PBZ issues Area Forecast Discussion (AFD) at Oct 6, 8:46 PM EDT566
FXUS61 KPBZ 070046
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
846 PM EDT Sun Oct 6 2024
.SYNOPSIS...
Showers and thunderstorms will continue ahead of a crossing cold
front tonight. Noticeably cooler temperatures and dry
conditions are expected Monday and through the work week.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
KEY MESSAGES:
- Severe thunderstorm risk will continue to decrease as a cold
front crosses the region.
- Cooler temperatures by morning behind the front.
-------------------------------------------------------------------
Convection overall has shown a general weakening trend over the
past hour as instability diurnally decreases. Effective shear
will remain at the 35 to 45 knot level over the next couple of
hours, and the front will continue to drive convective updrafts,
but those updrafts will likely not be strong enough to drive
cores high enough for large hail, take advantage of decreasing
levels of DCAPE, or be able to support the decreasing tornado
threat much longer. What possibly may have saved the area from a
more widespread tornado threat is the initially high LCL
values, and these were as high as they were, at least in part,
due to dewpoints coming in just a touch lower than previously
expected (around 60 as opposed to more general lower- mid 60s).
The Severe Thunderstorm Watch continues along and ahead of the
front for now. It will almost certainly expire on time, if not
be cancelled in its entirety a little early.
Nevertheless, likely/categorical PoPs are still needed as the
boundary continues across the CWA, and that boundary should exit
entirely by 06Z. Localized heavy rainfall with the thunderstorms
will not cause much of a flooding threat given the dry
antecedent conditions, but localized poor drainage/urban issues
cannot be entirely ruled out.
Clearing should be fairly rapid behind the front, but late
tonight, some clouds and a few isolated showers may return to
areas north of I-80 as the shortwave trough axis moves through.
In the wake of the front, overnight temperatures will fall to
near average.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:
- Dry weather and much cooler temperatures.
-------------------------------------------------------------------
Any showers north of Pittsburgh should end during the morning
with the departure of the shortwave trough axis. Much cooler
air arrives behind the front for Monday and Tuesday, with a drop
of 15 to 20 degrees from Sunday levels expected. Surface
ridging will extend into the region from an anticyclone dropping
into the middle Mississippi Valley. This surface high will then
extend its influence over the middle and upper Ohio Valley by
midweek, providing dry weather and continued near to below-
normal temperatures. Some very spotty frost potential may exist
both Tuesday and Wednesday mornings, although potential for this
appears higher later in the week.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
KEY MESSAGES:
- Dry weather continues through at least Saturday; light rain
possible by Sunday.
- Temperatures near to below normal through Thursday before a
warming trend starts Friday.
- Frost potential in some areas Thursday and Friday mornings.
-------------------------------------------------------------------
High pressure is forecast to persist across the middle and upper
Ohio Valley into at least Saturday, with fairly high confidence as
there is strong ensemble support for that outcome. The troughing
pattern aloft persists into Thursday, with continued near to below-
normal temperatures, before heights rise thereafter lead to a
warming trend for Friday and the weekend. Towards the end of the
forecast period, cluster analysis starts to show some disagreement
with trough/ridge strength and timing, mainly providing some small
uncertainties in temperatures. However, if troughing does
reestablish by Sunday, there is potential for some light rain thanks
to shortwaves traversing said trough.
Probabilities of morning lows below 37 degrees (representing at
least a threat of patchy frost) are at or above 50% for a good
portion of the area both Thursday and Friday mornings, with some of
the deeper valleys of northern West Virginia likely to experience a
hard freeze.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
A squall line with embedded thunderstorms riding along a cold
front is pressing through the area. FKL and BVI are already
on the back side of the cold front and have returned to VFR
conditions. HLG, PIT, AGC and DUJ are expected to see VIS drop
to MVFR conditions in rain, there is a chance that VIS drops
down to IFR in heavier rain. A return to VFR conditions is
expected from west to east. HLG, AGC, DUJ and PIT are expected
to clear out between 01-02z. LBE will be the last terminal to
see storms reach and clear the area and is expected to return
to VFR by 04z.
Storms may not hold together well enough to bring the same
impacts to MGW as other terminals. It is far enough south that
it may see similar conditions to ZZV that reported VCTS only
once and saw no impacts to VIS at all. As such, MVFR conditions
are not included in the TAF at this time.
After a return to VFR conditions late this evening, such
conditions are expected to prevail through the day.
.Outlook...
VFR conditions are highly likely through much of the rest of
the week under the influence of high pressure. Cooler
temperatures and light wind nights may result in brief periods
of morning river valley fog.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...CL
NEAR TERM...CL
SHORT TERM...CL
LONG TERM...CL
AVIATION...AK
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 6, 8:46 PM EDT---------------
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