Area Forecast Discussion
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FXUS61 KPBZ 211942
Area Forecast Discussion
National Weather Service Pittsburgh PA
342 PM EDT Tue Mar 21 2017
A strong cold front will sweep through tonight, bringing much
colder temperatures on Wednesday. A return to warmth is expected
by late this week, persisting into early next week as rain
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
An upper jet is evident on satellite as a cirrus plume spreading
across northern Ohio and southern Michigan. This jet will spread
across the region late this afternoon and evening, driving a
cold front across the forecast area.
For the remainder of the afternoon, increasing clouds are
expected. An invigorated field of low clouds also is expected as
the front passes, but little in the way of precipitation is
anticipated along the front.
In the wake of the front, a brief window for lake moisture-
driven snow showers could impact the I-80 corridor, and perhaps
the ridges. Any snow showers could drop a dusting of snow, but
wind profiles are not favorable for prolonged snow showers, and
the rapidly-drying air mass is not favorable for sustained
instability. Cold air is not expected to make it to the ridges
in time to promote rapid snow growth, so any accumulation there
should be trivial if any snow showers occur.
Maxima on Wednesday will be about 15-20F below climatologically-
normal values as very cold air lingers in the region amid
building high pressure. Clear sky, light wind and very-dry air
will promote strong radiational cooling Wednesday night, with
temps dropping into the mid-teens in many locations.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The surface high will translate ewd on Thursday as upper ridging
strengthens. Generally, a clear sky is expected, limited mainly
by any cirrus spilling over the ridge to the west.
Thursday night is a meteorological challenge, as cold (sub-
freezing) air will linger at the surface as strong warm air
advection begins aloft. Given the sely low-level flow, it is
quite plausible that low-level warming will lag the arrival of
the warm air aloft, leading to the possibility of a light
freezing rain/sleet event. At this time, the possibility has
been highlighted in the HWO.
The warm air aloft will mix rapidly to the surface Friday
morning in the warm sector, with temperatures rebounding to near
60F by afternoon.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
A fairly-active, split-stream jet pattern is expected for the
remainder of the forecast, with a series of closed lows expected
in the swrn CONUS and a progressive northern stream.
Moisture spreading ahead of these southern-stream lows will
bring a wetter and cloudier (but warmer) period into early next
week. Maxima in the 60s and minima in the upper 40s are
expected. Precipitation will be driven by the passage of these
ejecting lows, the timing of which is not clear at this time.
The most-consistent chance of rain /per MEX trends/ looks to be
late Sunday afternoon.
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Diurnal low-VFR cumulus will dissipate shortly before sunset.
Gusty northwest winds will develop this evening behind a
crossing front, with an additional round of low-VFR clouds.
Cannot rule out the possibility of some MVFR cigs at FKL/DUJ.
Clouds should dissipate late Wednesday morning along with wind
The next chance for widespread restrictions should come on
Friday with a front tracking across the lower Great Lakes.