Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1041 am EDT Sat Jul 4 2015
high pressure over the area will weaken today as low pressure
passes south of Long Island. Another weak high will build across
from the west tonight through Monday. A weak low and associated
warm front will then lift slowly up the coast Monday night into
Tuesday night. A slow moving cold front will approach on Wednesday
and possibly linger into Thursday...with a wave of low pressure
forming along it. High pressure will return for Friday.
Near term /until 6 PM this evening/...
forecast on track...with latest hi res hourly models suggest the
bulk of the rain remains confined to the northwest zones this
morning...likely weakening as it spreads eastward. Steadier rain
to the north of a wave of low pressure...moving off the Delaware-Maryland-Virginia
coast...looks to remain just south of Long Island.
Widespread measurable rainfall is not anticipated this
afternoon...but many areas could see a light rain shower or
sprinkle this afternoon. Overall...not a washout with some areas
Sided with the cooler GFS MOS for high temperatures...with upper 60s
north/west of NYC and lower 70s elsewhere.
There is a moderate risk of rip currents today.
Short term /6 PM this evening through 6 PM Sunday/...
cold/dry air advection should lead to dry conditions in time for
Independence day firework displays in most places...but with 700 mb-8
frontogenetic forcing and good low level moisture still lagging
across most of Long Island and southeast CT early this evening a
lingering rain shower or sprinkle possible into the early
evening. Skies should be mostly cloudy to start...then gradually
clear as high pressure starts to build in. Low temperatures should be in
the Lower/Middle 60s in NYC metropolitan and 55-60 elsewhere per a GFS/NAM
MOS guidance blend.
Expect Sunday to be mostly sunny...with afternoon fair weather cumulus
developing especially inland...with cyclonic flow aloft and a
developing surface thermal trough. This should also aid afternoon sea
breeze development. High temperatures are close or a little higher than
GFS MOS...with lower and middle 80s...warmest in NYC metropolitan and the
Long term /Sunday night through Friday/...
looks like we will have another very warm/dry day for Monday with
a good deal of sunshine.
Next chances of precipitation will come during middle week...first with a
weak low drifting up from the SW...then with a weakening cold
front moving in from the northwest. Continue with chance thunder from
late Monday night into Wednesday night. High temperatures for Tuesday/Wednesday are
somewhat tricky due to the uncertainty of cloud coverage.
More sunshine on Tuesday could push temperatures a little higher than forecast.
Wednesday should be the cooler of the two days...with a better chance of
greater cloud coverage.
A wave of low pressure could develop to our SW along the stalling
cold front...and eventually bring a chance of rain Thursday into Thursday
night...followed by dry conds on Friday as high pressure returns.
Aviation /15z Saturday through Wednesday/...
high pressure remains off the northeast coast today as a wave of
low pressure tracks south of Long Island.
Light east winds back slightly to the NE as the low tracks to the
south. However...it is possible that winds remain light east or
even southeast depending on the strength and track of the low. As
such...wind forecast confidence is low for this afternoon.
Winds become light this evening and remain light overnight.
Expect VFR cloud decks through the day today before clouds scatter
tonight. Any rain should be light and fairly brief...except at
kswf where -ra can be expected through at least 16z.
Outlook for 12z Sunday through Wednesday...
Tuesday-Wednesday...chance of MVFR in showers and thunderstorms.
low pressure passes just south of the waters today...and departs to
the east tonight. Winds will increase ahead of the low as they back
to a northeasterly direction. Over the ocean waters...a few gusts
late this afternoon may approach 25 kts. However...this should be
brief so will not Post any marine headlines at this time.
Ocean seas likely remain at 3 to 4 feet today...possibly touching
5 feet by evening. The ocean waters...particularly east...may build
to 5 feet late tonight with southerly swells. Seas/waves 1 to 2 feet
or less elsewhere today and tonight.
High pressure returns Sunday...and should remain in control into the
early portion of the week. By middle week...a cold front approaches the
waters. In general...a relatively weak pressure gradient remains in
place...so do not anticipate Small Craft Advisory conditions Sunday through Wednesday.
generally 1/10 to 1/4 of an inch of quantitative precipitation forecast is possible today
north/west of NYC...and less than 1/10 inch elsewhere. There is
still a good chance that part of Long Island and southern CT
could remain dry.
Significant precipitation could occur at some point during the
middle of next week as a weak low and warm front move up the coast
on Tuesday...then with a cold front approaching and stalling nearby
Wednesday into Thursday. Predictability is too low to offer any specifics at
combo of a recent full moon and some tidal piling via elevated
ocean seas could cause minor coastal flooding benchmarks to be
touched along the South Shore back bays of Nassau County at the
peak of the night-time high tides the next couple of days...