Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 271029
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
629 AM 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/...
Area of showers has mostly dissipated as it entered our NE NJ
counties so have lowered pops to slight chance. Also made minor
adjustments to hourly temps, dew points, and winds. Otherwise,
the forecast remains on track.

Shortwaves moving through today are progged to be weaker than they
were 24 hours ago. Still, SBCAPEs build to higher levels than
yesterday, and with some lift, have slight chance/chance
showers/tstms in the forecast for the city, adjacent areas, and
points north and west.

High temp forecast will be complicated by the uncertainty of cloud
cover. 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. Models are split regarding timing of the
cloudiest periods, but there are indications that outside of
convection, fewer cloud cover occurs late morning and afternoon
versus the first half of this morning. 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 /12Z FRIDAY THROUGH TUESDAY/...
The area will remain on the western side of the Bermuda High into
tonight.

VFR through the TAF period. Low chance of MVFR haze this morning
outside of city terminals, but potential is decreasing, so have
removed from TAFs with this update. Added VCSH to KTEB early this
morning, however there is uncertainty over whether the shower
holds together before it gets there. This afternoon, isolated-
scattered showers and thunderstorms are possible mainly to the
n/w of NYC...so have VCSH at KSWF/KHPN. Confidence in the
occurrence of a shower/thunderstorm at even these terminals is too
low to reflect explicitly in the TAFs at this time.

     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: End time of light and variable winds could be
off +/- 1-2 hours. Occasional gusts 15-20kt possible with
afternoon seabreeze. Very low chance of afternoon/early evening
shower/thunderstorm.

KLGA TAF Comments: End time of light and variable winds could be
off +/- 1-2 hours. Occasional gusts around 15kt possible with
afternoon seabreeze. Very low chance of afternoon/early evening
shower/thunderstorm.

KEWR TAF Comments: Very Low chance of MVFR haze 9-12z. End time
of light and variable winds could be off +/- 1-2 hours. Occasional
gusts around 15kt possible with afternoon seabreeze. Very low
chance of afternoon/early evening shower/thunderstorm.

KTEB TAF Comments: Very Low chance of MVFR haze 9-12z. End time
of light and variable winds could be off +/- 1-2 hours. Occasional
gusts around 15kt possible with afternoon seabreeze. Low chance of
afternoon/early evening shower/thunderstorm.

KHPN TAF Comments: Very Low chance of MVFR haze 9-12z. End time
of light and variable winds could be off +/- 1-2 hours. Occasional
gusts around 15kt possible with afternoon seabreeze.

KISP TAF Comments: End time of light and variable winds could be
off +/- 1-2 hours. Occasional gusts 15-20kt possible with
afternoon seabreeze.

.OUTLOOK FOR 06Z Saturday through Tuesday...
.Late Friday Night-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.

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 today, 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
SHORT TERM...JC
LONG TERM...DS
AVIATION...Maloit
MARINE...JC/DS
HYDROLOGY...JC/DS


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