-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 221504
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1104 AM EDT WED MAY 22 2013

.SYNOPSIS...
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A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD
FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN PASS
THROUGH THURSDAY NIGHT INTO FRIDAY MORNING. CANADIAN HIGH PRESSURE
WILL THEN BUILD IN FOR THE MEMORIAL DAY WEEKEND AND EARLY NEXT
WEEK.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HRRR IS THE ONLY MODEL WHICH SHOWS SHALLOW BACK DOOR FRONT MAKING
PROGRESS AS FAR TO THE S AND W AS IT DID...AND HOLDS THE FRONT
PRIMARILY TO OUT S AND W THROUGH MOST OF THE AFTERNOON. SUSPECT
THAT EVEN THE HRRR IS TOO FAST TO ERODE MARINE LAYER.

EXPECT MOST OF THE AREA TO BE CLOUDY THROUGH THE DAY AS A RESULT.

FOR NOW HAVE SIGNIFICANTLY SCALED BACK ON POPS FOR
TODAY...ESPECIALLY ACROSS THE SE 1/2 OF THE CWA...AND RESTRICTED
PROBABILITY OF THUNDER TO SLIGHT CHANCE AND THEN ONLY OVER NW
ZONES...AS STILL CANNOT RULE OUT CONVECTION FORMING OUTSIDE THE
CWA THEN MOVING IN.

TEMPERATURES LOWERED REFLECTING BLEND OF HRRR 2-METER TEMPERATURES
AND LAV GUIDANCE - WHICH IS NOT ALL THAT BAD. DID NOT GO AS WARM
AS THIS WOULD SUGGEST THOUGH OVER NW ZONES - GIVEN SUSPICION THAT
MARINE LAYER HOLDS ON. WILL HAVE BETTER IDEA WHICH WAY TO PLAY
NW/FAR W ZONES WITH NEXT UPDATE EARLY THIS AFTERNOON.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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HAVE CONCERN THAT IF THE MARINE LAYER DOES NOT DISSIPATE/FRONT
LIFT TO THE N BY THIS EVENING - THAT THE MARINE LAYER WILL
MAINTAIN ITSELF OVER MOST IF NOT ALL THE AREA TONIGHT. WILL
CONTINUE TO MONITOR TRENDS - BUT COULD END UP MAKING SIGNIFICANT
CHANGES TO TONIGHTS FORECAST IF CURRENT TRENDS HOLD.

SCT-ISOLD SHOWERS AND TSTMS THIS EVENING. CONVECTION SHOULD BE
SCATTERED AT BEST WITH ONLY MARGINAL INSTABILITY IN PLACE. SHOWERS
AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD THURSDAY AS THE
UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT APPROACH THE
AREA.

HIGHS ON THURSDAY IN THE MID TO UPPER 70S.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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MAIN ISSUE FOR THE START OF THIS PERIOD IS THE INTERACTION OF THE
EASTWARD MOVING CENTRAL US TROUGH WITH SEVERAL NORTHERN STREAM
SHORTWAVES ROTATING AROUND A PERSISTENT EASTERN CANADIAN TROUGH. THE
COMPLEX INTERACTION IS RESULTING IN TIMING AND AMPLIFICATION ISSUES
AS THIS TROUGH SLIDES TO THE EAST COAST. GFS CONTINUES TO BE SLOWER
THAN ALL THE GUIDANCE FRI INTO SAT AS THE UPPER LOW NEGATIVELY TILTS
AND CLOSES OFF AS IT APPROACHES THE MID ATLANTIC STATES. THIS WOULD
RESULT IN A PROLONGED PERIOD OF POST-FRONTAL RAIN INTO SAT. WITH
MAJORITY OF 00Z OPERATIONAL GUIDANCE TRENDING A BIT SLOWER...HAVE
ALSO TRENDED A BIT SLOWER WITH PRECIPITATION GRADUALLY TAPERING
OFF FRI AFTERNOON INTO FRI NIGHT. SUBSEQUENT MODEL TRENDS WILL
NEED TO BE CLOSELY MONITORED TO SEE IF THE FRONTAL SYSTEM SLOWS
DOWN EVEN FURTHER.

AS FOR THE SENSIBLE WEATHER...COLD FRONT SLOWLY CROSSES THE REGION
THU NIGHT INTO FRI. ALTHOUGH INSTABILITY WILL LIKELY BE FALLING TO
MARGINAL LEVELS THURSDAY NIGHT...WIDESPREAD SHOWER AND THUNDERSTORM
DEVELOPMENT IS LIKELY WITH ABUNDANT MOISTURE STREAMING AHEAD OF
APPROACHING SHORTWAVE ENERGY/COLD FRONT. THE SEVERE THREAT SHOULD
DIMINISH INTO THURSDAY NIGHT...WITH HEAVY RAIN THE MAIN THREAT
WITH PWATS ABOUT 2 STD ABOVE NORMAL AND STEERING FLOW NEARLY ALIGNED
WITH THE SLOW MOVING FRONT. WILL HAVE TO MONITOR THE EXTENT OF
INTERACTION OF THE FRONT WITH A SUBTROPICAL PLUME STREAMING UP THE
COAST THURSDAY NIGHT...WHICH IF CLOSER TO THE COAST WOULD ENHANCE
THE FLASH FLOOD THREAT. CONVECTIVE THREAT SHOULD DECREASE IN
THE WAKE OF THE COLD FRONT...BUT POTENTIAL WAVE DEVELOPMENT COULD
PROLONG LIGHT TO MODERATE POST-FRONTAL STRATIFORM RAINS THROUGH
FRIDAY INTO FRI NIGHT...PARTICULARLY ACROSS EASTERN SECTIONS.
AVERAGE BASIN RAINFALL SHOULD BE CLOSE TO AN INCH...WITH LOCALIZED
HIGHER AMOUNTS.

A DRYING NW FLOW SET UPS FRI NIGHT INTO SAT WITH STRONG COLD
ADVECTION. HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES AND INTO
THE MID ATLANTIC STATES THROUGH EARLY NEXT WEEK WITH TEMPERATURES
SEVERAL DEGREES BELOW SEASONABLE LEVELS.
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&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
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FRONTAL BOUNDARY CONTINUES TO LINGER OVER THE AREA THIS MORNING.
AS A RESULT...HAVE GONE MORE PESSIMISTIC WITH THE FORECAST
THROUGH THE DAY...SHOWING IMPROVEMENT IN CIGS AND VSBY GENERALLY
AROUND 17Z-21Z. HOWEVER CONFIDENCE IN THIS
IMPROVEMENT...ESPECIALLY FOR CIGS...IS LOW. POTENTIAL FOR WINDS
TO STAY LIGHTER / MORE EASTERLY FOR A LONGER PERIOD THAN INDICATED
IN TAFS AS WELL.

SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS
AFTERNOON...GENERALLY AT KSWF AND PERHAPS KHPN. MARINE LAYER
LIKELY TO KEEP TS AWAY FROM TERMINALS FARTHER SE.

IT COULD BE ANOTHER TRICKY NIGHT FORECASTING VFR/IFR CONDITIONS.
LATEST GUIDANCE IS HINTING AT IFR OR LESS CONDITIONS AT THE
OUTLYING TERMINALS...HOWEVER GUIDANCE DIFFERS ON TIMING AND JUST
HOW LOW CIGS AND VSBYS GET. WILL HOLD OFF IN LOWERING CONDITIONS
TOO MUCH WITH LOW CONFIDENCE HOWEVER THIS WILL NEED TO BE
MONITORED. HIGHEST CONFIDENCE OF IFR OR LOWER CONDITIONS WILL BE
AT KGON.

     NY METRO ENHANCED AVIATION WEATHER SUPPORT...

DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT:  HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)

KJFK FCSTER COMMENTS: LOW CONFIDENCE IN MUCH IMPROVEMENT AT
17Z...ESPECIALLY FOR CIGS. WINDS COULD STAY LIGHTER/MORE E FOR 1-2
HOURS LONGER THAN INDICATED IN TAF.

KLGA FCSTER COMMENTS: LOW CONFIDENCE IN MUCH IMPROVEMENT AT
17Z...ESPECIALLY FOR CIGS. WINDS COULD STAY LIGHTER/MORE E FOR 1-2
HOURS LONGER THAN INDICATED IN TAF.

KEWR FCSTER COMMENTS: LOW CONFIDENCE IN MUCH IMPROVEMENT AT
17Z...ESPECIALLY FOR CIGS. WINDS COULD STAY LIGHTER/MORE E FOR 1-2
HOURS LONGER THAN INDICATED IN TAF.

THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW...WHICH IMPLIES
SLANT RANGE VISIBILITY 4-6SM OR GREATER OUTSIDE OF CLOUD.

KTEB FCSTER COMMENTS: LOW CONFIDENCE IN MUCH IMPROVEMENT AT
17Z...ESPECIALLY FOR CIGS. WINDS COULD STAY LIGHTER FOR 1-2 HOURS
LONGER THAN INDICATED IN TAF.

KHPN FCSTER COMMENTS: LOW CONFIDENCE IN MUCH IMPROVEMENT AROUND
18-21Z...ESPECIALLY FOR CIGS.

KISP FCSTER COMMENTS: LOW POTENTIAL FOR CIGS/VSBY TO IMPROVE TO
MVFR OR HIGHER LEVELS AROUND 17-18Z. WIND SPEEDS MAY BE 1-2 HOURS
SLOWER TO INCREASE THAN SHOWN IN TAF.

.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.THURSDAY-FRIDAY...NUMEROUS SHRA AND TSTMS POSSIBLE. IFR POSSIBLE IN
FOG AND STRATUS.
.SATURDAY...RESIDUAL SHRA BEHIND A COLD FRONT WITH MVFR. BECOMING VFR
WITH NW WINDS INCREASING TO 20-30KT.
.SUNDAY...VFR WITH NW WINDS 20-25KT.
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&&

.MARINE...
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BASED ON HRRR AND LATEST TRENDS IN OBSERVATIONS AND WEB-CAMS HAVE
EXTENDED THE DENSE FOG ADVISORY FOR THE COASTAL OCEAN ZONES...NY
HARBOR AND THE SOUTH SHORE BAYS OF LONG ISLAND THROUGH 22Z. GIVEN
NO RESTRICTIONS OF 1NM OR LESS IN VISIBILITY EVIDENT ON SOUND OR
EASTERN BAYS OF LONG ISLAND...HAVE CANCELLED THE DENSE FOG
ADVISORY THERE.

SEAS ARE NOT INCREASING AS FAST AS FORECAST...SO HAVE ADJUSTED
DOWNWARD A FOOT OR SO ACROSS MOST OCEAN AREAS INTO THIS EVENING.

SEAS SLOWLY BUILD THIS AFTERNOON/EVENING N TO SCA LEVELS AND
REMAIN ABOVE SCA LEVELS THROUGH THURSDAY. SW FLOW INCREASES OVER THE
COASTAL OCEAN WATERS TONIGHT AS WELL WITH SFC BOUNDARY LIFTING TO
NEAR THE LONG ISLAND COAST IF NOT FARTHER N.

A COLD FRONT WILL MOVE EAST ACROSS THE AREA WATERS LATE THURSDAY
THROUGH FRIDAY AFTERNOON...WITH HIGH PRESSURE BUILDING THROUGH THE
WEEKEND. WINDS SHOULD GRADUALLY FALL BELOW MARGINAL SCA LEVELS
THURSDAY NIGHT...WITH SCA SEAS ON THE OCEAN LIKELY REMAINING ABOVE
SCA CRITERIA THROUGH SATURDAY MORNING WITH RESIDUAL SOUTHERLY
SWELLS. UNDERCUT WAVEWATCH BY A FOOT DURING THIS TIME AS IT WAS
SLOWER BRINGING THE FRONTAL SYSTEM ACROSS THE AREA. THERE IS THOUGH
SOME UNCERTAINTY WITH THE SEAS DUE TO THE TIMING DIFFERENCES AMONGST
THE MODELS.
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&&

.HYDROLOGY...
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SCT SHOWERS/TSTMS THIS EVENING WILL BE CAPABLE OF PRODUCING
LOCALLY HEAVY RAINFALL...WITH THE BEST CHANCES NORTH/WEST OF NYC.
TOTAL BASIN AVG QPF FOR WED-THU COULD BE 1/4 TO 1/2 INCH...WITH
LOCALLY HIGHER AMOUNTS IN TSTMS.

SHOWERS AND THUNDERSTORMS AHEAD OF AN APPROACHING COLD FRONT LATE
THU INTO FRIDAY MORNING...SHOULD PRODUCE AVERAGE BASIN
RAINFALL AMOUNTS CLOSE TO AN INCH...WITH LOCALIZED HIGHER AMOUNTS.
THERE IS THE POTENTIAL FOR TRAINING OF THUNDERSTORMS WHICH COULD
RESULT IN FLASH FLOODING. ADDITIONAL LIGHTER RAINFALL AMOUNTS ARE
LIKELY FRIDAY...POSSIBLY INTO FRIDAY NIGHT.

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.
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&&

.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ338-345-
     350-353-355.
     SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 6 PM EDT
     THURSDAY FOR ANZ350-353-355.
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&&

$$
SYNOPSIS...24/NV
NEAR TERM...24/MALOIT/NV
SHORT TERM...24
LONG TERM...NV
AVIATION...BC/PICCA
MARINE...24/MALOIT/NV
HYDROLOGY...24/NV