190
FXUS61 KOKX 151724
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
124 PM EDT Mon Jul 15 2024
.SYNOPSIS...
A thermal trough will be in place through Tuesday. A cold front
will approach from the west on Wednesday, moving through
Wednesday night into Thursday morning. High pressure will then
follow for late week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Patch of low clouds driven by moisture trapped beneath a sfc-
based temp inversion that was over the NYC metro area this
morning is now moving across Long Island and coastal CT, with
some mid level clouds to the north across interior S CT.
Radar shows shallow convection starting to develop in western
Orange County in line per 12Z NAMNest. SBCAPE ranges from
2000-3000 J/kg, but MLCAPE is only about half that, with some
CIN with fcst soundings showing a weak H8-9 cap. This cap should
erode with further daytime heating, and expect scattered
shower/tstms to progress from Orange across the lower Hudson
Valley and SW CT later this afternoon. Bulk shear values still
appear largely under 30 kt locally. Also a lack of strong
forcing may keep any activity more pop up in nature, with the
marine influence helping weaken activity along the coast. SPC
marginal risk for damaging wind covers areas N of NYC and all
of southern CT. Localized downpours are possible with any
thunderstorm and lead to minor flooding of poor drainage areas.
The clouds around the NYC metro area have held temps back to
the mid 80s so far, but expect them to recover this afternoon,
with another day of hot and humid conditions throughout. H8
temperatures near 20C will allow surface temperatures on a warm
SW flow to climb into the lower/mid 90s for most. With the
humidity though, max heat indices this afternoon likely top out
in the mid to upper 90s for a good portion of the area, and
perhaps into the lower 100s in portions of NYC and urban NE NJ.
Heat Advisory remains in place for all but SE Suffolk and SE New
London, where marine influence limits temperatures a bit.
Values may be more marginal for NE Suffolk, but given the
potential again on Tuesday, felt it was close enough to support
keeping in place for now. That said, there remains a caveat in
these values should any afternoon convection or subsequent
debris hinder temperatures.
Another night with low temps in the urban areas staying well
into the 70s to around 80 in the NYC metro.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Similar conditions expected on Tuesday, perhaps even a tad
warmer, with a chance for afternoon/evening convection once
again.
Guidance consensus continue to prog H85 temperatures at 21 or
22C on Tuesday, and this should yield surface temperatures into
the 90s once again for most areas. Not out of the question some
locales in urban NE NJ touch triple digits. Opted to use a
consensus of short term guidance for dew points rather than the
NBM, which has seemed to underdo mixing and yield Tds several
degrees too high in similar past events this season. Given all
this, heat indices should approach 100F across much of the
region this afternoon absent any convection or associated
debris. While values continue to flirt with excessive heat
warning criteria (105F or greater) in portions of NE NJ,
confidence in coverage is not high enough to warrant a watch at
this time. Certainly, some areas may approach or exceed this
value during peak heating, and conditions will be dangerously
hot regardless.
Yet another mid level wave approaches late Tuesday afternoon, and
CAMs depict varying solutions of scattered convection developing
along with it into the evening, primarily across the interior. Any
potential convective debris clouds would probably occur late enough
to limit any impact on potential high temperatures. This
convection may linger through the evening depending on timing
and placement of the wave, before conditions briefly dry out
overnight into Wednesday morning. Overnight temperatures in the
warmest locales of the NYC metro may not fall below 80 degrees.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Expect another day of high heat and humidity Wednesday as a cold
front approaches from the west. While there is little change in the
airmass ahead of the front, there is some uncertainty with frontal
timing, the onset of showers and thunderstorms, and convective
debris from upstream activity. Models have appeared to slow down the
timing a little from the previous run. Heat indices are generally
forecast to be 95 to 100 for much of the area, but due to those
uncertainties, the heat advisory will not be extended into Wednesday
at this time. Confidence would be higher if a consistent slowing
trend was already established. Also continued to blend in the
CONSALL with NBM dew points to knock them down slightly. NBM
typically has been too high and with winds S/SW, mixing may be
deeper, especially north and west of NYC.
Showers and thunderstorms become likely Wednesday afternoon into
the night with the approach of a cold front, which passes
through the area overnight. A few storms could become strong
and/or severe with some strengthening of the mid level flow and
moderate to potentially high instability. Heavy rainfall also a
good bet with PWATs around 2 inches. There is backing of the upper
flow to the SW as an upper trough approaches, so this will have to
be watched for potential training of the convection.
Chances for showers and thunderstorms will linger into Thursday,
with most of the area clear of any shower threat by mid-afternoon.
There will be a return to more typical high temperatures for this
time of the year, and dewpoints will be in the 60s.
Dry for at least Friday and Saturday with high pressure in control
and highs mostly in the middle and upper 80s. For Sunday, there are
some indications that a trough or weak cold front in association
with a trough aloft could bring a shower or thunderstorm to the
area, but will keep with a dry forecast for the time being as the
best forcing and deeper moisture will be to our north.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
A weak surface trough remains in the vicinity through the TAF
period.
Mainly VFR.
There will be two periods where showers/thunderstorms are
possible. The first will be this afternoon, 18z to 21z.
Confidence in any activity during this time period is low and
have kept the VCSH for NYC and added a TEMPO of TSRA at KSWF.
Given the way the current convection is evolving, the activity
is expected to stay north of NYC. The second period will be
around 02z to 05z this evening with an approaching cluster of
showers/thunderstorms. This cluster will be weakening, but
confidence in thunder is higher during this period and have
added a PROB30 to the TAF.
Winds mostly SW/S, increasing to around 10-15kt today. Winds
lower to about 5-10kt overnight and then increase again to
10-15kt Tuesday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Occasional gusts to 20kt possible.
Low confidence in TSTM occurrence this afternoon, but higher
confidence late this evening and early tonight, with timing
possibly off by 1-2 hours.
OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday Afternoon: Mainly VFR. A chance of evening showers and
thunderstorms and MVFR, mainly from NYC metro on NW. SW wind
gusts 15-20 kt afternoon into early evening.
Wednesday: VFR to start. MVFR or lower in showers and thunderstorms
late afternoon into the evening, with a chance of showers and
thunderstorms late at night.
Thursday: Mainly VFR. Chance of showers and thunderstorms.
Friday and Saturday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Sub SCA conditions largely prevail on all waters through
Tuesday.
A period of SCA conditions is possible, mainly on the ocean,
Tuesday night into Wednesday night with increased southerly flow
ahead of an approaching cold front. Ocean seas may linger at or
above 5 ft Thursday before subsiding. High pressure builds in
for the end of the week with sub SCA conditions.
&&
.HYDROLOGY...
With a humid air mass in place, any thunderstorms that develop
over the next several days will have the potential to produce
localized downpours. The risk of hydrologic impacts is limited
to the local scale, mainly for urban and poor drainage locations
through midweek.
&&
.TIDES/COASTAL FLOODING...
There is a moderate rip current risk on the ocean beaches
Monday and Tuesday due to 3-4 ft S swell 6-8s and S winds 10-15
kt. RCMOS and NWPS are generally in good agreement.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...Heat Advisory until 10 PM EDT Tuesday for CTZ005>011.
NY...Heat Advisory until 10 PM EDT Tuesday for NYZ067>075-078>080-
176>179.
NJ...Heat Advisory until 10 PM EDT Tuesday for NJZ002-004-006-
103>108.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...JC/BG/DR
NEAR TERM...BG/DR
SHORT TERM...DR
LONG TERM...JC
AVIATION...JT
MARINE...JC/BG/DR
HYDROLOGY...JC/BG/DR
TIDES/COASTAL FLOODING...