PBZ issues Area Forecast Discussion (AFD) at Oct 7, 12:45 PM EDT955
FXUS61 KPBZ 071645
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
1245 PM EDT Wed Oct 7 2026
.WHAT HAS CHANGED...
Rainfall from the expected remnant low of Isaias may arrive a
bit earlier than previously forecast, and overall rainfall
totals have shown a bit of an upward trend. Widespread flooding
risks remain low.
&&
.KEY MESSAGES...
1) Dry weather continues into the weekend, with a warming trend
by Saturday
2) The remnant low of Isaias may provide a soaking rain Sunday
into Sunday night, although widespread flood risks remain low
&&
.DISCUSSION...
KEY MESSAGE 1...
A 500mb trough axis rotates across the Great Lakes tonight into
Thursday, before a transition to a quasi-zonal pattern tomorrow
afternoon through Friday. A weak, moisture-starved cold front is
slated to cross the Upper Ohio Valley late tonight into Thursday
morning. A mostly dry passage is figured, but a few sprinkles
cannot be totally ruled out north of Pittsburgh tonight as the
boundary may scoop up some minimal moisture from the relatively
warm Lake Erie waters.
Dry weather then continues through Friday and Saturday as
surface high pressure remains in control. Temperatures remain a
a bit above climatology through Friday. Southerly flow and
rising heights behind the departing high may push daytime highs
some 10 degrees above climatology on Saturday.
KEY MESSAGE 2...
Current NHC guidance still has Isaias landfalling on the Gulf
Coast Friday night, and then its remnant low reaching the Lower
Ohio Valley later Sunday night or early Monday morning. Model
guidance starts to diverge thereafter on the exact track, but
most have the low turning east and nearing or crossing the
Atlantic coast by Monday. This relatively speedy crossing over
or near our region will most likely keep rainfall amounts from
becoming excessive. There does seem to be a lean towards a
faster arrival time of the rain, with onset possible around or
after midnight Saturday night.
The 13Z NBM has 48-hour mean rainfall totals through 8 AM
Monday of between 0.8 and 1.2 inches, with a north-to-south
gradient. 50th percentile levels are relatively similar to the
mean values, suggesting less of a bimodal distribution in
solutions than from the NBM runs yesterday. However, there has
been an increase in the mean values as compared to yesterday.
90th percentile levels now fall in the range of 1.75 to 2.25
inches, also higher than yesterday. This is still below current
6-hour flash flood guidance values, which are above 2.5 inches
areawide save for very small pockets. Overall, the threat of
widespread flooding concerns remains low, although isolated
urban and poor drainage issues could in theory arise. In
particular, localized street flooding from debris-blocked storm
drains could be a problem in the higher-end rainfall scenarios.
Trends will be monitored. If slower motion of the remnant low
becomes more likely, then higher rainfall totals could be more
of a concern. Severe thunderstorms risks are also very low. The
probability of 250 J/kg of SBCAPE remains under 30%, and longer-
range machine learning guidance keeps severe probabilities less
than 5%.
With the faster overall motion, any heavy rainfall threat
currently decreases after 12Z Monday as the remnants head to our
east. Still, relatively light showers may linger into Tuesday as
some long-range scenarios bring another shortwave across the
Great Lakes.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
An approaching dry cold front positioned near central Michigan will
influence southwest flow with gusts reaching up to 20 knots.
These gustier conditions will continue until the front passes
overnight.
Scattered cloud coverage expected ahead of the front. This
combined with the breezier conditions will aid in keeping
overnight lows warmer than the last few nights which will likely
inhibit any potential river valley fog development tomorrow
morning. With winds staying breezy overnight, the chance for
periods of low-level wind shear in the area has diminished.
By daytime tomorrow, scattered clouds will clear with diurnal
westerly wind gusting up to 20 knots. Winds will ease tomorrow
evening as the high pressure moves into the area.
Outlook...
Other than varying chances for morning river valley steam fog,
VFR is favored through the weekend until a disturbance late
Sunday into Monday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
DISCUSSION...CL
AVIATION...Lupo
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 7, 12:45 PM EDT---------------
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