January 22, 2012 Forecast Discussion

000
FXUS61 KALY 230027
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
727 PM EST SUN JAN 22 2012

.SYNOPSIS…
HIGH PRESSURE WILL MOVE EASTWARD OFF THE NEW ENGLAND COAST
TONIGHT…AS A WARM FRONT APPROACHES FROM THE OHIO VALLEY AND MID
ATLANTIC REGION. ON MONDAY…A POWERFUL LOW PRESSURE SYSTEM WILL
TRACK NORTHEASTWARD FROM THE UPPER GREAT LAKES INTO SOUTHEAST
CANADA. THIS SYSTEM WILL LIKELY BRING SOME LIGHT MIXED PRECIPITATION
IN THE MORNING…FOLLOWED BY A STEADY RAINFALL DURING THE AFTERNOON
AND EVENING. A COLD FRONT WILL PASS THROUGH MONDAY NIGHT…ALTHOUGH
THE AIR MASS BEHIND THE FRONT WILL BE MILD FOR THIS TIME OF YEAR.

&&

.NEAR TERM /THROUGH MONDAY/…
AS OF 7 PM EST…CLOUDS MOVING IN FROM THE SOUTH AND WEST. WITH
OVC SKIES…TEMPS AT KPOU NEAR STEADY. KALB ALREADY OVC028…WITH
CLOUDS CONTINUING TO MOVE NORTH. EXPECT KGFL AND THE NORTH
COUNTRY TO BE MOSTLY CLOUDY BEFORE MIDNIGHT. KALB 00Z SOUNDING
SHOWS WARMING ALOFT VIA A WARM NOSE AROUND 835 MB. WARMING WILL
CONTINUE ALOFT…AND SLOWLY MAKE IT DOWN TO THE SFC. HAVE NON
DIURNAL TREND STARTING FROM SOUTH TO NORTH…WITH ALL OF THE FA
WARMING AFTER MIDNIGHT.

AS OF 415 PM…ISSUED A FREEZING RAIN ADVISORY FOR THE ENTIRE AREA
STARTING LATE THIS EVENING ACROSS SOUTHERN AREAS AND EARLY MONDAY
MORNING FOR NORTHERN AREAS.

LOW STRATUS CLOUDS CREEPING NORTHWARD ACROSS THE
ULSTER…DUTCHESS…LITCHFIELD COUNTIES AS THE LOW LEVEL FLOW HAS
BECOME SOUTHEAST. THESE CLOUDS WILL ENVELOP THE EASTERN CATSKILLS
FIRST THIS EVENING…AND WILL SATURATE THE LOW LEVELS. DRY AIR ALOFT
WILL REMAIN…SO THERE IS A GOOD CHANCE OF FREEZING DRIZZLE
DEVELOPING AS THERE WILL BE NO ICE NUCLEI IN THE CLOUDS. THE CHANCE
OF FREEZING DRIZZLE WILL INCREASE FROM MAINLY THE CAPITAL REGION
SOUTHWARD OVERNIGHT…AS THE SAME EFFECT OCCURS WITH THE STRATUS
ENCROACHING AND LOW LEVEL SOUTH-SOUTHEAST FLOW STRENGTHENING. WILL
ALSO MENTION A CHANCE OF LIGHT SLEET TONIGHT DUE A SOMEWHAT DEEP
SUB-FREEZING LAYER BENEATH THE INVERSION DESPITE LACK OF ICE NUCLEI
IN THE CLOUDS. ANY SLEET ACCUMULATION WILL BE AROUND A TRACE.

ENHANCED UPSLOPE WILL LEAD TO SOME ICE ACCRETION WITH LIGHT FREEZING
RAIN EXPECTED IN THE EASTERN CATSKILLS WITH AROUND ONE TENTH OF AN
INCH OF ICE THROUGH MONDAY MORNING. OTHER AREAS WILL LIKELY SEE ONLY
A LIGHT GLAZE DUE TO FREEZING DRIZZLE. PRECIP WILL NOT BEGIN ACROSS
NORTHERN AREAS UNTIL AROUND SUNRISE OR SHORTLY AFTER. WARMER AIR
WILL GRADUALLY WORK IN FROM THE SOUTH…WITH POCKETS OF FREEZING
DRIZZLE OR LIGHT FREEZING RAIN CHANGING TO DRIZZLE/LIGHT RAIN. AREAS
TO NORTH SUCH AS THE WESTERN/SOUTHERN ADIRONDACKS COULD HAVE POCKETS
OF FREEZING DRIZZLE LINGERING INTO THE EARLY AFTERNOON.

THE MAIN TIME FRAME FOR A SLUG OF MODERATE RAIN TO MOVE ACROSS THE
ENTIRE AREA FROM WEST TO EAST WILL BE FROM MID AFTERNOON MONDAY
THROUGH MUCH OF MONDAY EVENING. THE RAIN WILL OCCUR AHEAD OF A COLD
FRONT APPROACHING FROM THE OHIO VALLEY. PWAT ANOMALIES ARE FORECAST
TO RANGE FROM +2 TO +3 STDEV SO RAINFALL RATES WILL BE IMPRESSIVE
FOR JANUARY. THERE COULD BE NARROW COLD FRONTAL RAINBAND OR SIMILAR
FEATURE ALONG THE LEADING EDGE OF THE COLD FRONT. THIS MAY HAVE SOME
CONVECTIVE ELEMENTS WHICH COULD RESULT IN SOME BRIEFLY GUSTY WINDS.
SHOWALTER VALUES FROM THE NAM/GFS ARE FORECAST TO REMAIN POSITIVE IN
OUR AREA AND FORECAST SOUNDINGS REVEAL A STABLE LAYER IN THE LOWEST
FEW THOUSAND FEET SO NOT EXPECTING WINDS TO GET VERY STRONG. THE
USUAL LOCATIONS THAT EXPERIENCE GUSTY WINDS IN A SOUTH-SOUTHEAST
FLOW REGIME COULD HAVE GUSTS OF 30-40 MPH FROM MONDAY AFTERNOON INTO
THE EVENING. TEMPS SHOULD WARM TO ABOVE FREEZING LEVELS ACROSS THE
ENTIRE AREA BY MID AFTERNOON.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/…
AS OF 425 PM…RAIN WILL END FROM WEST TO EAST BY LATE MONDAY
EVENING AS THE COLD FRONT PUSHES THROUGH. NOT LOOKING FOR A BIG
SURGE OF WIND BEHIND THE FRONT LATE MONDAY NIGHT INTO TUESDAY…AS
THE MAIN LOW PRESSURE CENTER WILL BE PASSING BY TO THE NORTH AND
WEST OF THE ST LAWRENCE VALLEY WHICH IS NOT A FAVORABLE TRACK. IT
WILL STILL BE BREEZY BUT WE WILL LIKELY NOT EXPERIENCE STRONG WEST
WINDS IN WAKE OF THE FRONTAL PASSAGE.

THE AIR MASS BEHIND THIS FIRST COLD FRONT IS NOT VERY COLD…AND IN
FACT MAX TEMPS ON TUESDAY BE BE WARMER THAN MONDAY DUE TO BETTER
MIXING POTENTIAL. LOWER TO MID 40S APPEAR ATTAINABLE FOR MUCH OF THE
AREA EXCEPT FOR COOLER 30S IN THE ADIRONDACKS. THE ONLY CHANCE FOR A
FEW RAIN/SNOW SHOWERS WILL BE ACROSS UPSLOPE AREAS OF THE WESTERN
ADIRONDACKS LATE MONDAY NIGHT INTO TUESDAY.

OTHERWISE…A SECONDARY COLD FRONT WILL PASS THROUGH TUESDAY
NIGHT…BUT WITH LIMITED MOISTURE WILL ONLY MENTION SLIGHT CHANCE TO
CHANCE POPS FOR SOME SNOW SHOWERS ACROSS AREAS NORTH AND WEST OF THE
CAPITAL REGION. THIS IS NOT AN ARCTIC BOUNDARY THOUGH…SO TEMPS
LATE TUESDAY WILL REMAIN ABOVE NORMAL.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/…
HIGH PRESSURE WILL BUILD INTO THE OHIO RIVER VALLEY ON
WEDNESDAY…PRODUCING DRY CONDITIONS OVER MOST OF THE AREA. THIS
HIGH WILL NOT LAST LONG AS A DEEP TROUGH OVER CENTRAL CANADA PUSHES
THE HIGH OFF THE MID ATLANTIC COAST ON THURSDAY. AHEAD OF THIS
TROUGH…SOME WAA WILL BRING 850 HPA TEMPS ABOVE FREEZING THURSDAY
INTO EARLY FRIDAY. THIS COULD LEAD TO A MIX OF RAIN AND SNOW…AND
POSSIBLY SOME SLEET…ESP SOUTH OF THE CAPITAL REGION AS AN
ASSOCIATED COLD FRONT BRINGS PRECIP INTO THE AREA THURSDAY NIGHT.
THE COLD FRONT SHOULD BE THROUGH THE FA SOMETIME ON FRIDAY…WITH
ONLY A FEW LINGERING SNOW SHOWERS OVER THE NORTH COUNTRY. BEHIND THE
COLD FRONT…850 HPA TEMPS WILL DROP INTO THE NEGATIVE SINGLE DIGITS.

AS THE AFOREMENTIONED SYSTEM IS AFFECTING OUR REGION…ANOTHER LOW
WILL BE SKIRTING THE GULF OF MEXICO…HEADING EASTWARD OVER THE
SOUTHEAST USA. THIS LOW WILL SHIFT NE LATE FRIDAY…POISED TO MOVE
TOWARD THE OBX…THEN HEAD FOR OUR REGION. ECMWF AND GFS DIFFER ON
TIMING AND STRENGTH…WITH THE ECMWF BEING THE MORE AGGRESSIVE
SOLUTION THIS TIME. THE GFS HAS A NORTHERLY LOW OVER THE GREAT LAKES
REGION RETARDING THE PROGRESSION OF THE COASTAL LOW AS THE GREAT
LAKES LOW BECOMES THE STRONGER OF THE TWO. WILL HAVE TO KEEP AN EYE
ON THIS…BUT OVERALL THE WEEKEND LOOKS TO BE ACTIVE AND WET.

THE PERIOD WILL START WITH TEMPERATURES ABOUT 5 DEGREES ABOVE
NORMAL…WARMING TO 10 DEGREES ABOVE NORMAL AHEAD OF THE FIRST
SYSTEM. BEHIND THE COLD FRONT…TEMPERATURES WILL NEAR NORMAL.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/…
AS OF 630 PM…MVFR STRATUS DECK HAD ALREADY SURGED NORTHWARD AND
REACHED KALB. IT HAD REACHED KPOU FROM EARLY SUNDAY AFTERNOON.
EXTRAPOLATING THE NORTHWARD SPEED OF THE STRATUS DECK…WOULD EXPECT
IT TO REACH KGFL BY AROUND 02Z. AS RESULT…MVFR CIGS ARE FORECAST
AT ALL THREE TAF SITES THROUGH THE NITE…WITH THE CIGS EXPECTED TO
GRADUALLY LOWER. MORE DIFFICULT PART OF THE FORECAST IS DETERMINING
WHEN -FZDZ WILL BEGIN AT EACH OF THE TAF SITES. AS OF 630 PM…RADAR
AND SURFACE OBSERVATIONS TO THE SOUTH OF THE REGION DO NOT INDICATE
ANY PCPN…SO IT WILL LIKELY TAKE AT LEAST SEVERAL MORE HOURS FOR
ANY -FZDZ TO DEVELOP AND BEGIN TO SPREAD NORTH THROUGH THE REGION.
HAVE GENERALLY FORECAST -FZDZ TO BEGIN AT KPOU SOMETIME BETWEEN 04Z
AND 08Z…AROUND 08Z AT KALB…AND AROUND 10Z AT KGFL. CIGS AND
VSBYS WILL CONTINUE TO LOWER AFTER SUNRISE MONDAY BUT ARE LIKELY TO
REMAIN IN THE MVFR RANGE UNTIL A FRONTAL BOUNDARY BRINGS WIDESPREAD
MODERATE RAIN TO THE REGION DURING THE MID AFTERNOON PERIOD. EXPECT
IFR CIGS/VSBYS IN MODERATE RAIN AT ALL THREE TAF SITES AFTER ABOUT
19Z-20Z.

BACKING UP IN TIME…AS WARMER AIR MOVES INTO THE REGION LATE
TONIGHT AND MONDAY MORNING…-FZDZ WILL SLOWLY CHANGE TO JUST -DZ.
EXPECT THIS TO OCCUR AROUND 13Z AT KPOU…AROUND 15Z AT KALB…AND
AROUND 18Z AT KGFL.

SURFACE WINDS WILL BE CALM OR LIGHT AND VARIABLE TONIGHT AND EARLY
MONDAY…THEN SOUTHEAST 5 TO 15 KTS.

OUTLOOK…
MON NITE…MVFR/IFR…RA LIKELY EARLY…VFR/MVFR SCT -SHRA-SHSN
LATE.
TUE-FRI…VFR…NO SIG WX.

&&

.HYDROLOGY…
NO HYDROLOGIC PROBLEMS EXPECTED THROUGH EARLY MONDAY.

A STORM SYSTEM WILL BRING MIXED PRECIPITATION CHANGING TO RAIN LATER
TONIGHT INTO MONDAY. A QUICK SHOT OF MODERATE TO HEAVY RAIN IS
POSSIBLE MONDAY AFTERNOON WITH A COLD FRONT WITH QPF VALUES BETWEEN
ONE QUARTER TO ONE HALF INCH WITH LOCALIZED AMOUNTS AROUND AN INCH
POSSIBLE.

WE MEASURED THE GROUND FROZEN TO A DEPTH OF 14 INCHES HERE AT THE
OFFICE ON SUNDAY. SOME LOCALIZED POOR DRAINAGE…URBAN AND SMALL
STREAM FLOODING MAY BE POSSIBLE LATER MONDAY DUE TO ENHANCED RUNOFF
FROM RAIN AND MELT ON FROZEN GROUND.

SOME SIGNIFICANT RISES ON MAIN STEM RIVERS ARE POSSIBLE MONDAY INTO
TUESDAY…BUT LARGER RIVER FLOODING IS NOT EXPECTED AT THIS TIME.
RISES WOULD BE ENOUGH TO BREAK UP WHAT RIVER ICE IS IN PLACE BUT ICE
IS NOT THICK ENOUGH TO CAUSE SIGNIFICANT ICE JAM PROBLEMS.

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…FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
MONDAY FOR CTZ001-013.
NY…FREEZING RAIN ADVISORY UNTIL NOON EST MONDAY FOR NYZ058-063.
FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
MONDAY FOR NYZ039-040-047>054-059>061-064>066.
FREEZING RAIN ADVISORY FROM 6 AM TO 2 PM EST MONDAY FOR NYZ032-
033-038-041>043-082>084.
MA…FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
MONDAY FOR MAZ001-025.
VT…FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
MONDAY FOR VTZ013>015.

&&

$$
SYNOPSIS…JPV
NEAR TERM…KGM/JPV
SHORT TERM…JPV
LONG TERM…KGM
AVIATION…GJM
HYDROLOGY…SND

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