Area Forecast Discussion
Issued by NWS Upton, NY-- Remove Highlighting --
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FXUS61 KOKX 301443
Area Forecast Discussion
National Weather Service New York NY
1043 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/...
A mid deck is moving across the Lower Hudson Valley with some weak
returns on radar. There has been a downward trend with these
echoes over the last hour as there is still some subsidence to
overcome with weak ridging aloft and surface high over the area.
Also noting some drier air advecting southward under a light
northerly flow over the interior where dew points have fallen into
the lower 60s. Have adjusted PoPs to account for the latest trends,
but otherwise the forecast remains on track.
As the weak ridge aloft flattens today, a broad trough east of the
Rockies tracks slowly eastward. Clouds will gradually increase
as warm advection ensues and surface low pressure slowly
approaches from the Ohio Valley. Still appears as though the
best coverage of showers and thunderstorms will be from the city
north and west this afternoon. This is where the best instability
and lift will reside. As the activity translates eastward, there
should be a downward trend in intensity as the precipitation
encounters the surface high just to the east.
Highs will be in the lower to middle 80s.
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
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.
.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 /15Z SATURDAY THROUGH WEDNESDAY/...
No significant changes made to previous TAFs. There is some
patchy stratus out there, but conditions remain VFR.
Showers are likely this afternoon, mainly west of NYC, then
becoming more widespread late tonight. Isolated thunderstorms
Light N/NE winds this morning, becoming S/SE by afternoon at 5 to
10 KT. Winds back to the more E/SE tonight as the low approaches
from the west.
.OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...
.Sunday-Monday Night...Chance of showers and possibly a tstm.
MVFR or lower conditions possible.
.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.