401
FXUS61 KPBZ 270536
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
136 AM EDT Thu Jun 27 2024

.SYNOPSIS...
Dry weather resumes today with shower and thunderstorm chances
returning for the weekend. Near normal temperatures today will
rise into the weekend.

&&

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

- Fog development expected this morning.
- Dry weather resumes today with near normal temperatures.

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A moist, cool airmass remains after recent showers and
thunderstorms across the region, and with relatively light wind
and temps approaching saturation, patchy fog development is
expected overnight (especially for river valleys absent of low
level cloud coverage). Any stratus or fog should erode by mid-
morning, with mainly upper- level clouds lingering thru the day.

Cool, dry northwest flow will develop as high pressure builds
in from the northwest with increasing subsidence diminishes
lingering stratocu through the morning, which should eventually
turn into scattered afternoon cumulus. Cold advection and
partial cloud cover will result in more seasonable afternoon
temperature while post- frontal mixing may support NW wind gusts
around 20 mph.

&&

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

- Dry weather continues.
- Temperature rises above normal again Friday.

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The surface high will shift over New England by Friday as
heights aloft rise ahead of the next upper level shortwave
trough. Positioning of the high will support weak warm, moist
advection amid mostly clear skies to raise area temperature
about 5 degrees above the daily average. Broad ascent may
increase mid to high level clouds and even low probability
showers Friday night as weak perturbations ahead of the main
upper level trough axis.

&&

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

- Shower and thunderstorm chances return Saturday into Sunday
  with the next low pressure system.
- Low probabilities exist for a damaging wind and flooding
  threat with these thunderstorms.

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

Broad ascent within warm, moist southwesterly flow ahead of the
main upper level trough axis will support increasing shower and
thunderstorm probabilities starting early Saturday morning.
Arrival of a more notable embedded shortwave and the surface
cold front Saturday afternoon and evening is likely to help
concentrate convective activity (currently favoring NW PA) and
spreading it southeast through Sunday morning.

Variation in storm timing and environment remains large due to
differences in upper trough depth/timing as well as convective
evolution prior to its (and cold fronts) arrival. Latest
analysis suggests a low probability risk for damaging wind
(mean values currently show 30-40kts of 0-6km shear) and
localized flooding (tall-skinny CAPE values around 1500 J/kg
with PWATs approaching daily maxima). Will mention threat in HWO
and monitor evolving forecasts for this period.

Dry weather and seasonable temperature is likely by late Sunday
into Monday as the upper trough axis moves east and high
pressure builds in from the western Great Lakes.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Little change was made to the 06Z TAFs for tonight with much of
the forecast still on track for some fog and low cloud
development tonight. Probabilities of IFR vis restrictions
remain highest to the west of KPIT with probabilities towards
60% due to anticipated clearing and recent rainfall. The
probabilities of IFR cigs remain highest (70% to 90%) east of
PIT, with plenty of moisture near the surface and nocturnal
cooling. Some combination of restrictions was noted for all
ports with lifting anticipated into the day. Broken decks are
favored just after sunrise. By afternoon, there is a 80% to 50%
probability that broken decks become scattered as we transition
to VFR boundary layer cumulus.

Cloud cover is expected to clear tomorrow night as mixing
ceases. This may lend to patchy MVFR vis restrictions late
overnight in fog. This remains most likely for river valley
ports and north of I-80.


.Outlook...

VFR is expected through Fri amid high pressure. Restrictions
are possible Fri night with a crossing warm front.

Restrictions are likely Sat and Sat night with showers and
thunderstorms ahead of and along a crossing cold front. VFR
returns Sun under high pressure.

&&

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

&&

$$

SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...Frazier
AVIATION...Milcarek