457
FXUS61 KPBZ 172215 AAC
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
615 PM EDT Wed Jul 17 2024

.SYNOPSIS...
Showers and thunderstorms will continue through the evening with
a crossing front. High pressure will return dry conditions and
seasonable temperatures the remainder of the week and into the
weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
KEY MESSAGES:

- Showers and storms expected along and ahead of a cold front
  crossing through this evening.

- A small threat of strong to severe wind gusts remains, as does
  the risk of isolated flooding, although both threats will
  decrease with time.

 __________________________________________________________________

Update focused on minor adjustments over the next several hours
based on radar and observation trends. Outflow moving out ahead from
the main convective line has helped to sap its strength to some
degree, and the overall environment for strong wind gusts
remains poor with lackluster lapse rates and unfavorable DCAPE
values. An isolated strong to severe gust or two cannot be
totally ruled out, mainly in eastern Ohio where slightly more
favorable MLCAPE/DCAPE is located. Also, despite the lingering
high PWAT values, flooding concerns are lessening with time as
well as the overall line becomes more progressive, with urban
areas most likely to see any impact from localized 1-2"/hour
rainfall rates. The cold front itself is just now crossing into
the northwest corner of the CWA, and will continue to slowly
progress to the southeast through the evening.

Once the main line departs the region by 01Z/02Z, a few
scattered showers may linger ahead of the crossing boundary,
which should exit the region shortly after midnight. Partial
clearing is expected overnight, although stratocumulus may
linger particularly in the ridges. Patchy fog cannot be ruled
out as well, although ongoing mixing may limit its extent to
some degree. Dewpoints and temperatures will drop off through
the night as well, although a noticeable difference will likely
wait until daytime mixing on Thursday.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
KEY MESSAGES:

- Dry and cool conditions Thursday with temperatures moderating
  to near normal Friday.

  _________________________________________________________________

Dry and seasonable conditions are expected as surface high
pressure builds eastward over the region. Low- level cold and
dry advection will keep temperatures near or even a few degrees
below average Thursday and Thursday night with valley fog
chances.

Stout mixing into the day on Friday under high pressure will
result in temperatures near normal, and fairly low humidity.
This will leave the area feeling comfortable for the last day of
the work-week.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
KEY MESSAGES:

- Mainly dry weekend with high pressure in control.

- Precipitation chances return for the start of the week.
-------------------------------------------------------------------

Digging trough over the central Plains may lead to a slight
increase in 500mb heights Saturday/Sunday. This may also bring
some moisture return to the upper Ohio Valley but at this time,
precipitation looks to be limited to the ridges south and east
of PGH. With rising heights, temperatures will trend higher to
slightly above normal. Strengthening southwesterly flow will
return precipitation chances into early next week ahead of
approaching low pressure.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
Line of showers and storms will exit to the south of the region
early in the forecast period. A return to VFR conditions is then
expected.

The biggest question overnight will be the formation of fog. The
combination of clear to partly cloud skies and the rain
this afternoon/evening, is a good setup for fog. However, drier
air will be spreading southward overnight behind an exiting
cold front. Latest probs show a 50-70% chance of MVFR fog
generally in the ridges and some of the river valleys. Seeing
the same probs for IFR vis as well. Will mention fog at all
ports overnight and bring the forecast down to IFR in the
eastern ports and those near the rivers.

Fog will burn off quickly after sunrise and a return to VFR is
expected at all ports. Sct CU should develop with daytime
heating on Thursday.

.Outlook...
VFR is expected Friday through Sunday under building high
pressure.

&&

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

&&

$$

SYNOPSIS...34/CL
NEAR TERM...34
SHORT TERM...34
LONG TERM...34/88
AVIATION...22