FXUS61 KALY 071627
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1127 AM EST MON DEC 7 2009
.SYNOPSIS...
A WEAK LOW PRESSURE SYSTEM WILL APPROACH FROM THE WEST
TODAY...BRINGING CLOUDS...ALONG WITH SNOW SHOWERS AND FLURRIES TO
CENTRAL AND NORTHERN PORTIONS OF THE REGION THIS AFTERNOON AND
EVENING. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD EASTWARD ACROSS
THE REGION LATE TONIGHT AND TUESDAY...ACCOMPANIED BY FAIR AND
SEASONABLY COLD CONDITIONS. A STRONG STORM SYSTEM WILL APPROACH FROM
THE GREAT LAKES FOR WEDNESDAY...BRINGING A WINTRY MIX CHANGING TO
RAIN.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAVE ADJUSTED TEMPS SLIGHTLY FOR THIS AFTERNOON AS TEMPS WILL ONLY
RISE ANOTHER FEW DEGREES WITH CLOUD COVER AND -SHSN IN PLACE. HAVE
LEFT POPS IN TACT AS VALLEY AREAS LIKELY TO SEE LITTLE SNOW AND
EVEN ACROSS HIGHER TERRAIN THE SNOW HAS HAD A HARD TIME WORKING TO
THE SURFACE AS EVIDENCED BY SURFACE OBS AND WEB CAMS.
FROM PREVIOUS AFD ISSUED AT 430 AM EST...A WEAKENING LAKE EFFECT
SNOW BAND WAS OCCURRING ACROSS EXTREME NORTHERN HERKIMER AND
HAMILTON COUNTIES. HOWEVER...AS THE INVERSION LOWERS...AND LOW
LEVEL WINDS BACK INTO THE SW...THIS BAND SHOULD WEAKEN AND/OR LIFT
N OF THE REGION BY SUNRISE.
A RATHER POTENT UPPER LEVEL SHORTWAVE...CURRENTLY TRAVERSING THE MID
MISSISSIPPI RIVER VALLEY...WILL CONTINUE MOVING RAPIDLY ENE
TODAY...REACHING OUR REGION BY THIS EVENING. DESPITE FAIRLY HEALTHY
UPPER LEVEL DYNAMICS...LOW LEVEL MOISTURE WILL BE RATHER SCARCE. IN
ADDITION...THE SFC LOW WILL REMAIN RATHER WEAK. THUS...WE DO EXPECT
THICKENING CLOUDS TODAY...ALONG WITH SNOW SHOWERS DEVELOPING LATER
THIS AFTERNOON. HOWEVER...THE SNOW SHOULD REMAIN INTERMITTENT AND
SOMEWHAT SHOWERY...AND REMAIN CONFINED MAINLY TO AREAS FROM THE
CAPITAL REGION N AND NW. THERE COULD BE A FEW HEAVIER SNOW SHOWERS
TOWARD SUNSET...WHICH WILL NEED TO BE WATCHED DUE TO TIMING
COINCIDENT WITH THE PEAK RUSH HOUR. AT THIS TIME...IT APPEARS THAT
SNOWFALL AMOUNTS SHOULD REMAIN LESS THAN ONE INCH...WITH ONLY A
COATING EXPECTED FROM ALBANY S AND E INTO THE BERKS. MUCH OF THIS
ACCUM SHOULD OCCUR MAINLY ON COLDER...GRASSY SURFACES...GIVEN THE
EXPECTATION FOR MAX TEMPS TO WARM INTO THE MID 30S IN MOST AREAS.
THESE MAXES ARE CLOSEST TO THE MET MOS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
TONIGHT...THE AFOREMENTIONED SHORTWAVE WILL CROSS OUR REGION THIS
EVENING. NORTHERN PORTIONS OF THE REGION...ESPECIALLY FROM THE
MOHAWK RIVER VALLEY NORTHWARD...LOOK TO BE WITHIN THE REMAINING
DEFORMATION AREA...AND SHOULD HAVE THE GREATEST CHANCE FOR
MEASURABLE SNOW BEFORE MIDNIGHT. AGAIN...WE CURRENTLY EXPECT ACCUMS
TO ONLY REACH ONE INCH WITHIN THIS REGION...AND SLIGHTLY LESS
FURTHER S AND SE. THEN...SOME LINGERING SNOW SHOWERS/FLURRIES ARE
POSSIBLE AFTER MIDNIGHT...ALONG WITH SOME POSSIBLE LAKE ENHANCEMENT
ACROSS PORTIONS OF THE THE WESTERN DACKS INTO THE WESTERN MOHAWK
VALLEY...WHICH COULD LEAVE 1-3 INCHES OF ADDITIONAL SNOWFALL WITHIN
ANY PERSISTENT SNOW BAND. OTHERWISE...WE STILL EXPECT CLOUDS TO
LINGER ACROSS CENTRAL AND NORTHERN AREAS GIVEN A LOWERING
INVERSION...AND AMPLE LAKE MOISTURE. THUS...WE HAVE LEANED A BIT
CLOSER TO THE WARMER MET MOS FOR MINS...WHICH ARE MAINLY IN THE MID
20S WITHIN THE VALLEYS...AND LOWER 20S FOR SOME HIGHER
ELEVATIONS...AS WELL AS ACROSS PORTIONS OF THE MID HUDSON
VALLEY...WHERE LESS CLOUDS ARE EXPECTED...POTENTIALLY ALLOWING FOR A
MORE ROBUST FALL IN TEMPS.
TUE...SOME LINGERING SNOW SHOWERS/FLURRIES WILL REMAIN POSSIBLE
ACROSS THE WESTERN DACKS THROUGH THE MORNING...BUT THESE SHOULD
TAPER DURING THE AFTERNOON AS THE AFOREMENTIONED SUBSIDENCE
INVERSION LOWERS FURTHER...AND WINDS GRADUALLY BECOME LIGHT AND BACK
IN DIRECTION...DISRUPTING ANY LAKE BANDS THAT STILL EXIST. LOWER
CLOUDS COULD STILL LINGER INTO AT LEAST THE MIDDAY HOURS ACROSS
CENTRAL/NORTHERN PORTIONS OF THE REGION...GIVEN THE EXPECTED WNW LOW
LEVEL FLOW ADVECTING MOISTURE FROM THE LAKES. FOR MAX TEMPS...HAVE
SIDED WITH A MAV/MET MOS BLEND...ACCOUNTING FOR THE POSSIBILITY THAT
CLOUDS PERSIST LONGER.
TUE NT/WED...COMPLEX STORM SYSTEM WILL INTENSIFY AND HEAD INTO THE
CENTRAL GREAT LAKES ON WED...WHILE A WEAK SECONDARY LOW MAY DEVELOP
ALONG THE WARM FRONT AND HEAD TOWARD THE GULF OF MAINE. GIVEN THAT
THE PRIMARY LOW IS EXPECTED TO REMAIN QUITE STRONG...ENOUGH WARM AIR
IS EXPECTED TO BECOME ENTRAINED IN THE MID/UPPER LEVELS OF THE
ATMOSPHERE TO PREVENT AN ALL SNOW SCENARIO FOR OUR REGION.
HOWEVER...LOW LEVEL COLD AIR MAY BE TOUGH TO SCOUR OUT...ESP N OF
THE MOHAWK RIVER VALLEY...POTENTIALLY LEADING TO AT LEAST A PERIOD
OF MIXED PRECIP...INCLUDING FREEZING RAIN LATE WED MORNING INTO THE
AFTERNOON. AT THIS TIME...IT APPEARS AS IF A BURST OF MOD/HVY SNOW
IS POSSIBLE REGION WIDE WITH THE INITIAL BURST OF WARM ADVECTION
EARLY WED MORNING...WITH A QUICK 1-3 INCHES OF ACCUM IN MANY VALLEY
LOCALES...INCLUDING WITHIN THE CAPITAL REGION...AND PERHAPS 3-6
INCHES ACROSS NORTHERN PORTIONS OF THE CAPITAL REGION INTO THE LAKE
GEORGE/SARATOGA/GLENS FALLS AREA...AND INTO THE MOHAWK VALLEY AND
SOUTH CENTRAL VT BEFORE ANY CHANGEOVER TO SLEET/FREEZING RAIN/RAIN
BY LATE MORNING. AND...FOR PORTIONS OF THE SOUTHERN DACKS...SLIGHTLY
HIGHER ACCUMS OF 4-8 INCHES ARE POSSIBLE...IN ADDITION TO A FEW
TENTHS OF AN INCH OF ICE ACCRETION. THIS CURRENT SCENARIO WOULD
POINT TO WINTER WEATHER ADVISORY CRITERIA...AND WILL ADDRESS IN
HWOALY SINCE WE ARE CURRENTLY THINKING CRITERIA SHOULD FALL SHORT OF
WARNING LEVELS. NEVERTHELESS...DUE TO THE TIMING OF THE SNOW/MIXED
PRECIP...AND SINCE THIS WILL BE THE SEASONS FIRST SUCH EVENT...WE
EXPECT THIS EVENT TO HAVE A RATHER HIGH SOCIETAL IMPACT WED MORNING.
THE PRECIP SHOULD CHANGE TO PLAIN RAIN BY WED AFTERNOON FROM THE
CAPITAL REGION SOUTH...AND EVENTUALLY ACROSS MUCH OF THE REGION BY
LATE AFTERNOON. WINDS WILL ALSO BECOME LOCALLY GUSTY WED
AFTERNOON...ESP ACROSS HIGHER ELEVATIONS ACROSS SW VT AND NW
MA...WHERE GUSTS COULD APPROACH ADVISORY LEVELS. WILL ADDRESS THIS
IN THE HWOALY. FOR TEMPS...WE EXPECT MINS WED AM TO FALL INTO THE
25-30 RANGE WITHIN MOST VALLEYS...EXCEPT TO 20-25 ACROSS THE NORTH
COUNTRY AND SOUTHERN VT...WITH MOST MINS OCCURRING SEVERAL HOURS
BEFORE 12Z/WED AND THEN RISING. FOR WED MAXES...GENERALLY SIDED
CLOSE TO THE MET MOS...WITH MID/UPPER 30S EXPECTED ACROSS MANY
AREAS...EXCEPT TO 40-45 ACROSS PORTIONS OF THE MID HUDSON VALLEY.
WED NT...STEADIER PRECIP SHOULD BE TAPERING OFF FROM SW TO NE WED
EVENING...WITH JUST RAIN SHOWERS EXPECTED EARLY. A PERIOD OF DRYING
IS POSSIBLE DURING WED NT...ESP WITHIN THE VALLEYS AS STRONG W WINDS
DEVELOP. THEN...SOME LAKE ENHANCED/OROGRAPHIC EFFECT SNOW SHOWERS
ARE EXPECTED TO OCCUR LATE WED NT ACROSS THE WESTERN DACKS.
ELSEWHERE...TEMPS MAY INITIALLY REMAIN STEADY OR EVEN RISE A BIT
EARLY DUE TO DEEP AND STRONG MIXING...WITH TEMPS GRADUALLY FALLING
INTO THE 20S TO LOWER 3OS BY THU AM...COLDEST ACROSS HIGHER
ELEVATIONS ACROSS WESTERN AREAS. WINDS COULD APPROACH ADVISORY
LEVELS IN SOME AREAS TOWARD THU MORNING...ESP ACROSS THE WESTERN
ADIRONDACKS WHERE SFC PRESSURE RISES WILL BE GREATEST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
MJO TRENDING TO WEAK PHASE 8 OR NEUTRAL JUST OUTSIDE OF PHASE 8.
THIS WOULD SEEM TO SUPPORT SOME SEMBLANCE OF A BROAD NORTHERN STREAM
UPPER TROUGH OVER EASTER NORTH AMERICA. SINCE THE CORE OF COLDEST
AIR CROSSED THE POLE FROM SIBERIA RECENTLY...SETTING UP IN
NORTHERN/CENTRAL CANADA...SOME OF THIS COLD AIR WILL AFFECT OUR
REGION.
SYSTEM EXITS THURSDAY MORNING...AND HIGH PRESSURE SLOW TO BUILD INTO
THE REGION FROM THE MIDWEST AND OH VALLEY. DECENT PRESSURE GRADIENT
BETWEEN STRONG LOW PRESSURE IN EASTERN CANADA AND THE HIGH
PRESSURE...WILL PRODUCE WEST LOW LEVEL FLOW...AND WITH CONSIDERABLY
COLD BOUNDARY LAYER TEMPERATURES...LAKE EFFECT CLOUDS AND SNOW
SHOWER ACTIVITY WILL SET UP THURSDAY THROUGH PERHAPS SATURDAY. MOST
AREAS WILL SEE PERIODS OF CLOUDS AND PERHAPS SOME FLURRIES...WITH
POSSIBLE ACCUMULATIONS IN HERKIMER AND HAMILTON COUNTIES.
BASED ON THE CLOUD COVER AND BOUNDARY LAYER COOL DOWN...HIGHS
THURSDAY IN THE MID 30S IN THE HUDSON VALLEY...UPPER 20S TO LOWER
30S MOST OTHER PLACES. NIGHTTIME LOWS THURSDAY NIGHT THROUGH
SATURDAY NIGHT WILL BE IN THE TEENS MOST HUDSON VALLEY AREAS...INTO
THE SINGLE NUMBERS IN THE MOUNTAINS. HIGHS FRIDAY THROUGH SUNDAY IN
THE UPPER 20S TO AROUND 30 HUDSON VALLEY...TO LOWER TO MID 20S
MOUNTAINS.
OTHER THAN THE LAKE EFFECT MOISTURE...NO LARGER SCALE SYSTEMS ARE
PREDICTED TO AFFECT OUR REGION THROUGH NEXT SUNDAY...BUT NEED TO
WATCH ONE SYSTEM EXPECTED TO TRACK SOUTH OF THE REGION LATE IN THE
WEEK. HIGH PRESSURE TIMED TO MOVE INTO OUR REGION AROUND SATURDAY
AND SUNDAY...TURNING SURFACE FLOW TO NORTH AND NORTHWEST...AND
EVENTUALLY VERY LIGHT...SO LAKE EFFECT SNOW SHOULD END SATURDAY
THROUGH SUNDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL CONTINUE...WITH LAKE EFFECT CLOUDS AND MOISTURE
OCCASIONALLY NOSING EAST INTO THE KALB AND KGFL AREAS WITH SCATTERED
VARIABLE BROKEN CLOUDS AT AROUND 5000 FEET THROUGH THIS MORNING.
SOME SCATTERED SNOW SHOWER ACTIVITY IS EXPECTED MIDDAY INTO THIS
EVENING AT KGFL AND KALB...ASSOCIATED WITH ANOTHER WEAK SYSTEM
TRACKING OUT OF THE OH/TN VALLEY. SINCE THE SNOW SHOWER ACTIVITY
WILL BE SCATTERED...JUST USING VCSH AT KGFL AND KALB. CONTINUED
LAKE MOISTURE AND CLOUD COVER WILL LIKELY RESULT IN CEILINGS JUST
DROPPING INTO THE MVFR RANGE OVERNIGHT...AROUND 2500-3000 FEET AT
KALB AND KGFL...BUT REMAINING VFR AT KPOU.
WINDS WILL BE NEAR THROUGH THE EARLY MORNING HOURS...THEN SHIFT
TO THE S-SW AROUND 5 KT OR LESS THIS MORNING...CONTINUING THIS
AFTERNOON...THEN DIMINISHING BACK BELOW 5 KT OVERNIGHT.
OUTLOOK...
MON NGT-TUE...VFR. NO SIG WX.
WED...MVFR/IFR. SN/RA LIKELY.
THUR...VFR/MVFR...CHC -SHSN. WINDY.
FRI...VFR. SO SIG WX.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS EXPECTED THROUGH EARLY WEDNESDAY AS ANY
PRECIPITATION UP TO THAT TIME WILL COME IN THE FORM OF SNOW AND THUS
HAVE NO DIRECT IMPACT ON THE RIVERS.
ON WEDNESDAY...SNOW MIXING WITH OR CHANGING TO RAIN COULD PRODUCE
SOME HYDRO PROBLEMS...ESPECIALLY FROM ALBANY SOUTH AND EAST WHERE
THE GREATEST AMOUNT OF RAIN IS EXPECTED TO FALL AND TEMPERATURES
WARM UP THE MOST.
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...KL
NEAR TERM...KL/11
SHORT TERM...KL
LONG TERM...NAS
AVIATION...NAS
HYDROLOGY...KL/GJM
