-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 201127
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
727 AM EDT MON MAY 20 2013

.SYNOPSIS...
A WARM FRONT LIFTS TO THE NORTH TODAY AND WILL SINK SOUTH CLOSER TO
THE AREA ON TUESDAY. A COLD FRONT IN THE VICINITY OF THE AREA
TUESDAY NIGHT WILL LIFT BACK AS A WARM FRONT ON WEDNESDAY. A WARM
AND HUMID AIRMASS WILL THEN REMAIN OVER THE REGION UNTIL A COLD
FRONT MOVES THROUGH THURSDAY NIGHT OR FRIDAY. HIGH PRESSURE
RETURNS FOR THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
VSBYS HAVE DROPPED TO 1/4 SM OR LESS IN MANY LOCATIONS ON LONG
ISLAND...COASTAL CONNECTICUT AND SOUTHERN WESTCHESTER THIS
MORNING...SO HAVE ISSUED A DENSE FOG ADVSY FOR THESE AREAS THROUGH
10 AM. ORIGINALLY THOUGHT IT WOULD TAKE A BIT FOR VSBYS TO IMPROVE
WITH LIGHT WINDS AT THE SFC...BUT ALREADY SEEING SOME IMPROVEMENT
SO THIS MAY BE CANCELLED EARLY. MESOSCALE MODELS ALSO INDICATING
DRY WEATHER THIS MORNING AND NOT SEEING ANYTHING IN WATER VAPOR
IMAGERY TO TRIGGER ANY SHOWER ACTIVITY...SO HAVE REMOVED POPS
UNTIL THIS AFTN. REST OF FORECAST IS ON TRACK.

LOW PRESSURE RIDES ALONG A FRONT WELL TO THE NORTH TODAY. WEAK
FRONTAL BOUNDARY TO THE SOUTH SHOULD WEAKEN AND DISSIPATE THIS
MORNING.

DENSE FOG DEVELOPED ALONG AND NORTH OF A FRONTAL BOUNDARY JUST SOUTH
OF THE LOCAL AREA. LOW CLOUDS AND FOG WILL SLOWLY BURN OFF AS THE
MORNING PROGRESSES. SOME BREAKS OF SUN ARE POSSIBLE THIS
AFTERNOON. HOW MUCH CLEARING OCCURS WILL DETERMINE THE AMOUNT OF
DAYTIME HEATING/INSTABILITY...WHICH WILL AID IN TSTM DEVELOPMENT
THIS AFTERNOON AND EVENING...HOWEVER...THINKING COVERAGE WILL BE
ISOLD TO WDLY SCT AT BEST. WITH PW NEAR 1.5...ANY SHOWER/TSTM COULD
PRODUCE LOCALLY HEAVY RAIN. WILL MAINTAIN CHANCE POPS.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
FRONTAL BOUNDARY REMAINS JUST TO THE NORTH AS RIDGE PREVAILS ACROSS
THE NORTHEAST AHEAD OF UPSTREAM TROUGH.

SOUTHWEST LOW LEVEL FLOW WILL LIGHTEN THIS EVENING...AND AMPLE
MOISTURE COULD LEAD TO THE DEVELOPMENT OF FOG ONCE AGAIN. ANY
LINGERING DIURNAL SHOWERS/TSTMS WILL DIMINISH IN COVERAGE...AND MOST
OF THE NIGHT SHOULD BE DRY.

WITH AREA IN THE WARM SECTOR...TEMPERATURES WILL REMAIN QUITE
MILD...50S TO AROUND 60.

ON TUESDAY...TEMPS WARM THROUGH THE 70S...TO AROUND 80 AWAY FROM THE
WATER...WITH 70S ELSEWHERE. ANY MORNING FOG WILL BURN OFF TO PARTLY
SUNNY SKIES. AFTERNOON SHOWERS OR THUNDERSTORMS ARE POSSIBLE ONCE
AGAIN.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MEDIUM RANGE MODELS/ENSEMBLES ARE IN DECENT GENERAL AGREEMENT WITH
THE REGION LYING ON THE NORTHERN PERIPHERY OF EAST COAST RIDGING
DURING THE MIDWEEK...WITH PHASING EASTERN CANADIAN AND CENTRAL US
TROUGHS...EVENTUALLY TRANSLATING A DEEP TROUGH TO THE EAST COAST FOR
THE END OF THE WEEK/WEEKEND.

FOR TUESDAY THROUGH THURSDAY...MODELS CONTINUE TO DIFFER IN LOCATION
OF A FRONTAL BOUNDARY. THE PREDICTABILITY ISSUES ARE BASED ON
SUBTLE DIFFERENCES IN INTERACTION OF THE UPPER ENERGIES AND
RELATIONSHIP WITH EAST COAST RIDGING. THE LOCATION OF UPPER
CONFLUENCE WILL DETERMINE HOW STRONGLY CANADIAN HIGH PRESSURE BUILDS
SE INTO NEW ENGLAND...AND THE TIMING AND MOVEMENT OF A BACK DOOR
COLD FRONT. LATEST GUIDANCE DOES NOT BRING THE BACKDOOR COLD FRONT
THROUGH THE CWA TUESDAY NIGHT...BUT ITS STILL QUESTIONABLE WHETHER
IT SINKS INTO THE AREA OR REMAINS JUST N. HAVE TRENDED IN THIS
DIRECTION AND BROUGHT IT ABOUT HALFWAY THROUGH...BUT TEMPS TUE NIGHT
WILL BE AFFECTED BY THIS. THE BOUNDARY THEN LIFTS BACK NORTH AS A
WARM FRONT ON WEDNESDAY.

TO THE SOUTH OF THE FRONT...AN UNSEASONABLY WARM AND MOIST AIR MASS
WILL BE IN PLACE. DEPENDING ON THE TIMING AND LOCATION OF THE
FRONTAL BOUNDARY...SHORTWAVES AT THE SOUTHERN EDGE OF THE
WESTERLIES...FAVORABLE INSTABILITY AND WIND FIELDS PRESENT THE
POTENTIAL FOR CONVECTIVE COMPLEXES TO DEVELOP AND PROPAGATE ALONG
THIS BOUNDARY. ANY MCS WOULD BRING THE THREAT FOR FLASH FLOODING AND
SEVERE WEATHER.

MODELS HAVE COME BETTER INTO LINE WITH THE PHASING OF THE MIDWEST
UPPER TROUGH AND EASTERN CANADIAN UPPER TROUGH AT THE END OF THE
WEEK. COLD FRONT LOOKS TO TRACK THROUGH THE AREA THU NIGHT. A
PRE-FRONTAL TROUGH IN THE WARM...MOIST AIRMASS PRECEDING THE FRONT
ON THU...WILL BE THE TRIGGER FOR SCT SHOWERS AND TSTMS DURING THE
AFTN AND EVE HOURS. THERE IS THE POTENTIAL FOR SOME STORMS TO BE
STRONG TO SEVERE BASED ON LATEST PROFILES. LINGERING SHOWERS ARE
POSSIBLE ON FRI WITH THE UPPER TROUGH MOVING THROUGH.

MODEL GUIDANCE IS SIGNALING A DRIER AND SLIGHTLY BELOW SEASONABLE
WEEKEND...WITH EAST COAST MEAN TROUGHING AND CANADIAN HIGH PRESSURE
BUILDS INTO THE REGION.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
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A NEARLY STATIONARY FRONT WILL REMAIN SOUTH OF THE AREA AS IT
WEAKENS EARLY THIS MORNING. THE FRONT WILL REDEVELOP TO THE NORTH
OF THE TERMINALS AS A WARM FRONT MID TO LATE MORNING.

THE AREA WILL THEN BE IN THE WARM SECTOR AS LOW PRESSURE MOVES TO
THE NORTH. MORNING FOG AND STRATUS WILL IMPROVE AS THE MORNING
PROGRESSES...BUT LIKELY AFTER THE MORNING PUSH. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS WILL BE POSSIBLE IN THE AFTERNOON. THE
WIND WILL BE SOUTHERLY...AND BECOME MORE SOUTHWESTERLY LATE IN THE
AFTERNOON INTO THE EARLY EVENING. SEA BREEZE INFLUENCE IS LIKELY.

MAINLY VFR THIS EVENING AS ANY SHOWERS OR THUNDERSTORMS WEAKEN. FOG
SHOULD REDEVELOP BY MIDNIGHT.

     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)

KEWR FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT. WEST WINDS SHOULD TURN TOWARD THE SOUTHWEST
THIS MORNING.

THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.

KJFK FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT. SEA BREEZE POSSIBLE THIS AFTERNOON.

KLGA FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT.

KTEB FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT.

KHPN FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT.

KISP FCSTER COMMENTS: AMENDMENTS LIKELY FOR TIMING OF FOG AND
STRATUS IMPROVEMENT.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.TONIGHT...MAINLY VFR...MVFR OR LOWER CONDITIONS POSSIBLE IN
FOG...MAINLY EAST OF THE NEW YORK CITY TERMINALS.
.TUESDAY-FRIDAY...DURING THE DAY...A CHANCE OF MVFR OF LOWER
CONDITIONS IN SHOWERS/TSTMS. AT NIGHT...A CHANCE OF MVFR OF LOWER
CONDITIONS IN STRATUS/FOG.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
MORNING FOG WILL SLOWLY IMPROVE AS THE DAY PROGRESSES. SEAS ARE
STILL EXPECTED TO BUILD CLOSE TO 5 FT...THEREFORE SCA FOR HAZ SEAS
REMAINS IN EFFECT. MARGINAL SCA SEAS ARE POSSIBLE ON THE OCEAN
INTO TONIGHT...BUT WAVEWATCH IS STILL RUNNING A BIT HIGH...SO HAVE
LOW CONFIDENCE IN EXTENDING THE ADVSY BEYOND TODAY.

A GENERAL SOUTHERLY FLOW WILL PREVAIL TODAY THROUGH TUESDAY. SEAS
SHOULD SLOWLY SUBSIDE TONIGHT AND TUESDAY...WITH MAINLY SUB SCA
CONDITIONS ANTICIPATED.

DUE TO THE POOR PERFORMANCE OF WAVEWATCH OVER THE LAST 2 DAYS...HAVE
LOW CONFIDENCE IN ITS FORECAST DURING THE LONG TERM PERIOD. SCA FOR
SEAS MAY BE NEEDED ON THE OCEAN WATERS TUE NIGHT. AS THE PRES
GRADIENT INCREASES ON WED...SUSTAINED WINDS WILL INCREASE WITH SEAS
LIKELY AT SCA LEVELS. A STRONG INVERSION OVER THE WATERS WILL
INHIBIT WINDS ALOFT FROM MIXING DOWN...ALTHOUGH WINDS COULD REACH
SCA LEVELS ON THE OCEAN THU/THU EVE. THE PRES GRADIENT RELAXES AS A
COLD FRONT MOVES INTO THE WATERS THU NIGHT AND WINDS AND SEAS WILL
DIMINISH BELOW SCA LEVELS THROUGH THE REST OF THE PERIOD.
-- End Changed Discussion --

&&

.HYDROLOGY...
SCATTERED SHOWERS AND TSTMS COULD PRODUCE LOCALLY HEAVY DOWNPOURS
TODAY. THIS COULD LEAD TO A LOW END FLASH FLOOD THREAT. SCT
SHOWERS/TSTMS TUESDAY THROUGH FRI ARE CAPABLE OF PRODUCING
LOCALLY HEAVY RAINFALL...WITH AN ATTENDANT LOW END FLASH FLOOD
THREAT.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR CTZ009>012.
NY...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR NYZ071-
     078>081-177-179.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL NOON EDT TODAY FOR ANZ330-335-338-340-
     345-350-353-355.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM EDT THIS
     EVENING FOR ANZ350-353-355.
-- End Changed Discussion --

&&

$$