Area Forecast Discussion
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FXUS61 KPBZ 220353
Area Forecast Discussion
National Weather Service Pittsburgh PA
1153 PM EDT Tue Mar 21 2017
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 chances
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --Increased winds and cold air advection overnight as a cold front
dives south across the forecast area. Although light snow is not
out of the realm of possibility for a brief period of time in
the vicinity of the front...have opted to remove any mention
from the forecast based on latest satellite and radar trends as
well as forecast soundings continuing to show strong
subsidence/shallow boundary layer. The main change to sensible
weather will be the decrease in temperatures and increase in
winds...as temperatures dip into the twenties and wind gusts
between 25-30mph on average develop behind the front with a
strong pressure gradient.
Continued strong cold advection will result in temperatures
10-15 degrees below normal today as high pressure builds
overhead. Winds will subside by tonight allowing winds to
decouple...allowing for a strong radiational cooling night
under clear skies.
Temperatures will drop into the mid-teens in many locations.
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.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
High pressure will maintain dry conditions through Thursday with
moderating temperatures expected.
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 southeasterly 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 /04Z WEDNESDAY THROUGH SUNDAY/...
Gusty WNW wind will gradually turn more northerly over the
evening hours as more cold air moves in, especially aloft. While
all sites will start to a broken mid-deck, cold air off the
surface and increasing low level instability will allow for
some lake-induced stratocumulus to start to move into the area,
however really only KFKL and KDUJ should manage much of a
ceiling out of it. Wind gusts will continue through the day on
Wednesday, however drier air advancing southward should really
start to eviscerate cloud cover quickly after sunrise. That
said, by 15z or so, all sites should again be VFR.
The next chance for widespread restrictions should come on
Friday with a front tracking across the lower Great Lakes.