Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 280246
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1046 PM EDT WED JUL 27 2016

.SYNOPSIS...
Weak high pressure overnight will give way to an approaching cold
front Thursday. A wave of low pressure approaches and passes
nearby Friday. This low moves east of the region Friday night.
Weak high pressure briefly builds into the region for Saturday.
Unsettled weather returns for the end of the weekend and start of
next week with the passage of another low pressure system. Drier
weather is expected for Tuesday and Wednesday as high pressure
returns.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Mostly clear conditions remain late tonight with temperatures and
dewpoints still within a few degrees of forecast values. Only
slight adjustments were made to better match observed trends,
notably with dewpoints. These have increased a few degrees along
the coast over the last few hours. The forecast overall remains on
track.

Aloft, the upper trough moves across the upper Great Lakes
region. A surface cold front accompany this features moves well to
the north. Meanwhile, another weak frontal boundary remains to our
south, with a series of weak lows along it.

Weak high pressure remains offshore, and a light south flow
prevails across the region. Dew points increase slightly, and as
temperatures fall overnight under mostly clear skies, patchy fog
formation is possible as boundary layer begins to saturate. Not
quite sure of extent of any fog, but it is possible as hinted at
by the models with their light moisture conveyed in the QPF fields
between 06Z and 12Z.

Lows tonight will range from the lower 60s well inland, to the
middle 70s in NYC metro.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
Through this time period, upper trough axis extending south
across the great lakes region/Ohio Valley and into the upper
Mississippi Valley will move east, with embedded Vorts in the mid
and upper level flow tracking east. Frontal boundary to the south
remains Thursday, as a series of low pressure centers ride along
it, the strongest of which approaches Thursday night and Friday.
Better jet support Friday, and enhanced lift along with abundant
moisture advecting east/northeast will allow for rain/possibly
heavy Friday.

Prior to that, isolated thunder per high resolution models
develops along seabreeze boundary Thursday afternoon. Kept pops
in slight chance range as coverage should be isolated, and this
assumes ample moisture up the column materializes.

One more warm to hot day is expected Thursday, with highs in the
upper 80s to around 90 under partly sunny skies. With higher
humidity levels, heat indices will run a degree or two above
actual air temps.

Temps will remain seasonably warm Thursday night, and not quite as
much of a range is expected as clouds increase, and rain chances
increase.

With the passage of a wave of low pressure, possibly just to our
south, temperatures on Friday will be cooler, upper 70s to around
80 thanks to clouds and rain. This has trended lower than previous
forecast.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Low pressure moving across the region moves east Friday night, with
just some left over showers and possibly a thunderstorm. Weak high
pressure briefly returns on Saturday, with most of the forecast
guidance keeping conditions dry. As a result, will keep conditions
dry on Saturday.

Unsettled weather returns Saturday night into Monday, as another
shortwave and low pressure system moves across the region. Expect
another round of showers and thunderstorms, with some storms
producing locally heavy rainfall.

High pressure builds back into the region early next week, providing
dry conditions.

Temperatures will remain seasonable Saturday through Wednesday with
temperatures climbing into the 80s each day.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Light southerly flow at city terminals tonight with light and
variable winds at outlying terminals. Winds will become southerly
at all terminals on Thursday increase to around 10 kt near the
coast in the afternoon with seabreeze enhancement.

Mainly VFR through the TAF period. There is a low probability of
MVFR/IFR ceilings or visibilities late tonight at coastal
terminals. Preference continues to be for VFR to prevail, but have
tempo MVFR visibility at KGON towards daybreak.

A few showers and thunderstorms possible Thursday
afternoon/evening, mainly NW of the city terminals, but
probability is too low to include in TAFs at this time.

.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.Thursday Night into Friday Night...MVFR or lower possible in
showers and thunderstorms, possibly widespread on Friday.
Patchy Fog.
.Saturday...VFR.
.Saturday Night into Monday...Iso-Sct showers and thunderstorms
possible.

&&

.MARINE...
The forecast remains on track. Conditions will remain below SCA
with a weak pressure gradient in place.

As a weak front approaches, and weak wave of low pressure moves
by Thursday night and Friday, expect sub SCA conditions to
continue across the area waters.

A light pressure gradient over the area waters will result in sub-
sca conditions this weekend and early next week. However, any
thunderstorms that develop on the waters may produce brief SCA
conditions.

&&

.HYDROLOGY...
There is potential for significant rainfall from late Thursday
night into Friday night. Locally heavy rainfall is possible, which
could cause flooding. Exact evolution of this potential storm
remains unclear, so it remains too early for specifics.

&&

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

&&

$$
SYNOPSIS...BC/PW
NEAR TERM...JM/PW
SHORT TERM...PW
LONG TERM...BC
AVIATION...DS
MARINE...BC/JM/PW
HYDROLOGY...BC/PW


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