Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPBZ 211120
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
720 AM EDT Fri Jul 21 2017

.SYNOPSIS...
Relatively quiet today, a shower or storm is possible over the
southern half of the area. More activity expected this weekend,
perhaps with more strong storms and heavy rain Saturday and
Saturday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Quick morning update to adjust early morning PoPs based on the
latest radar observations and trends as convection has
diminished, for now. Otherwise, forecast remains as is this
afternoon.

Previous... Will keep low chance to slight chance PoPs across
the southern counties today, as whatever is left of Thursday`s
weak boundary gets hung up over Central West Virginia. A weak
upper level wave is expected to dive southward toward the
boundary this afternoon. Very warm temperatures aloft will
provide a cap, thus the low chance PoPs. Rest of the area looks
warm, muggy and dry.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
Model differences arise again this weekend with the timing and
strength of a shortwave that will dive through the region in
the northwest flow aloft. For now will lean away from the very
energetic NAM solution for Saturday/Saturday night. Because of
these large differences in the models, have low confidence at
this point for most of the weekend. The next major shortwave
trough is expected to bring showers and storms to the area
sometime on Saturday and continue into Saturday night. In
addition to the upper level wave, a surface cold front will
drift through the area Saturday night. By favoring a solution
closer to the GFS, have slowed likely PoPs on Saturday, focusing
them more toward the afternoon hours. There will be many
factors at play on Saturday, which will determine the strength
of the convection. Amount of sunshine, very warm air aloft, timing
of wave, timing of surface front and the possibility of surface
reflection developing along the front which will impact the
speed at which the boundary moves through. Hopefully, a model
consensus will develop over the next few runs.

Differences continue into Sunday, as does the low confidence in
the forecast.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A general Great Lakes/northeast U.S. trough will be carved out
by Monday, with this pattern holding into mid-week. Temperatures
will fall back to near or just below normal during this period.
After lingering showers, Tuesday and Wednesday appear dry with
high pressure settling over the region. A return to northwest
flow may herald increasing rain chances Thursday.

&&

.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
After patchy fog clears mid-morning...VFR conditions expected
through the day. Slight chance of shra/tsra at southern
locations but not enough confidence in coverage for inclusion in
the TAF at this time.

.OUTLOOK...
Additional rounds of storms are expected through the weekend,
and morning fog is possible as well.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.