Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 250612
Area Forecast Discussion
National Weather Service New York NY
212 AM EDT THU AUG 25 2016
High pressure will remain to the south through Thursday.
A weakening front will approach Thursday night, then move across
on Friday, followed by high pressure this weekend. A cold front
will approach early next week, and may then linger nearby through
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Upper ridge remains anchored to our south tonight, as the area
remains on the southern edge of the westerlies.
Patch of high clouds will move across next several hours, with
mostly clear skies still anticipated.
Expect temps tonight to run a little warmer than the past couple of
nights as the air mass modifies. Lows will range from the lower
70s in NYC, to the 60s elsewhere.
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
Ridge remains anchored to the south Thursday and Thursday night as
the area remains on the southern edge of the westerlies.
A weak trough approaches from the west. Expect an increase in mid
and higher level clouds from the west late in the day, with a
good amount of sunshine all day further east.
Will cap pops to slight chance, mainly for western sections late in
the day. Slight chance pops spread east at night. High resolution
models indicate spotty showers moving across the area at night. NWP
model solutions output minimal QPF, or keep conditions dry for the
High temps will range from around 80 over eastern coastal
locations, to the upper 80s in northeast NJ.
At night, persistent southerly flow along with plenty of clouds will
result in warm temps, with a much smaller range in low temps, upper
60s to middle 70s.
There is a moderate risk for rip current development at the ocean
beaches Thursday into Thursday evening.
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The latest NWP model suite is in good agreement through this
weekend, then they begin to diverge a bit early next week. A strong
upper anticyclone will build towards the region Friday and then
remain over the Middle Atlantic this weekend. The ridge may begin to
shift south and weaken a bit on Monday as a northern stream
shortwave traverses across SE Canada. Differences arise with the
timing and how much the ridge breaks down. Differences continue
through the middle of next week with how much ridging rebuilds
A weak cold front will move through late Friday. Friday will be hot
and humid with temperatures surging into the upper 80s and lower
90s. Heat indices will reach the middle 90s and could reach the
upper 90s if dew points stay higher than forecast in the afternoon.
This is possible if more moisture pools along and ahead of the cold
front. However, thermal profiles show potential mixing up to around
850 hPa in the afternoon which should help to lower dew points into
the upper 60s in the afternoon. There will be a good amount of dry
air in the upper atmosphere as heights actually will rise.
Instability is also marginal as there may be a cap around 15kft, so
have lowered PoPs to just slight chance.
High pressure builds down from SE Canada this weekend with a light
northerly flow and slightly cooler air. The most noticeable
difference will be less humidity as dew points generally in the
lower and middle 60s. This will preclude the need for a heat
advisory in NYC since heat indices should only be in the upper 80s
this weekend, close to actual air temperatures.
Another cold front approaches late Sunday night into Monday. The
main shortwave forcing passes well to the north so have mainly kept
PoPs at slight chance with chance PoP across the interior. The
boundary may then stall near the area Tuesday into Wednesday.
This will all be tied to how strong the ridge aloft ends up and if
the upper jet stays well to the north leaving the boundary behind.
Overall, above normal and humid conditions should continue next
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --High pressure off the Northeast coast slowly moves east through
tonight, giving way to a weak frontal system approaching from the
Ohio Valley. A pre-frontal trough will approach from the west
VFR through the TAF period. There is a low chance of showers
northwest of the New York City during the afternoon and early
Winds generally SSW less then 10 KT, to light and variable at
outlying terminals overnight. Winds increase during the morning
hours and become southerly. Gusts up to 20KT possible near the
.Outlook for 06Z Friday through Monday...
.Thursday night-Friday...Mainly VFR. Slight chance of showers with
MVFR conditions. Isolated thunder possible on Friday.
-- End Changed Discussion --
Southerly winds should run around 15 kt overnight, with ocean
seas as high as 4 ft near the NY harbor entrance and 2-3 ft
elsewhere, higher than originally forecast.
With high pressure remaining just to the south, southerly flow
will prevail through Thursday night. Speeds will increase again
late in the day Thursday, and winds over the ocean waters may
approach SCA criteria.
Ocean seas should build to at least 4 ft by late Thu afternoon
into Thu night. Guidance suggests 5 ft seas are not out of the
For the non ocean waters, seas/waves should remain 2 ft or less.
There remains the potential for a tropical swell on the waters
late this weekend and early next week. Seas could build to
around 5 ft Sunday into Monday with this long period SE swell.
No significant widespread precipitation is expected into next week.