454
FXUS61 KOKX 031148
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
748 AM EDT Wed Jul 3 2024
.SYNOPSIS...
High pressure along the coast will gradually work farther
offshore today. A weak frontal system will then approach from
the west tonight into Thursday, stalling over the area Thursday
Night into Friday. A warm front will lift through Friday night,
followed by a cold frontal passage Saturday afternoon and
night. The front will linger over the area and weaken on Sunday
and Monday, then lift back through Monday night into Tuesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
Shortwave upper ridging today flattens tonight, as a shortwave
trough slides east through Quebec and Ontario. At the surface,
high pressure along the coast slides offshore, with a weak
frontal system approaching from the west tonight.
Return flow strengthens today as high pressure moves offshore and
gradient tightens ahead of frontal system well to the west. Fair
conditions (sunshine filtered/partially obscured by high
clouds, particularly in the morning) and moderately strong
hybrid synoptic/seabreeze development expected to push well
inland today. Gusty S/SE winds 20-25 mph likely along the coast
in the afternoon. This will result in increasing humidity
levels and near seasonable temps in the upper 70s/lower 80s
along the coast to mid 80s to the west of the Hudson River.
A weak frontal system approaches tonight, with warm and muggy
conditions in return flow and increasing mid-deck. A few
showers possible N&W of NYC late tonight in response to
approaching front and increasing convectively induced vort
activity in flow aloft.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
General agreement on broad upper troughing across southeastern
Canada slowly retreating northward on Friday, while a closed low
develops over the northern plains and slides east into the
Great Lakes. This will place the region on the southern edge of
an active (convectively induced vorts and enhanced weak
shortwaves) southwesterly upper flow.
At the surface, a weak cold front/pre-frontal trough approaches
on Thursday and then settles over the region Thu Night into
Friday, perhaps dissipating in the vicinity. Seasonably warm and
very humid conditions with continued WAA WSW flow aloft (lower
80s coast to mid to upper 80s NYC metro and areas N&W).
Weak shortwave/vort energy moving through the upper flow may be
trigger for scattered tsra/downpour development in vicinity of
weak pre-frontal trough/cold front to the west and possible
isolated development along well inland moving sea breeze
boundary in a moist and sub-tropical environment (2"+ PWATS)
Thu aft/eve. Considerable mid deck cloud cover, weak
instability (weak mid-level lapse rates and weak capping), weak
deep layer shear, and weak surface convergence point to limited
deep convection potential. With above ingredients though,
scattered heavy downpours still possible, and can`t rule out an
isolated thunderstorm threat (mainly w of the Hudson R Thu
aft/eve) in form of weakening convection sliding eastward from
PA. There is a bit more of a signal compared to 24 hrs ago of a
convectively induced weak shortwave helping to steepen lapse
rates and increase shear to the west of the region, to support
this organized convective potential Thu aft/eve. SPC HREF 3"/3hr
of 10 to 30 percent is currently centered over SE PA into SW
NJ, signaling where the better threat for more widespread and
deeper convection exits. Expecting some clarity on this threat
over the next 24 hrs in NWP and CAMs.
Although thunder threat should wane as any shower activity
slides to the coast Thu eve, scattered heavy downpours threat
exists into 4th of July eve/night events as the weak frontal
boundary stalls across the region and shortwave energy moves
thru aloft. Warm and muggy conditions Thu Night, with potential
for nocturnal stratus/fog development.
Considerable model spread on progression/placement of frontal
boundary on Friday (either passing to the east, stalling overhead,
lifting north as warm front), dependent on Thu Night convective
shortwave strength and progression. First and last scenarios
would likely result in less unsettled, sunnier and very warm and
humid conditions (mid to upper 80s). Meanwhile, if boundary
stalls over the region Friday, expectation would be considerable
cloudiness and scattered diurnal shower/tstm activity in moist
and weakly unstable environment, with temps remaining seasonably
warm (lower to mid 80s). More clarity over the next 24 to 48
hrs.
One more point, the very warm and humid conditions will have
peak heat indices likely running 90 to 95 Thu thru Sat for NE
NJ into portions of LoHud. There is a low potential for heat
advisory issuance at some point during this time period in this
area.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Guidance is coming into clearer focus with the evolution and timing
of systems affecting the area from late this week into early next
week. THe overall pattern will feature a longwave trough to the west
and a Western Atlantic ridge, with well defined disturbances moving
through the flow aloft Fri night and again on Tue. The first of
these will lift a warm front through, which will serve more to
increase dewpoints than bring significant temperature change. This
should get the heat index close to or just over 95 in NE NJ and
maybe in the lower elevations NW of NYC.
A cold front follows for Sat afternoon/evening with chance of tstms.
The front should move into the area and weaken on Sunday, with deep
layer moisture shunted to the south and a dry fcst with lower
dewpoints if not temps for most of Sunday into daytime Mon. PoP
increases to chance late Mon night into Tue AM west of NYC, and then
across most of the area Tue night as the next disturbance and
associated deep layer subtropical moisture arrive.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
VFR as high pressure along the coast gradually works farther
offshore through this evening, and a weak frontal system begins
to approach late tonight. Winds pick up SW 10-15G20kt this
afternoon, then diminish tonight. Some BKN cigs possible late
tonight but still VFR.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled AMD expected.
OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
Thursday: MVFR or lower cond possible with any afternoon or
nighttime showers/tstms. IFR cigs possible late at night at the
Long Island/CT terminals.
Friday and Saturday: MVFR or lower cond possible at times with
continued chance of showers/tstms.
Sunday: 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 --
Southerly flow strengthens today with the high departing to the
east and a weak frontal system approaching from the west.
Marginal SCA gusts possible this aft/eve and Thu aft/eve at
entrance to NY Harbor and western Great South Bay with coastal
jet development. Ocean seas may approaching 5 ft in this area
Thursday.
Better chance of SCA cond Sat afternoon/night on the ocean as
long fetch S flow increases to 15-20 kt, with a few gusts close
to 25 kt. This should builds seas to 5 ft during this time.-- End Changed Discussion --
&&
.HYDROLOGY...
A weak frontal system will approach Thursday and linger into
Friday. Isolated slow moving thunderstorm and heavy downpours
producing 2"/hr rainfall rates are possible Thu aft/eve, mainly
west of the Hudson River. The threat is low and isolated at this
point.
Another slow moving front possible for this weekend. Additional
frontal boundaries will affect the region into early next week.
It is still too soon to determine the risk of any hydrological
impacts from these multiple frontal boundaries affecting the
area late this week into early next week.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a moderate risk for rip current development along local
Atlantic facing beaches today and Thursday with a combo of
building southerly wind wave and 1 to 2 ft E/SE swell.
Rip risk could become locally high for W LI and NYC beaches in
the late aft/eve both days with enhanced seabreeze formation
and large tidal range.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BG/NV
NEAR TERM...NV
SHORT TERM...NV
LONG TERM...BG
AVIATION...BG
MARINE...BG/NV
HYDROLOGY...BG/NV
TIDES/COASTAL FLOODING...NV