Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
258 am EDT Thursday Sep 3 2015
a cold front approaches from the north and passes through late in
the day into tonight. High pressure builds down from southeastern
Canada overnight into Friday and remains in control through early
next week. A cold front then moves through the region during the
middle of next week.
Near term /today/...
weak high pressure in place keeps US dry during the morning. A
cold front then combines with sufficient cape and just enough
moisture for low chances of showers and thunderstorms this afternoon.
Went closer to mav MOS for high temperatures based on temperatures aloft and
expected timing of sea breezes and cloud cover. Highs therefore
generally a degree or two warmer than yesterday in most cases.
Dewpoints and heat index values should be low enough to preclude any
heat advisories...and will mainly be a couple of degrees higher than
Short term /tonight through 6 PM Friday/...
the cold front eventually pushes south of the County Warning Area tonight with low
chances of showers/thunderstorms again this evening. A trailing shortwave
pushing south then keeps a slight chance of showers for some
sections during the overnight hours. The shortwave exits to the SW
with an isolated shower still possible Friday morning for primarily
NE New Jersey and the city. Negative vorticity advection...surface ridging and subsidence should then
keep the entire County Warning Area dry during the afternoon. Models are however
showing some lingering middle level moisture...so some areas could
remain mostly cloudy through the afternoon...primarily southwestern
zones. A mav/NAM MOS blend looked good for high temperatures and
should be 7-10 degrees cooler than today's in most cases.
Although minimum humidity levels should be in the 50s...gusty east
winds Friday afternoon may pose a enhanced concern for spread of
brush fires due to 400-500 kbdi values and available fine fuels.
Along the coast...the potential exists for a high rip current risk
late in the day due to easterly winds and wind waves.
Long term /Friday night through Wednesday/...
gradually increasing drought and fire weather concerns through the
High pressure...both at the surface and aloft...builds over the East
Coast this weekend with the center of the high passing through New
England. With low pressure developing over the southeast U.S. Coast...a
tightening east to northeast gradient will develop over the tri-
state area for Saturday...and then winds shift to more of a
southerly flow for Sunday as the high moves offshore.
Temperatures on Saturday will be right around normal...topping off in the
upper 70s to around 80. With warm air advection underway for Sunday...highs will
climb into the middle and upper 80s.
Bermuda high pressure then strengthens along the East Coast with
increasing heat and humidity for the start of the new week. Highs on
Monday and Tuesday will top off in the middle to upper 80s...and
possibly around 90 for NYC and NE New Jersey. Surface dewpoints will also rise
into the low to middle 60s for much of the area and in the middle to upper
60s for Long Island and southeast CT.
The ridge along the coast breaks down and moves offshore late
Tuesday/Tuesday night...and then a cold front approaches on
Wednesday and moves through during the middle to the end of next
Aviation /07z Thursday through Monday/...
a cold front approaches from the north this morning...then crosses
the area this afternoon and evening.
Mainly VFR through the taf period. A period of MVFR to IFR fog is
possible mainly outside of the city terminals early this morning.
Haze aloft is possible at the city terminals early this morning as
well. There is a low chance for isolated-scattered showers/thunderstorms
this afternoon and evening mainly to the north/west of city terminals. At
this time confidence in timing/occurrence is too low to place in
Light and variable winds will give way to a north-NE flow under 10 knots
at city terminals by middle-late morning and at kteb/kswf by early
afternoon. Seabreeze likely at CT terminals this morning and
probable at kjfk/kisp by early afternoon. Seabreeze is probable at
klga/kewr by late afternoon. Seabreeze is also possible at kteb
and khpn but confidence is too low to reflect in tafs. Winds
become light and variable throughout again this evening.
Outlook for 06z Friday through Monday...
late Thursday night-Friday...mainly VFR. Isolated
shower/thunderstorm possible mainly to the west of city terminals
into Friday afternoon. NE-east winds g15-20kt possible Friday.
Friday night...VFR. East-NE winds g15-20kt possible.
relatively tranquil conditions for today and this evening with a
weak surface pressure gradient remaining in place. Winds then pick
up late tonight into Friday as high pressure builds down from the
north...tightening the pressure gradient. There could be a few gusts
up to 25 knots over the ocean waters by late afternoon...and seas could rise
to 5 feet by evening as well over the eastern ocean waters. Models
have trended a little weaker and later with increasing winds...plus
wavewatch has delayed the onset of 5 feet seas for the past couple of
runs. Add to this that would be a late third-period event...will
therefore hold off on Small Craft Advisory issuance for now and let the day shift see
if trends continue and issue Small Craft Advisory as necessary.
A tight east to northeast gradient remains over the waters on
Saturday...and wind gusts to 25 knots along with 4-6 feet seas are likely
on the ocean waters before conds gradually subside Saturday night.
With high pressure over the waters for the start of the new week...conds
will remain below Small Craft Advisory criteria.
no widespread significant rainfall is forecast today through the
middle of next week. Drought will continue to develop region wide.
Long Island and southern CT are currently experiencing moderate