000
FXUS61 KOKX 201155
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE UPTON NY
655 AM EST THU NOV 20 2008
.SYNOPSIS...
UNSEASONABLY COLD AIR WILL REMAIN THROUGH THE WEEKEND...AS A SERIES
OF UPPER LEVEL DISTURBANCES MOVE ACROSS. THE FIRST OF THESE WILL
MOVE THROUGH EARLY THIS MORNING...FOLLOWED BY ANOTHER LATE TONIGHT
INTO FRIDAY...AND THE LAST IN THE SERIES MOVING THROUGH DURING
FRIDAY NIGHT. STRONG HIGH PRESSURE PUSHING SOUTHEAST FROM CENTRAL
CANADA INTO THE PLAINS STATES THROUGH FRIDAY WILL THEN BUILD
EASTWARD THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
APPROACHING MID LEVEL VORT WITH ACCOMPANYING H8 TROUGH IS CURRENTLY
SPARKING A BAND OF SNOW SHOWERS ACROSS CENTRAL NY AND NE PA. EWR
TDWR SHOWED SOME OF THESE MAKING IT INTO NORTHERN NJ...AND THINK
THESE WILL MOVE ACROSS THE REST OF THE CWA EARLY THIS MORNING...WITH
LOW CHANCE POP (AND A POSSIBLE QUICK DUSTING) OVER INLAND SECTIONS
AND SLIGHT CHANCE ELSEWHERE. AFTER THIS DISTURBANCE MOVES THROUGH...
CYCLONIC FLOW AND WEAK POSITIVE H8 THETA E ADVECTION BENEATH AN
INVERSION SHOULD HELP MAINTAIN PARTLY TO MOSTLY CLOUDY SKIES THIS
AFTERNOON. FOR MAX TEMPS HAVE UNDERCUT MAV...WHICH WAS OFF BY ABOUT
2-5 DEGREES YESTERDAY... WITH MID 30S INLAND AND UPPER 30S FOR NYC
METRO AND THE COAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
FLOW ALOFT TURNS W AND THEN SW TONIGHT AS A STRONG MID LEVEL
SHORTWAVE DIGS SE TOWARD THE UPPER GREAT LAKES...WITH WEAKLY
CYCLONIC H8 FLOW AND MID LEVEL INVERSION HELPING MAINTAIN PARTLY
CLOUDY SKIES. ANOTHER MID LEVEL VORT WITH ACCOMPANYING SFC-H8
REFLECTION MOVING TOWARD THE AREA IN ADVANCE OF THE AMPLIFYING GREAT
LAKES TROUGH WILL BRING INCREASING CLOUDS AFTER MIDNIGHT...AND
PERHAPS A PERIOD OF LIGHT SNOW LATE TONIGHT INTO FRI MORNING...
MAINLY TO THE NYC METRO AREA AND PORTIONS OF THE LOWER HUDSON
VALLEY. WITH THE STRONGEST FORCING PASSING JUST SOUTH OF NYC AND
LONG ISLAND...HAVE ONLY FORECAST CHANCE POP ATTM...WITH ANY POSSIBLE
ACCUMULATION ON THE LIGHT SIDE...A DUSTING TO POSSIBLY AN INCH...
POSSIBLY IMPACTING THE MORNING COMMUTE.
THE AMPLIFYING TROUGH TO THE WEST SHOULD ALSO INITIATE CYCLOGENESIS
OFF THE MID ATLANTIC COAST FRI AFTERNOON AND NIGHT WHILE BECOMING
NEGATIVELY TILTED...AND FORECAST MODELS ARE IN CLOSE AGREEMENT THAT
THE DEVELOPING SURFACE LOW SHOULD PASS WELL SE OF THE 40/70
BENCHMARK...SO DO NOT EXPECT ANYTHING MORE THAN A SLIGHT CHANCE POP
FOR THE AFTERNOON ACROSS NYC AND LONG ISLAND. AS THIS UPPER TROUGH
SWINGS ACROSS FRI NIGHT...EXPECT THERE COULD BE A FEW WIDELY
SCATTERED SNOW SHOWERS ACROSS THE INTERIOR. TEMPS ON FRI SHOULD BE
HELD CLOSE TO THOSE OF THU DUE TO CLOUD COVER AND ANY PRECIP....ONCE
AGAIN MID/UPPER 30S.
WINDS PICK UP FRI NIGHT INTO SAT AS THE OFFSHORE LOW INTENSIFIES...
PULLING DOWN YET ANOTHER BATCH OF UNSEASONABLY COLD AIR...WITH LOWS
FROM THE UPPER TEENS TO MID 20S BOTH FRI/SAT NIGHT...AND ONLY RISING
TO WITHIN A COUPLE OF DEGREES EITHER SIDE OF FREEZING ON SAT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
COLD AIR ADVECTION WITH NW WINDS WILL CONTINUE TO KEEP TEMPERATURES
BELOW NORMAL ON SUNDAY. TEMPERATURES WILL MODERATE SOMEWHAT ON MON
AS SURFACE HIGH PRESSURE DRIFTS OFF THE COAST AND WINDS SHIFT TO
THE WSW.
LOW PRESSURE FORECAST TO DEVELOP ACROSS THE UPPER GREAT
LAKES/MIDWEST COULD IMPACT THE REGION LATE MONDAY INTO WEDNESDAY.
THERE REMAINS MODEL UNCERTAINTY ABOUT THE TIMING AND INTENSITY OF
THIS SYSTEM. MODEL RUNS HAVE BEEN TRENDING WARMER...THOUGH PRECIP
MAY STILL START AS LIGHT SNOW OR A MIX IN INTERIOR LOCATIONS MON
NIGHT. HAVE KEPT LOW POP FOR WED TO REFLECT UNCERTAINTY IN MODEL
SOLUTIONS.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
LOCALIZED MVFR CONDITIONS IN -SN AT KSWF THROUGH 14Z THIS
MORNING...OTHERWISE VFR. NW WINDS EARLY WILL BACK TO THE WEST
DURING THE MORNING AND THEN BACK TO THE NW TONIGHT REMAINING LESS
THAN 10 KT (AROUND 10 KT THIS MORNING AND AFTN NYC
TERMINALS). LOW END VFR THROUGH THE AFTERNOON...THEN SCT OUT BY
EVENING. ANOTHER MID AND UPPER LEVEL DISTURBANCE APPROACHES
TONIGHT...BUT 06Z GUIDANCE HAS PRECIP PASSING TO OUR SOUTH. CIGS
WILL LOWER AFTER 06Z AND CAN`T RULE OUT A FEW FLURRIES LATE
TONIGHT AT NYC TERMINALS JUST YET.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...GENERALLY VFR FRIDAY
THROUGH SUNDAY. BRIEF ISOLD SUB VFR CONDITIONS ARE POSSIBLE FRIDAY
MORNING. MORE FLURRIES AND ISOLD MVFR CONDITIONS POSSIBLE FRI
NIGHT INTO SAT. SUB VFR CONDS POSSIBLY DEVELOPING ON
MON...DEPENDING ON TIMING OF NEXT FRONTAL SYSTEM.
&&
.MARINE...
WINDS AND WAVES WILL REMAIN BELOW ADVISORY LEVELS THROUGH FRI
MORNING. LOW PRESSURE WILL DEVELOP AND INTENSIFY SE OF THE 40N 70W
BENCHMARK ON FRIDAY CAUSING THE PRESSURE GRADIENT TO INCREASE
BETWEEN THIS STORM AND STRONG CANADIAN HIGH PRESSURE OVER THE
MIDWEST. SCA CONDITIONS WILL LIKELY DEVELOP ON THE OCEAN WATERS BY
LATE FRI AFTERNOON. AS THE HIGH MOVES EAST AND THE LOW MOVES NORTH
WHILE CONTINUING TO STRENGTHEN FRI NIGHT AND SAT...THE GRADIENT WILL
REMAIN TIGHT WITH SCA CONDITIONS...POSSIBLY GALE FORCE WINDS ON THE
WATERS. DO NOT HAVE THE CONFIDENCE TO RAISE A GALE WATCH WHICH WOULD
BE PRIMARILY FOR THE 4TH AND 5TH PERIODS AS IT APPEARS IT WILL BE A
CLOSE CALL. SCENARIO LOOKS VERY SIMILAR TO TUESDAY/S STORM...WHICH
JUST BARELY REACHED GALE FORCE GUSTS ON THE EASTERN SOUND AND OCEAN
WATERS. SO WILL LET THE DAY SHIFT HAVE ANOTHER LOOK AT IT AND DECIDE
IF A GALE WATCH IS NECESSARY. HOWEVER...WILL HOIST THE SCA FOR THE
OCEAN WATERS FRI AFTERNOON AND EARLY EVENING.
THE PRESSURE GRADIENT STARTS TO RELAX SAT NIGHT...BUT FLAGS WILL
LIKELY BE NEEDED INTO SUN MORNING UNTIL CENTER OF THE HIGH BUILDS
OVER THE EASTERN SEABOARD.
SCA CONDITIONS WILL LIKELY RETURN ON MONDAY AND TUESDAY WITH THE
NEXT CLIPPER/COASTAL SYSTEM.
&&
.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION EXPECTED OVER THE NEXT 7 DAYS.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM TO 6 PM EST FRIDAY FOR ANZ350-
353-355.
&&
$$
