Area Forecast Discussion
Issued by NWS Upton, NY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KOKX 271453
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1053 AM EDT Tue Jun 27 2017

.SYNOPSIS...
A cold frontal passage occurs this evening. A Bermuda high sets
up Wednesday night. Then a frontal system passes north of the
region Thursday through Friday night. A cold front approaches
Saturday and moves across Sunday into Sunday night. The front
may linger south of the region early next week with otherwise
weak high pressure returning.

&&

.NEAR TERM /THROUGH TONIGHT/...
Best large scale lift is passing to the east of the area this
morning in conjunction with upper jet and mid level short wave.
The forecast dilemma for this afternoon is with continued
destabilization of the airmass due to cooling aloft with the
approach of the upper trough and whether that will sufficient
enough to offset subsidence. Have maintained scattered showers
and thunderstorms this afternoon into early this evening with a
pre-frontal trough/weak cold front. Shear is weak and
instability is moderate. Steep low-level lapse rates up to 85H
indicate potential for strong gusty winds. Small hail also a
possibility with wet bulb zero values around 7 kft.

Cold front moves east of the area this evening with perhaps a
few showers or thunderstorms across eastern Long Island and
southeast Connecticut, otherwise it will be another dry,
seasonably cool night.

There is a mdt risk for rip current development today.

&&

.SHORT TERM /WEDNESDAY/...
Despite very steep low lvl lapse rates, subsidence should keep
the area dry. There could be some flat cumulus, however with
condensation pres deficits around 40, even this may be
difficult, especially away from any terrain enhancement. Despite
the cool airmass aloft, deep mixing will allow for highs to be
only a few degrees blw average. A blend of guidance was used for
this.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
The jet lifts north of the region and stays north of the region
midweek going through much of the weekend. It starts to move farther
south into the region Sunday afternoon into Sunday night, before
lifting back north of the region early next week.

The mid and upper level flow transitions to more of a zonal flow mid
into late week and then transitions to more of a ridging pattern
going into the weekend. Shortwave approaches for second half of
weekend, presenting more of a trough pattern and SW flow aloft,
before returning to a quasi-zonal flow early next week.

High pressure moves off into the Western Atlantic, building
Wednesday night, and then slowly drifting farther out to sea through
Thursday night. Meanwhile, a warm front moves north of the Great
Lakes and into Northern New England Thursday into Thursday night.
There is a trailing cold front to the west that looks to weaken
Thursday night before moving northward as a warm front Friday into
Friday night. A cold front from the west approaches Saturday and
moves across Sunday into Sunday night. Possibly this could get
delayed as shown by the ECMWF, hence the longer time window
stated for its passage.

The frontal boundary of the weakening cold front Thursday night into
Friday is forecast to be close enough to warrant a chance of a
shower or thunderstorm. The chance continues into Friday night. The
next chance of showers and thunderstorms will be this weekend.
There will be a slight chance of showers and thunderstorms
forecast for early next week with frontal boundary possibly
lingering not too far away to the south of the region. Not
expecting a total washout as coverage is expected to be mainly
isolated to scattered. The showers and thunderstorms will be
driven by the diurnal heat and the instability that generates.

Temperatures start off near normal Wednesday night and Thursday but
then trend warmer for the rest of the forecast period. It will be
getting warmer and more humid. The temperatures will average about 3-
5 degrees above normal. Temperatures are forecast to be well
into the 80s Thursday through Monday with some locations in the
NY Metro and Northeast NJ reaching near 90 for Friday and
Saturday.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
Mainly VFR as a trough of low pressure passes across the
terminals late this afternoon and evening.

Light and variable winds will become S-SSE 14-15z at 10 kt or
less. Speeds will increase in the afternoon to 10-15 kt with
direction gradually veering to the SW by late afternoon and
evening. Winds become W-WNW overnight 10 kt or less.

Showers with brief MVFR visibilities are possible at KGON
til 15z. A shower/thunderstorm is also possible this afternoon.

   ...NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: Wind direction will likely be variable with
speeds 5 kt or less through 15z. An occasional gust 18-20 kt
possible in the afternoon.

KLGA TAF Comments: Wind direction will likely be variable with
speeds 5 kt or less through 15z. An occasional gust 18-20 kt
possible in the afternoon.

KEWR TAF Comments: Wind direction will likely be variable with
speeds 5 kt or less through 15z.

The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Gusts this afternoon may end up occasional.

KHPN TAF Comments: An occasional gust 16-19 kt possible this
afternoon.

KISP TAF Comments: An occasional gust 16-19 kt possible this
afternoon.

.OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
.Wednesday...VFR.
.Thursday...VFR. Chance of a late day shower/thunderstorm.
.Friday and Saturday...MVFR or lower possible in showers and
thunderstorms.

&&

.MARINE...
Winds and seas are progged to remain blw sca lvls thru Wed.

Sub SCA conditions are expected Wednesday night. Then SCA becomes
more probable Thursday through Friday night for the ocean with seas
reaching between 5-7 ft for much of the time. Wind gusts reach 25-30
kt much of the timeframe as well. Also during Thursday and Thursday
night, higher wind gusts near 25kt will be more widespread for
just about all waters, with hence probable SCA conditions for
all waters. Ocean seas are forecast to linger in SCA range
Saturday with waves near 5 ft particularly east of Fire Island
Inlet. Much of the remainder of the weekend will have sub SCA
conditions forecast.

&&

.HYDROLOGY...
No hydrologic impacts expected through the beginning of next
week.

&&

.EQUIPMENT...
Observations from KFRG (Farmingdale, NY) are not available.
Observations from KHPN (White Plains NY) and KHVN (New Haven CT)
are being disseminated through backup methods. All is due to
an FAA communication line outage. Return to service time is
unknown.

&&

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

&&

$$

SYNOPSIS...JMC/JM
NEAR TERM...DW
SHORT TERM...JMC
LONG TERM...JM
AVIATION...BC/DS
MARINE...JMC/JM
HYDROLOGY...JMC/JM
EQUIPMENT...//



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.