Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 271827
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
227 PM EDT FRI MAY 27 2016

.SYNOPSIS...
Bermuda High pressure will remain across the region through the
weekend. A cold front will pass through the area Monday into
Tuesday. High pressure returns for the middle of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Convection has fired well nw. Will need to keep an eye on western
zones, west of the Hudson, for possible shower and thunderstorm
development early. HRRR continues to develop convection, along
the seabreeze boundary. Will seabreeze boundary be enough to
break the cap. With increasing cape as the afternoon progresses,
coverage increases warranting chance pops.

The forecast remains on track.

Shortwaves moving through today are progged to be weaker than they
were 24 hours ago. No changes to temps at this time. 850 mb temps
and sea breeze progress should be close to those of yesterday, but
yesterday featured a mostly sunny sky for most of the day for most
locations. Will forecast high temps lower than what occurred
yesterday. Looks like clouds will be more numerous and more opaque
this time around. Have gone above a guidance blend for high
temps, especially across Long Island where guidance has been too
low during the past couple of days.

There is a moderate risk of rip current development at the Atlantic
beaches Today into this evening.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
An evening shower/thunderstorm is possible northwest of the city,
then with the loss of instability and only weak lift, dry
overnight.

For Saturday, still no significant source of lift outside of weak
mid level shortwaves, but SBCAPEs will be building once again away
from sea breezes. Again, will go with only slight chance to
chance pops, focused more toward the afternoon and away from areas
cooled by sea breezes.

Highs on Saturday should be warmer than on Friday with warmer temps
at the top of the mixed layer, and probably less cloud cover
overall. Again, needed to adjust a guidance blend upward to account
for the low bias as of late, especially over Long Island.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Deep middle and upper level ridging over the Tri-State will continue
for the remainder of the weekend with Bermuda high pressure at the
surface. Any isolated or scattered convection that develops Sat
afternoon north and west of the city will quickly dissipate after
sunset as there is not much support other than from daytime heating.
A backdoor front may approach from the north Sunday morning, but
models seem to have come more in line with the boundary staying
north of the area. This makes sense given the strong ridging aloft
and generally weak surface flow. The front likely retreats northward
Sunday afternoon and may act as a focus for some scattered
showers/storms, so will show low chance pops for the northern
interior which will be closest to the boundary.
Sundays high temperatures will be in the upper 80s to possibly near
90 in NE NJ. A stronger southerly flow closer to the coast should
hold temperatures down a bit with highs closer to 80 degrees.

The ridge breaks down and shifts into the western Atlantic Sunday
night as a shortwave and its associated cold front approaches from
the west. Increasing SW flow aloft will advect in much deeper
moisture over the region. Models indicate precipitable waters
approaching 2 inches by Monday morning as a plume of tropical
moisture surges northward ahead of a tropical disturbance near the
SE coast. These values are close to the maximum observed
precipitable water for May 30 per SPC Sounding Climatology. The
shortwave trough should push the deepest moisture and best lift east
of the area by Monday evening. Have adjusted pops with this forecast
package to show an increasing trend Sunday night with likely pop
across the entire area on Monday morning. Pops trend down through
the afternoon. Models on occasion can break down ridges too quickly,
so it is possible that this timing will be adjusted in future
forecasts. Instability looks marginal at this time so will only
include slight chance thunder wording in the forecast. Locally heavy
rainfall is possible with any shower/storm due to the high moisture
content of this air mass. Temperatures will be much cooler on
Monday and closer to seasonal norms due to clouds and
precipitation.

The cold front looks to be much slower and may not fully move
through the area until Tuesday. With best moisture well offshore,
have trended to a dry one overnight Monday into Tuesday. High
pressure then builds into the region as ridging rebuilds aloft.
There are differences between the GFS and ECMWF with its placement
of the ridge axis and therefore its surface high. These differences
also exist in their ensemble systems so have leaned close to model
consensus for Wednesday and Thursday. Above normal temperatures
forecast on Tuesday and the temperatures should return closer to
seasonal norms Wednesday and Thursday.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The area will remain on the western side of the Bermuda High into
Saturday with a thermal trough across then interior each
afternoon.

Convection was developing along the NJ coast in the vicinity of
the seabreeze front. This will likely have impacts to the gates to
the west and southwest of the NYC terminals this afternoon into
early this evening. Confidence remains low on thunderstorms at the
NYC terminals as well as KISP and KBDR due to the airmass forecast
to stabilize over the next few hours. However, based on latest
radar imagery will mention VCSH. Highest confidence is at KSWF.

VFR outside of any convection. MVFR fog/haze possible - probable
outside of NYC/Long Island terminals tonight.

South winds around 10 kt today with local seabreeze enhancements.
Easterly winds across LI Sound will influence KBDR through part of
this afternoon. There is some uncertainty with the timing of the
winds veering back to the south. Winds become SW at under 10kt
this evening and then gradually increase back to around 10 kt Sat
morning.

     NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: Occasional gusts 15-20kt possible with
afternoon seabreeze. Low chance of afternoon/early evening
shower/thunderstorm.

KLGA TAF Comments: Occasional gusts 15-20kt possible with
afternoon seabreeze. Low chance of afternoon/early evening
shower/thunderstorm.

KEWR TAF Comments: Occasional gusts around 15-20kt possible with
afternoon seabreeze. Low chance of afternoon/early evening
shower/thunderstorm.

KTEB TAF Comments: Occasional gusts around 15-20kt possible with
afternoon seabreeze. Low chance of afternoon/early evening
shower/thunderstorm.

KHPN TAF Comments: Low chance of afternoon/early evening
shower/thunderstorm.

KISP TAF Comments: Occasional gusts 15-20kt possible with
afternoon seabreeze.

.OUTLOOK FOR 18Z Saturday through Wednesday...
.Saturday afternoon-Sunday...Mainly VFR with afternoon
seabreezes. There is a chance of MVFR or lower in any isolated to
scattered afternoon/evening showers/thunderstorms; mainly to the
n/w of NYC.
.Sunday night-Monday...MVFR or lower probable with showers and
thunderstorms.
.Monday night-Tuesday...Becoming VFR Monday night. Seabreezes
likely Tuesday afternoon.

&&

.MARINE...
The western periphery of Bermuda high pressure remains across the
waters through Saturday. Winds and seas are expected to remain below
small craft levels during this period, however, late this afternoon
into early evening there could be occasional gusts to 25 kt over
the ocean waters west of Fire Island Inlet. Will also be watching
seas as they build close to 5 feet across the outer waters.

A weak pressure gradient across the waters will keep winds and seas
below sca levels Saturday night through Tuesday.

&&

.HYDROLOGY...
Isolated to scattered thunderstorms are possible mostly for the
inland areas this afternoon, this evening, and Saturday
afternoon. However, no significant widespread precipitation is
expected through the weekend.

Rainfall amounts around one half to three quarters of an inch are
possible on Monday with locally higher amounts. Localized urban
or poor drainage flooding is possible from the heaviest rain.

&&

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

&&

$$
SYNOPSIS...JC/DS
NEAR TERM...JC/DS/PW
SHORT TERM...JC
LONG TERM...DS
AVIATION...DW
MARINE...JC/DS/PW
HYDROLOGY...JC/DS


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