Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 252041
Area Forecast Discussion
National Weather Service New York NY
341 PM EST Sat Feb 25 2017
Showers and scattered thunderstorms with a cold frontal passage
this evening. Cool high pressure then builds south of the area
through Monday. A slow moving warm front will approach from
Monday night into Tuesday night, the lift north on Wednesday.
Low pressure passing to the north will drag a trailing cold
front through late Wednesday night or early Thursday. Another
cold front will pass through on Friday.
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
Need to check the calendar. I can`t recall the last time I`ve
seen a line of storms extend from Quebec south to North
Carolina in February with nearly 2000 CG in the past hour.
Impressive to say the least.
Anyway, SVR Watch 40 up until 02Z (which we`ll be able to cancel
around 00Z) for west of the Hudson - as well as Putnam, NY. There`s
plenty of shear which has prompted the inclusion of a possible
tornado in the Watch. The best thermodynamics are over SE PA
where the 20Z SPC Meso Analyses shows 1000 J/Kg of SBCAPE and
LI`s of -4 C. Thus, expect storms to get well into the western
zones before they weaken rapidly as they start to ingest the
For the NY Metro - the loss of daytime heating and the marine
air support not extending the watch to the east. That being
said, still expect a gust to 30 to perhaps 40 KTS in the 00Z
The rain ends quickly overnight and northwest winds usher in a
more seasonal airmass.
.SHORT TERM /MIDNIGHT TONIGHT THROUGH SUNDAY NIGHT/...
Seasonable weather returns for Sunday. NW winds gust up to 30
mph through the day and then diminish at night. With clear
skies and light winds, expect decent radiational cooling Sunday
Temperature guidance remains consistent and was accepted.
.LONG TERM /MONDAY THROUGH SATURDAY/...
NWP guidance fairly close through the period, though did side with
slower NAM at first with approaching weak mid level shortwave moving
through a flat upper longwave ridge. After that, went with a 00Z
ECMWF/12Z GFS blend, with increasing chances of rain in large scale
WAA, and likelihood of rain Tue night through Wed night ahead low
pressure passing to the north and an approaching trailing cold
front. As mild/humid air streams northward with dewpoints in the
50s, fog likely Wed night that could be dense along the coast. Cold
fropa late Wed night could be accompanied by brief heavier showers.
After cold fropa on Thu, drier/colder air will arrive on a gusty W
then NW flow, with wind gusts 30-40 mph possible especially NYC
metro and coastal sections. Another cold frontal passage expected
late Friday, and kept fcst dry but did increase clouds with its
Temps should remain on the mild side through Thu, with at least 50s
each day and lower 60s for NYC metro/NE NJ on Wed. Much colder for
Thu night and beyond, with lows in the lower 30s NYC metro and 20s
elsewhere Thu night and Sat night, and even colder Fri night, with
teens and 20s.
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
A cold front moves across this evening with high pressure
building in from the west thereafter. Mainly MVFR to VFR
conditions this afternoon and some isolated IFR with some
lingering low level stratus. Low level stratus will eventually
scatter out leaving MVFR/VFR stratus.
With the cold front for city terminals and terminals KHPN and KSWF,
expecting a brief period of showers and embedded thunderstorms
while to the east, just a brief period of showers is expected in
a general timeframe from west to east of 22Z-03Z. After this,
mainly VFR conditions are expected.
Winds will be SE veering to S with wind speeds near 10 kt
gusting at times to 15-20 kt. After the cold frontal passage,
an abrupt shift in wind direction and speed is expected as winds
veer to W-WNW near 15 kt gusting 25-30 kt. Winds could
occasionally peak a few kts higher than forecast.
.OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
.Sunday...VFR. NW winds G20-25KT likely.
.Sunday night-Monday evening...VFR. W-SW winds G15-20KT Monday.
.Late Monday night-Thursday...Chance of MVFR or lower at times
with any showers. W-NW winds G20-30 KT Thursday.
Small craft advisory (SCA) on the coastal waters for through
the day on Sunday in the wake of a cold frontal passage this
SCA conditions will linger through Sunday night on the Ocean
waters as winds slowly subside, but seas will remain at or above
the 5 FT criteria.
Mon into Mon Eve: SCA for the eastern ocean waters via
favorable WSW fetch of 15-20 kt wind on northern periphery of
offshore high pressure.
Wed afternoon/night: SCA conds on the ocean waters via increasing S-
SW flow ahead of an approaching low pressure system. Dense fog
likely to develop as very moist air moves over the colder waters.
Thu into Thu night: Cold fropa followed by W-NW gales on the ocean
and SCA conds elsewhere.
Around a half inch of rain with locally higher amounts can be
expected through tonight. Rainfall of 1/2 to 3/4 inch possible
from Tue night into Thu morning. No hydrologic issues expected.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EST Sunday
Small Craft Advisory until 6 PM EST Sunday for ANZ350-353-355.