Scientific Forecaster Discussion
fxus61 kokx 261129
Area forecast discussion
National Weather Service New York New York
729 am EDT Fri may 26 2017
low pressure tracks off the New England coast today. Weak high
pressure builds in tonight and Saturday, then retreats to the
northeast as a weak wave of low pressure passes near the region
Sunday into Monday. A cold front approaches from the west on
Tuesday, then crosses the area Tuesday night. A series a weak
waves of low pressure will result in unsettled weather for the
middle of next week.
Near term /until 6 PM this evening/...
forecast update to reflect just some minor adjustments based on
on current radar trends and 10z temperatures. Otherwise, no
significant changes were made to the forecast.
Showers across the area this morning will dissipate in both
coverage and intensity as both the upper and surface lows move
off the New England coast today. The heaviest rain will occur
across far eastern Long Island and southeast Connecticut this
morning with the potential for up to a quarter inch of
rainfall. Much of this rain will exit the area by 8-10 am.
Deep-layered cyclonic flow on the backside of departing low
pressure will result in plenty of clouds and scattered showers
across the region today. There should though be enough drying in
a gusty west flow for some some sun this afternoon. In turn
though, this could kick off some additional showers. Any
precipitation should be brief.
High temperatures will be near seasonable levels, ranging from
the 60s across far eastern Long Island and southeast
Connecticut, to the lower and middle 70s elsewhere.
Short term /6 PM this evening through 6 PM Saturday/...
heights build aloft as the upper low moves out into the
northern Atlantic. Weak high pressure builds in at the surface
tonight into the first half of Saturday, then offshore with a
weak return flow developing Saturday afternoon. There is a
chance of showers late Saturday afternoon, mainly to the north
and west of NYC as a mid level short approaches from the west.
Temperatures will be near seasonable levels with clouds
increasing in the afternoon due to warm advection ahead of the
aforementioned mid level short wave trough.
Long term /Saturday night through Thursday/...
an unsettled weather pattern will continue through the long term
A weak wave of low pressure will pass south of the region Saturday
night into Sunday, followed by another shortwave late Sunday night
into Monday. With model differences with respect to timing and
placement of these weak waves, will only go chance or slight chance
pops. The better of the two days for precipitation will be Monday.
An easterly flow will result in mostly cloudy skies for much of
Sunday and Monday.
A broad closed low then slowly tracks from Ontario into western
Quebec from Monday night through Thursday, with shortwaves rotating
around the base of the low from time to time. The timing of these
shortwaves is somewhat difficult this far out, but for now it
appears that most energy will be focused north of the region. As a
result, there is a chance of isolated to scattered showers - mainly
over northern portions of the tri-state. Also, cannot rule out a
rumble of thunder Tuesday/Tuesday night with the passage of a
surface cold front.
The easterly flow across the region Sunday and Monday will keep
temperatures below normal. Temperatures return to more seasonable
levels Tuesday through Thursday.
Aviation /12z Friday through Tuesday/...
low pres over srn New England will track into the Gulf of ME
MVFR or lower this mrng, then improvement to VFR is expected by 16-
Showers will decrease in coverage and intensity thru the day.
Dry weather is expected tngt into Sat mrng.
West to northwest flow will develop in the wake of the low. This flow
will continue thru the rest of the taf period.
New York Metro enhanced aviation weather support...
Detailed information, including hourly taf wind component forecasts,
can be found at: http:/www.Weather.Gov/zny/n90
Kjfk taf comments: cigs may bounce between MVFR and IFR thru
Klga taf comments: cigs may drop blw 1000 ft at times before 15z.
Kewr taf comments: some variability in cigs possible thru 15z.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kteb taf comments: vrb cigs possible thru at 15z.
Khpn taf comments: cigs may drop to 400 ft at times thru 14z.
Kisp taf comments: cigs may drop to 400 ft at times thru 14z.
Outlook for 12z Saturday through Tuesday...
Saturday night-Monday...MVFR/IFR possible in showers. East/southeast winds.
Tuesday...improving to VFR. S/southeast winds.
west winds behind departing low pressure and a southerly swell
will keep seas above 5 ft on the ocean waters through tonight.
High pressure then builds across the area Saturday with sub-Small Craft Advisory
A light pressure gradient over the region Saturday night-Wednesday
will result in conditions remaining below Small Craft Advisory
levels. Unsettled weather however can still be expected as a series
of weak disturbances move across or near the area waters.
an additional quarter inch of rainfall is possible, mainly
across far eastern sections of the area this morning.
Another round of rain is possible from Sunday night into late
Monday. At this time, it appears that average precipitation amounts
will remain below a quarter of an inch. No hydrologic impact will be
experienced from this system.
the combination of high astronomical tides and a southerly swell
will keep water levels within striking distance of minor
coastal flood benchmarks for potentially several high tide
cycles through this weekend into early next week for the more
vulnerable locations. The new moon was yesterday and tide
levels will gradually begin to lower this weekend. However, the
swell will likely inhibit water levels from receding much in the
South Shore back bays of western Long Island today with a minor
coastal food episode likely during the higher of the two tide
cycles this evening. Thus, a coastal flood advisory has been
issued for southern Queens and southern Nassau counties. A
statement is also in effect for isolated minor coastal flooding
across lower New York Harbor. Elsewhere, the coastlines adjacent
to western Long Island Sound could also come close tonight, but
confidence is low at this time.
New York...coastal flood advisory from 8 PM to 11 PM EDT this evening for
Marine...Small Craft Advisory for hazardous seas until 6 am EDT
Saturday for anz350-353-355.