Scientific Forecaster Discussion
fxus61 kokx 290738
Area forecast discussion
National Weather Service New York New York
338 am EDT Thu Jun 29 2017
high pressure settles over the western Atlantic today as a warm
front passes well to the north through tonight. The offshore high
will dominate the weather on Friday into Saturday. A cold front
will slowly approach over the weekend and pass by late Sunday.
High pressure will then build in from the northwest through the
beginning of next week.
Near term /until 6 PM this evening/...
middle and upper level cloud cover will continue to stream across
the region this morning. This moisture, largely resulting from
weakening convective complexes over the Great Lakes and upper
Midwest, is spilling over weak ridging aloft. The day will
likely start out mostly cloudy, but expect these clouds to thin
and scatter out heading into the afternoon with just some
scattered cumulus and cirrus clouds.
High pressure moves over the western Atlantic with a steadily
tightening pressure gradient into the afternoon. Increasing S-south-southwest
flow will result with sustained winds near the coast 15-25 mph with
gusts 30-35 mph. The strongest winds look to reside across Long
Island and southeastern Connecticut this afternoon.
Temperatures are a bit tricky today due to cloud cover to start the
day and then increasing onshore flow this afternoon. Highs across
the NYC Metro, NE NJ, and lower Hudson Valley will likely reach the
middle and upper 80s with Long Island and southern Connecticut in
the upper 70s to lower 80s. If stronger southerly flow takes shape
sooner than expected, much of Long Island and coastal Connecticut
may not make it out of the 70s.
Dangerous rip currents are expected at the ocean beaches,
particularly in the afternoon and evening. A high rip current risk
remains in effect.
Short term /6 PM this evening through 6 PM Friday/...
the main story for tonight will be increasing humidity levels and
much warmer temperatures than recent nights. A wave of low pressure
moves into the Great Lakes region with its associated warm front
settling across northern New England. Other than some weak short
wave energy, there is not much in the way of support for convection
tonight. Have confined slight chance pops to the interior where a
bit more elevated instability is progged to reside, but think the
night should largely be dry. Low temperatures in the upper 60s to
near 70 are forecast.
Ridging builds over the western Atlantic on Friday. Temperatures and
humidity levels continue to increase with temperatures approaching
90 degrees in the NYC Metro and NE New Jersey and upper 80s across the
interior. Onshore flow will hold readings down into the upper 70s on
the immediate shore and lower 80s just inland across Long Island and
southern Connecticut. Gusty S-south-southwest winds expected again, but not as
strong as Thursday, mainly 20-25 mph near the coast. Diurnal heating
is the only source for any convection with chance pops confided to
the northwest interior.
Long term /Friday night through Wednesday/...
an upr low over the Canadian prairie Fri ngt will drop sewd and
reach Lake Superior by sun ngt. This will begin to carve out SW flow
aloft thru the period across the fcst area. Under this flow regime,
the best chance for rain is generally across the interior, or even
just NW of the fcst area, until significant forcing reaches the
region. Because of this, pops were limited to 30 percent thru the
weekend. The wild card will be residual convective complexes which
would be capable of kicking off a round of rain and tstms. It will
be warm and humid over the weekend with a blend of model data used
for temps. Although the mainly sly flow will limit temps,
particularly across Long Island and CT, it will keep the humidity up
until a wly component is added by sun ngt. The only reason fog was
not included attm is because the winds may not fall off sufficiently
overnight. Otherwise, the sly flow will keep the ocean choppy and
result in a continued rip risk thru at least Sat.
The upr trof, based on the 00z European model (ecmwf) and GFS data, comes thru Mon
and Tue. This will provide some DPVA and help to steepen lapse
rates, however it appears the deepest moisture will have been
shunted offshore by this point, allowing for only isold-sct coverage
of any shwrs and tstms. Pops were limited to 30 percent Mon and Tue
because of this.
Wed looks to be between the departing upr trof and the next
approaching system. The fcst has been kept dry as a result.
Aviation /08z Thursday through Monday/...
high pressure slowly drifts offshore through Thursday night.
Mainly VFR conditions expected. Winds will be SW 5-10 kt for
city terminals and kisp tonight into early Thursday with
otherwise light and variable winds.
S-SW winds increase to 10-20 kt with gusts mostly around 20-25
kt Thursday into Thursday evening with some peak gusts to 30kt
for early evening. Strongest and most southerly winds expected
at kjfk and klga. Winds decrease late Thursday night to 10-15
kt with gusts to 20 kt.
Outlook for 00z Friday through Monday...
Friday-Saturday morning...mainly VFR. Chance of shra/tstm
north and west Friday afternoon/evening. SW gusts 25 kt Fri PM.
Saturday afternoon-Sunday...chance showers/thunderstorms with
sub-VFR conditions. SW gusts 20-25 kt Sat PM.
increasing S-south-southwest flow today as pressure gradient tightens with high
pressure moving offshore. Small Craft Advisory continues on all waters starting this
morning and running through midnight on near shore waters and
through Friday on the ocean. Winds will gust to 25-30 kt on all
waters, especially this afternoon. Gusts should stay below 34 kt,
but it would not be out of the question for a few isolated gusts to
reach 34 kt. Ocean seas will quickly build through the day, reaching
5 to 6 ft this evening. Winds on the ocean may briefly fall below 25
kt late tonight, but should once again reach around 25 kt on Friday.
Ocean seas will continue to run 5-6 ft through Friday.
Winds and seas will remain at sca lvls on the ocean Fri ngt thru Sat
ngt before subsiding on sun. Elsewhere, winds appear to remain just
blw sca lvls attm. Winds and seas are progged to stay blw sca lvls
Mon and Tue.
no hydrologic impacts expected into the middle of next week.
observations from kfrg (farmingdale, ny) may still be sporadic
due to a communication line outage. Return to full service time
is still unknown.
New York...high rip current risk from 8 am EDT this morning through this
evening for nyz075-080-081-178-179.
Marine...Small Craft Advisory from noon today to midnight EDT tonight
Small Craft Advisory from noon today to 6 PM EDT Friday for