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000
FXUS61 KOKX 221815
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
215 PM EDT WED MAY 22 2013

.SYNOPSIS...
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.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BACK DOOR COLD FRONT THAT WENT THROUGH OVERNIGHT REMAINS STALLED
OUT TO THE W AND S OF THE AREA. HRRR AND RAP ARE THE ONLY MODELS WITH
ANY CLUE TO ITS EXISTENCE. LOOKING AT TRENDS IN VISIBLE SATELLITE
AND RAP SOUNDINGS...HAVE DOUBTS ABOUT HRRR/RAP SHOWING BOUNDARY
PUSH BACK INTO FAR W ZONES AS A WARM FRONT LATE THIS AFTERNOON.

AS A RESULT HAVE KEPT FORECAST CLOUDY-MOSTLY CLOUDY AND LOWERED
TEMPERATURES AGAIN. NOW FORECASTING HIGHS MAINLY IN THE 70S...WITH
UPPER 60S AT THE IMMEDIATE COAST.

STILL APPEARS MOST OF THE AREA WILL BE DRY THIS AFTERNOON PER
HRRR/RAP. HOWEVER WITH CONVECTION FIRING W OF AREA...HAVE KEPT
SLIGHT CHANCE TO CHANCE POPS THIS AFTERNOON OVER THE NW 1/2 OF THE
CWA WITH A SLIGHT CHANCE OF THUNDER. ANY THUNDERSTORMS WILL MOST
LIKELY BE ELEVATED IN NATURE AS THEY MOVE OVER THE AREA DUE TO THE
MARINE INVERSION IN PLACE...SO THE SEVERE THREAT THIS AFTERNOON IS
NIL ACROSS THE SE 1/2 OF THE CWA AND LESS THAN 5 PERCENT ELSEWHERE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
INCREASING CONCERN THAT THE MARINE LAYER WILL NOT DISSIPATE/FRONT
LIFT TO THE N BY THIS EVENING - AND 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.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
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.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
FRONTAL BOUNDARY CONTINUES TO LINGER OVER THE AREA THIS AFTERNOON.
AS A RESULT...IMPROVEMENT HAS BEEN QUITE SLOW. IFR/MVFR CIGS AND
VSBY GENERALLY THE STANDARD. SOME POTENTIAL FOR A LITTLE MORE
IMPROVEMENT PRIMARILY AT NW TERMINALS.

RECENT OBS SHOW WINDS FINALLY TURNING S AT KJFK/KEWR...WHICH MAY
BE A SIGN OF BRIEFLY INCREASING VSBY/CIGS. HOWEVER...BASED ON
CURRENT OBS AND DEVELOPING S WIND...GROWING POTENTIAL FOR IFR
VSBY TO PUSH BACK INTO COASTAL TERMINALS OVER NEXT FEW HOURS.

POTENTIAL FOR CONDITIONS TO DROP SOLIDLY INTO IFR AGAIN
TONIGHT...HOWEVER MUCH UNCERTAINTY EXISTS OVER TIMING AND EXTENT.
POTENTIAL ALSO EXISTS FOR LIFR/VLIFR ACROSS COASTAL TERMINALS.

DID NOT SHOW TS IN TAFS ON THURSDAY JUST YET...AS UPPER-LEVEL FLOW
INDICATES STORMS MAY BE SLOW TO APPROACH WESTERN TERMINALS AND
COULD HOLD OFF UNTIL LATE IN THE DAY. HOWEVER...LOW END
POTENTIAL EXISTS AT W TERMS GENERALLY 23/18Z THRU 24/00Z.

     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: POSSIBILITY FOR VSBY TO DROP QUICKER/LOWER
THAN FORECAST LATE THIS AFTERNOON INTO THIS EVENING.

KLGA FCSTER COMMENTS: POTENTIAL FOR CIGS TO GO VFR BRIEFLY THIS
AFTERNOON AND EARLY THIS EVENING. WIND DIRECTION MAY STAY E/NE A
COUPLE HOURS LONGER THAN INDICATED IN TAF.

KEWR FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF
OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST
TONIGHT.

KTEB FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF
OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST
TONIGHT.

KHPN FCSTER COMMENTS: CIGS MAY RISE HIGHER THAN INDICATED IN TAF
OVER NEXT 2-3 HOURS. POTENTIAL FOR VSBY/CIGS LOWER THAN FORECAST
TONIGHT.

KISP FCSTER COMMENTS: POSSIBILITY FOR VSBY TO DROP QUICKER/LOWER
THAN FORECAST LATE THIS AFTERNOON INTO THIS EVENING.

.OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
.THURSDAY-FRIDAY...NUMEROUS SHRA AND TSTMS POSSIBLE....PRIMARILY
THUR NIGHT AND FRIDAY. IFR POSSIBLE IN FOG AND STRATUS.
.SATURDAY...SHRA LIKELY WITH MVFR OR LOWER. N WINDS 25-30G35KT.
.SUNDAY...MOST LIKELY VFR WITH NW WINDS 20-25KT. POTENTIAL FOR G
UP TO 40KT.
.MONDAY...VFR. NW WINDS 15-20G25KT.

&&

.MARINE...
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.

THERE SEEMS TO BE INCREASING POTENIAL FOR DENSE FOG OVER THE
SOUTHERN WATERS TO CONTINUE TONIGHT. IF TRENDS HOLD...WILL EXTEND
THE DENSE FOG ADVISORY IN TIME THROUGH TONIGHT WITH THE LATE
AFTERNOON FORECAST ISSUANCE.

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 TO SCA LEVELS ON THE
COASTAL OCEAN WATERS 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.

&&

.HYDROLOGY...
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.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
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.

&&

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