Area Forecast Discussion
Issued by NWS -- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KPBZ 210529
Area Forecast Discussion
National Weather Service Pittsburgh PA
129 AM EDT Fri Oct 21 2016
A crossing cold front and large upper level system, will generate
more rain today. Much cooler weather will follow for the weekend.
.NEAR TERM /THROUGH TODAY/...
For the overnight, will be tracking a series of shortwaves moving
northeastward in the tight southwest flow aloft. The late night
energy will help to push the cold front and its associated low
pressure further east. By 12z the entire system will begin to
cross the ridge counties, pushing the axis of heavier rain into
Central Pennsylvania. Using a blend of hires data and current
radar and satellite trends, have update the PoPs overnight,
timing the movement of higher probability with the front.
Temperatures have also been updated.
The surface system will weaken this morning as it drifts east of
my forecast area. Behind the exiting front, strong cold air
advection will ensue, and the main upper level trough axis will
move over my Ohio counties early this afternoon. This will keep in
the chance for showers throughout the day and provide steady or
slowly falling temperatures. Additionally, surface winds will
increase with gusts of 20 to 25mph possible this afternoon.
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
the trough axis will pass to the east of the area late this
evening, and the colder air will continue to advect in. Will need
to keep in the chance for precipitation overnight with the cold
air advection and a saturated low level. However, as inversion
heights lower, expect any showers to become more spotty and light.
Cold advection in northwest flow, will keep in shower chances
Saturday, but this too will drift eastward as the large upper
level low swings northeastward toward New England. Latest hires
nam run is actually showing a lake enhanced band developing
Saturday morning, which will drift eastward throughout the day.
This looks reasonable considering the cold air aloft and the lack
of directional shear between the winds in the mid and lower
levels. Will shift PoPs eastward in correlation with the timing of
the possible band. Locations in the ridge counties, especially on
the peaks, could see a few snow showers mix in Saturday morning.
Building high pressure will bring and end to any lingering showers
over the northeast Saturday evening.
Dry Sunday, with a decrease in cloud cover as warm air advection
gets underway. Temperatures will recover on Sunday to near seasonal
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A fast moving shortwave is progged for an early week passage, with
most of the shower chances remaining north of PIT. Ridging is
progged thereafter through mid week before another trough advances
out of the Midwest by late week. Temperatures should average a few
degrees below seasonal levels through the period.
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A few terminals continue to hold on to MVFR or even VFR conditions
at the start of the TAF period, but with very moist low levels and
widespread rain, IFR and spotty LIFR are expected to develop or
persist at all terminals, and continue through much of Friday. Rain
will lighten with time, resulting in slow visibility improvement
through the day, but low ceilings will continue. Only late on
Friday and during Friday evening will locations from PIT on west
improve back to MVFR.
.OUTLOOK /FRIDAY NIGHT THROUGH MONDAY/...
Periodic restrictions are expected into Sunday as an upper trough
crosses the area.
MD...Flash Flood Watch until noon EDT today FOR MDZ001.
OH...Flash Flood Watch until noon EDT today FOR OHZ039>041-048>050-
PA...Flash Flood Watch until noon EDT today FOR PAZ007>009-013>016-
WV...Flash Flood Watch until noon EDT today FOR WVZ001>004-012-021-