Scientific Forecaster Discussion
fxus61 kokx 280540
Area forecast discussion
National Weather Service New York New York
140 am EDT Mon may 28 2018
a stationary front will remain south of the area through
tonight as a wave of low pressure tracks out to sea. Meanwhile,
high pressure builds in from near Nova Scotia. The high weakens
Memorial Day but remains in the region Monday night. A backdoor
frontal passage will occur on Tuesday, allowing high pressure
to build in through the middle of the week. The remnants of
Alberto may then impact the region into the weekend.
Near term /until 6 am this morning/...
a stationary front will remain well south of Long Island
overnight as a wave of low pressure near the 40n 70w benchmark
departs further into the Atlantic. Meanwhile, high pressure
centered over the Canadian Maritimes is extending down the Lee
of the Appalachians. This will result in a continued NE flow
across the area, with speeds decreasing overnight as the
pressure gradient relaxes. Additionally, although drier air at
the sfc will continue to advect in from the north overnight,
moisture trapped below a low level inversion will keep cloudy
skies in place.
Meanwhile, an upper trough tracks through the northeast with
weak vort maxes moving through the flow. Will keep chance and
slight chance probabilities through tonight, however, mid/upper
levels have been drying and precipitation will be either light
rain or drizzle. With weak height rises to the west and north
late tonight will taper and end precipitation chances. Lows will
generally be in the 50s across the area.
Short term /6 am this morning through 6 PM Tuesday/...
the upper shortwave will be moving east with heights slowly
rising Monday morning. Light precipitation will be ending,
however, would not be surprised if precipitation shuts off
below 10z. A northwest flow will persist. Temperatures will
rebound Monday, but remain below seasonal normals.
The western portion of the stationary front will be pushed east
and north as a warm front, mainly across upstate NY, Monday into
Monday afternoon, as an upper trough remains across eastern
Canada into New England. The front will be weak with little
forcing. The GFS is more aggressive with bringing precipitation
to near the lower Hudson Valley by late in the day. Will leave
dry at this time, however, there is a chance of a few showers to
develop as instability increases with 100-200 j/kg of Cape.
Monday night will be dry, with light winds. With low level
moisture in place all guidance is indicating potential for fog
to develop, possibly becoming dense along the coast late Monday
night. At this time will mention patchy 2 mile fog restrictions.
There is a moderate risk of rip current development at the
ocean beaches on Mon.
Long term /Tuesday night through Sunday/...
little change in the long term as the models remain in good
agreement. A weak backdoor front comes thru on Tue. The NAM is
dry, the GFS and European model (ecmwf) suggest something in the isold to perhaps
sct category W of the Hudson late in the day. The model qpf may
be a grid scale issue, with the center of any progged
convection centered S and W of the cwa. A dry fcst has been
maintained. The warmer superblend was used for high temps.
Hipres for Wed with fair wx. The nbm was used for temps, which
resulted in a slight increase in the fcst highs. The remnants of
Alberto are progged to travel roughly up the MS valley on Wed,
merging with the upr low which is currently spinning near Salt
Lake City. This eventual hybrid sys slowly tracks thru the
region Fri-sun. Mid lvl moisture transport into the region could
support some isold-sct shwrs and tstms on Thu, then the main
sys could produce better chcs thru sun. Right now, the best
dynamics remain generally N of the cwa, although the timing and
position of these features are highly uncertain this far out,
especially concerning Alberto in the mix. As a result, the fcst
maintains only slgt chc pops for Thu, low chc (30 percent) for
Fri and Sat, and slgt chc again on sun. The nbm was used for
temps, which again resulted in an increase in highs Thu-Sat.
Aviation /06z Monday through Friday/...
high pressure in the Canadian Maritimes will remain wedged
between the Lee of the Appalachians and departing low pressure
tonight while gradually weakening through Mon.
Conditions are predominantly MVFR to locally
IFR, and may lower a bit overnight, however drier air
associated with the building high will allow for generally MVFR
overnight with VFR returning on Mon. There is some uncertainty
with the timing of ceilings lifting above 2kft and they make take
until morning to lift above this threshold. Some spotty light
rain and/or drizzle remains confined to southeast CT and eastern Li
before diminishing early this morning.
NE remain below 10kt. NE-east flow will generally shift to a more
southerly direction by Monday afternoon.
Outlook for 06z Monday through Friday...
Monday night...patchy MVFR fog possible overnight.
Thursday...mainly VFR. MVFR or lower possible late.
Friday...MVFR or lower in -shra. Isold ts possible.
a developing wave of low pressure along a stationary front
south of the forecast waters in combination with building high
pressure along coastal New England have resulted in an
increased, and gusty, NE to east flow, especially across the ocean
waters. A strong pressure gradient force will continue through
much of tonight as the wave of low pressure tracks to the east.
Will continue with the scas for the ocean waters through
tonight, and for the eastern Long Island Sound and eastern bays
through this evening. A sca has also been issued til midnight
for the wrn sound and S shore bays.
High pressure will build late tonight into Monday and remain
into Monday night. A weaker pressure gradient force will then
be across the forecast waters. Winds and seas will remain below
Small Craft Advisory levels Monday and Monday night.
Winds and waves are expected to remain blw sca lvls Tue-Fri.
Conditions may deteriorate next weekend.
no hydrologic impacts are anticipated through Thu. There is a
low potential for locally heavy rain Fri-sun depending on the
timing and placement of Alberto remnants.
NYC National oceanic and atmospheric administration weather radio station kwo-35 (162.55 mhz) is off the
air for an extended period of time.
Marine...Small Craft Advisory until noon EDT today for anz350-353-355.