Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 050524

Area Forecast Discussion
National Weather Service New York NY
1224 AM EST Mon Dec 5 2016

High pressure moves offshore overnight as a weak frontal system
moves in for Monday morning. High pressure briefly returns Monday
night into early Tuesday, before giving way to low pressure
passing well south of our region Tuesday night into Wednesday. A
rather strong cold front passes through Thursday into Thursday
night bringing unseasonably cold weather for Friday into the
weekend a well as strong gusty winds.


With increasing high clouds, ideal radiation cooling will end, and
temps should begin to hold steady or rise where radiational
cooling took place this evening.

Latest NWP suggest forecast is on track with very few changes
from previous. PCPN reaches the Hudson around 09Z and rapidly
expands east. Have increased POPs to Categorical 80% late tonight
into the morning rush in all zones.

Snow inland...with some RASN for the CT Coast back to NE NJ. Rain
for City and Long Island...some wet flakes may mix in there too.
On Long Island with the radiational cooling early tonight, surface
temps may be below freezing - so some icing is possible. Have
issued a Special Weather Statement (SPS) for the wintry weather
during the morning rush.

Temps warm quickly early in the morning.


Highs in the 45-50 degree range - or about 3-4 degrees warmer
than previous as the PCPN is quick to depart. Lingering light
rain/DZ and low clouds expected in the morning.

All NWP appears very consistent with this system. QPF is around
0.15" - again very consistent.

High pressure returns for Monday night.


A progressive flow will prevail across the continental United
States at the beginning of the work week. Dry weather at the start
of the extended period will become wet as a southern stream
shortwave phases with a northern stream negative trough by 12Z
Tuesday. Upper ridging quickly flattens Tuesday. With the
progressive flow opted to bring probabilities into the region by
Tuesday afternoon, more in line with the faster GFS. The northern
and southern stream systems to remain distinct and the area likely
will be in a cull. Light rain and possibly drizzle will continue
through Wednesday.

Another shortwave, moving into the Pacific northwest during
Tuesday will rotate through the northern stream trough digging the
trough, becoming nearly fully latitudinal during Thursday. Again
opted for the faster GFS with the timing of this next system as
the flow remains progressive. As the shortwave moves off the
northern coast rapid deepening of the low will occur Thursday
night into Friday. There is still some uncertainty with the depth
of the low and how quickly the low moves off the northeast coast.
Again the GFS is faster and deeper with the low. Some of the
coldest air of the season is possible behind the cold front with
temperatures as much as 10 degrees below normal Friday night into
Saturday night.


A frontal system moves through during the morning, and is followed
by high pressure late in the day.

Conditions will lower to MVFR by 7-10Z as light precipitation
overspreads the area. Expecting primarily rain across the city and
coastal terminals of LI. Farther inland, precipitation at KSWF will
fall predominately as snow, possibly tapering to light rain or
drizzle. Precipitation at KHPN/KBDR and KGON may start as a
rain/snow mix before transitioning to all rain.

IFR conditions are possible a few hours on either side of 12Z (10-
15Z). VFR returns during the afternoon and through the evening as
skies clear.

Light E/SE winds shift to the S, then SW by late morning and
afternoon at around 10 kt as the system approaches and crosses the
area. W/NW winds then prevail late in the day. A gust or two to 15
to 20 kt is possible briefly with the wind shift to the W.

NW winds lighten during the evening.

.Late tonight...VFR.
.Tuesday...VFR early, then MVFR possible with a chance of light
rain or drizzle.
.Tuesday night-Wednesday...IFR in drizzle and light rain.
.Thursday...MVFR possible with a chance of rain.


High pressure gives way to a weak frontal system Monday morning,
but winds and seas remain relatively tranquil. Another high builds
late and Monday night.

High pressure will be exiting the forecast waters Tuesday as a low
approaches from the southwest and then moves off the Mid Atlantic
coast Tuesday night, remaining well south of the forecast waters
Wednesday. Winds and seas are expected to remain below small craft
with the exception of the possibility of seas nearing 5 FT on the
far outer ocean zones late Tuesday night through Wednesday as the
low passes.

Thursday into Thursday night another frontal system will move
through the forecast waters with a strong cold passing through
Thursday night. Strong and gusty northwest winds will develop behind
the front with the potential for gale conditions Thursday night into
Friday night across all the forecast waters.


No hydrologic impacts are anticipated the next 7 days.




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