041
FXUS61 KPBZ 231451
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1051 AM EDT Thu May 23 2024

.SYNOPSIS...
Showers and storms are likely to develop south of Pittsburgh
after 5pm today with a new disturbance. Foggy conditions are
expected overnight into early Friday south of Pittsburgh, PA.
Periodic thunderstorm chances are expected through the holiday
weekend as a series of upper level disturbances cross the
region.

&&

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

-Ridging over the region will keep the area mostly dry through
 through 6pm.
-A disturbance to our south will advance late this afternoon and
 stir up showers and storms late this evening into the overnight
 hours; probabilities are high south of I-70 for convection
 redevelopment.
-Fog is expected to develop south of Pittsburgh during the
 overnight hours under warm, moist airmass.

_____________________________________________________________

A stationary boundary is currently situated between
Morgantown,WV and Pittsburgh,PA early this morning. A few
showers are stirring in northern West Virginia within a warm,
moist airmass (dew points south of I-70 are still in the
mid-60s). Lightning probabilities are low given convection is
below the freezing level (10kft).

Elsewhere, drier air from the north has advanced in the wake of
the late night passing front and cloud coverage has decreased.
Warm, dry conditions are likely to last for a large portion of
the region under ridging. However, Hi-Res models have been
consistent that a shortwave late this evening from the south
will cause redevelopment of showers and storms after 6pm.
Instability will be plentiful (1000J/kg to 1500J/kg) during the
passing of the shortwave. However, shear will be mostly weak
(effective shear less than 30kts). A few storms may be
considered strong south of I-70 with DCAPE values ranging
between 500J/kg to 700J/kg for a brief time period.

The probability of strong storms will likely decrease as we
approach midnight as outflow from lingering convection decreases
the potential of dry, cool cores surging to the surface. The
threat will likely evolve to heavy rain due to slow moving
storms.

The potential for fog late tonight increases in the vicinity of
the stalled boundary and where showers and storms were
considered robust and/or long lasting.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
KEY MESSAGES:


- High pressure and brief ridging should keep the area dry
  Friday.
-A crossing shortwave will return the risk for showers and
 storms Saturday.
 _____________________________________________________________

Confidence is increasing that dry weather will develop Thursday
night into Friday as shortwave ridging crosses the region with
high pressure at the surface. Minimal airmass change with
slightly higher heights should promote above normal temperature
again.

Ensembles are leaning toward a wave crossing the region
Saturday producing showers and thunderstorms; timing varies,
but potential exists for convection to exit east of the area
before evening activities. That variability leads to an
inconclusiveness on severe potential but note that analogs for
the pattern and machine-learning analysis suggests at least a
low probability for hazardous weather that day.

&&

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

- Variability remains high on long term forecast and may be
  predicated on prior day`s convective outcomes.
- Overall, periodic showers and thunderstorms with slightly
  above normal temperature is favored through the holiday
  weekend and into next week.
  ____________________________________________________________

A more well-organized low pressure system is becoming the
favored pattern development to end the holiday weekend as it
lifts through the Great Lakes. Higher probabilities for showers
and thunderstorms are expected during this time frame but it is
unlikely to be "all day" rain type of events. Early analogs for
this pattern also suggest at least a low probability for
hazardous weather, but much variation in that potential remains.

Long range suggests a shift to a cooler, dry pattern by the
middle of next week as upper troughing develops over the Great
Lakes. Expect temperature to fall below the seasonal average,
with Tuesday potentially being the transition day from shower
activity to dry weather.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
VFR and light wind expected through the TAF period, except for
MGW where a shower or storm will be possible late afternoon /
early evening in the vicinity of a stalled front.

.Outlook...
Periodic thunderstorm chances and restrictions are likely
through the weekend as an active weather pattern continues.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...22/Frazier
LONG TERM...Frazier
AVIATION...88