284
FXUS61 KPBZ 031737
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
137 PM EDT Mon Jun 3 2024

.SYNOPSIS...
Aside from an isolated afternoon shower or thunderstorm across
the higher terrain, dry conditions are expected through Tuesday.
Rain returns Wednesday into Thursday with periodic rain chance
thereafter. Temperatures remain above average through much of
the week, cooling slightly into the weekend.

&&

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

- Dry weather with above-normal temperature.
- An isolated shower/thunderstorm or two is possible across the
  WV ridges this afternoon.

--------------------------------------------------------------

A low-probability chance for isolated thunderstorms continues
this afternoon primarily in the WV ridges, but weak ridging
will keep most of the area dry today. Rising heights, warm
advection, and decreasing cloud cover this afternoon should
drive high temperatures 5 to 10 degrees above normal (and 10-15
above Sunday`s highs).

Clouds will continue to dissipate overnight, leaving mostly
clear conditions. This will allow some fog development again
tonight, but increased mixing overnight should prevent
widespread formation. Overnight lows will drop into the 50s and
60s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Dry weather continues through Tuesday.
- Temperatures continue to trend up.

-------------------------------------------------------------------

Weak upper ridging will continue on Tuesday, maintaining mostly
dry conditions for the day. Isolated diurnal convection is again
possible Tuesday afternoon, mainly in the ridges. With a weak
surface high pressure shifting just off the east coast by
Tuesday morning, warm/moist advection will increase with
southerly flow. This will drive area temperatures 10+ degrees
above average (mid/upper 80s). NBM shows a 50-60% chance of
several hotspots (e.g. downtown Pittsburgh) briefly hitting 90F.

&&

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

- Showers and thunderstorms are expected Wednesday into Thursday
  with crossing low pressure.
- Periodic showers with cooler conditions are expected into the
  weekend with a slowly crossing upper-level low.

-------------------------------------------------------------------

An unsettled period is expected Wednesday into the weekend as an
upper level low slowly crosses from Manitoba through the Great
Lakes.

The most focused period of convection looks to be Wednesday
afternoon and overnight with a crossing shortwave and sfc
dewpoints in the upper 60s contributing to increased sfc-based
instability during the afternoon/early evening. Latest CSU ML
continues to support a low-end severe weather (wind) threat, but
potential will hinge on timing of initial convection (afternoon
or evening) and arrival of the front (overnight into Thursday
morning). For now, SPC still has us outlooked in a General
Thunder only, but we will continue to monitor.

Brief clearing is expected behind the front, but the upper-
level low will dig across the Great Lakes Thursday and Friday
and into New England by Saturday. This will keep cooler and
showery conditions in the forecast for the second half of the
week, generally favoring each afternoon. While there is low
confidence on pinpointing the best timing of these showers each
day, ensembles do agree on the general showery pattern with
upper troughing persisting through the weekend and possibly into
early next week.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
The earlier fog and stratus has lifted into a low-based cumulus deck
that is straddling the VFR/MVFR threshold. Expect coverage of these
clouds to continue to rise to VFR levels and to slowly decrease
through late afternoon under weak surface ridging. There is a small
but non-zero chance of an isolated shower or storm over the WV
terrain that should not impact TAF sites.

Most guidance is indicating some fog potential tonight, but with
some drying both of the surface and the boundary layer, expect that
this will be a little less widespread as compared to this morning.
NBM probabilities of less than 1 mile visibility are highest to the
south and east of Pittsburgh, and hit fog the hardest at MGW as a
result.  Do have a period of IFR fog at several other terminals,
while more western sites like PIT, BVI, and ZZV likely evade most
impacts.

Any fog will lift by 13Z, leaving mainly VFR conditions and a high
cloud deck in their wake.  Wind, like today and tonight, will be
largely light and variable underneath a building upper ridge.

.Outlook...
VFR conditions are favored until the next low pressure system
generates widespread showers and thunderstorms Wednesday into
Thursday. Fog, favoring the river valleys, could occur near dawn
prior to that next system.

&&

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

&&

$$

SYNOPSIS...Rackley
NEAR TERM...Rackley
SHORT TERM...Rackley
LONG TERM...Rackley
AVIATION...CL