Area Forecast Discussion
Issued by NWS Upton, NY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KOKX 301043
Area Forecast Discussion
National Weather Service New York NY
643 AM EDT SAT JUL 30 2016
High pressure moves off the New England coast today as low
pressure slowly approaches from the Ohio Valley. This low tracks
along a frontal boundary to the south into early next week. An
upper level disturbance passes through on Tuesday with high
pressure then returning through Friday.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Weak ridging aloft will flatten today as a broad trough east of
the Rockies tracks slowly eastward. Clouds will gradually increase
today as waa ensues and sfc low pres slowly approaches from the
Ohio Valley. Overrunning rain will overspread the area during the
mid to late afternoon...but could start moving into NYC and areas
west by early afternoon. Soundings are indicating some weak
instability with high moisture content through the column...thus
embedded tstms with heavy rain is possible...mainly N and W of
NYC where the RRQ of a 55-65kt upper jet will be present.
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
-- Changed Discussion --As deep layered ridging strengthens across the plains and SW
US and a cutoff low pressure system tracks across western
Canada...the downstream H5 flow will amplify. Unsettled weather
continues through into early next week as the amplifying upper
level trough approaches. However...the shortwave and LFQ of jet
stream are progged to lift through western New York State late
tonight and Sunday. Divergence aloft will pass through western
portions of the local area Sun aftn with additional showers and
tstms expected. With abundant moisture still present through the
column...some storms could produce heavy rainfall.
Sfc low pres approaching from the west slowly passes S of Long
Island Sunday night through Monday night...followed by the upper
trough axis on Tue. Sct showers/tstms remain a possibility with
locally heavy rainfall.
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.LONG TERM /TUESDAY THROUGH FRIDAY/...
Drier weather builds into the area Tuesday through Friday. A few
isolated showers will be possible on Tuesday right behind the
Temperatures remain at or slightly below normal through Tuesday.
Then, an increase in heat and humidity start to return.
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
High pressure briefly builds tonight into the first half of
Saturday. Then low pressure slowly approaches from the Ohio Valley.
Mainly VFR conditions are expected overnight with increasing mid
clouds. Patchy fog development, generally for terminals away from
New York metro, is possible overnight. Low probability for VSBY
reductions to MVFR or lower in BR.
Showers are possible Saturday afternoon, especially west of NYC.
Light winds overnight into Saturday morning. Winds become S/SE in
the afternoon at 5 to 10 KT.
.OUTLOOK FOR 06Z SATURDAY NIGHT THROUGH WEDNESDAY...
.Saturday night into Sunday...Chance of showers and possibly a tstm.
MVFR or lower conditions possible.
.Sunday night-Monday night...Chance of showers. MVFR conditions
.Tuesday-Wednesday...Mainly VFR, although isolated showers
A frontal boundary will remain south of the waters through early
next week until low pressure passes to the east Monday night into
early Tuesday. This will result in a mainly E/SE flow which will
be strongest Sunday afternoon/evening, with possible gusts up to
20 kt on the ocean waters. High pressure will then follow for the
mid week. Sub-sca conditions are forecast during the period.
A large range of rainfall is expected across the area this
weekend. Average QPF from this afternoon through Sunday evening is
expected to be from around 1/3 of and inch to 1 inch east of NYC
and 1 to 1 3/4 inches N and W of NYC. Locally higher amounts are
possible in any heavier showers. Minor urban flooding would be
the main hydrologic impact in any heavier shower/thunderstorm.