Area Forecast Discussion
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FXUS61 KPBZ 230155 AAC
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
955 PM EDT Sat Oct 22 2016
High pressure will end showers this evening, followed by dry and
seasonably cool conditions through Sunday. Quick-moving low
pressure will provide increasing chances for rain showers Sunday
.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --Aside from nominal adjustments to reflect current observations,
forecast appears to be in good shape. No significant changes
needed with this update. Previous discussion follows...
Remaining lake-enhanced streamers will diminish during the next
few hours as flow backs to wly amid building high pressure. This
high pressure will be fleeting as a clipper system moves sewd
toward the Great Lakes region.
Warm advection in advance of this system will support only modest
decreases in temperature overnight, thus suppressing concern for
frost outside of the highest ridges, where the growing season
already ended earlier this month. Overnight minima thus can be
expected in the upper 30s in the northern zones and lower 40s
elsewhere. Lower 30s will be common in the ridges, where cold air
has lingered all day.
Amid increasing warm air advection and decent insolation, temps on
Sunday should reach low 60s by afternoon. Cloud cover will begin
to thicken late in the day as the clipper system approaches, but
precipitation is not likely to encroach on the forecast area
until Sun evening, when somewhat-deeper moisture begins to advect
into the region.
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.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
While quality moisture will be shallow Sunday afternoon, moisture
advection and modest isentropic upglide should yield sufficiently-
deep moisture to produce light precipitation in at least nrn
sections of the forecast area and the ridges. MOS guidance and
deterministic models suggest the likelihood of light but
measurable precipitation in these areas, so a broader range in PoP
was included for the Sun night timeframe. Previous discussion
A weak shortwave and a fast moving cold front will cross the
region later Sunday night into early Monday, followed by dry
high pressure for Tuesday. Chance POPs with frontal passage as
moisture will be limited. Temperatures behind the front will be
around 5 degrees below the seasonal average.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The next significant weather will be with a fairly-strong
shortwave and surface low pressure moving across the Great Lakes
later Wednesday night into Thursday. Likely POPs were included
for this system until it shifts east to New England later Thursday
night. Another cold front will approach by Saturday, bringing
shower chances back to the forecast. Temperatures will be near or
just below the seasonal averages through the period.
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Improvement to VFR is expected at most of the terminals overnight,
though stratocu may linger in the northern and eastern ports
through early morning or until we lose the moisture fetch from
lake Erie. What lingering showers that remain will also diminish,
with only VCSH maintained at DUJ for a couple of hours.
Brief ridge of high pressure should maintain VFR conditions
through the TAF period but clouds will be increasing in advance of
the next fast-moving low pressure system, expected to bring rain
to portions of the region Sunday night.
W-NW wind will back to the W-SW through the period, with gusts
expected again in the afternoon with anticipated surface heating.
.OUTLOOK /SUNDAY NIGHT THROUGH THURSDAY/...
Restrictions are possible with a Sunday night cold front, and with
subsequent upper troughing and northwest flow through Tuesday.
Restrictions are possible again with the approach of Low Pressure