Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 261145

Area Forecast Discussion
National Weather Service New York NY
745 AM EDT THU MAY 26 2016

The region will be under the influence of a westward extension of
the Bermuda High through the weekend. A cold front approaches from
the west Monday, then pushes through the area Monday night. This
front then stalls out near or just to the south of the area
through Wednesday as high pressure builds to the north.


Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.

Dry weather expected this morning with deep-layered ridging. A
shortwave embedded within ridge approaches late in the day, and with
increasing mid-level moisture there could be a shower or
thunderstorm by late, primarily over the NW zones where CAPES will
be higher. Limiting factors however will be some capping aloft with
relatively stable mid-level lapse rates.

High temperatures will be well above normal as they were yesterday.
Thinking is that most spots will be a little cooler than yesterday,
more so at the coastal areas as sea breezes will begin earlier this
time around and affect more areas. Additionally, 850 mb temps are
forecast to be about a degree Celsius cooler.

There is a moderate risk of rip current development at the
Atlantic beaches today into this evening.


500 mb shortwave enters tonight, but weakens as it moves across the
region. Loss of instability will help keep any showers/storms
isolated to scattered in nature.

850-700 mb shortwave slowly moves through the CWA during Friday.
Moisture depth and lift will be greater during the morning, but
CAPES will be higher in the afternoon. Will therefore go no higher
than chance pops for now. High temps still well above normal with
850 mb temps climbing back up to 15-16C. Amount of cloud cover and
sea breezes should offset the max temp potential somewhat, but in
general, going with highs a little cooler than today in most
spots, primarily due to more cloud cover.


A westward extension of the Mid-Atlantic Ocean based sub-tropical
ridge builds in Friday night-Saturday, then retreats back to the
southeast Saturday night and Sunday. The result will be continued
very warm and humid conditions across the region. There will also
be some mainly diurnal isolated-scattered showers and
thunderstorms from Friday evening through Sunday as well.

Temperatures during this time frame were based on a blend of all
available guidance, with NAM 2-meter temperatures blended in Friday
night-Saturday night, and a mix down from 975-850 hPa, per BUFKIT
soundings, blended in for highs on Saturday. Lows will run around 10
degrees above normal both Friday and Saturday night. Highs Saturday
and Sunday should run around 10-15 degrees above normal.

The forecast for Sunday night-Wednesday is very much dependent on
the interaction between a northern stream shortwave that is forecast
to move across the Great Lakes and a possible closed low near the
mid-Atlantic Coast. There is quite a spread in model solutions, with
the GFS showing the most interaction between these two systems and
the ECMWF the least. The CMC-Global is somewhat in between these two
solutions, but trends closer to the ECMWF with time. It should be
noted that the ECMWF and GFS basically flipped solutions from the
12z to the 00z runs. The result is a low confidence forecast from
Sunday night-Wednesday.

For now will run with pops increasing to chance throughout Sunday
night for showers and thunderstorms, continuing on Monday, then
tapering off Monday night. Given uncertainties in how quickly the
airmass changes on Tuesday, have included some diurnal convection
then, however, if the ECMWF/CMC are correct, Tuesday could end up
dry. Given the overall uncertainty then maintain mainly slight
chance pops for Tuesday night and Wednesday.

For temperatures Sunday night-Wednesday, the Superblend was used,
with above normal temperatures forecast, but not quite as warm
as this weekend.


VFR forecast.

High pressure builds to the south today and tonight.

Light southwest wind early this morning will shift to the south
for most terminals, a combination of a general wind flow and sea
breeze. It is becoming increasingly likely that a sound breeze
will affect KLGA from about 14Z through 16Z, and winds here will
be more southeasterly during this time period. Thereafter, it will
shift to the south. Wind speeds should max to just above 10 kt.

A shower or thunderstorm is possible across the terminals late
tonight into Friday morning. However, chances are too low to
mention in the TAFs. Better chances for showers and thunderstorms
for northwest terminals such as KSWF and KHPN.

     NY Metro Enhanced Aviation Weather Support...

Detailed information...including hourly TAF wind component fcsts
can be found at:

KJFK TAF Comments: No unscheduled amendments expected.

KLGA TAF Comments: Amendments may be needed if sound breeze does
not develop.

KEWR TAF Comments: No unscheduled amendments expected.

The afternoon KEWR haze potential forecast is green...which
slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 00Z Friday through Monday...
.Thursday night through Friday morning...Mainly VFR but sub-VFR
possible in showers/evening thunderstorms.
.Friday through Friday night...Mainly VFR, but sub-VFR possible in
isolated showers and evening thunderstorms.
.Saturday...Mainly VFR. Isolated showers and thunderstorms north
of NYC/Long Island.
.Sunday...Sub-VFR possible in afternoon showers and thunderstorms.
.Monday...Sub-VFR possible in showers and thunderstorms.


Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.

A weak to moderate pressure gradient over the region through
Monday will keep winds to 15 kt or less over the waters around
Long Island. With no significant swells forecast during this time
frame, seas will remain below Small Craft levels as well.


No significant widespread precipitation expected through Thursday
night. Local minor flood impacts from heavier showers/tstms are
possible on Friday.

There is the potential for locally heavy rainfall, for areas mainly
N/W of NYC Saturday and Sunday, with a higher chance of a more
widespread moderate to heavy rainfall from Sunday night into Monday,
and possibly lingering farther into next week. For this weekend, the
main threat is ponding of water on roadways, with a low risk of
minor flooding of urban and poor drainage areas (once again the main
threat this weekend will be to the N/W of NYC). At this time, there
is too much uncertainty to specify any threat for early next week,
other than to note the situation bears watching.





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