Scientific Forecaster Discussion
fxus61 kokx 261522
Area forecast discussion
National Weather Service New York New York
1122 am EDT Mon Jun 26 2017
weak high pressure moves offshore this afternoon. Another cold
front moves across Tuesday into Tuesday night. High pressure
builds to the south Wednesday. A warm front crosses the region
late Thursday, with warm, humid and unsettled weather Friday
through the weekend.
Near term /until 6 PM this evening/...
made some minor adjustments to forecast database based on
On the large scale, a longwave trough remains west of the region
today. A subtle shortwave embedded within this longwave trough
with some slight height falls is expected by mid to late this
afternoon. This in combination with daytime instability allows
for a low potential for a shower or thunderstorm. This will be
confined to mainly north and west of NYC. At the surface, a cold
front will be moving across the region and weakening. Today's
highs were a combination of gmos and ecs, mid 70s to low 80s.
There is a moderate risk for the development of rip currents
Short term /6 PM this evening through 6 PM Tuesday/...
the front will become weaker with time. Instability will become
more elevated but a lack of a trigger will keep mainly dry
conditions tonight. Lows tonight were a blend of gmos and mav,
low 50s to low 60s.
For Tuesday, starting in the morning, there will be abundant
clouds. The height falls will be accompanied by greater value of
positive vorticity advection during the day. The longwave
trough still is west of the region tonight into Tuesday but on
Tuesday the amplitude of this shortwave is higher. There
wavelength of the shortwave is getting less, indicating a
sharper overall large scale trough. The chances for showers and
thunderstorms will be higher than those of the previous day.
Another cold front moves across Tuesday. Temperatures were a
combination of gmos and ecs, mid 70s to near 80.
Long term /Tuesday night through Sunday/...
upper trough passes Tuesday evening, with weak ridge building
Wednesday. Upper flow flattens late in the week, becoming SW ahead
of Midwest trough over the weekend.
At the sfc, high pressure builds Tuesday night, passing to the south
Wednesday. Low pressure passes across the Great Lakes region
Thursday, with warm front passing across the area by that time.
Thereafter, frontal boundary remains just to the north of the area
as low pressure rides along it, also passing north. Then next low
approaches ahead of upstream trough, passing north for the
latter portion of the weekend. Subtle placement/timing differences
noted in medium range guidance.
In general, unsettled weather looks likely from late Thursday,
through the weekend. Scattered showers and thunderstorms can be
expected, with coverage higher during the daytime each day.
Instability appears to be weak Thursday, but builds thereafter per
operational GFS. Li's as low as -5 c with long narrow cape's and
increasing pwat's, over 2 inches by Saturday, in a unidirectional
flow supports potential for flash flooding - mainly in urban areas.
Low humidity and below normal temperatures expected Wednesday, then
temperatures rebound to near normal Thursday, and above normal late
in the week into the weekend. However, do not foresee heat issues at
Aviation /15z Monday through Friday/...
VFR through the taf period with high pressure south and east of
Winds will gradually back to the SW into this afternoon with
speeds increasing to around 10 kt. Afternoon sea breeze
development shifts winds to the south at coastal terminals, 10
to 15 kt. Winds will gradually diminish overnight.
There is a low chance for a shower or storm northwest of NYC Metro
terminals this afternoon/evening.
... 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: an occasional gust up 20 kt possible this
Klga taf comments: timing of sea breeze may be off by 1-2 hours.
An occasional gust up 20 kt possible this afternoon.
Kewr taf comments: gusts may end up more occasional this
afternoon. Sea breeze could move across terminal 19-21z,
backing winds more to the south than forecast.
Kteb taf comments: an occasional gust 18-20 kt possible this
afternoon. Low chance sea breeze moves across terminal 20-22z,
backing winds more to the south than forecast.
Khpn taf comments: an occasional gust up to 18-20 kt possible
Kisp taf comments: timing of sea breeze may be off by 1-2 hours.
Outlook for 12z Tuesday through Friday...
Tuesday...mainly VFR. Chance of a late day shower/thunderstorm.
Thursday-Friday...mainly VFR. Chance of a late day
with an overall weak pressure gradient remaining across the
region, winds and seas are expected to remain below Small Craft
Advisory criteria (25kt winds, 5 ft seas) through Tuesday.
High pressure builds Tuesday night and passes south Wednesday. Sub
Small Craft Advisory conditions expected during this mid week period.
Then, winds back around to the S/SW as the high departs to the east
and a warm front passes. Winds increase, and Small Craft Advisory conditions are
possible later Thursday, and Thursday night. These persistent winds
continue Friday. Seas build Thursday and remain elevated Friday.
no hydrologic impacts expected through Thursday. There is
potential for localized flash flooding associated with Summer
convection Friday through the weekend - mainly in urban areas.
River flooding is not anticipated.
astronomical tides are still running high with potentially
another round of isolated minor coastal flooding for the South
Shore back bays, which could be seen with the high tides
tonight (approximately between 10pm and 12am). The water levels
would only be expected to touch the minor benchmarks, again for
just a few gages in the South Shore bays.
observations from kfrg (farmingdale, ny) are not available.
Observations from khpn (white plains ny) and khvn (new Haven ct)
are being disseminated through backup methods. All is due to
an FAA communication line outage. Return to service time is
In addition, multiple observations across the area are not being
disseminated due to FAA comms issues.
long term...precipitable water