Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
806 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 north and west of
NYC where the rrq of a 55-65kt upper jet will be present.
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 500 mb 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 /12z Saturday through Wednesday/...
high pressure builds offshore the New England coast today with
low pressure approaching form the Ohio Valley.
Mainly VFR conditions with increasing mid clouds. Patches of stratus/fog
across Li and CT terminals should mix out within the next hour.
Showers are likely this afternoon, mainly west of NYC, then becoming
more widespread late tonight. Isolated thunderstorms possible.
Light north/NE winds this morning, becoming S/southeast by afternoon at 5 to
10 knots. Winds back to the more east/southeast 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 east/southeast 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 quantitative precipitation forecast 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 north and west 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.