Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 210533
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
133 AM EDT THU AUG 21 2014

.SYNOPSIS...
HIGH PRESSURE REMAINS CENTERED TO THE NORTH AND EAST OF THE AREA
THROUGH THURSDAY NIGHT. MEANWHILE...WAVES OF LOW PRESSURE ALOFT
MOVE ACROSS THE REGION TONIGHT AND AGAIN THURSDAY INTO THURSDAY
NIGHT. AN UPPER LEVEL DISTURBANCE WILL TRACK THROUGH THE AREA ON
FRIDAY AS HIGH PRESSURE BUILDS DOWN FROM EASTERN CANADA. THIS HIGH
WILL GRADUALLY BUILD DOWN THE EASTERN SEABOARD THROUGH THE MIDDLE
OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SHOWERS OVER EASTERN PA AND WESTERN NJ SHOULD BEGIN TO IMPACT
WESTERN SECTIONS OF THE CWA BETWEEN 5-6Z. H5 SHORTWAVE WILL
CONTINUE TO MOVE SLOWLY EAST ACROSS THE REGION TONIGHT AS LOW
LEVEL MOISTURE INCREASES THROUGH THE NIGHT...ALLOWING FOR PRECIP
TO REACH THE GROUND. BEST CHANCES WILL BE ACROSS WESTERN
ZONES...BUT WILL KEEP POPS CAPPED AT CHANCE AS THE ACTIVITY WILL
BE SCATTERED.

LOWS TONIGHT WILL DROP INTO THE UPPER 60S IN/AROUND NYC AND IN THE
LOW TO MID 60S MOST OTHER LOCATIONS. EASTERN ZONES WILL DROP INTO
THE MID/UPPER 50S.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
THERE WILL BE SOME SHOWERS ONGOING DURING THE FIRST HALF OF THE
DAY...AS A SHORTWAVE SWINGS ACROSS THE AREA. BEST CHANCES WILL AGAIN
BE ACROSS WESTERN AND NORTHERN ZONES...AS RIDGING NOSES IN ACROSS
OUR EASTERN SECTIONS. INCLUDED ISO THUNDER ACROSS THE APPROXIMATE
WESTERN THIRD OF THE AREA...WHERE MODEL FIELDS INDICATE A LITTLE
MORE IN THE WAY OF MUCAPE. ADDITIONALLY...THESE AREAS WILL BE LESS
INFLUENCED BY THE MARITIME AIR BEING ADVECTED ACROSS THE AREA THANKS
TO E/SE ONSHORE FLOW.

DUE TO THE AFOREMENTIONED ONSHORE FLOW AND INCREASED CLOUD
COVER...TEMPS WILL BE COOLER THAN THE PREVIOUS DAY...WITH MANY AREAS
STAYING IN THE 70S / BELOW NORMAL FOR THIS TIME OF YEAR.

AS THE FIRST WAVE DEPARTS TO THE EAST THURSDAY AFTERNOON AND
EVENING...SUBSIDENCE ALOFT AND THE CONTINUED SURFACE RIDGING POKING
IN FROM THE NORTH AND EAST WILL ALLOW MOST PLACES TO BE DRY LATER IN
THE DAY. CHANCES WILL THEN INCREASE AGAIN OVERNIGHT...AS THE UPPER
LOW TO THE NW OPENS AND APPROACHES THE AREA.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS ARE IN GOOD AGREEMENT THAT THE H5 PATTERN ACROSS NOAM AT THE
START OF THE LONG TERM PERIOD WILL CONSIST OF A STRONG BROAD RIDGE
ACROSS THE SE CONUS WITH A DEEP TROUGH OUT WEST WITH AN UPPER LOW
CUTTING OFF OVER THE PAC NW AND AN OMEGA BLOCK OVER ERN CANADA WITH
A WEAK CUTOFF LOW MOVING THROUGH NEW ENGLAND.

SOME UNCERTAINTY WITH THE SPECIFIC DETAILS AND TIMING OF VORT MAXES
MOVING AROUND THE LEFT SIDE OF THE UPPER LOW ONCE IT SLIDES
OFFSHORE...BUT THE GENERAL TREND APPEARS TO BE DECREASING CHC`S OF
SHOWERS DURING FRI AS DEEP LAYERED RIDGING BUILDS INTO THE NORTHEAST
FROM THE N. MAY NEED TO ADD SLIGHT TO LOW CHC POPS AT TIMES THROUGH
SAT IN SUBSEQUENT FORECAST PACKAGES TO ACCOUNT FOR THESE TIMING
DIFFERENCES. ADDITIONALLY...THE AMOUNT OF CLOUD COVER FOR FRI AND
SAT IS ALSO QUESTIONABLE AS A RESULT.

OTHERWISE...EXPECT DRY AND SEASONABLE CONDS THROUGH THE MIDDLE OF
NEXT WEEK AS THE H5 FLOW AMPLIFIES IN RESPONSE TO THE BLOCKING
PATTERN. SFC HIGH PRES WILL BUILD DOWN THE ERN SEABOARD DURING THIS
TIME WITH AN ELY FLOW EXPECTED AT LEAST INTO MON. THIS WILL
CONTRIBUTE TO BELOW NORMAL TEMPERATURES THOUGHT THIS TIME...BUT AS
HEIGHTS RISE TUE AND WED...TEMPERATURES WILL REBOUND TO NEAR NORMAL
LEVELS.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
WEAK HIGH PRESSURE REMAINS OVER THE AREA.

WITH THE EXCEPTION OF POSSIBLE IFR CONDITIONS IN FOG AT
KGON...MAINLY EXPECT VFR CONDITIONS THROUGH THE MORNING AND
AFTERNOON HOURS. THERE WILL BE ISOLATED TO SCATTERED SHOWERS...AND
ANY SHOWER COULD REDUCE CEILINGS OR VSBYS TO MVFR BRIEFLY. BEST
CHANCE FOR SHOWERS ACROSS NYC METRO AND NORTH AND WEST.

POSSIBLE HIGHER COVERAGE OF SHOWERS TONIGHT AS AN UPPER LEVEL
DISTURBANCE MOVES THROUGH. BEST CHANCE NYC METRO AND NORTH AND WEST.

LIGHT WINDS BECOME SOUTHEAST OR SOUTH 5 TO 10 KTS DURING THE DAYTIME.

.OUTLOOK FOR 06Z FRI THROUGH MON...
.TONIGHT...VFR...ALTHOUGH MVFR CEILINGS/VSBYS ARE POSSIBLE IN SCT
SHOWERS/TSTMS.
.FRI-MON...VFR.

&&

.MARINE...
WITH HIGH PRESSURE STILL EXTENDING ACROSS THE WATERS THURSDAY...AND
ONLY STARTING TO LIFT OUT THURSDAY NIGHT...WINDS AND SEAS WILL
REMAIN BELOW SCA CRITERIA DURING THIS TIME. EASTERLY FLOW WILL BE ON
THE INCREASE LATE THURSDAY THOUGH.

WIND GUSTS ARE EXPECTED TO REMAIN BLO SCA LEVELS...ALTHOUGH COULD
COME CLOSE TO 25 KT ON THE OCEAN WATERS LATE FRI/FRI EVE. AN
INCREASING E-NE FLOW WILL RESULT IN BUILDING SEAS ON THE OCEAN WITH
SCA CONDS EXPECTED BETWEEN FRI NIGHT AND SUN NIGHT. THE GRADIENT
RELAXES THEREAFTER WITH SEAS DIMINISHING.

&&

.HYDROLOGY...
A FEW THUNDERSTORMS ARE POSSIBLE ON THURSDAY ACROSS THE LOWER HUDSON
VALLEY AND INTERIOR NE NJ. ANY STORMS WILL HAVE THE POTENTIAL TO
PRODUCE LOCALLY HEAVY RAIN...BUT BASIN AVERAGED TOTALS ARE FORECAST
TO REMAIN LIGHT...AS ANY THUNDERSTORMS SHOULD BE ISOLATED.

NO SIGNIFICANT RAINFALL IS EXPECTED IN THE EXTENDED.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...24/PICCA
NEAR TERM...PICCA/JP/MPS
SHORT TERM...PICCA
LONG TERM...24
AVIATION...PW
MARINE...24/PICCA
HYDROLOGY...24/PICCA





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