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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 230508
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
108 AM EDT THU MAY 23 2013

.SYNOPSIS...
A STALLED FRONT WILL REMAIN IN THE VICINITY INTO THURSDAY. A COLD
FRONT WILL THEN SLOWLY APPROACH FROM THE WEST THURSDAY...THEN MOVE
INTO WESTERN PORTIONS OF THE TRI-STATE THURSDAY NIGHT. A WAVE OF
LOW PRESSURE DEVELOPS ALONG THIS SLOW MOVING COLD FRONT
FRIDAY...REMAINS JUST EAST OF THE REGION SATURDAY...AND THEN
TRACKS NORTH ALONG THE NEW ENGLAND COAST ON SUNDAY. HIGH PRESSURE
OVER THE GREAT LAKES BUILDS SOUTHEAST ACROSS THE AREA MONDAY INTO
TUESDAY. A WARM FRONT WILL THEN APPROACH FROM THE SOUTHWEST BY MID
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
OUTFLOW BOUNDARY THAT HAD BEEN KICKING UP SHOWERS OVER ORANGE
COUNTY EARLIER HAS ENTERED A MORE STABLE AIRMASS. PERHAPS IT COULD
STILL TRIGGER A SHOWER OR TWO EAST OF THE HUDSON. ANOTHER OUTFLOW
BOUNDARY OVER SE PA...STRETCHING INTO MD IS PRODUCING SHOWERS AND
ISOLATED THUNDERSTORMS. SOME OF THESE COULD SPILL INTO THE CITY
AND NE NJ LATE AT NIGHT. MODELS ARE FORECASTING A LOW-MID LEVEL
SHORTWAVE SHIFTING IN FROM THE SOUTH TOWARDS DAYBREAK. THIS COULD
PERHAPS ENHANCE THE COVERAGE OF SHOWER ACTIVITY.

OTHERWISE...MOSTLY CLOUDY WITH PATCHY FOG. STILL A CHANCE THAT
FOG COULD BECOME LOCALLY DENSE NEAR THE COAST LATE AT NIGHT...BUT
IT WOULD SEEM THAT THIS WOULD HAVE TO BE ADVECTION FOG DUE TO THE
WINDS. NOT ANTICIPATING DENSE FOG ADVISORIES OVER LAND AT THIS
TIME.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
MIXING ASSOCIATED WITH PASSING 700-500 HPA SHORTWAVE THURSDAY
MORNING SHOULD ERODE THE MARINE INVERSION - BUT STILL WILL BE
LEFT WITH QUITE A BIT OF MID TO HIGH CLOUDS WITH MOIST SW FLOW
ALOFT.

PRE-FRONTAL TROUGH MOVING INTO THE LOWER HUDSON VALLEY/NE NJ
THURSDAY AFTERNOON SHOULD SERVE AS TRIGGER FOR SCT-NUMEROUS SHRA
WITH EMBEDDED TSRA. LIKELY POPS MAINLY FROM NYC-INTERIOR SW CT
ZONES ON W AND CHANCE POPS EAST OF THAT LINE. SOME SUGGESTION FROM
NAM/GFS THAT EASTERN AREAS WILL REMAIN DRY THURSDAY...BUT FOR NOW
TOO MUCH LOW-MID LEVEL MOISTURE AND INCREASING LOW LEVEL JET TO
FORECAST THAT AT THIS TIME.

WITH 30-35 KT BULK SHEAR...1000-1500 J/KG OF CAPE AND BULK
RICHARDSON NUMBERS 15-30 HAVE THE POTENTIAL FOR ISOLATED SEVERE
STORMS THURSDAY AFTERNOON ACROSS NE NJ/LOWER HUDSON VALLEY AND
MAYBE NYC AND SW CT ZONES. MAIN THREAT IS GUSTY WINDS AND LARGE
HAIL. ALSO NEED TO WATCH FOR LOW LEVEL HELICITY WITH S SFC FLOW
AND SW FLOW AT 850 HPA.

FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 975 HPA NEAR
THE COAST AND 950 HPA INLAND...WITH NAM 2-METER TEMPERATURES AND A
BLEND OF MAV AND MET GUIDANCE. FORECASTING VALUES AROUND NORMAL
EAST TO A FEW DEGREES ABOVE NORMAL WEST.

DEEP SW FLOW ALOFT...BECOMES DIFFLUENT AT 500 HPA AFTER MIDNIGHT.
HAVE THE POTENTIAL FOR HEAVY RAINFALL AS A RESULT. REFER TO THE
HYDROLOGY SECTION FOR DETAILS. SEVERE THREAT COULD LINGER INTO THE
EVENING ACROSS WESTERN ZONES AS WELL.

FOR LOWS THURSDAY NIGHT USED A BLEND OF MAV/MET GUIDANCE WITH
VALUES FORECAST AROUND 10 DEGREES ABOVE NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
MODELS HAVE TRENDED CONSIDERABLY SLOWER AND DEEPER WITH THE
APPROACHING UPPER TROUGH OVER THE MID SECTION OF THE COUNTRY. THERE
IS VERY GOOD AGREEMENT WITH THE 12Z GFS AND ECMWF ON TAKING A CLOSED
UPPER LOW FROM THE MID ATLANTIC STATES ON FRI NE TO OVER NEW ENGLAND
ON SUN. THE NAM AND GGEM ARE TRENDING IN THAT DIRECTION...BUT ARE
MORE PROGRESSIVE BEYOND 00Z SAT. PREFERENCE AT THIS TIME IS TO GO
WITH THE SLOWER GFS/ECMWF SOLUTION BASED ON MODEL TRENDS AND THE RUN
TO RUN CONTINUITY BEING EXHIBITED OVER THE LAST SEVERAL MODEL CYCLES.

AS FOR SENSIBLE WEATHER...THIS RESULTS IN A WET...COOL WEEKEND WITH
THE POTENTIAL FOR ANOTHER 1 TO 2 INCHES OF RAINFALL IN THE FRI-SAT
TIME FRAME. SINCE THIS IS A BIG ADJUSTMENT FROM THE PREVIOUS
FORECAST...HAVE RAMPED UP RAIN CHANCES FRI INTO SAT...BUT THESE MAY
BE UNDERDONE...ESPECIALLY FOR SAT WHERE THERE IS A TREND IN THE
FORECAST TO DRY THINGS OUT SAT INTO SUN. LATEST ECMWF KEEPS
CONDITIONS WET INTO SUN WITH A GUSTY NW FLOW ON THE BACKSIDE. SO
THIS IS THE POINT IN THE FORECAST WHERE CONDITIONS MAY CONTINUE TO
DETERIORATE WITH SUBSEQUENT MODEL RUNS.

ONCE AGAIN...WHILE THE FORECAST HAS AGGRESSIVELY TAKEN A DOWNWARD
NOTE FOR THE HOLIDAY WEEKEND...RAIN CHANCES MAY BE ON THE INCREASE
SAT INTO SUN BASED ON LATEST TRENDS IN THE MODEL GUIDANCE.

IN ADDITION...SOME OF THE RAINFALL ON FRI...OR AT LEAST THE FIRST
HALF OF THE DAY MAY BE CONVECTIVE WITH LOCALIZED HEAVY RAINFALL WITH
ANY EMBEDDED THUNDERSTORMS. THEREAFTER...THE AIRMASS STABILIZES IN
THE LOW-LEVELS WITH POST-FRONTAL RAIN/SHOWERS...PRIMARILY DRIVEN BY
FRONTOGENETIC FORCING ON THE BACKSIDE OF THE LOW. WIND GUSTS SAT
INTO SUN MAY BE UP TO 35 MPH...BUT THIS IS THE POTENTIAL...WITH THE
FORECASTS SIGNIFICANTLY LOWER AT THIS TIME.

AS FOR TEMPS...DAYTIME HIGHS WITH THE CLOUD COVER AND RAIN WILL BE 5
TO 10 DEGREES BELOW NORMAL. STAYED BELOW GUIDANCE. OVERNIGHT LOWS
WILL BE CLOSE TO SEASONABLE. A GRADUAL WARM-UP TO NEAR SEASONABLE
LEVELS IS THEN FORECAST MON-WED.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN NORTH OF THE TERMINALS
THROUGH THE FORECAST PERIOD. A LOW PRESSURE SYSTEM AND COLD FRONT
APPROACH SLOWLY FROM THE WEST DURING THE DAY THURSDAY.

AN AREA OF SHOWERS MOVING INTO EASTERN PENNSYLVANIA WILL WEAKEN
OVERNIGHT WITH SCATTERED SHOWERS POSSIBLE IN THE NYC VICINITY
AROUND 08Z.

MVFR CEILINGS AND VISIBILITIES IN FOG POSSIBLE AFTER 07Z ALTHOUGH
CONFIDENCE IN THIS OCCURRING ESPECIALLY AT THE NYC TERMINALS IN
DIMINISHING. IFR CEILINGS AND MVFR VISIBILITIES IN FOG POSSIBLE AT
THE TERMINALS EAST OF NEW YORK CITY...CEILINGS MAY BECOME LIFR AFTER
09Z.

MVFR CONDITIONS LIKELY DURING THURSDAY WITH SHOWERS DEVELOPING AFTER
17Z. ISOLATED THUNDERSTORMS WILL BE POSSIBLE ALSO.

WIND WILL BE GENERALLY FROM THE SOUTH 10 KT OR LESS THROUGH LATE
TONIGHT...THEN SOUTH TO SOUTHWEST 10 TO 15 KT LATE TONIGHT INTO
THURSDAY.


.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THURSDAY NIGHT-FRIDAY...NUMEROUS SHRA...ISOLATED TSTMS POSSIBLE.
MVFR TO IFR IN SHOWERS...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 GUSTS
UP TO 40KT.
.MONDAY...VFR. NW WINDS 15-20G25KT.

&&

.MARINE...
-- Changed Discussion --
DENSE FOG ADVISORY REMAINS UP FOR ALL WATERS THROUGH 6AM DUE TO
FOG RESTRICTING VSBY TO LESS THAN 1 NM. THIS ADV MAY HAVE TO BE
EXTENDED THROUGH THE MID-MORNING HOURS. AT THE SAME TIME...THIS
COULD ALSO BE CANCELLED BEFORE 6AM AS THE STRENGTH OF THE WIND
MIGHT OUTWEIGH THE INFLUENCE OF HIGHER DEWPOINT AIR ADVECTING OVER
RELATIVELY COLDER SEA SURFACE TEMPERATURES.

SEAS COMING UP TO SCA LEVELS AND WILL CONTINUE THROUGH THURSDAY
NIGHT. WINDS ALSO INCREASE LATE TONIGHT AND REMAIN UP INTO
THURSDAY NIGHT. INCREASING LOW LEVEL JET THROUGH THURSDAY NIGHT
INCREASES POTENTIAL FOR SCA LEVEL GUSTS OVER THE COASTAL OCEAN
WATERS - SO HAVE KEPT HEADLINE AS SCA VICE CONVERTING TO AN SCA
FOR HAZARDOUS SEAS.

MARINE INVERSION APPEARS WILL LIMIT MIXING - SO WHILE COULD SEE
OCCASIONAL GUSTS TO 25 KT OVER THE REMAINDER OF THE WATERS FROM
LATE TONIGHT INTO THURSDAY NIGHT - DO NOT HAVE CONFIDENCE TO ISSUE
SCA AT THIS TIME FOR THE NON-OCEAN ZONES.

THERE IS A GOOD POTENTIAL FOR SCA CONDITIONS TO CONTINUE THROUGH THE
UPCOMING WEEKEND AS LOW PRESSURE FORMS OVER THE WATERS ON FRI AND
LIFTS SLOWLY TO THE NORTH AND EAST. SCA CONDITIONS ARE BECOMING
INCREASINGLY LIKELY...WITH THE POTENTIAL FOR GALE CONDITIONS SAT
INTO SUN. WINDS AND SEAS BEGIN TO SUBSIDE LATE SUN INTO MON WITH
HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES REGION.
-- End Changed Discussion --

&&

.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND 3/4 TO 1 INCH BASIN AVERAGE QPF
THURSDAY AND THURSDAY NIGHT WITH LOCALLY HIGHER AMOUNTS.

DO NOT EXPECT ANY WIDESPREAD FLOOD THREAT THURSDAY FROM ANY
SHRA/TSRA BUT COULD SEE SOME MINOR FLOODING UNDER ANY STRONGER
CONVECTION - ESPECIALLY IF THERE IS ANY TRAINING.

THE HEAVIEST RAINFALL IN THIS TIME FRAME WILL BE LATE THURSDAY
NIGHT - WITH LOCALIZED RAINFALL RATES OF 1-1.5 INCHES/HR POSSIBLE
NOTING PRECIPITABLE WATERS OF 1.5-1/75 INCHES IN THIS TIME
FRAME. IF THESE RATES ARE REALIZED...ESPECIALLY IF THE STORMS
PRODUCING THEM PASS OVER AREAS RECEIVING LOCALLY HEAVY RAINFALL
THURSDAY...THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING.

THE THREAT FOR LOCALIZED HEAVY RAINFALL WILL CONTINUE INTO THE FIRST
HALF OF FRI WITH EMBEDDED CONVECTION. THEREAFTER...A STRATIFORM RAIN
AND/OR SHOWERS DEVELOPS ON THE BACKSIDE OF DEVELOPING LOW PRESSURE.
AN ADDITIONAL 1 TO 2 INCHES OF RAINFALL IS POSSIBLE FRI INTO SAT.
THIS MAY EXACERBATE ANY ONGOING FLOODING. RAIN MAY LINGER EVEN INTO
SUN BASED ON LATEST MODEL TRENDS.

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...
-- Changed Discussion --
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     ANZ330-335-338-340-345-350-353-355.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ350-353-355.
-- End Changed Discussion --

&&

$$
SYNOPSIS...MALOIT/DW
NEAR TERM...JC/MALOIT/MPS
SHORT TERM...MALOIT
LONG TERM...DW
AVIATION...MET
MARINE...JC/MALOIT/DW
HYDROLOGY...MALOIT/DW