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fxus61 kokx 190932 
afdokx

Area forecast discussion
National Weather Service New York New York
432 am EST sun Nov 19 2017

Synopsis...
a strong cold will sweep across the area early this morning with
high pressure building in its wake. The high will pass to the
south Monday and Tuesday, followed by a cold front on Wednesday.
Another area of high pressure will build late week, followed by
low pressure moving across on Saturday.

&&

Near term /until 6 am this morning/...
prefrontal showers moving across the area early this morning.
Although there were a few lightning strikes in southern and
central New Jersey earlier, it appears that the airmass has become a
bit more stable, most likely due to both low and mid level
inversions. Thus, have left thunder out of the forecast.

09z obs indicate that the warm front has just lifted through all
locations except the western half of Orange County. It should be
dragged through the remainder of the County shortly before the
cold fropa, which is quickly tracking eastward from central PA,
with a brief increase in temps. Front timed to move through the
Metro area around 12z with showers ending, although there will
be a burst of higher winds right behind it.

Uncertainty is still high at this point regarding wind
potential. The warm front has moved through coastal areas, with
winds slowly increasing in its wake, though with a strengthening
inversion above the surface, reflected by a developing stratus
field across eastern Long Island and Connecticut. VAD wind
profile data from kokx and kjfk radar show 50-55kt at 2000 ft as
the low-level jet moves across the area, and so depending on
the height of the inversion at least Wind Advisory level
sustained speeds and gusts may mix to the surface early this
morning prior to the cold front arrival. Although winds will be
strong, based on current observations and expected conditions,
sustained winds near 40 mph and gusts near 60 mph appear less
likely, so the High Wind Warning will be dropped from eastern
areas.

Otherwise, winds may briefly weaken as showers move through, before
strengthening ahead of and behind the cold front. Thereafter, strong
winds appear likely across all areas, particularly in the late
morning and afternoon as the system departs. Current obs in Maryland
are showing gusts in the range of 45-50 mph immediately following
the frontal passage, so the Wind Advisory will remain in place.

High temps will likely occur early this morning for many
locations, before falling during the late morning and aftn from
west to east as strong cold air advection commences.

&&

Short term /6 am this morning through 6 PM Monday/...
winds gradually decrease tonight, although will still remain
quite gusty with the departing low still strengthening as it
lifts into southeast Canada and high pres building to the S. All high
res guidance indicates that lake effect streamers remain north and west
of the area, except perhaps for a few hours this eve in Orange
County. Otherwise, partly cloudy skies tonight will give way to
mostly sunny conds on Monday. Lows in the upper 20s to mid 30s
tonight and highs in the 40s on Monday, although gusty winds
will make it feel like its only in the 30s.

&&

Long term /Monday night through Saturday/...
aloft, models agree early in the period as initial shortwave passes
east/northeast. Downstream shortwave will then make fast eastward
progress. Here is where some differences arise. Northern stream
potent shortwave tracks across the Great Lakes region as it lifts
northeast, with most of the energy and associated dynamics lifting
well to our north Wednesday. Southern stream trough lags a bit as it
moves across the Gulf states. By late Wednesday into Thursday,
operational GFS seems to be a deep/strong outlier with regard to
closed low around the Gulf states as the trough makes eastward
progress.

This upper trough weakens over the western Atlantic Thursday, with
next shortwave in the northern stream moving eastward toward the
northeast by next weekend.

At the sfc, high pressure passes to the south Monday and Tuesday.
Gusty northwest flow will back around the SW as the high tracks east.

Thereafter, a cold front passes Wednesday. This front is associated
with northern stream shortwave. This looks like the best chance for
measurable precipitation, late Tuesday night into Wednesday, chance
pops.

Waves of low pressure likely develop along the front well to our
south in the Wednesday night/Thursday time frame. Again, GFS appears
to be an outlier with wave of low pressure developing and passing
close enough for measurable precip Thursday. Otherwise, model
consensus suggest any precip remains to our southeast as ridge
builds to the northwest and waves remain far enough to the southeast.
Will maintain a dry forecast as a result, leaning toward consensus.
However, this will need to be watched.

Dry through Friday before the next chance for precip arrives with
the shortwave, clipper low Saturday.

As for temperatures Monday-Saturday, followed a model/MOS blend.
Below normal temperatures Monday will warm to slightly above normal
Tuesday as warm air advection occurs behind the high. Behind a cold front
Wednesday, normal temps likely fall to below normal Thursday and
Friday before rebounding yet again in warm air advection ahead of the clipper low
Saturday.

&&

Aviation /09z Sunday through Thursday/...
a cold front moves through around daybreak with high pressure
building behind it through this evening.

S flow will increase through the morning hours with gusts returning
to all terminals between 9-11z. Kjfk may see stronger sustained
speeds without gusts initially until flow shifts more to the SW-west
this morning. The gusts will initially be 20-30 kt, increasing to 30-
40 knots towards day break. Some eastern terminals may see peak gusts
45 knots. Low level wind shear is also forecast until around 12z. S-SW winds shift to
the west-west-northwest 12z-15z with gusts frequently 35-40 knots during the day. The
gusts will begin to weaken late in the afternoon and early in the
evening.

Mainly VFR-MVFR conditions to start with conditions improving to
VFR 12z-15z behind the cold front.

Outlook for 06z Monday through Thursday...
Monday...VFR. West-northwest winds g20-30kt. Gusts diminish gradually at
night.
Tuesday...mainly VFR. MVFR possible late Tuesday night in showers.
SW winds g15-20kt.
Wednesday...MVFR possible with showers during the day. VFR at
night. West-northwest winds g15-20kt.
Thursday...VFR.

&&

Marine...
seas continue to build ahead of strong southwest flow.
Gale-force winds are already occurring across the ocean waters
and will spread elsewhere through the day, especially following
the cold frontal passage later this morning. Less confidence
exists in storm- force winds across the eastern sound and ocean
areas east of Fire Island, though given strong winds above the
surface, potential certainly exists for these to mix to the
surface. Gale-force winds will continue into tonight, before
gradually weakening to Small Craft Advisory-levels tomorrow. Small Craft Advisory conditions may
continue through Tuesday night before winds and seas gradually
subside into Wednesday through Friday as high pressure builds
across the area.

&&

Hydrology...
a few bands of moderate to locally heavy showers with a strong
cold frontal passage this morning should cause no more than
local nuisance impacts. Additional rainfall of 1/4 to 1/2 inch,
through late morning.

&&

Tides/coastal flooding...
latest surge is running between 1/2 to 1 1/2 ft on the South
Shore bays of Li. At this rate, minor coastal flooding
benchmarks could be met, however winds will be shifting to the
west/northwest right before high tide, thus these values could decrease a
bit in western portions of the bays and cause the start of tidal
piling across eastern portions of the Great South Bay into
Moriches Bay. Have maintained the coastal flood statement
addressing brief and localized minor coastal flooding impacts.

&&

Okx watches/warnings/advisories...
CT...Wind Advisory until 6 PM EST this evening for ctz007>012.
Wind Advisory from 7 am this morning to 6 PM EST this evening
for ctz005-006.
New York...Wind Advisory until 6 PM EST this evening for nyz071>075-
078>081-176>179.
Wind Advisory from 7 am this morning to 6 PM EST this evening
for nyz067>070.
New Jersey...Wind Advisory until 6 PM EST this evening for njz006.
Wind Advisory from 7 am this morning to 6 PM EST this evening
for njz002-004-103>108.
Marine...Storm Warning until noon EST today for anz330-340-345-350-353.

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