Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
337 PM EST Sat Nov 28 2015
a cold front will move slowly towards the middle- Atlantic into
Sunday. High pressure will remain in control on Monday. A low
pressure system then impacts the region Tuesday into Wednesday. A
cold front moves across late Wednesday and Wednesday night
followed by high pressure building for the end of the week into
Near term /until 6 am Sunday morning/...
A broad trough gradually sinks into the northeast tonight with an
embedded shortwave approaching late tonight...while southern
stream energy approaches the middle Atlantic late tonight.
Cold front sinks towards the middle-Atlantic tonight. Light Post
frontal rain activity appears to wane from northwest to southeast this evening
with increasing subsidence and middle-level drying as high pressure
builds into the area from the northwest. Models signaling a second round
of light rain across New Jersey and Delaware-Maryland-Virginia late tonight into early
Sunday morning in response to aforementioned shortwave energies
and resultant wave development through the middle-Atlantic front
along cold front. Local area will be on northern fringe of
this...with primarily southern areas (nyc/New Jersey metropolitan and li) of tri-
state having potential for being skirted by light rain.
Cloud cover and weak cold air advection will keep temperatures slightly above
normal...generally upper 30/lower 40s...except 20s in far interior
where late clearing and light winds could allow for radiational
cooling. If this occurs...potential for patchy black ice
development across interior portions of lower Hudson Valley and
Short term /6 am Sunday morning through Sunday night/...
Weak but broad upper troughing remains over the area during this
period...while high pressure builds in from the north.
Northern and southern stream shortwave energy east and most favorable
jet couplet move east Sunday afternoon...with associated middle-
Atlantic surface wave moving offshore. Any lingering light rain over
southern zones should push S and east Sunday morning...with drying
conditions into the afternoon as high pressure builds in. Although
low/middle deck should clear out with increasing subsidence...a jet
cirrus deck likely remains through the day.
Northerly flow will allow for gradual cold air advection through the day. Although
temperatures will start relatively mild for this time of
year...clouds...limited mixing and cold air advection should limit temperatures to
seasonable levels...mid/upper 40s to around 50.
Mostly clear skies Sunday night...with continued cold air advection on NE flow.
Mixed low-levels should keep temperatures from bottoming out along the
coastal plain and holding in the 30s. Interior valleys could drop
well down into the 20s/upper teens with better potential for
Long term /Monday through Friday/...
The latest models continue to come into better agreement with the
overall pattern through the long term. A period of unsettled
weather is becoming likely for the middle of the upcoming week
as a low pressure system impacts the region.
Monday into Monday night...high pressure will move across northern
New England during the day and then offshore at night. Upper level
ridging builds overhead as well. Slightly below normal temperatures
are forecast with mostly clear skies during the day. Moisture begins
to increase at night as southeast flow begins to increase with the high
moving offshore. A nearly vertically stacked low pressure system
moves across the northern plains into the Great Lakes region Monday
night as the ridge axis begins to shift to our east. Warm advection
also commences Monday night. Model guidance is indicating some
potential for a weak wave of low pressure to develop along or just
off the middle Atlantic coast as well late Monday night. If this does
develop...interior locations could see some very light freezing rain
late Monday night since temperatures are expected to drop near
freezing. However...there will be a battle of warmer air moving into
the region at the surface and if enough lift and moisture will be
present for precipitation to develop. Other than interior locations
of Orange County...a dry forecast is indicated for the entire area
Tuesday-Wednesday...a low level warm advection pattern continues
Tuesday morning with increasing moisture and lift. Biggest
uncertainty continues to be how low temperatures are at daybreak
across the interior and if any precipitation develops. Due to this
uncertainty...will mention small chance of freezing rain here. As the
morning progresses...temperatures will warm well above freezing and
if precipitation develops early enough...the pytpe will be rain
across the entire area. Probability of precipitation increase to high chance Tuesday
afternoon. The precipitation that does develop should be light as the
best lift will be to the west...closer to an upper level cutoff low
moving into the Great Lakes region. Rain becomes likely Tuesday
night as a warm front approaches from the south and the upper low
approaches from the west. The upper level low opens up on
Wednesday...but a good amount of energy and divergence aloft should
continue lift across the region and the likelihood of rain. The 12z
GFS is quickest with ending the rain Wednesday afternoon...with the
12z ecwmf about 6 hours slower. Have sided closer to the ecwmf with
the timing of this system. A solution closer to the 12z European model (ecmwf) would
bring the cold front through Wednesday night as the trough lifts
across the region. Temperatures will be above normal during this time
Thursday-Saturday...shortwave trough lifts to our NE on Thursday
with upper ridging taking shape overhead. High pressure builds in at
the surface Thursday...and will remain in control through Saturday.
Some differences noted aloft between the latest models...but overall
these differences will have minimal impact on sensible weather. Dry
conditions during this period with temperatures averaging near
Aviation /20z Saturday through Thursday/...
Expect a short period of IFR/MVFR ceilings and spotty light rain this
afternoon before VFR conditions return this evening. The onset of the
lower ceilings could be delayed as much as 2 hours...while improving
this evening could be delayed on the same time scale.
Northerly winds less than 10 knots will continue through sun.
Outlook for 18z Sunday through Thursday...
Tuesday...rain/fog with IFR conds by after.
Wednesday...MVFR or IFR conds possible in the morning...with
Thursday...VFR. Northwest g20-25kt
long period southeast swells at the ocean buoys continue at 5-6 feet. Will
continue to take a blend between wavewatch and nwps and continue Small Craft Advisory
for hazardous seas through tonight. Nwps suggests marginal Small Craft Advisory seas
to continue on the water through the day...but wna3 indicated of
swells falling to around 4 feet. Will hold off on extending Small Craft Advisory into
sun at this point due to marginal event...but potential for 5 feet
ocean seas to linger through Sunday.
NE flow strengthens Sunday night between high to NE and southern
low...bringing likelihood for Small Craft Advisory conds with marginal Small Craft Advisory gusts and
Small Craft Advisory seas re-developing Sunday night.
Small Craft Advisory conditions are likely to continue on the ocean waters Monday.
Pressure gradient will be relaxing some as high pressure builds over
the waters allowing wind gusts will be subsiding through the day.
Seas are likely to stay above 5 feet through the day however. 5 feet seas
are possible for the first portion of Monday night...but then should
subside below 5 feet late Monday night into Tuesday morning.
Low pressure and a frontal system will impact the waters late
Tuesday into Wednesday bringing the next chance of Small Craft Advisory conditions on
the ocean waters.
Rainfall amounts through tonight will be light and few
hundredths of an inch.
A low pressure system could bring an average of one inch of rain
Tuesday into Wednesday.
Marine...Small Craft Advisory for hazardous seas until 6 am EST Sunday