725
FXUS61 KOKX 201633
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1233 PM EDT Mon May 20 2024

.SYNOPSIS...
High pressure across the area will gradually slide east through
the middle of the week, while a frontal system lifts across the
Plains and into the Great Lakes Tuesday into Wednesday. A cold
front approaches Thursday, and moves through the area Thursday
night. Weak high pressure returns for Friday into Friday night.
Another frontal system may affect the area late next weekend.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --
Forecast is mostly on track. Mostly sunny with some cu
development this afternoon, mainly north and west of NYC and
along sea breezes. It will be seasonably warm today as a high
amplitude upper level ridge moves into the area. At the surface,
high pressure across the Northeast and Mid Atlantic will
gradually slide east. This will result in a light SE flow
developing this afternoon.

For highs, used a blend of the NBM deterministic and NBM 50th
percentile. While there will be a marine influence with weak
onshore flow developing, temperatures have overachieved by
several degrees the last couple of days. This blend keeps
temperatures closer to the warmer GFS and ECS MOS. Lows tonight
will in the 50s, very close to normal.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
The warm ridge aloft across the area will gradually work
offshore through the middle of the week. A storm system emerging
from the Plains on Tuesday lifts NE into the upper Midwest and
and western Great Lakes Tuesday night and then north of the
Great Lakes on Wednesday. The trailing cold front progresses
east into the Ohio Valley. Ahead of the system, temperatures
will steadily warm through the period, with highs getting well
into the 80s by Wednesday, with even 90 possible in some spots.
Coastal areas while cooler due to a marine influence should be
able to heat up fairly quickly in the morning before a SW flow
backs more to the S. Due to subsidence, the airmass is pretty
dry, another factor for a strong warmup. Once again, like in
the near term, took a blend of the NBM deterministic with the
warmer 50th percentile. This produces highs 10 to 15 above
normal and lows 5 to 8 degrees above normal. Heat indices
Wednesday afternoon are close to the ambient temperatures and
below Heat Advisory criteria.

Any convection during this time is forecast to stay north and
west of the area. However, there is moderate to high instability
to the north and west of NYC Wednesday afternoon, but no notable
lifting mechanism and a high LFC. SPC Day 3 outlook does show
the potential across that area for general thunderstorms.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Some key points during this timeframe:

* Well above normal temperatures continue for Thursday albeit a
  couple degrees cooler than Wednesday.

* Chance of thunderstorms Thursday into Thursday night, possibly
  strong to severe across parts of the interior.

High pressure off the East Coast continues to push east Wednesday
night into Thursday, while a cold front slowly approaches from the
west. Aloft, a ridge axis will push off the East Coast, allowing for
heights to fall Thursday.

Although a couple of degrees cooler than Wednesday, thanks to an
increase in clouds, high temperatures on Thursday are expected to be
in the upper 70s to mid 80s range.

There will be a chance for showers and thunderstorms out ahead and
along the cold front for Thursday into Thursday night. The cold
front is forecast to move across Thursday night. Chances for showers
and thunderstorms decrease late Thursday night after the cold
frontal passage.

There is potential for some thunderstorms to be strong to severe
with the cold front as surface CAPE values look to be up to near
1000-1700 J/kg and forecast 0-6 km AGL bulk shear of 35 to 45 kt.
The best chances for strong to sever storms will be across locations
north and west of NYC where temperatures will be relatively warmer.
No hydrologic concerns at this time as showers and thunderstorms
will be fast moving, really limiting total rainfall accumulations.

Dry conditions are forecast Friday through Friday night with the
return of weak high pressure. High temperatures on Friday will be
cooler than Thursday, but still above normal, ranging from the
middle 70s to lower 80s for much of the region.

There is a fair amount of uncertainty for next weekend. The ECMWF
has a weak low passing to our south, while the GFS holds off any
precipitation until the next frontal system next Sunday thanks to
high pressure more centered over the Northeast and a bit stronger as
compared to the ECMWF. The Canadian is similar to the GFS. Did not
want to completely discount the ECMWF just yet, and even if it does
impact the region, it looks to be just light rain showers. So, given
uncertainty, stuck close to the NBM this far out.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Weak surface high pressure remains over the area through tonight.

Stratus started to burn off across the NYC metro area allowing
for VFR conditions. It should remain VFR through the TAF
period. There is the potential for MVFR cigs to move back in
tonight, but the signal for this is not as strong with the
guidance and so only went as low as low end VFR (BKN035) and
SCT020 to show the MVFR potential tonight. KGON is the only
terminal with enough confidence to prevail MVFR conditions
tonight.

Sea breezes late this morning into the early afternoon,
shifting winds SE-S near 10 kt. Winds become light and variable
for outlying terminals.

   NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Uncertainty with how far west MVFR cigs will go tonight.


OUTLOOK FOR 15Z TUESDAY THROUGH FRIDAY...

Tuesday-Wednesday: VFR. Chc S-SW gusts around 20kt both
afternoons.

Thursday: VFR in the morning, then a chance of afternoon and evening
MVFR with showers and thunderstorms. Chc SW gusts around 20kt.

Friday: VFR. Chc NW gusts around 20kt.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

&&

.MARINE...
Sub-advisory conditions are expected across all waters through
the end of next week. However, Tuesday and Wednesday afternoons
are likely to see a coastal jet produce gusts up to 20 kt and
seas of 3 to 4 ft in the NY Bight. Seas may also briefly touch
5 ft on the ocean waters Thursday night just ahead of the cold
front.

&&

.HYDROLOGY...
There are no hydrologic concerns through the upcoming week.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

SYNOPSIS...JP/DW
NEAR TERM...JC/DW
SHORT TERM...DW
LONG TERM...JP
AVIATION...20/JP
MARINE...JP/DW
HYDROLOGY...JP/DW