Scientific Forecaster Discussion
fxus61 kokx 221149
Area forecast discussion
National Weather Service New York New York
749 am EDT sun Oct 22 2017
dry and mild today as high pressure pulls away from the region.
The weather then becomes rather unsettled for Tuesday and
Wednesday with potentially heavy rain. Relatively strong gust
winds are likely on Tuesday. Dry weather returns for late week
into the weekend.
Near term /until 6 PM this evening/...
0630 am EDT update - no changes at this time.
Other than some gradual increase in cirrus - looks like a fine
day with temps still about 15 degrees above normal in the mid to
upper 70s. Forecasting 1 degree short of the record at kbdr -
elsewhere we'll fall 5 to 10 degrees short. GFS/European model (ecmwf) MOS blend
used which seems to work very well on Saturday.
Short term /6 PM this evening through 6 PM Monday/...
low level moisture increases tonight with a light southeast flow.
Models suggest stratus moving in with better chances of at least
a broken deck occurring west of eastern Li and CT. This leads
to a partly to mostly cloudy Monday. There appears to be enough
isentropic and low level lift for a chance of a sprinkle in the
afternoon as there's significant subsidence above 800 hpa
causing stratocu to spread.
Highs will still range mostly 70-75.
Long term /Monday night through Saturday/...
nwp remains on track with a deep upper level trough with strong
meridional flow approaching the region Monday night as the jet
dives into the southeast. The question that remains is the
timing of the very slow moving frontal passage. The gefs has
about 10 members that support the slower deterministic European model (ecmwf)
timing. Thus, a good chance for rain to continue through
Wednesday especially on Long Island and CT.
Then, mainly dry weather is expected by Thursday night through
Winds are a potential issue Tuesday through Tuesday evening.
There is a low level jet ahead of the cold front and the models
have pretty good agreement with the 50-60 knots magnitude. Thinking
of gusts of 35 to perhaps 45 knots.
Have kept the tstms for Tue afternoon and evening with potential for
long Narrow Cape.
Aviation /12z Sunday through Thursday/...
VFR through at least 06z Mon as high pres gradually moves east
S/southeast winds 8-12 kt develop later this morning and afternoon
with seabreeze enhancement at coastal terminals.
Aft 06z tonight, the second night of onshore flow, may start
seeing indications of fog and/or stratus development, however
the high may not be far enough offshore for MVFR/IFR ceilings. High
clouds could also limit fog development. Would like to see more
of the hi-res guidance later today before committing to IFR
Outlook for 12z Monday through Thursday...
Mon...morning MVFR/IFR possible in stratus/fog, then VFR. S/southeast
g20 kt Mon aftn.
Mon night-Tue...potential a period of S/southeast g30-40 knots with low level wind shear
south-southwest 45-55kt@2kft for coastal terminals. MVFR/IFR developing in
-radz Mon night, continuing with rain showers and low prob/sparse thunderstorms and rain
Tue night-Wed...IFR possibly continues in rain showers Tue night,
improving to MVFR Wed.
Wed night-Thu...VFR, with iso-sct MVFR in rain showers.
quiet conds on all waters through Mon as high pressure over the
area slowly shifts east. The pressure gradient will begin to
tighten on Mon as low pressure strengthens over the Great Lakes.
Small Craft Advisory conds are expected to develop Mon night with the potential
for gale force gusts Tue into Tue night, all waters. The gale
potential will depend on mixing over the waters, but should be
able to mix down 35-40kt forecast at 1000mb, especially over the
ocean. Winds just off the deck may be slightly weaker on the
non- ocean waters and gales may only occur with any heavier
Winds will slowly diminish from west to east Tue night, and the
progression of the front/low level jet will determine the end time for the
Small Craft Advisory/gale hazards. May need to keep headlines up into Wed for the
eastern waters. Seas on the ocean are forecast to remain above
5 ft through Thu, due to a southeast swell from a good fetch around
the departing high. This could be overdone however.
expect nuisance urban ponding late Tuesday into Wednesday,
especially across the New York Metro, Long Island and southern CT.
Storm total of 1.5 to 3" now expected, but flash and river
flooding are not anticipated.