.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Current shower as of 11AM EDT is stationed along a IPT-SEG-MDT
line, and this activity is expected to gradually wane as it
moved eastward and out the forecast area by ~15Z Wednesday, with
a SCT-BKN VFR cumulus deck expected to follow throughout the
afternoon. A few diurnally driven showers/thundershowers may
develop (PROB30) between 17Z-21Z over the eastern terminals
(KIPT/KMDT/KLNS) as the shortwave continues exiting the region,
though most areas will remain dry. The 12Z TAF package resolves
these mentions with PROB30s with lowest confidence on timing and
coverage. Otherwise, southwest winds will increase to around 10
kts, with gusts of 15 to 20 kts likely during the day.
High clouds will filter overhead Wednesday evening ahead of a
potent low pressure system moving across the Great Lakes. A band
of -SHRA/-RA will overspread much of the Commonwealth from west
to east overnight, followed by the passage of a decaying MCS.
While the MCS will be weakening as it encounters more stable air
across central Pennsylvania, it will be coincident with an
unseasonably strong nocturnal LLJ (~65 kts at 850 mb, above the
99th percentile for this time of year). As such, a period of
LLWS concerns + southerly ridgetop wind gusts are likely
overnight into Thursday morning for virtually all terminals,
along with the potential for gusty winds to be transported
within the weakening MCS. The main change with regards to this
was penciling in some PROB30s for TSRA at BFD where there is
slightly higher confidence in some TS at the airfield and
extending LLWS mentions further east towards IPT/UNV/JST/AOO
towards the end of the TAF package.
Outlook...
Thu...Restrictions possible in -SHRA/-TSRA.
Fri...Showers ending.
Sat-Sun...Chance of afternoon showers and thunderstorms over the
north and west.
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