743
FXUS61 KOKX 081633
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1233 PM EDT Thu Aug 8 2024
.SYNOPSIS...
A stationary front across the Mid Atlantic today will begin to
lift north as a warm front, passing through the waters Friday
morning. Tropical storm Debby is forecast to weaken into a
depression and pass well west of the waters Friday night as it
interacts with an approaching frontal system. The associated cold
front will likely pass through the area Friday night into early
Saturday morning. Broad low pressure then remains north of the
area, with a few surface troughs/weak cold frontal passages
though the middle of next week.
Please refer to the latest official forecast on Debby from the
National Hurricane Center.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
No significant changes at this time.
A band of showers continues to move northward through the lower
Hudson Valley and western Long Island, into southwestern
Connecticut at midday. And, additional showers remain possible
through tonight.
A strengthening subtrop ridge over the western Atlantic and a
digging upper low across the Upper Midwest into the Great Lakes
will help to funnel Tropical Storm Debby northward across inland
areas of the Carolinas. This will also force a stationary front
over the Mid Atlantic states northward later today, approaching
the area by daybreak Friday. This will keep the area in
generally weak warm advection with increasing chances of
showers. Airmass destabilizes late tonight as the warm front
approaches with some embedded thunderstorms possible after
midnight. The best chance will be from NYC and points north and
west. Any rainfall today into the first half of the night will
generally be light and scattered in nature. However, the
tropical nature of the airmass and efficient warm precip
processes could produce brief downpours especially late tonight
into Friday morning.
Cloud cover, easterly flow, and showers will result in another
day of small diurnals between morning lows and daytime highs.
Highs today are forecast to be in the upper 60s to lower 70s, 10
to 13 degrees below normal. Lows tonight will generally only
drop a few degrees. In addition, east winds will gradually veer
to the SE tonight with the airmass becoming increasingly humid
with dew points getting into the 70s for much of the area.-- End Changed Discussion --
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
The aforementioned upper low will be just north of the Great
Lakes on Friday, gradually working east and sending a strong
cold front toward the area. Debby by this time is forecast to be
a depression tracking north along the spine of the central
Appalachians. The system will interact with the approaching cold
front producing a band of heavy rain producing showers and
thunderstorms. The band will likely not enter areas north and
west of NYC until late afternoon or early evening Friday. Prior
to that time, warm advection showers/embedded thunderstorms will
lift across the area during the morning hours, most numerous
north and west of the NYC metro. Much of the area could then see
a prolonged dry period, especially from NYC and points east.
The heavy band of rain will then work east during the nighttime
hours. Trends the last couple of days have been for a faster
system with less rainfall for the forecast area. Rainfall
amounts from this morning into Saturday morning are forecast to
be between 1 and 2 inches, highest across inland areas due to a
strengthening southerly and enhanced orographic lift. Localized
higher amounts are likely with PWATs approaching 2.50". This
would break the daily max and approach the all-time high of
2.62" for the upper air site at OKX. The latter of which was set
August 19, 1955 when TS Dianne passed near the area. WPC has
the eastern half of the area under a marginal risk for excessive
rainfall, and the western half a slight risk. Thus, isolated to
scattered instances of flash flooding are expected across the
area.
In addition, a strong SE flow behind the front and a
strengthening vertical wind profile show large hodographs across
the area with helicity values above 250. Upper air sounding
profiles show a skinny CAPE, supporting slow rising updrafts for
heavy rainfall and a localized tornado threat. Winds will
likely gust up to 40 mph, highest across the south shore of LI
Friday afternoon and night. The cold front works passes east of
the area Saturday morning with drying conditions and
temperatures getting into the lower and middle 80s under a
westerly flow.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A dry period is expected in the long term, with temperatures
right around or below normal and plenty of sun. An upper level
trough lingers over the eastern US, while a broad surface low
remains well to our northeast. A few surface troughs or weak
cold frontal passages are possible through the middle of next
week. The current pattern will hold tropical air south of the
area, with dewpoints expected to be in the upper 50s to low 60s
for most the long term. With low moisture and weak lift, any of
the surface trough/weak cold frontal passages are expected to be
dry.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
A stalled front will remain south of the area, pushing
northward tonight into Friday.
IFR to MVFR cigs with all terminals becoming IFR, except KSWF
and KGON which will likely be in the afternoon. Showers expected
much of the TAF period, becoming a bit more widespread. There
could be some embedded isolated thunderstorms late tonight into
early Friday morning. Confidence is too low to include in the
TAF at this time.
Winds will be out of the E/NE through the TAF period, speeds less
than 10 knots early this morning become 10 to 15 knots today.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of category changes may be off by a few hours.
Occasional gusts up to 20 kt possible this afternoon.
Embedded isolated thunderstorms possible late tonight into early
Friday morning.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday through Saturday morning: MVFR/IFR in TSRA. SE gust
25-30kt possible. LLWS likely for a brief period late Friday into
Friday night.
Saturday Afternoon through Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
-- Changed Discussion --
Marginal small craft conditions have developed on the ocean
waters, and will continue into tonight and Friday morning. Have
issued a Small Craft Advisory from current time to 18Z Friday,
with the start of the Gale Watch.
As Post Tropical Cyclone Debby passes to our west, southerly
winds will be on the increase with the potential for gale force
gusts developing on the ocean waters and the Great South Bay
Friday afternoon. Thus, a gale watch is in effect for Friday
afternoon and night. Elsewhere, a SCA is in effect with
occasional gale force gusts still possible. Seas on the ocean
could build to 8 to 11 feet by Friday night. Winds and seas will
then subside on Saturday behind a cold front with a westerly
flow.
SCA conditions could linger on the ocean Saturday night with 5 ft
seas. Sunday through the rest of the forecast, conditions will
likely be below SCA with a weak pressure gradient over the area.
Please refer to the latest official forecast on Debby from the
National Hurricane Center.-- End Changed Discussion --
&&
.HYDROLOGY...
Isolated to scattered flash flooding will be possible Friday
into Saturday morning, with the overall more likely period for
impacts being late Friday afternoon through Friday night.
Rainfall rates of mostly 1-2 inches per hour will be possible
during this time. Both river/stream flooding and urban/poor
drainage flooding will be possible given antecedent
rains/saturated grounds. The overall higher chances for flooding
will be across NE NJ, NYC, and the Lower Hudson Valley into
western CT where WPC maintains a slight risk of flash flooding.
There are no hydrologic concerns Saturday night through the middle
of next week with dry conditions expected.
&&
.TIDES/COASTAL FLOODING...
A moderate risk for rip current development is expected today,
increasing to a high risk on Friday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...High Risk for Rip Currents from Friday morning through Friday
evening for NYZ075-080-081-178-179.
NJ...None.
MARINE...Small Craft Advisory from 11 AM Friday to 6 AM EDT Saturday
for ANZ331-332-335-338-340.
Gale Watch from Friday afternoon through late Friday night for
ANZ345-350-353-355.
Small Craft Advisory until 2 PM EDT Friday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...JT/DW
NEAR TERM...MET/DW
SHORT TERM...DW
LONG TERM...JT
AVIATION...IRD
MARINE...MET/JT/DW
HYDROLOGY...JT/DW
TIDES/COASTAL FLOODING...