Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
606 am EDT Sat Apr 25 2015

Synopsis...
an upper level system over the northeast will dominate the weather
into the beginning of next week. High pressure builds in for the
middle of the week...followed by a frontal system for the end of
the week.

&&

Near term /through Sunday/...
quick update to adjust temperatures. Otherwise...no other changes.

Upper low over northern ME/eastern Canada will drift to just S of Nova
Scotia today. At the same time...low pressure will track off the NC
coast and out to sea. This puts the County Warning Area in a subsident
region...and despite the cold pool aloft...should suppress precipitation
chances. As a result...maintained the dry forecast for today. Subsidence
begins to weaken tonight...but instability is also reduced with the
loss of surface heating. This instability increases however during the
day on sun...with convective temperatures in the upper 50s to near 60. Some
weak middle level lift should help provide a trigger. Kept probability of precipitation
low...but went with coverage wording. Temperatures through the period close
to gmos25.

&&

Short term /Sunday night through Tuesday night/...
cooling bl Sun night so precipitation chances diminish. Stronger upper support on
Monday...so precipitation coverage expected to be greater than sun. Changed
wording to scattered...with probability of precipitation around 40 reasonable at this time. Chances again
wane a bit overnight...but there is a better chance at showers hanging
in past dark with the shortwave energy moving through. Another chance for
some isolated showers Tuesday afternoon...especially CT and perhaps Li...with
the 500 mb low over 400 miles east of Montauk. Daytime heating is lost
and the upper forcing is weak to non by Tuesday night...so a dry forecast.

&&

Long term /Wednesday through Friday/...
a broad area of hi pressure builds over the northestern Continental U.S. On Wednesday. Dry weather
expected as a result. Increasing heights will allow for a
noticeable warming trend...with temperatures approaching 70 along and west
of the Hudson. With weak flow...sea breezes will likely limit
temperatures on Li and CT. The GFS brings an upper low through in the Thursday-Friday
period. The European model (ecmwf) brings this upper level system to the NC coast and
spawns a 980s low over the Atlantic. This low is prognosticated to generally
track to the east-northeast and therefore not impact the County Warning Area. Made no changes
to probability of precipitation for the period...keeping the low chances already in the
grids. Temperatures close to gmos25 for this period.

&&

Aviation /10z Saturday through Wednesday/...
over the next day...weakening low pressure over the Canadian
Maritimes will be slow to work offshore...while another area of
low pressure passes well to the south across the Tennessee Valley and
Carolinas. In between...weak high pressure will prevail across
the area.

This will allow for a continuation of VFR conditions with west/northwest
flow in the morning. The flow backs around to the west/SW in the after
due to a trough developing across the area. Local seabreezes may
develop if the flow weakens enough. The best chance for this to
occur will be at kjfk and kbdr. Winds then veer around to the north
late Sat night as high pressure noses in from the northwest.

Outlook for 06z Sunday through Wednesday...
Sat night-Sunday night...mainly VFR.
Mon-Tue...possible MVFR with showers.
Tuesday night-Wed...VFR.

&&

Marine...
sub-Small Craft Advisory conditions are forecast through the middle of next week as a
large area of high pressure over the middle section of the country
works slowly east. There could be a short period this morning where
northwest gusts come close on the ocean waters...and again on Tuesday as a northerly
flow strengthens between a broad area of low pressure over the
western Atlantic and high pressure building in from the west.

&&

Fire weather...
min relative humidity will fall into the 20s today. Wind gusts are forecast to be in
the 15-20 miles per hour range...which is blw red flag criteria.

&&

Hydrology...
significant precipitation is not expected through next week.

&&

Climate...
record lows and forecast lows for Saturday April 25

Newark New Jersey...34/1936......35
Bridgeport CT 32/1956....33
Central Park New York 29/1919..36
LaGuardia New York 36/1971.....38
Kennedy New York *37/1971......36
Islip New York 36/2012.........31

*and previous years

&&

Okx watches/warnings/advisories...
CT...freeze warning until 9 am EDT this morning for ctz005>012.
New York...freeze warning until 9 am EDT this morning for nyz067>070-
078>081.
New Jersey...freeze warning until 9 am EDT this morning for njz002-004-
103>105-107.
Marine...none.

&&

$$
Synopsis...jmc
near term...jmc
short term...jmc
long term...jmc
aviation...dw
marine...dw
fire weather...
hydrology...jmc
climate...

National Weather Service Glossary of Abbreviations