-- Discussion containing changed information from previous version are highlighted. --
649
FXUS61 KPBZ 191206
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
806 AM EDT Sun May 19 2024

.SYNOPSIS...
High pressure will provide mainly dry weather and a warming
trend in temperatures through Tuesday. Showers and storms return
Wednesday through late week.

&&

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

- Morning fog possible, followed by mostly sunny skies.
- Above-normal temperatures continue as a warming trend begins.
  _____________________________________________________________

Latest RGB satellite composites confirm fog is beginning to
develop in area river valleys. Expect this trend to continue
through sunrise as fog potentially becomes more widespread, with
the most dense pockets focused along rivers and in areas where
the heaviest rain fell earlier in the weekend. Fog should
dissipate rather quickly after sunrise with the onset of diurnal
heating/mixing. An upper ridge building overhead in the wake of
the Friday/Saturday trough should keep winds light and
temperatures warm throughout the day, with highs climbing into
the low to mid 80s across much of the area this afternoon,
around 10 degrees above normal for this time of year.

Mostly clear skies, light winds, and above-normal temperatures
continue straight through tonight with lows expected to remain
in the mid to upper 50s across the area.

&&

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

- Dry weather can be expected through Monday night.
- Temperatures continue to climb to 10-15 degrees above normal.
  _____________________________________________________________

Dry weather is still forecast for the majority of the region
through Monday night as the upper ridge remains in place
overhead. Temperatures continue to warm as well, reaching the
mid to upper 80s during the afternoon, roughly 10-15 degrees
above normal for this time of year. Lows Monday night remain in
the 60s for most areas outside of the ridges, where mid to upper
50s remain likely.

&&

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

- Dry and quite warm Tuesday.
- Rain chances return for Wednesday and Thursday, with some potential
  for strong thunderstorms.
- Seasonable temperatures and lower rain chances are expected Friday
  and Saturday.
____________________________________________________________

Dry weather prevails through Tuesday night as the upper ridge
slowly works its way off of the Atlantic Seaboard. A very weak
shortwave moving through its northwest periphery traverses the
lower Great Lakes Tuesday afternoon and could bring just enough
lift to support a few isolated showers and storms across NW PA
and NE OH. This is reflected in the forecast with low-end PoPs
(~20%) primarily north of I-80 and across our northernmost tier
of Ohio counties. The bigger impact on Tuesday will be
temperatures, with plenty of sunshine and dry antecedent
conditions pushing values further into the upper 80s and
potentially closing in on 90 degrees in some areas. Ensemble
probabilities for highs on Tuesday reaching 90+ degrees are >50%
in river valleys and urban areas at this time. It`s not out of
the question for some of the "cooler" daily records (86 at DUJ,
91 at PHD, and 92 at PIT/MGW) to be within reach.

While models continue to show some minor differences with the
strength and timing of a series of troughs ejecting from the
central Rockies across the Plains during the middle part of the
week, the larger overall signal generally favors a deepening
upper low over the Upper Great Lakes Wednesday morning and a
second shortwave trough subsequently rotating around its
southern periphery and across the lower Great Lakes Wednesday
night into Thursday. The result of this pattern is increasing
chances for showers and thunderstorms both Wednesday and
Thursday across the local area, with the highest probabilities
(currently 50-70%) coincident with the latter shortwave timing
Wednesday night and Thursday morning. We will continue to watch
for the potential for severe weather with this system, as
CIPS/CSU severe guidance continues to show some potential,
particularly on Wednesday. Temperatures on Wednesday, while
still expected to run above normal, may be knocked down a few
degrees compared to Tuesday due to the increasing cloud cover
and coverage in showers and storms.

Model divergence increases as we look beyond the cold front
passage on Thursday, but it does appear that the passage of
additional weak shortwaves may provide lower-end chances
(20-40%) for rain straight through the weekend, with
temperatures returning closer to climatology during that time.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Lingering IFR fog restrictions remain at a few sites (HLG, AGC,
ZZV) this morning with river valley fog showing quite nicely on
satellite imagery. FKL/DUJ have seen low level moisture
manifest as stratus and are still stuck in LIFR to IFR CIGs.
Expect these restrictions to improve within the next couple
hours and by 14z or shortly thereafter all sites will return to
VFR and remain there with high confidence through today with
mostly clear skies and light to calm winds under high pressure.

Patchy fog remains possible (40-60% chance) Sunday night once
again, but mainly after 06Z and east of Pittsburgh.

.Outlook...
VFR and dry weather with high confidence are expected Monday
and Tuesday under the influence of high pressure. Precipitation
chances and associated restrictions return Wednesday with the
passage of a cold front.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Cermak/CL
NEAR TERM...Cermak/Rackley/CL
SHORT TERM...Cermak/CL
LONG TERM...Cermak/CL
AVIATION...MLB/Milcarek