February 7, 2012 Forecast Discussion

000
FXUS61 KALY 071750
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1250 PM EST TUE FEB 7 2012

.SYNOPSIS…
- Changed Discussion —
A COLD FRONT WILL CONTINUE TO DRIFT SOUTH ACROSS THE REGION
THROUGH THE AFTERNOON. WEAK HIGH PRESSURE WILL THEN BUILD INTO THE
REGION TONIGHT…AND REMAIN OVER THE REGION THROUGH THURSDAY. AT
THE SAME TIME…A WEAK DISTURBANCE WILL BE PASSING OFF THE MID
ATLANTIC COAST EARLY WEDNESDAY NIGHT…WHICH COULD BRING SOME SNOW
SHOWERS TO AREAS WELL SOUTH OF ALBANY WEDNESDAY EVENING.
- End Changed Discussion -

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
— Changed Discussion —
AS OF 1240 PM EST…COLD FRONT HAS MOVED THROUGH FA WITH STRONG
COLD AIR ADVECTION EXPECTED DURING THIS AFTERNOON. EXPECT TEMPS TO
FALL BY 3 TO 5 DEGREES THIS AFTERNOON ACROSS SOUTHERN PORTION OF
FA AND 5 TO 10 DEGREES ACROSS NORTHERN PORTION OF FA. H8 TEMPS ARE
EXPECTED TO DROP TO BETWEEN -6 C AND -12 C BY 00Z THIS EVENING. WHILE
THERE HAVE BEEN SOME BREAKS IN THE CLOUD COVER IN THE VALLEYS WITH
PARTLY SUNNY CONDITIONS THROUGH THE MID DAY PERIOD…EXPECT THAT
SKIES WILL BE MOSTLY CLOUDY ACROSS THE MOUNTAINS DURING THE
AFTERNOON. BULK OF CLEARING AT THIS TIME REMAINS ACROSS AREAS FROM
THE SAINT LAWRENCE VALLEY NORTH.

AS OF 915 AM EST…A COLD FRONT CONTINUES TO MOVE NORTH TO SOUTH
ACROSS UPSTATE NY AND NEW ENGLAND THIS MORNING. THE FRONT APPEARS
TO HAVE REACHED THE CAPITAL REGION/I-90 CORRIDOR WITH THE SFC
WINDS VEERING THE W/NW. TEMPS WILL LIKELY REACH THEIR MAX VALUES
IN THE LATE MORNING/EARLY PM…AND THEN DROP OR BE STEADY INTO THE
MID AFTERNOON. ACTUALLY FURTHER NORTH…TEMPS WILL FALL INTO THE
LOWER 30S AND 20S. THIS BOUNDARY IS MOISTURE STARVED…WITH LITTLE
PCPN WITH IT. WE KEPT A NARROW WINDOW OF ONLY SLIGHT CHC POPS FOR
THE WRN DACKS/WRN MOHAWK VALLEY FOR ISOLD SNOW SHOWERS OR FLURRIES
UNTIL NOONTIME. THE KALB 12Z SOUNDING SHOWS A STRONG LOW LEVEL
INVERSION AT ABOUT 835-800 HPA. THE CLOUDS WILL TAKE SOME TIME TO
ERODE THIS AFTERNOON. THE LEADING EDGE OF THE CLOUDS IS FINALLY
REACHING THE MID AND LOWER HUDSON VALLEY. WE LOWER MAX TEMPS A FEW
DEGREES THERE /LOWER 40S NEAR KPOU/. WE ARE SEEING SOME CLEARING
ALONG THE SOUTHERN CANADIAN BORDER. WE WILL CONTINUE TO MONITOR
THE SATELLITE PICTURE FOR THE NEXT ESTF IN THE EARLY PM. FOR
NOW…WILL TRENDS TO PARTLY CLOUDY CONDITIONS BY THE MID
AFTERNOON.

PREVIOUS NEAR TERM…

AS OF 530 AM…WIDE VARIATION IN TEMPS ACROSS THE REGION
CONTINUES…WITH CURRENT TEMPS STILL NEAR FORECAST HIGHS FOR TODAY.
HAVE ADJUSTED HOURLY TEMP/CLOUD GRIDS TO REFLECT CURRENT CONDITIONS.
OTHERWISE…PREVIOUS FORECAST IS UNCHANGED.

PREVIOUS DISCUSSION
AS OF 400 AM…COLD FRONT AS DELINEATED BY THE CLOUD BAND IS SLOWLY
WORKING SOUTH THROUGH THE FORECAST AREA EARLY THIS MORNING…BUT
COLDER AIR STILL LAGGING BACK ACROSS SOUTHERN CANADA AND MAY TAKE A
WHILE BEFORE MOVING INTO THE FORECAST AREA. TEMPS HAVE ACTUALLY
RISEN IN MOST PLACES AS THE CLOUDS MOVED IN AND SURFACE WINDS PICKED
UP. ONLY PLACES OVER THE SOUTHERN THIRD OF THE FORECAST AREA HAVE
READINGS IN THE 20S DUE TO CLEAR SKIES AND LIGHT WINDS…WHILE THE
REST OF THE FORECAST AREA HAS READINGS STILL IN THE 30S…AND CLOSE
TO OR STILL ABOVE THE FORECAST HIGHS FOR TODAY. WITH SUCH A
DISORGANIZED PATTERN TO CURRENT TEMPS…DIFFICULT TO GET HOURLY
TEMP GRIDS IN ORDER. IN GENERAL…HOURLY TEMPS ARE FORECAST TO ONLY
RISE A FEW DEGREES…IF AT ALL…AT MOST PLACES OVER THE NORTHERN
TWO-THIRDS OF THE FORECAST AREA TODAY…WHILE FORECAST TO RISE FROM
THE MID 20S AND LOWER 30S TO HIGHS IN THE UPPER 30S TO MID 40S
ACROSS THE SOUTH. NOT MUCH PCPN EXPECTED WITH THE CLOUD BAND/FRONTAL
BOUNDARY. UPSTREAM RADARS INDICATE VERY FEW RETURNS. HAVE ONLY
FORECAST SLIGHT CHANCE TO LOW CHANCE POPS OVER THE FAR NORTHWEST
PART OF THE FORECAST AREA DURING THE MORNING HOURS.
— End Changed Discussion —

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/…
FOR TUESDAY NIGHT THROUGH THURSDAY EXPECT HIGH PRESSURE TO BE THE
DOMINANT FEATURE AS THE FIRST HIGH PRESSURE CENTER CRESTS ACROSS OUR
REGION TONIGHT…THEN WEAKENS AS THE NOSE OF OF A LARGE RIDGE OF
HIGH PRESSURE OVER THE MID MISSISSIPPI VALLEY EXTENDS INTO OUR
REGION WEDNESDAY NIGHT INTO THURSDAY. THERE WILL BE A FAST MOVING
LOW PRESSURE SYSTEM PASSING SOUTH OF OUR AREA AND OFF THE MID
ATLANTIC COAST WEDNESDAY NIGHT. HOWEVER…THIS SYSTEM APPEARS TOO
FAR SOUTH FOR MOST OF THE FORECAST AREA TO SEE ANY PCPN…BUT HAVE
FORECAST SLIGHT CHANCE POPS FOR SNOW ACROSS THE EXTREME SOUTHERN
PORTION OF FORECAST AREA WEDNESDAY EVENING.

LOWS TONIGHT WILL RANGE FROM AROUND 5 BELOW ZERO NORTHWEST TO THE
UPPER TEENS SOUTHEAST. HIGHS ON WEDNESDAY WILL BE IN THE UPPER 20S
TO MID 30S. LOWS WEDNESDAY NIGHT WILL BE IN THE TEENS AND LOWER
20S…WITH HIGHS THURSDAY IN THE 30S TO LOWER 40S.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/…
LOOKS LIKE THE MAINLY DRY PATTERN SHOULD CONTINUE THROUGH THE LONG
TERM…WITH ONE COLD FRONT TIMED AROUND THE FRIDAY NIGHT TIME
FRAME. A STRONGER COLD FRONT COULD TRACK THROUGH THE REGION LATER
INTO THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. THE DETAILS OF
THE REINFORCING COLD ARE QUITE UNCERTAIN AS DIFFERENT SOURCES OF
GUIDANCE RESOLVE THE POLAR VORTEX DROPPING SOUTH AND ROTATING
THROUGH EASTERN CANADA WITH DIFFERENT TIMING AND TRACKS.

STILL…GUIDANCE STILL SUGGESTS THE SOUTHERN STREAM IS MOSTLY CUT
OFF…SO VERY LITTLE MOISTURE SHOULD BE ASSOCIATED WITH THE FRONTAL
PASSAGES. THEE ARE HINTS THAT A STRONG NORTHERN STREAM UPPER IMPULSE
ROTATING THROUGH THE REGION AND MERGING WITH THE POLAR VORTEX COULD
SUPPORT DEVELOPMENT OF A LOW PRESSURE CENTER OFF LONG ISLAND AND NEW
ENGLAND TOWARD THE BEGINNING OF NEXT WEEK AND POTENTIALLY THE
COLDEST AIR OF THE SEASON COULD ARRIVE IN OUR REGION ONCE THE SYSTEM
EXITS. JUST SOMETHING TO KEEP AN EYE ON.

SO…TEMPERATURES ABOVE NORMAL THURSDAY NIGHT INTO FRIDAY…WITH
HIGHS FRIDAY IN THE 40S…AROUND 30 SOUTHERN ADIRONDACKS. COLD
ADVECTION SATURDAY WITH HIGHS IN THE 20S TO AROUND 30…SOME UPPER
TEENS IN HIGHER ELEVATIONS OF THE EASTERN CATSKILLS…SOUTHERN
ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. JUST A LITTLE POTENTIAL
WARMING SUNDAY AHEAD OF THE STRONGER COLD FRONT…WITH HIGHS IN THE
20S TO AROUND 30. WITH UNCERTAINTIES ABOUT THE CHARACTER OF THE
TRACK AND TIMING OF THE POLAR VORTEX AND THE STRONGER COLD FRONT…
JUST SUGGESTING HIGHS MONDAY SIMILAR TO SUNDAY UNTIL DETAILS BECOME
CLEARER AS WE GET CLOSER TO NEXT WEEKEND.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/…
— Changed Discussion —
A COLD FRONT CONTINUES TO MOVE SOUTHWARD ACROSS SOUTHERN NEW YORK
AND SOUTHERN NEW ENGLAND. HIGH PRESSURE WILL BUILD IN FROM
SOUTHEASTERN CANADA OVERNIGHT. AN UPPER LEVEL DISTURBANCE MOVING
ACROSS THE MID ATLANTIC REGION WEDNESDAY MORNING WILL SPREAD SOME
MID LEVEL CLOUDS BACK INTO PARTS OF THE REGION TOMORROW.

VFR CONDITIONS WILL DOMINATE THE NEXT 24 HOURS. A BRIEF PERIOD OF
HIGH MVFR CIGS IS POSSIBLE FOR KGFL BTWN 18Z-21Z. WE EXPECT CIGS TO
BE IN THE 3.5-6 KFT AGL RANGE IN THE WAKE OF THE FRONT…BEFORE
DRIER AIR FILTERS IN…AND THE CLOUD COVER BECOMES MORE SCATTERED IN
THE LATE AFTERNOON AND EARLY EVENING. THE STRONG SUBSIDENCE
ASSOCIATED WITH THE SFC HIGH WILL YIELD A PERIOD OF CLEAR SKIES FOR
THE E-CNTRL NY TERMINALS. SOME MIDLEVEL CLOUDS WILL MOVE BACK INTO
KPOU CORRIDOR AFTER MIDNIGHT. THERE WILL LIKELY BE A SHARP CUTOFF
IN THE EXTENT OF THE MID AND HIGH CLOUDS TOMORROW MORNING.

THE WINDS WILL BE FROM THE N/NW AT AROUND 10 KTS…WITH LOCALLY A NE
WIND KGFL FOR A BRIEF PERIOD THIS AFTERNOON. A FEW GUSTS AT KALB
WILL BE AROUND 20 KTS. EXPECT THE WINDS TO LIGHTEN 7 KTS OR LESS
TOWARDS 00Z…AND BECOME LIGHT TO CALM PRIOR TO MIDNIGHT. THE WINDS
WILL BE VARIABLE AND LIGHT AT 5 KTS OR LESS LATE MORNING INTO THE
AFTERNOON.

OUTLOOK…
WED-FRI…VFR…NO SIG WX.
FRI NIGHT-SUN…MAINLY VFR…SLIGHT CHC OF SNOW SHOWERS.
— End Changed Discussion —

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED THROUGH THE NEXT 5 DAYS. ANY PCPN
WILL BE IN THE FORM OF LIGHT SNOW SHOWERS NORTHWEST THIS MORNING…
AND ACROSS FAR SOUTHERN PORTION OF THE FORECAST AREA WEDNESDAY
EVENING. REMAINDER OF THE FORECAST AREA IS EXPECTED TO BE DRY. SOME
GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS OF
THE HSA.

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/WASULA
NEAR TERM…GJM/11/WASULA
SHORT TERM…WASULA
LONG TERM…NAS
AVIATION…WASULA
HYDROLOGY…GJM

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License