Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 020027 AAB

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
827 PM EDT Sat Oct 1 2022

Rain associated with post-tropical cyclone Ian will move
eastward slowly through Sunday morning before subsiding Sunday


Synoptic ascent acting on deep moisture associated with the
remnants of Ian continues to support two bands of enhanced
rainfall: one enhanced by jet ascent from near KN38 (Wellsboro PA)
to KBTP (Butler PA) and a second within a deformation zone from
near KIDI (Indiana PA) to KW22 (Buckhannon WV).

The former, jet-supported zone of ascent is shifting ewd,
leading to an erosion of the nrn band from the western side, and
the focus for widespread rain is shifting mainly to the srn
deformation zone.

Rain rates in both areas appear more moderate compared to the
cold, light rain showers observed elsewhere, so overall totals
will be enhanced from Clarion to Dubois and Marienville, as well
as much of the WV ridge zones east of Morgantown. Despite the
enhanced ascent in these two regions, though, overall rain
rates through tonight are expected to remain insufficient for
flooding concerns.


The remnants of Ian will decay Sun as dry air north of the
Great Lakes is advected swd, and the remnant low opens and
tracks east. The net result will be rapidly decreasing rain
chances Sun morning. However, patchy rain showers may renew
late Sun afternoon as a result of lingering vorticity advection
before waning Sun evening.


Building high pressure over the OH Valley Mon afternoon through
Thu will return seasonable temperature during the day. However,
clear sky and a drastic drop in low-level moisture may lead to
favorable conditions for radiational cooling overnight, with the
potential for frost.

Ensembles suggest a shift in the overall atmospheric pattern
late next week as mature low pressure south of Alaska amplifies
an elongated downstream ridge over the Plains, leading to the
intrusion of unseasonably cold air into the Great Lakes region.
This air mass may warrant frost or freeze headlines for part of
the region next weekend.


Areas of rain with the remnant low of Ian, and low MVFR/patchy
IFR restrictions, will continue tonight for most ports south of
I-80. More persistent IFR is expected to continue through Sun
afternoon for MGW, where more rain and low-level moisture is
expected. The rain should begin to taper off late tonight and
Sun from NW to SE as the low exits the east coast. A gradual
improvement to VFR is expected for most ports by late Sun as
high pressure begins to build in behind the low.

VFR is expected until restriction potential returns with a late
Thu cold front.





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