665
FXUS61 KOKX 011759
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
159 PM EDT Thu May 1 2025
.SYNOPSIS...
High pressure will shift off the New England coast this
afternoon. A warm front will then approach tonight and lifts
through early Friday morning. A cold front will then slowly
approach Saturday into Saturday night, with a wave of low
pressure developing along it. This frontal system will linger
near the area through early next week, as a cutoff upper low
develops to the southwest.
&&
.NEAR TERM /THROUGH TONIGHT/...
Upper ridge axis shifts to the east later this afternoon into
this evening as surface high pressure drifts off Cape Cod.
Dry conditions expected thru the day. Winds veer SE into the
afternoon as the high moves offshore, and the resultant onshore flow
limits temperatures along the coast with SSTs still in the lower
50s. Highs there top out in the upper 50s to middle 60s, with
lower 70s expected away from the marine influence in the LoHud
Valley and NE NJ.
As the high shifts farther east tonight, low pressure tracks
into the Great Lakes with the associated warm front approaching
the local region. This introduces increased cloud cover, along
with the chance for showers late tonight into Friday morning.
Can`t rule out a spotty thunderstorm with this activity either
with some elevated instability evident in some BUFKIT forecast
soundings, but coverage overall appears limited, and some
locales may not see precipitation. The front lifts through
toward daybreak, and could see areas of fog break out in its
wake into Friday morning as the shower activity exits.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A more active pattern looks to develop in this period, with an
increasing likelihood of unsettled conditions persisting thru at
least early next week.
Behind the warm fropa early Fri AM, a much warmer air mass advects
in on deep SW flow. Any fog around in the morning burns off and S/SW
flow and deep mixing allow temps west of the Hudson to rise into the
80s, or a good 15 degrees above climo for early May, while coastal
areas remain in the 60s to around 70.
As the East Coast ridging shifts farther offshore, several northern
stream shortwaves dig a trough from the Canadian Plains into the
Mississippi River Valley Friday into Saturday. The pre-frontal
trough approaches western portions of the area Friday aft/eve,
bringing the potential for scattered showers and thunderstorms,
mainly for NYC and points N&W in a weakly forced, but marginally
unstable/modest shear environment. A more stable airmass along the
coast will likely have any convection dissipating as it overspreads
the coast and encounters this environment. Conversely, could be
dealing with stratus/fog development for southern and eastern
coastal areas late Friday into Sat with moist onshore flow over cold
waters (lower 50 SSTs). CSU MLP still indicates a marginal severe
threat, which seems conditionally possible.
Perhaps a better chance for organization of scattered shower and
thunderstorm activity ahead of the approaching cold front Saturday
afternoon and evening for NYC and points NW once again with approach
of northern shortwave in a marginally unstable and strong deep layer
shear environment. Although airmass is similar on Friday to
Saturday, potential for more in the way of convective debris on
Saturday limiting full insolation.
Better agreement amongst global guidance relative to this time
yesterday, with most ensemble members now signaling a cutoff low
closes off to the SW of the region this weekend thru early next
week as an omega blocking pattern develops across the Eastern
US into Western Atlantic. The result being the aforementioned
cold front stalling to the west of the region and strong
Canadian maritime high to the NE leading to a persistent Atlantic
subtropical moisture flow into next week.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The combo of a cutoff upper low developing over the Ohio Valley and
an amplifying upper high over the western Atlantic will be the main
drivers of sensible wx for the area. A feed of subtropical Atlantic
moisture into the area between these two systems will keep us
unsettled through the period and offer the likelihood of some
periods of heavier showers, whose exact timing and rainfall amts are
still uncertain. Latest guidance suggests best time frames for
heavier rainfall may be Sunday night into Mon morning and more so
Tue into Tue night. Latest ECMWF ensemble is focusing in more on
Tue, showing higher probabilities of 1-2 inches in 24 hours in that
time frame, and 90th percentile QPF of over 3 inches.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
High pressure north of the area will move off the coast this
afternoon. A warm front then approaches tonight, lifting north
of the terminals Friday morning.
VFR conditions will prevail into this evening before conditions
deteriorate with the approach of the warm front. MVFR conditions
are expected to develop around midnight at the NYC metro
terminals, followed by IFR after 06Z and LIFR possible towards
daybreak at some locations. Scattered showers are also possible
overnight ahead of the approaching front, along with an isolated
thunderstorm. VFR conditions will return between 12-15Z at the
metro terminals as the warm front pushes north.
SE winds around 10 kt will continue through this afternoon.
Winds then diminish to around 5 kt overnight before returning
out of the S after the warm frontal passage Friday morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of both the deterioration to sub-VFR conditions overnight
and improvement back to VFR Friday morning could be off by 1-2
hours.
.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
Friday: VFR. Showers/tstms possible in the afternoon and at
night. S winds G15-20kt in the afternoon.
Saturday: MVFR or lower cond possible with chance of
showers/tstms. S winds G15-20kt.
Sunday: MVFR or lower cond possible with chance of showers/tstms.
Monday: MVFR or lower cond possible with chance of showers/tstms.
E-NE winds G20-25kt.
Tuesday: MVFR or lower cond possible with chance of
showers/tstms. S winds G15-20kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds and seas remain low through tonight with high pressure
in close proximity to the coastal waters.
Marginal S/SW SCA gusts possible on the ocean Fri aft/eve and then
once again Sat aft/eve with approach of cold front. More confidence
in ocean seas building to 5 ft during this time, lingering into
Sunday morning based on persistent S/SW flow.
Increasing E flow on Mon may bring minimal SCA cond to the
ocean waters, with E winds gusting to 20-25 kt and seas building
to 5 ft.
&&
.FIRE WEATHER...
SE flow at 5 to 12 mph develops into this afternoon. RH values
get as low as 25-35%, increasing above 40 percent along the
coast later this afternoon with strengthening onshore flow.
An SPS for elevated risk of fire spread has been issued for NE
NJ zones where it will take longer for RH to rise with more of a
delay in the onshore flow. Wetting rains are possible late
tonight into Friday.
&&
.HYDROLOGY...
There is potential for heavy rain of over 2 inches next week in
the Sunday night-Tue night time frame. Exact timing/duration of
any heavier periods of rain and exact amounts/impacts remain
uncertain.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BG/DR
NEAR TERM...JE/DR
SHORT TERM...DR
LONG TERM...BG
AVIATION...FEB
MARINE...BG/DR
FIRE WEATHER...
HYDROLOGY...BG/DR