CONTINUED WITH SUPPRESSING THIS STORM SOUTH OF OUR
REGION WITH NO EVIDENT OF PHASING WITH THE NORTHERN STREAM. THIS
MODEL HAS INDICATED THIS SCENARIO FOR SEVERAL RUNS.

FOR NOW…WILL CONTINUE WITH LOW CHANCES FOR A CHANCE MOSTLY SNOW
SOUTH OF REGION SUNDAY NIGHT INTO MONDAY…SLIGHT CHANCES FROM THE
CAPITAL REGION NORTHWARD. CONFIDENCE OF A SIGNIFICANT SNOW IS VERY
LOW AT THIS (WELL BELOW 30 PERCENT) SO NO MENTION OF IT IN OUR
HAZARDOUS WEATHER OUTLOOK).

WHATEVER STORM WE HAVE (OR DON/T HAVE) WILL MOVE TO EAST OR
SOUTHEAST BY TUESDAY. THIS STORM WILL PULL MORE CHILLY CANADIAN AIR
OUR WAY…BUT PROBABLY NOT AS COLD AS WE HAVE BEEN ENDURING.
HOWEVER…THE OVERALL PATTERN DOES NOT CHANGE SO TEMPERATURES WILL
CONTINUE TO RUN AT LEAST A BIT BELOW NORMAL.

FIGURE ON HIGH TEMPERATURES TO GENERALLY RUN FROM THE LOWER 30S IN
NORTHWEST ZONES EACH DAY…TO MID 40 IN OUR SOUTHEASTERN ZONES EACH
DAY. OVERNIGHT LOWS WILL GENERALLY BE TEENS NORTH…20S SOUTH. KEEP
IN MIND…IF THE STORM WERE TO COME NORTH ON MONDAY AND BRING
PRECIPITATION…TEMPERATURES WOULD LIKELY BE COLDER ACROSS THE
ENTIRE REGION…IN THE 30S EVERYWHERE.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/…
VFR CONDITIONS LOOK TO PREVAIL THROUGH THE TAF PERIOD THROUGH 12Z
THURSDAY.

LAKE EFFECT SNOWS WILL CONTINUE DOWNWIND OF LAKE ONTARIO AND LAKE
ERIE…HOWEVER THEY ARE EXPECTED TO HAVE LITTLE IF ANY IMPACT ON THE
TAF SITES THROUGH THE END OF THE TAF PERIOD AT 12Z THURSDAY. AT THE
SURFACE LOW PRESSURE WILL BE OVER THE CANADIAN MARITIMES AND WILL
BEGIN TO MOVE WESTWARD AS ITS DRAWN UNDER THE UPPER LOW TODAY.

THERE IS A POSSIBILITY THAT SOME OF THE BANDS MAY REACH KGFL…KALB
AND KPSF ERLY THIS AFT AND LAST INTO EARLY EVENING. DUE TO
UNCERTAINTY WILL ONLY INCLUDE A VCSH IN THE TAFS AT THESE SITES FOR
NOW.

WEST-NORTHWEST WINDS WILL DECREASE THIS EVENING…DOWN TO AROUND
5KTS FROM THE WEST.

OUTLOOK…
THU-FRI…MAINLY VFR.
SAT-SUN…VFR. NO SIG WX.
MON…VFR. CHC SUB-VFR IN SNOW OR RAIN SOUTH OF KALB.
&&

.FIRE WEATHER…
NO CRITICAL FIRE WEATHER CONCERNS FOR THE NEXT FIVE DAYS.

WIDESPREAD SNOWCOVER WILL BE IN PLACE OVER THE REGION THROUGH THE
REMAINDER OF THE WEEK.

A LINGERING UPPER LEVEL LOW WILL KEEP PLENTY OF CLOUDS…ADDITIONAL
SNOW SHOWERS AND BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND.

&&

.HYDROLOGY…
NO HYDROLOGICAL PROBLEMS EXPECTED THROUGH THE WEEK.

A LINGERING UPPER LEVEL LOW WILL ALLOW FOR SNOW SHOWERS AND
FLURRIES…MAINLY ACROSS NORTHERN AND HIGH TERRAIN AREAS THROUGH
FRIDAY NIGHT.

WHILE DAYTIME TEMPERATURES WILL RISE ABOVE FREEZING IN VALLEY
AREAS OVER THE NEXT FEW DAYS…TEMPS SHOULD DROP BELOW FREEZING AT
NIGHT. SLOW MELTING OF SNOW IS POSSIBLE OVER THE NEXT FEW
DAYS. RIVER AND STREAM LEVELS WILL MAINLY HOLD STEADY THROUGH THE
WEEKEND.

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 6 AM EDT THURSDAY FOR NYZ032-
033.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…HWJIV
NEAR TERM…HWJIV
SHORT TERM…HWJIV
LONG TERM…HWJIV
AVIATION…HWJIV/NAS/IRL
FIRE WEATHER…FRUGIS/HWJIV
HYDROLOGY…FRUGIS

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