306
FXUS61 KOKX 271951
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
351 PM EDT Tue Aug 27 2024
.SYNOPSIS...
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High pressure moves offshore tonight with a cold front sliding
through on Wednesday. High pressure will then build down from the
north Thursday into Friday. A frontal system will affect the area
for the weekend, with Canadian high pressure building in for
early next week.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH WEDNESDAY/...
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High pressure does get further offshore through tonight. After a
clear start, clouds are predicted via NWP to get into the region
later at night, especially for the western half of the area. Have
chosen to go with slight chance PoPs despite the fact that CAMs not
really showing much tonight, although there appears to be an
elevated weak boundary which could very well fire up a few showers
later at night into early Wednesday morning. In any event, the night
is expected to be primarily dry. It will be humid though and
seasonably warm with not much of a temperature spread across the
region with dew point readings in the upper half of the 60s on a
light S to SW synoptic flow. Night time lows are expected to range
from the upper half of the 60s to the lower 70s.
For Wednesday things have changed from previous forecast cycles. The
CAMs do not look nearly as impressive with respect to shower and
convective activity. After looking at various forecast cycles there
is a warm layer at 5 to 12 kft which assists in capping things some.
It will take more effort to get parcels to the level of free
convection (LFC). Thus the CAMS are hinting at reflectivity but have
difficulty in getting any meaningful convection to fire across the
CWA. One could argue that the NSSL, and NAM make the best attempt,
and perhaps the HRRR as well. The HRRR on most of its recent runs
has suggested that convection gets going just south of the CWA.
After collaboration with SPC, the region is now in mainly a marginal
risk of severe weather on Wednesday, with is a downgrade previously
from a slight risk. If a couple of storms do form, they will be
capable of some strong gusty winds, but this looks like a low
likelihood relatively speaking from earlier.
Regarding temperatures on Wednesday the cold front appears to be
getting a bit more of a quicker push to the SE. The upper level
disturbance also appears to get sheared in the guidance. Thus there
appears to be more of a westerly component to the flow towards later
morning into the early afternoon. This would serve to mix out things
a bit more and lead to slightly lower dew point readings. Heat
indices will likely range from the mid to upper 90s, and technically
this is a tad below heat advisory criteria (the one day criteria).
But it appears to be close enough to at least leave the heat
advisory up for now and continue it for the same zones that were
issued previously. In any event, it is going to be hot and humid so
keeping with the same messaging in products.-- End Changed Discussion --
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
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For Wednesday night the flow quickly goes northerly during the late
evening, and then northeast after 6z. Dew point readings drop into
the middle and upper 50s up north, and the lower and middle 60s
elsewhere, thus it begins to feel more comfortable going into
Thursday morning with low temperatures primarily getting through the
60s.
A few showers post frontal may attempt to get into western sections
periodically late Wednesday night and during Thursday. The lower
levels dry out quite a lot, but cannot rule out a few sprinkles of a
quick shower mainly for western sections during this timeframe.
Otherwise expect partly to variably cloudy skies and much more
comfortable conditions with temperatures likely getting to about 5
degrees below average for the day Thursday. Daytime highs will
be in the middle and upper 70s for the most part.-- End Changed Discussion --
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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Good model agreement in weak shortwave troughing over the northeast
US moving east Thu Night into Friday, with shortwave upper ridging
briefly building in Friday into Fri Night. Rest of forecast period
will be influenced by an expanding central Canadian trough, centered
around closed upper low spinning through northern Ontario/Quebec
Friday thru Monday. Troughing will amplify across the NE Sat thru
Mon as a couple of shortwave troughs slide through the region. Model
spread in shortwave timing increases a bit towards the end of the
period, but overall fairly good agreement.
At the surface, Canadian high pressure centered over northern New
England Thu Night, gradually slides east through Friday Night. The
result will be a maritime Canadian airmass advecting into the region
on persistent ENE flow. Onshore flow under subsidence/waa inversion
aloft may result in stratus development and a few showers
particularly across western areas into Friday morning, before deep
layered ridging strengthens. Temps will run slightly below
seasonable.
Weak lead shortwave approaches Sat and crosses Sat night with
associated pre-frontal trough approaching Sat aft/eve, and crossing
Sat Night. Good moisture advection and warm rain process ahead of
the trough (PWATS +2 std), with weak/elevated instability. Combined
with strengthening synoptic lift, this should present the potential
for scattered to numerous showers and isolated tstm threat late
Sat/Sat eve, translating east Sat night. Temps moderating to near
seasonable on Saturday with increase humidity levels.
Main upper trough axis approaches Sun/Sun Night, with pre-frontal
trough sliding east and cold front approaching. Potential for
isolated to scattered showers/thunderstorm activity, but
considerable cloud cover and best moisture/llj axis potentially
moving east, could mute activity. Temps slightly above seasonable
with Tds in upper 60s/lower 70s.
Trough axis slides overhead Monday and east Monday Night, with cold
front passing east Sunday Night into Monday morning. Drying
conditions Monday on NW flow as Canadian high pressure builds from
the NW. Sct-bkn instability cu and a few showers possible,
particularly across interior Mon aft. Temps nears seasonable.-- End Changed Discussion --
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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VFR with high pressure in control through this evening. A cold front
begins approaching tonight and moves across the area on Wednesday.
S-SE winds around 10 kt or less for most sites through early this
evening. Some interior sites may remain VRB into the evening. Winds
briefly diminish this evening before gradually increasing and
becoming SW towards day break Wednesday. SW winds around 10 kt are
expected in the morning, but will veer to the W and then NW into the
afternoon. NW winds 10-15 kt with gusts up to 20 kt expected in the
afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of wind shift to the S-SE may be off by 1-2 hours at KLGA,
KEWR, and KTEB this afternoon.
A shower is possible Wednesday morning. There is also a low
probability of a shower/thunderstorm Wednesday evening, but
confidence is too low to include in TAF at this time.
OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday PM: VFR. NW wind gusts 15-20 kt. Low probability of a
shower/thunderstorm.
Thursday: Mainly VFR. Slight chance of an afternoon/evening
showers/thunderstorm north and west of the NYC terminals.
Friday: VFR.
Saturday: Chance of showers, possible thunderstorms and MVFR or
lower.
Sunday: Mainly VFR. Chance of a shower/thunderstorm, mainly in the
afternoon and evening.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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A SW flow prevails through tonight with ocean seas up to 3 ft. Ocean
seas nudge up a bit closer to 4 ft for the eastern ocean by
Wednesday afternoon with a cold front approaching and moving through
the waters later in the day. There may be a brief period of small
craft gusts Wednesday afternoon for the eastern most ocean water s.
The winds do switch to the W on Wednesday, then quickly to the NW,
N, and NE through Wednesday night. By early Thursday morning a
period of marginal small craft wind gusts are possible for the
southern near shore and ocean waters via a tightening NE flow. Small
craft, or at least marginal small craft conditions will remain
possible for the ocean waters through much of the day Thursday with
gusts mainly 18 to 25 kt and mainly 4 ft seas.
Marginal SCA seas likely on the ocean Thursday night with 15g20kt
E/NE winds flow. Winds and seas gradually subside on Friday, with a
weak pressure gradient keeping all waters below SCA criteria Friday
night this weekend.-- End Changed Discussion --
&&
.HYDROLOGY...
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No hydrological impacts are anticipated during Wednesday with any
storms that do form being widely scattered to isolated, and will
also move along quickly. Any hydro impacts towards the weekend
towards Saturday appear minimal at this time.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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There is a moderate risk of rip currents on Wednesday as southerly
winds wave build to 3 ft, combined with a lingering 1 ft se swell.
High rip/longshore current risk (high rip current risk especially
along jetties and groins) Thursday as easterly winds waves build to
4 to 6 ft.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NYZ069>075-
176>178.
NJ...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NJZ004-006-
103>108.
MARINE...None.
&&
$$
SYNOPSIS...JE/NV
NEAR TERM...JE
SHORT TERM...JE
LONG TERM...NV
AVIATION...DS
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...