066
FXUS61 KALY 190906
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
406 AM EST TUE NOV 19 2024
SYNOPSIS
TODAY AND TOMORROW WILL BOTH FEATURE TRANQUIL WEATHER
WITH ABOVE NORMAL TEMPERATURES BEFORE A, A POTENT STORM SYSTEM
ARRIVES WEDNESDAY NIGHT, BRINGING SOME MUCH-NEEDED RAIN TO THE
REGION. RAIN IS EXPECTED TO CHANGE TO SNOW IN THE HIGH TERRAIN AREAS
THURSDAY NIGHT BEFORE TAPERING TO VALLEY RAIN AND HIGH-ELEVATION
SNOW SHOWERS FRIDAY INTO THE WEEKEND. THURSDAY THROUGH THE WEEKEND
WILL FEATURE MUCH COOLER TEMPERATURES AS WELL.
NEAR TERM /UNTIL 6 PM THIS EVENING/
AS OF 4:00 AM EST...OUR REGION REMAINS SANDWICHED BETWEEN LOW
PRESSURE OVER SOUTHEAST ATLANTIC CANADA AND A NARROW RIDGE OF
HIGH PRESSURE OVER WESTERN NY DOWNSTREAM OF A BUILDING UPPER
RIDGE. THE INCOMING SURFACE HIGH AND SUBSIDENCE ARE LEADING TO
TRANQUIL WEATHER CONDITIONS, ALTHOUGH WINDS REMAIN BREEZY IN
SOME AREAS, ESPECIALLY IN WESTERN NEW ENGLAND, WHERE THE
PRESSURE GRADIENT IS STRONGER. WITH FORECAST SOUNDINGS SHOWING
MOISTURE TRAPPED BENEATH A LOW-LEVEL INVERSION, WE ARE SEEING
STRATUS OVER THE HIGH TERRAIN OF THE ADKS AND SOUTHERN GREENS,
WHICH IS HELPING TO KEEP TEMPERATURES HERE MORE ELEVATED. THESE
CLOUDS ARE EXPECTED TO REMAIN IN PLACE THROUGH EARLY THIS
MORNING. HOWEVER, AREAS THAT DO REMAIN CLEAR, ESPECIALLY SOUTH
AND WEST OF THE CAPITAL DISTRICT, SHOULD SEE TEMPERATURES
CONTINUE TO DROP LATE TONIGHT AS THE SURFACE HIGH BUILDS IN AND
WINDS BECOME LIGHT, WITH MAINLY IN THE 30S AND A FEW UPPER 20S
IN SOME OF THE OUTLYING AREAS.
TODAY, THE UPPER RIDGE REMAINS JUST TO OUR WEST, PUTTING OUR
REGION IN AN AREA OF LARGE-SCALE SUBSIDENCE. THIS, COMBINED WITH
A NARROW RIDGE OF SURFACE HIGH PRESSURE BUILDING OVERHEAD, WILL
LEAD TO TRANQUIL CONDITIONS. TEMPERATURES WILL RUN A FEW TO
SEVERAL DEGREES ABOVE NORMAL TODAY WITH A RELATIVELY WARM
AIRMASS ALOFT. SKIES SHOULD BE PARTLY CLOUDY, ALTHOUGH A FEW
MORE MID AND HIGH CLOUDS WILL BE POSSIBLE LATE THIS AFTERNOON
AND EVENING.
SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/
TONIGHT AND WEDNESDAY...UPPER RIDGE AXIS MOVES OVERHEAD TONIGHT
AND SLIDES OFF TO OUR EAST TOMORROW, AS DOES THE SURFACE HIGH.
AS THIS HAPPENS, A POTENT UPPER LOW WILL BE TRACKING SOUTHWARDS
INTO THE UPPER MIDWEST AND WILL QUICKLY BECOME VERTICALLY
STACKED WITH A SURFACE LOW THAT DEVELOPS OVER MICHIGAN. THE WARM
FRONT ASSOCIATED WITH THIS SYSTEM WILL APPROACH FROM THE SOUTH
TONIGHT AND ATTEMPT TO LIFT NORTHWARDS TOMORROW, ALTHOUGH AT
THIS TIME IT LOOKS LIKE THE SURFACE WARM FRONT WILL STRUGGLE TO
GET NORTH OF I-90. DESPITE LIGHT WINDS TONIGHT, INCREASING
CLOUDS AHEAD OF THE WARM FRONT WILL KEEP TEMPERATURES MAINLY IN
THE 30S, WITH SOME 20S POSSIBLE ACROSS PORTIONS OF THE ADKS,
UPPER HUDSON VALLEY, AND SOUTHERN VT. TOMORROW, WE LEANED ABOVE
GUIDANCE FOR THE I-84 CORRIDOR WITH HIGHS WELL INTO THE 50S AND
LEANED BELOW GUIDANCE FOR AREAS NORTH OF THE WARM FRONT WITH
HIGHS MAINLY IN THE 40S TO AROUND 50.
MAIN FOCUS OF THE SHORT TERM PERIOD WILL BE A POTENT STORM
SYSTEM THAT LOOKS TO IMPACT THE REGION BEGINNING WEDNESDAY
NIGHT. THE UPPER LOW WILL SLIDE FROM THE GREAT LAKES OVER THE
OHIO VALLEY THURSDAY, THEN TRACK ACROSS PA THURSDAY NIGHT. THE
OCCLUDED FRONT ASSOCIATED WITH THE VERTICALLY STACKED LOW TO OUR
WEST WILL TRACK THROUGH THE REGION WEDNESDAY NIGHT, BRINGING
WIDESPREAD RAINFALL TO THE REGION. A SURFACE LOW DEVELOPS ALONG
THE FRONT OFF THE COAST OF NJ BENEATH THE LEFT EXIT OF THE UPPER
JET, THEN TRACKS SOUTH OF LONG ISLAND BEFORE RETROGRADING BACK
INTO SOUTHERN NEW ENGLAND AND EVENTUALLY EASTERN NY BY THURSDAY
NIGHT AS IT GETS CAPTURED BY THE UPPER LOW AND DEEPENS BELOW 990
MB. WIT STRONG CYCLONIC VORTICITY ADVECTION ALOFT, THE LEFT
EXIT OF THE UPPER JET NEARBY, AND A BAND OF MID-LEVEL FGEN
ALONG THE OCCLUDED FRONT, WIDESPREAD RAIN IS EXPECTED WEDNESDAY
NIGHT INTO THURSDAY. WITH THE UPPER LOW TRACKING TO OUR SOUTH,
THE COLDER AIR WRAPPING AROUND THE UPPER LOW MOVES IN FROM THE
WEST/SOUTHWEST THURSDAY EVENING AND NIGHT, FACILITATING A
TRANSITION TO SNOW FOR AREAS ABOVE 1000 FT IN ELEVATION BY 12Z
FRIDAY. THE EXACT TIMING OF THE RAIN TO SNOW TRANSITION REMAINS
UNCERTAIN AND WILL DEPEND ON THE EXACT TRACK OF THE UPPER LOW
AND SURFACE LOW, BUT IT DOES APPEAR LIKELY THAT AT LEAST SOME
SNOW WILL ACCUMULATE IN THE HIGH TERRAIN AREAS. WINTER WEATHER
ADVISORIES WILL LIKELY BE NEEDED IN THE COMING DAYS FOR PORTIONS
OF THE EASTERN CATSKILLS, SOUTHERN ADKS, AND SOUTHERN GREENS.
AS FAR AS IMPACTS FROM THIS SYSTEM, WE WILL SEE A WIDESPREAD
0.75 TO 1.5 INCHES OF RAIN, WHICH IS MUCH-NEEDED WITH ONGOING
DROUGHT CONDITIONS ACROSS THE REGION. GIVEN THE ANTECEDENT DRY
CONDITIONS, FLOODING IS NOT A CONCERN WITH THIS SYSTEM. THE
HEAVIEST PRECIP AMOUNTS OF LOCALLY OVER 2" WILL FALL ACROSS THE
EASTERN CATSKILLS AND SOUTHERN GREENS DUE TO EAST/SOUTHEAST
UPSLOPE ENHANCEMENT, BUT SOME OF THIS PRECIP WILL FALL AS SNOW.
PROBABILITIES FOR ACCUMULATING SNOW CONTINUE TO INCREASE IN THE
HIGH TERRAIN FOR THURSDAY NIGHT, ESPECIALLY IN THE CATSKILLS
WHERE PROBABILISTIC GUIDANCE SHOWS A BETTER THAN 75% CHANCE OF
OVER 3" OF SNOW. SOME OF THE MOUNTAIN SUMMITS COULD SEE OVER 6"
OF SNOW BY 12Z FRIDAY, BUT THESE HIGHER ACCUMULATIONS LOOK TO BE
CONFINED MAINLY TO AREAS ABOVE 3000 FT IN ELEVATION AT THIS
TIME. PWSSI GUIDANCE SHOWS A 40 TO 60% OF "MODERATE IMPACTS" IN
THE CATSKILLS DUE TO SNOW LOAD, WITH LOWER PROBABILITIES ACROSS
THE ADKS AND SOUTHERN GREENS. WITH SNOW TO LIQUID RATIONS MUCH
LESS THAN 10:1, THE SNOW WILL BE WET AND HEAVY, AND ISOLATED
POWER OUTAGES DUE TO THE WEIGHT OF THE SNOW ON TREE LIMBS CAN'T
BE RULED OUT IN THESE HIGH TERRAIN AREAS. EVEN VALLEY AREAS
COULD SEE A FEW SNOW FLAKES MIX IN TOWARDS DAYBREAK FRIDAY,
ESPECIALLY WITH ANY DYNAMIC COOLING/HEAVIER PRECIP RATES.
HOWEVER, WE ARE NOT CURRENTLY EXPECTING MUCH IF ANY
ACCUMULATION IN THE VALLEYS WITH MARGINAL THERMAL PROFILES AND
ANTECEDENT WARM GROUND CONDITIONS.
LONG TERM /FRIDAY THROUGH MONDAY/
*KEY MESSAGE 1: CONFIDENCE IS INCREASING IN THE OCCURRENCE OF A HIGH-
ELEVATION SNOW EVENT FRIDAY INTO SATURDAY MORNING WHOSE RESULTING
ACCUMULATIONS COULD WARRANT THE ISSUANCE OF OUR FIRST WINTER
HEADLINES OF THE SEASON.
*KEY MESSAGE 2: THE PROBABILITY OF ADVISORY-LEVEL SNOWFALL, AT
LEAST 4", IS LOW TO MEDIUM (20-50%) FOR THE HIGH-TERRAIN REGIONS OF
THE SOUTHWEST ADIRONDACKS IN NEW YORK AND THE SOUTHERN GREENS IN
VERMONT. HOWEVER, FOR THE EASTERN CATSKILLS IN NEW YORK, THE
PROBABILITY OF ADVISORY-LEVEL SNOWFALL IS MEDIUM TO HIGH (40-70%).
THE LARGE-SCALE STORM SYSTEM THAT WILL HAVE BROUGHT OUR FIRST
SUBSTANTIAL RAINFALL IN SEVERAL WEEKS WEDNESDAY NIGHT THROUGH
THURSDAY WILL REMAIN IN CLOSE PROXIMITY TO EASTERN NEW YORK AND
WESTERN NEW ENGLAND FOR THE START OF THE EXTENDED FORECAST PERIOD
FRIDAY MORNING. THERE REMAINS SOME RUN-TO-RUN DISCREPANCY IN THE
EXACT LOCATION OF THE UPPER-LEVEL, CLOSED LOW AND ASSOCIATED SURFACE
CYCLONE RELATIVE TO OUR FORECAST AREA, HOWEVER, GENERAL CONSENSUS
PLACES THE CORE OF THE SYSTEM IN AND AROUND THE I-95 CORRIDOR. AND
THOUGH, BY THIS TIME, THE SYSTEM IS EXPECTED TO BEGIN A GRADUAL
WEAKENING TREND, IT WILL STILL BE PACKING A PUNCH WITH 500 MB
HEIGHTS ANTICIPATED TO REACH 2 TO 2.5 STDEV BELOW NORMAL.
WITH THE CORE OF THE UPPER-LOW LOOKING TO BECOME POSITIONED JUST TO
OUR SOUTH, WE REMAIN WITHIN NORTHEASTERLY FLOW ABOUT ITS NORTHERN
PERIPHERY SUCH THAT MOISTURE WILL CONTINUOUSLY FEED INTO THE REGION
OFF THE ATLANTIC. PERSISTENT, BROAD, CYCLONIC FLOW, AIDED BY
REINFORCEMENT OF VERTICAL ASCENT WITH THE PERTURBATION OF NUMEROUS
VORTICITY LOBES ABOUT THE CORE OF THE LOW, WILL SUSTAIN WRAP-AROUND
PRECIPITATION ON ITS NORTHWESTERN FLANK THROUGHOUT THE DAY FRIDAY.
WHILE LARGE VALLEY AREAS WILL LIKELY SEE RAIN AS THEIR PRIMARY
PRECIPITATION TYPE, A TRANSITION TO WET SNOW IS ANTICIPATED BY
FRIDAY MORNING IN THE HIGHER TERRAIN REGIONS OF THE SOUTHWEST
ADIRONDACKS, EASTERN CATSKILLS, AND SOUTHERN GREENS AS A RESULT OF
BOTH COOL AIR ADVECTION AND ADIABATIC COOLING ON THE BACK SIDE OF
THE LOW. OROGRAPHIC ENHANCEMENT OF VERTICAL ASCENT IN THESE AREAS
WILL INCREASE THE PROBABILITY OF SNOWFALL TOTALS REACHING ADVISORY-
LEVEL CRITERIA ESPECIALLY AT THE HIGHEST PEAKS OF THESE MOUNTAIN
RANGES. AT THIS TIME, THE NBM-CONUS PROBABILISTIC 24-HOUR SNOWFALL
FORECAST ALLUDES TO A LOW TO MEDIUM PROBABILITY (20-50%) OF
GREATER THAN 4" OF SNOWFALL IN THE SOUTHWEST ADIRONDACKS AND
SOUTHERN GREENS BY SATURDAY MORNING. THE EASTERN CATSKILLS,
HOWEVER, LOOK TO MAKE THE TRANSITION TO SNOW QUICKER THAN THE
AFOREMENTIONED AREAS, DRIVING THE PROBABILITY FOR ADVISORY-LEVEL
SNOW INTO THE MEDIUM TO HIGH CATEGORY (40-70%). WILL CONTINUE
TO MONITOR CONDITIONS AS LEAD TIME DECREASES AND ISSUE HEADLINES
ACCORDINGLY.
CYCLONIC FLOW KEEPS HOLD OF THE REGION THROUGH MUCH OF THE WEEKEND,
LEADING TO ADDITIONAL SHOWERS, PRIMARILY IN THE FORM OF LAKE EFFECT
FOR THE SOUTHWEST ADIRONDACKS AND EASTERN CATSKILLS, THOUGH THE MOST
WIDESPREAD RAIN AND SNOW WILL TAPER OFF BY SATURDAY MORNING AS THE
UPPER-LOW BEGINS TO SHIFT AWAY FROM THE REGION TO THE NORTH AND
EAST. LAKE EFFECT SHOWERS CONTINUE ON AND OFF THROUGH SUNDAY BEFORE
WEAK RIDGING BUILDS IN ALOFT TO REINFORCE DRY CONDITIONS FOR THE
START OF THE NEW WORK WEEK. OVERALL, TEMPERATURES LOOK TO FALL INTO
THE "NORMAL" RANGE THROUGHOUT THE LONG TERM PERIOD WITH HIGHS
IN THE MID/UPPER 30S TO UPPER 40S/LOW 50S WITH THE EXCEPTION
BEING ELEVATIONS IN EXCESS OF 1500 FT WHERE LOW 30S ARE LIKELY.
LOW TEMPERATURES WILL GENERALLY RANGE FROM THE MID/UPPER 20S TO
LOW/MID 30S.
AVIATION /08Z TUESDAY THROUGH SATURDAY/
THROUGH 06Z WEDNESDAY...VFR CONDITIONS PREVAIL ACROSS ALL
TERMINALS THIS MORNING WITH THE ANTICIPATION OF A CONTINUANCE
THROUGHOUT THE 06Z TAF PERIOD. WINDS WILL PREVAIL GENERALLY OUT
OF THE NORTH TO NORTHWEST AT SUSTAINED SPEEDS UNDER 10 KT.
OUTLOOK...
WEDNESDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...RA.
THURSDAY: HIGH OPERATIONAL IMPACT. DEFINITE RA.
THURSDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
FRIDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
SATURDAY: LOW OPERATIONAL IMPACT. BREEZY. SLIGHT CHANCE OF SHRA.
SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
SUNDAY: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
FIRE WEATHER
IN COORDINATION WITH SURROUNDING OFFICES AND MA STATE PARTNERS,
A RED FLAG WARNING HAS BEEN ISSUED FROM 700 AM TO 600 PM EST
TODAY FOR BERKSHIRE COUNTY IN WESTERN MASSACHUSETTS AND AN SPS
FOR LITCHFIELD COUNTY. RH VALUES LOOK TO BOTTOM OUT AT 35 TO
45% ACROSS THE MID HUDSON VALLEY, CATSKILLS, AND WESTERN CT
TODAY. WINDS WILL BE MUCH LIGHTER THAN YESTERDAY WITH MAX GUSTS
OF ONLY 10 TO 15 MPH, ALTHOUGH ISOLATED HIGHER GUSTS OF 15 TO 20
MPH WILL BE POSSIBLE THIS AFTERNOON IN THE LITCHFIELD HILLS, AND
SOUTHERN GREENS. TODAY SHOULD BE THE LAST DAY WITH FIRE WEATHER
CONCERNS FOR THE FORESEEABLE FUTURE, AS WINDS TOMORROW WILL BE
EVEN LIGHTER THAN TODAY AND MINIMUM RH VALUES WILL BE IN THE 45
TO 55% RANGE OR HIGHER. A WIDESPREAD SOAKING RAINFALL IS
EXPECTED WEDNESDAY NIGHT AND THURSDAY, WITH CLOUDY CONDITIONS
AND SHOWERS CONTINUING INTO THE WEEKEND.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...RED FLAG WARNING FROM 7 AM THIS MORNING TO 6 PM EST THIS
EVENING FOR MAZ001-025.
VT...NONE.
SYNOPSIS...MAIN
NEAR TERM...MAIN
SHORT TERM...MAIN
LONG TERM...GANT
AVIATION...GANT
FIRE WEATHER...PICARD/SPECK/MAIN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page