Scientific Forecaster Discussion
fxus61 kokx 210550
Area forecast discussion
National Weather Service New York New York
1250 am EST Thu Nov 21 2019
high pressure builds into the region through Thursday before sliding
offshore Thursday night. A cold front then crosses the area on
Friday, followed briefly by high pressure Saturday. Low pressure
may impact the region Saturday night into Sunday, before high
pressure returns early next week.
Near term /until 6 am this morning/...
current forecast is generally on track. Had to adjust clouds
slightly as they have eroded a bit slower than anticipated. But
overall clouds are eroding across much of the area, with broken
clouds still remaining further east across the County Warning Area. Temperatures
were also running a bit too cold, so adjusted them up a touch
for the next few hours.
Upper ridging and surface high pressure continues to build into the
region. Winds will continue to diminish as the gradient
slackens late in the overnight and into this morning. Temperatures
across the interior will fall into the upper 20s. Closer to the
coast, temperatures will be in the 30s where it will be slower
for winds to come down.
Short term /6 am this morning through 6 PM Friday/...
Thursday will be relatively quiet as high pressure slides through
the region. Warm air advection develops in the afternoon as winds
turn from the northwest to a more westerly/southwesterly direction.
Under a sunny sky, temperatures will moderate into the upper
40s to lower 50s.
A warm front will then lift across the area on Thursday night.
Increasing clouds and continued SW flow will keep temperatures a few
degrees warmer than previous nights. It is likely that low
temperatures will be reached earlier in the night with better
radiational cooling conditions with high pressure overhead before
the increasing southwesterly flow.
Long term /Friday night through Wednesday/...
a fairly progressive flow pattern continues to be shown by the
models into the long term. Models have come into a bit better
agreement today with a developing surface low pressure system
impacting the area Saturday night into Sunday.
Before the weekend system, ridging both at the surface and aloft
Thursday night will give way to an amplifying northern stream
shortwave on Friday. This shortwave and associated cold front will
move across the area on Friday afternoon. Guidance has been
relatively consistent with this as a dry system, with little to no
precipitation associated with it. The system exits offshore
late Friday afternoon and early evening. Winds will increase
Friday night behind the front with northwest wind gusts 25 to 30 mph
before tapering on Sunday.
A split flow pattern develops across the Great Lakes by early
Saturday. A southern stream surface low develops over the southeast
by Saturday morning. The northern stream shortwave currently located
over the North Pacific, should be near the northern plains on
Saturday. Both the GFS and European model (ecmwf) have the low pressure tracking
just south of the Long Island coast Saturday night into Sunday
and have trended further west relative to previous cycles.
Saturday will largely be dry across the area with precipitation
chances increasing quickly from south to north Saturday night. Have
increased pops slightly across the northern half of the area
Saturday night into Sunday morning. Thermal profiles indicate
that this is a mainly rain event across the cwa, and the trend
for far northwest parts of the County Warning Area is warm. However, can't rule
out the potential for some spotty freezing rain far northwest
Orange County late Saturday evening or early Sunday morning, but
confidence is low as surface temperatures remain at or just
above freezing. The system is progressive which should help to
limit the duration of any impacts with the low.
High pressure returns early next week with another frontal system
approaching from the Central Plains by midweek.
Aviation /06z Thursday through Monday/...
high pressure builds to the south today and tonight.
Broken clouds are expected to scatter as the morning
progresses. VFR prevails. Mid/high clouds increase
late in the day and in the evening.
Northwest winds are expected through the morning, mainly
10 kt or less. Winds will back to the west during the
afternoon, and southwest toward evening. Speeds expected
to be 5-10 kt.
Outlook for 06z Friday through Monday...
Friday...VFR with a low chance of MVFR in rain showers.
Wind SW around 15 kt, shifting to the northwest with gusts
20-30 kt in the afternoon and into the night.
Saturday night...becoming MVFR to IFR in rain at the
coastal terminals, a mix possible north of west of the
Sunday...chance MVFR/IFR in the morning, with conditions
improving during the afternoon. Mainly rain with a
chance of wintry mix north and west of the NYC terminals.
Winds northwest around 15 kt gusting 20 to 25 kt in the afternoon.
a Small Craft Advisory is in effect for ocean waters through
Thursday morning. Northwest winds will gust to 25 kt before
diminishing Thursday morning as high pressure builds in. Seas will
fall below Small Craft Advisory levels by Thursday morning.
Winds and seas increase to Small Craft Advisory levels ahead of a cold front on
Friday. The cold front passes east Friday afternoon with Small Craft Advisory wind
gusts on all waters continuing Friday night. There could be a few
gale gusts on the waters east of Moriches Inlet, but this does not
appear to be of long duration. Ocean seas will slowly subside behind
the front into Saturday morning.
Conditions will briefly fall below Small Craft Advisory levels on Saturday and
Saturday night. Small Craft Advisory conditions are possible again on Sunday
afternoon into Monday morning as low pressure passes north of the
area. The track of the low will ultimately determine how high seas
build and the intensity and duration of stronger winds.
no hydrologic impacts are anticipated through Saturday.
NYC National oceanic and atmospheric administration weather radio station kwo35 (162.55 mhz) is operating
at reduced power until further notice.
Marine...Small Craft Advisory until 7 am EST this morning for anz350-