Scientific Forecaster Discussion
fxus61 kpbz 222126 cca
Area forecast discussion...corrected
National Weather Service Pittsburgh PA
426 PM EST Wed Feb 22 2017
warm weather will continue until the passage of a Saturday
Near term /through Thursday/...
a correction was included for the aviation section.
Residual showers to the north of I 80 will end quickly early
this evening as the supporting jet streak shifts eastward.
Forecast adjustments were centered on cloud cover given the
late afternoon break over the immediate upper Ohio area.
Subsidence under a shortwave ridge is expected to further suppress
clouds intially this evening, but the moisture surge on the Van
of another weak shortwave should support an increase once again
through the predawn hours.
That weak trough may generate some scattered showers on Thursday,
but weak support with a weak wind field and instability will be
the limiting precip factors. The chance for showers should
suffice for the precip forecast.
Warm temperatures continue under the warm advection regime. See
climate section for record highs which may be in jeopardy.
Short term /Thursday night through Saturday/...
any scattered showers will taper from south to north as a warm
front lifts northward across the area on Thursday night. This
process will plant US firmly in the warm sector for much of
Friday, and will result in dry weather and a peaking of the warm
temperatures. Highs on Friday will soar into the 70s for the
The models are continuing the slower trend with the well-
advertised frontal passage, which is now slated for Saturday
morning or early afternoon. Have slowed pop progression a bit
as a result. The timing of the passage would still not seem to
favor much of a severe threat given the expected lack of
buoyancy, but with strong flow and plenty of shear to enhance
updrafts, any storms may need to be monitored for wind gusts.
Long term /Saturday night through Wednesday/...
behind the cold front, wraparound showers will drop in coverage
Saturday night, with snow showers possible. Sunday will likely
be the only completely dry day in the extended forecast. Model
guidance is then a little uncertain with timing of a system on
Monday before having surprisingly good agreement on Wednesday.
Have stuck close to the superblend through this portion of the
forecast. After slightly below normal temperatures on Sunday,
high temperatures will increase through the period, with 60s
once again a possibility by the first day of March.
Aviation /21z Wednesday through Monday/...
some improvement to ongoing MVFR ceilings is expected this evening
as a shortwave ridge moves over the area and temperature falls
below convective thresholds. However, deterioration is anticipated
late tonight as another disturbances enhances overall ascent and
improves the moisture supply. IFR ceilings and some isolated to
scattered showers are anticipated for early Thursday with
moderate to weak confidence.
widespread restrictions are likely with the approach and passage
of a cold front on Friday night and earlyu Saturday.
record high temperatures for climate sites:
Wed Thu Fri
--------- -------- --------
pit 70 (1922,30) 70 (1922) 70 (1875,1906)
zzv 67 (1992) 64 (2000) 70 (1961)
mgw 70 (1980) 68 (1996) 75 (1975)
duj 60 (1983) 63 (1985) 60 (1985)
hlg 57 (1949) 62 (2000) 63 (2016)
phd 73 (1997) 69 (1975) 66 (1985)