January 12, 2012 Forecast Discussion

000
FXUS61 KALY 121302
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
800 AM EST THU JAN 12 2012

.SYNOPSIS…
A COMPLEX STORM SYSTEM WILL BRING A WINTRY MIX OF PRECIPITATION
TO EASTERN NEW YORK AND WESTERN NEW ENGLAND TODAY. THE
PRECIPITATION WILL TRANSITION TO RAINFALL DURING THIS MORNING FROM
THE CAPITAL REGION AND THE MOHAWK VALLEY SOUTH AND EAST…AS A
COASTAL LOW QUICKLY MOVES NORTHEAST OF LONG ISLAND. ANOTHER LOW
PRESSURE SYSTEM WILL MOVE NORTHEAST FROM THE OHIO VALLEY TONIGHT
INTO FRIDAY WITH MAINLY RAIN AND SNOW SHOWERS SOUTH AND MIXED
PRECIPITATION TRANSITIONING TO SNOW NORTH…AS WELL AS BLUSTERY
AND COLD CONDITIONS TO CLOSE THE WORK WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 7 AM EST…995 MB COASTAL LOW WAS LOCATED NEAR CAPE MAY WITH
THE PRIMARY LOW BACK ACROSS NORTHERN OHIO. BULK OF PCPN WITH THE
MAIN SURGE OF PCPN HAS TAPERED OFF FROM THE CAPITAL DISTRICT SOUTH
TEMPORARILY ALTHOUGH NEXT SURGE OF PCPN MAINLY IN THE FORM OF RAIN
ASSOCIATED WITH THE UPPER TROUGH AND VORT AXIS MOVING ACROSS
NORTHERN NEW JERSEY AND NORTHEAST PA. WILL LEAVE REMAINING
ADVISORIES IN PLACE FOR NOW AS STILL SOME MIXED PRECIPITATION
FALLING. AREAS TO THE NORTHWEST WHICH ARE STILL BELOW FREEZING
HAVE REPORTED A PROLONGED PERIOD OF SLEET AND FREEZING RAIN
ESPECIALLY ACROSS THE WESTERN MOHAWK VALLEY AND PORTIONS OF THE
WESTERN ADIRONDACKS. HAVE ADJUSTED HOURLY GRIDS TO BETTER FIT
CURRENT OBS AND RADAR TRENDS. ALSO HAVE ADJUSTED QPF…SNOW AND
ICE AMOUNTS SLIGHTLY TO REFLECT LATEST REPORTS AS WELL AS EXPECTED
ADDITIONAL AMOUNTS. BULK OF THE MIXED PCPN IS EXPECTED TO BE OVER
BY THE END OF THE MORNING COMMUTE EXCEPT ACROSS FAR NORTHERN AREAS
AND WILL KEEP ADVISORY UP THROUGH THE AFTERNOON AT THIS TIME FOR
THE SOUTHERN ADIRONDACKS.

AS OF 4 AM EST…995 MB COASTAL LOW HAS MOVED OVER THE DELMARVA
PENINSULA AND IS TRACKING TOWARD LONG ISLAND AS THE PRIMARY LOW TO
THE WEST REMAINS OVER NORTH CENTRAL OHIO. TEMPERATURES HAVE COOLED
ACROSS MOST OF THE CENTRAL PORTION OF THE FA DURING THE LAST FEW
HOURS AS DEWPOINTS HAVE RISEN. FAR NORTHERN PORTIONS OF THE FA
HAVE SEEN TEMPS AND DEWPOINTS RISE WITH FAR SOUTHEAST PORTION OF
FA NOT ABLE TO TAP ENOUGH COLD AIR TO SUPPORT MUCH IN THE WAY OF
MIXED PCPN WITH MOSTLY RAIN OCCURRING. PARTIAL THICKNESS
VALUES…MODEL SOUNDINGS AND HRRR TEMPS ALL SUPPORT A GRADUAL
TRANSITION DURING THE MORNING TO ALL RAIN EXCEPT ACROSS THE
SOUTHERN ADIRONDACKS WHERE A WINTRY MIX WILL CONTINUE INTO THE
AFTERNOON. BEST FRONTOGENESIS IS NOW OCCURRING ACROSS THE
NORTHERN HALF OF FA AND THIS WILL SLIDE NORTH AND EAST OF THE FA
BY 12Z. ALREADY SEEING SOME BREAKS IN THE PCPN OCCURRING ACROSS
FAR SOUTHEAST PORTION OF FA AND EXPECT THAT THIS WILL CAUSE PCPN
TO DIMINISH IN INTENSITY FROM SOUTH TO NORTH OVER THE NEXT SEVERAL
HOURS…ALTHOUGH ONE MORE ROUND OF FAIRLY INTENSE PCPN IS
EXPECTED ASSOCIATED WITH THE UPPER TROUGH AND VORT AXIS LATER THIS
MORNING. HAVE ADJUSTED POPS TO REFLECT RADAR TRENDS…PTYPE
ADJUSTED BY PARTIAL THICKNESS VALUES GOING CLOSER TO MAV WITH
FORECAST ESSENTIALLY BACK TO THAT WHICH WAS ISSUED AT 4 AM
YESTERDAY. SNOW AMOUNTS WERE GENERALLY CREATED USING A SNOW TO
LIQUID RATIO OF 6:1. HIGHEST SNOWFALL ACCUMULATIONS WILL BE IN THE
MOUNTAINS WHERE 2 TO 6 INCHES OF SNOW IS EXPECTED…HIGHEST TOTALS
OVER SOUTHERN GREEN MOUNTAINS WITH GENERALLY AN INCH OR TWO IN THE
VALLEYS. ICE ACCRETION WILL GENERALLY BE AN INCH OR LESS EXCEPT UP
TO A QUARTER OF AN INCH IS POSSIBLE ACROSS PORTIONS OF THE
SOUTHERN ADIRONDACKS AND THE SOUTHERN GREEN MOUNTAINS.

EXPECT TEMPS TO SLOWLY RISE FROM CURRENT VALUES IN THE MID TO
UPPER 20S NORTH AND LOW TO MID 30S SOUTH TO THE LOW TO MID 30S
NORTH AND UPPER 30S TO MID 40S SOUTH THIS AFTERNOON.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/…
PSEUDO WARM FRONT LIFTS NORTHWARD THURSDAY EVENING AS MID LEVEL DRY
SLOT ADVANCES NORTHWARD ACROSS THE REGION. BUFR PROFILES DO SUGGEST
AMPLE LOW LEVEL MOISTURE WHICH WILL BE CLOSE TO THE -10C ALOFT FOR
ENOUGH ICE NUCLEI TO WARRANT THE LOW CHANCE POPS FOR THE REGION
OVERNIGHT. MAIN DYNAMICS WITH OHIO VALLEY SYSTEM BEGINS TO ENCROACH
OUR WESTERN ZONES WELL AFTER MIDNIGHT WHERE WE WILL INCREASE POPS.
THERMAL PROFILES WILL REMAIN A CHALLENGE…ESPECIALLY FOR PORTIONS
OF THE MOHAWK VALLEY AND DACKS WHERE SURFACE TEMPERATURES ARE
EXPECTED TO DROP BACK INTO THE UPPER 20S AND LOWER 30S. THIS POSES
A PROBLEM WITH THE CHANCE FOR FREEZING RAIN/DRIZZLE DUE TO THE
AFOREMENTIONED POTENTIAL LACK OF ICE NUCLEI.

POTENT MID LEVEL JET COINCIDING WITH IMPRESSIVE FRONTOGENESIS WILL
MAKE FOR AN INTERESTING WEATHER ON FRIDAY MORNING. QG DIAGNOSTIC
FIELDS ARE IMPRESSIVE WITH RAPIDLY INCREASING VERTICAL VELOCITIES
OVER THE CWA AND STEEPENING MID LEVEL LAPSE RATES. WOULD NOT BE
SURPRISED TO FIND A FEW SQUALLS EMBEDDED ALONG THE ARCTIC COLD FRONT
THAT WILL MOVE EAST OF THE CWA BY LATE MORNING FRIDAY /AS SUGGESTED
IN THE EXPERIENTIAL HIRES WINDOWS OF MESOSCALE MODELS/. IN
FACT…TEMPERATURES IN THE WAKE OF THE FROPA SHOULD DROP BACK BELOW
FREEZING WHICH COULD RESULT IN BLACK ICE FORMATION WHERE SURFACES
ARE NOT TREATED. LINGERING SURFACE TROUGH AXIS AND DEFORMATION
DYNAMICS OVER WESTERN AND EASTERN NY COULD PROLONG THE SNOWFALL
WHICH WILL BE MONITORED CLOSELY. FURTHERMORE…LAKE ONTARIO
CONTRIBUTION IS EXPECTED TO INCREASE FRIDAY AFTERNOON INTO FRIDAY
NIGHT WITH A 270-280 WIND DIRECTION AND INCREASING LAKE DELTA T/S.
SEVERAL INCHES OF SNOW /AND BLOWING SNOW/ ARE POSSIBLE FOR PORTIONS
OF THE MOHAWK VALLEY…SOUTHERN DACKS. DUE TO FORECAST CHALLENGES
THAT REMAIN WITH RESPECT TO THE WIND TRAJECTORIES AND THE TIMING OF
THE INVERSION LEVELS DROPPING BELOW 5K FEET…WE WILL NOT HOIST ANY
HEADLINES AT THE PRESENT TIME. WE WILL HIGHLIGHT IN THE HWO.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/…
OVER THE WEEKEND…THE NORTHEAST WILL BE DOMINATED BY A LARGE SCALE
TROUGH. THIS WILL KEEP TEMPS A LITTLE COOLER THAN THEY HAVE BEEN
RECENTLY AND SOMEWHAT BELOW NORMAL. HOWEVER…IT WON/T BE BRUTALLY
COLD BY ANY STRETCH. THE 12 UTC GEFS IS SHOWING 850 HPA TEMPS
GENERALLY NEAR NORMAL…WITH A BRIEF PERIOD OF ABOUT 1-2 STD BELOW
NORMAL. THE LATEST DETERMINISTIC 12 UTC GFS IS SHOWING 850 HPA
TEMPS OF AROUND -15 DEGREES C FOR SATURDAY…AND -16 TO -18 DEGREES
ON SUNDAY. THIS WILL TRANSLATE TO MAX TEMPS IN THE 20S TO LOW 30S ON
SATURDAY…AND MAX TEMPS IN THE TEENS TO LOW 20S FOR SUNDAY. MIN
TEMPS ON SAT AND SUN NIGHTS WILL GENERALLY BE IN THE SINGLE
DIGITS…WITH BELOW ZERO READINGS ACROSS THE HIGH TERRAIN. WHILE
THIS WILL PROBABLY WIND UP BEING SOME OF THE COLDER NIGHTS OF THE
SEASON SO FAR…IT/S STILL NOT FAR FROM WHAT IS CONSIDERED NORMAL OR
EXPECTED FOR THIS TIME OF THE YEAR.

IT WILL REMAIN FAIRLY DRY OVER THE WEEKEND. THE CYCLONIC FLOW MAY
ALLOW FOR SOME CLOUDS…ESP IN AREAS DOWNWIND OF LAKE ONTARIO.
HOWEVER…THE FLOW WON/T BE OVERLY CONDUCIVE FOR LAKE EFFECT…AND
INVERSION HEIGHTS OF ONLY AROUND 1 KM WILL KEEP ANY LAKE EFFECT SNOW
SHOWERS AS FAIRLY LIGHT AND CONFINED CLOSE TO THE LAKE SHORE. WILL
ONLY ALLOW A BRIEF PERIOD CHC POPS FOR PARTS OF THE MOHAWK
VALLEY/SCHOHARIE COUNTY FOR SAT MORNING…BEFORE LOWERING POPS TO
SLIGHT CHC FOR THE REMAINDER OF SATURDAY.

HIGH PRESSURE WILL MOVE ACROSS THE REGION FOR MONDAY. THIS WILL
CONTINUE THE DRY WEATHER. TEMPS WILL CONTINUE TO BE A LITTLE ON THE
COOL SIDE…BUT NOTHING UNHEARD OF FOR MID JANUARY…WITH 20S FOR
MOST AREAS. SOME CLOUDS WILL BEGIN TO INCREASE FOR MONDAY NIGHT
AHEAD OF AN APPROACHING STORM SYSTEM. MIN TEMPS MAY ACTUALLY WIND
UP BEING EARLIER IN THE NIGHT…AS TEMPS MAY SLOWLY RISE OVERNIGHT
WITH AN INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW. FOR NOW…HAVE
GONE WITH MIN TEMPS IN THE TEENS IN MOST AREAS.

A STRENGTHENING LOW PRESSURE AREA WILL RACE FROM THE UPPER GREAT
LAKES TOWARDS NORTHERN QUEBEC ON TUESDAY. AN ARCTIC FRONT ASSOCIATED
WITH THIS STORM SYSTEM WILL SWING THROUGH OUR AREA ON TUESDAY. THIS
WILL ALLOW FOR SOME RAIN/SNOW SHOWERS…WITH P-TYPE DEPENDENT ON
ELEVATION/BOUNDARY LAYER TEMPS. MOST VALLEY AREAS WILL PROBABLY WARM
UP JUST ENOUGH TO KEEP MOST OF THE PRECIP AS RAIN…ESP CONSIDERING
THIS STORM IS COMING FROM THE WEST WITH A STORM SYSTEM TRACKING WELL
NORTH OF THE AREA. TEMPS LOOK TO REACH THE 30S IN VALLEY
AREAS…WITH MAX TEMPS IN THE UPPER 20S TO NEAR FREEZING IN THE HIGH
TERRAIN. PRECIP WILL BE SHOWERY IN NATURE AND QPF WILL BE RATHER
LIGHT…WITH LESS THAN A QUARTER OF AN INCH IN MOST AREAS.

IN THE WAKE OF THIS SYSTEM…COOLER AIR WILL AGAIN FILTER INTO THE
REGION FOR TUESDAY NIGHT INTO WEDNESDAY. SOME LAKE EFFECT COULD
AFFECT FAR WESTERN AREAS. TEMPS LOOK TO GO BACK BELOW NORMAL FOR
WEDNESDAY…WITH MAINLY TEENS AND 20S FOR MAX TEMPS.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/…
AS OF 800 AM…THE HEAVIEST PRECIPITATION HAS MOVED NORTH OF THE
TERMINALS. HOWEVER…THERE ARE MORE SHOWERS OF MAINLY RAIN WORKING
TOWARD KPOU.

REMOVED LLWS FROM KPOU SINCE THEY ARE REPORTING WIND GUSTS TO NEAR
20KTS AND THE ALY RAOB INDICATED THE WIND AT 2000 FEET AROUND 35KT
(NOT 45KTS). NARROWED THE TIME OF LLWS FROM MID TO LATER MORNING AT
KALB AND KGFL AS THAT IS WHEN THE STRONGEST WIND ALOFT MOVE THROUGH.

ALSO REMOVED ANY MENTION OF FREEZING RAIN FROM KGFL.

IFR/MVFR STRADDLE AT BOTH KALB AND KGFL BUT AS PCPN CHANGES TO RAIN
MVFR CONDITIONS WILL PREVAIL. WILL KEEP CIGS PREVAILING AT 2000 FEET
OR LESS ALTHOUGH WITH A DOWNSLOPING WIND…EVEN THESE MIGHT
OCCASIONALLY RISE UP TO VFR AS THEY DID AT KALB JUST BEFORE 800 AM.

OUR INCOMING 12Z RAOB STILL INDICATED A PRETTY STRONG ESE WIND OFF
THE DECK AT AROUND 1500 FEET. HOWEVER…IT MIGHT BE QUITE A STRONG
AS FORECASTED BY THE MODELS. WE WILL REVIEW THE LOW LEVEL WIND SHEAR
ASPECT WHEN THE ENTIRE RAOB COMES THROUGH. FOR NOW…CONTINUE WITH
LOW LEVEL WIND SHEAR UP TO 2000 FEET WITH AN E OR ESE WIND AROUND
40/45KTS THROUGH MUCH OF THE MORNING.

EVEN AFTER THE SYSTEM PASSED BY LATER TODAY…WE SHOULD HOLD ONTO
MVFR CLOUDS THROUGH MUCH OF THE NIGHT. AS LONG THAT HAPPENS…ANY
IFR FOG SHOULD BE LIMITED. HOWEVER…CONFIDENCE IN THIS THINKING IS
ONLY MODERATE…SO THIS PORTION OF THE TAF COULD CHANGE WITH
TIME.

ANOTHER UPPER LEVEL DISTURBANCE AND COLD FRONT WILL LIKELY BRING
ANOTHER ROUND OF RAIN SHOWERS ON FRIDAY…SWITCHING TO SNOW SHOWERS
AS THE DAY WEARS ON. THE WIND WILL PICK UP FROM THE WEST AND THERE
COULD EVEN BE SOME MORE INTENSE SNOW SQUALLS.

OUTLOOK…
FRI-FRI NT…MVFR/IFR…RAIN OR MIXED PRECIPITATION ENDING AS
SNOW. BECOMING WINDY.
SAT-MON…VFR…NO SIG WX.

&&

.HYDROLOGY…
A COMPLEX STORM SYSTEM CURRENTLY IMPACTING THE FA WILL CONTINUE TO
BRING MIX PRECIPITATION TO THE HYDROLOGIC SERVICE AREA THIS MORNING
TRANSITIONING TO ALL RAIN…ESPECIALLY SOUTH AND EAST OF THE SOUTHERN
ADIRONDACKS BY THE AFTERNOON. THE PRECIPITATION WILL BE ASSOCIATED
WITH A COASTAL OR SECONDARY LOW THAT WILL MOVE NORTHEAST OF LONG
ISLAND BY THIS AFTERNOON. THE PRIMARY LOW WILL REMAIN TO THE WEST
OVER THE OHIO VALLEY AND THE GREAT LAKES REGION. TOTAL LIQUID
EQUIVALENT VALUES WILL RANGE FROM A HALF AN INCH TO AROUND AN INCH
BY THURSDAY EVENING. WE ARE EXPECTING SOME DOWNSLOPING TO REDUCE
TOTAL QPF AMOUNTS TO AROUND A HALF AN INCH TO TWO THIRDS OF AN INCH
IN THE UPPER HUDSON VALLEY…AND PORTIONS OF THE LAKE GEORGE REGION.
THE HEAVIEST QPF WILL TEND TO BE SOUTH AND WEST OF THE CAPITAL
REGION. WE ARE EXPECTING MINIMAL IMPACT ON THE MAIN STEM RIVERS WITH
SOME MINOR RISES AT BEST. MOST OF THE PRECIPITATION WILL FALL AS
SNOW…SLEET AND FREEZING RAIN OVER THE NORTHERN BASINS.

TONIGHT…A BRIEF LULL WILL OCCUR BETWEEN THE SYSTEMS…WITH A
DRY SLOT. THERE MIGHT BE SOME SPOTTY FREEZING RAIN OR DRIZZLE
NORTH AND WEST OF THE CAPITAL REGION WITH SPOTTY PLAIN RAIN SOUTH
AND EAST. THE NEXT STRONG UPPER LEVEL DISTURBANCE WILL BRING RAIN
AND SNOW SHOWERS ON FRIDAY….AS IT MOVES OVER UPSTATE NY. THERE
COULD EVEN BE A FEW INTENSE SNOW SQUALLS. TOTAL QPF FROM THIS
SYSTEM LOOKS LIKE TWO TENTHS OF AN INCH SOUTHEAST TO TWO THIRDS OF
AN INCH NORTHWEST. COLDER AIR AND LAKE EFFECT SNOW SHOWERS WILL
BE POSSIBLE FRIDAY NIGHT INTO 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…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR CTZ001.
NY…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ038>041-
043-047>054-058-061-063-082>084.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ032-
033-042.
MA…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MAZ001-025.
WIND ADVISORY UNTIL NOON EST TODAY FOR MAZ001.
VT…WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VTZ013>015.
WIND ADVISORY UNTIL NOON EST TODAY FOR VTZ013-014.

&&

$$
SYNOPSIS…11/NAS
NEAR TERM…11
SHORT TERM…BGM
LONG TERM…FRUGIS
AVIATION…HWJIV
HYDROLOGY…11

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