PBZ issues Area Forecast Discussion (AFD) at Oct 23, 7:51 PM EDT026
FXUS61 KPBZ 232351
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
751 PM EDT Wed Oct 23 2024
.SYNOPSIS...
Low rain chances return into this evening with the passage of a
cold front. Seasonable to above average temperatures can be
expected Thursday and Friday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
KEY MESSAGES:
- Scattered showers and thunderstorms with a passing cold front
- Northwest wind subsides overnight
-------------------------------------------------------------------
Cold front is currently crossing eastern Ohio/southwestern
Pennsylvania. Scattered low-topped thunderstorms have managed
to form along the boundary, working with weak instability (less
than 500 J/kg of surface-based CAPE) and 30-40 knots of
effective shear. A couple of the storms have been prolific
lightning-producers, and small hail/wind gusts to 40 MPH are
certainly possible in the stronger cells. Severe weather is not
anticipated at this time, as available instability will continue
to wane from here over the next couple of hours. Scattered
coverage will continue along the boundary as it advances east of
the ridges by 06Z, with some expansion southward expected as it
approaches the terrain. A gust of wind may also accompany the
boundary as it crosses. Wind gusts have largely subsided away
from the front and storms, but northwest wind behind the front
will keep the boundary layer mixed overnight. Low temperatures
will run a couple degrees above the climatologic means, due to
this mixing and still-elevated dew points in the upper 30s and
lower 40s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
KEY MESSAGES:
- Dry and seasonable temperatures return Thursday in the wake of
a cold front
- Ridging will return above average temps Friday
-------------------------------------------------------------------
Confidence is high that by early Thursday morning the cold
front will be positioned east of the Laurel Highlands and
cooler temperatures will return. Given the overall dry pattern
with the passage of the aforementioned trough, cloud coverage
will be limited in the wake of the front. Afternoon high
temperatures will likely be near average (low-60s/upper-50s).
Upper-level flow will become zonal Friday and strong warm air
advection is expected ahead of an approaching cold front. Shower
chances will increase late Friday into eastern Ohio with
ejecting moisture from the southwest along warm front. Linger
low-level dry air across western PA may dissolve precipitation
chances through at least midnight.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
KEY MESSAGES:
- Confidence is increasing that above average temperatures
return Monday and continue through mid-week after a brief
period of near-normal temps Sat/Sun
-------------------------------------------------------------------
According to the grand ensemble of long range models, the
overall depth of an eject trough over the Great Lakes is up for
debate on Saturday morning. However, variability for 500mb
height range only about 4 decimeters. The NBM 25th percentile
and 75th percentile ranges in temperatures by about 3-4 degrees
(upper-50s vs. low-60s). Regardless, temperatures will likely
be seasonable Saturday into Sunday with northwest flow.
Light rain chances are possible late Saturday into Sunday.
However, probability of 0.10 inches in 24 hours is less than
40% given elevated dry air noted on ensemble soundings.
Above average temperatures will likely return as a ridge axis
builds over the Great Lakes Monday and remains stationary over
the East Coast mid-week.
According to the NAEFS and GEFS climate anomalies, in regards
to heights/temperatures, the Mid-Atlantic notes a 2.0 to 2.5
standard deviation above average and could once again create
near record daily temperatures. The 95th percentile for the NBM
depicts temperatures in the upper-70s and low-80s Tuesday and
Wednesday.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
An advancing cold front will promote isolated thunderstorms
mainly for western PA as it crosses early this evening through
04z.
VFR will generally resume after its passage as high pressure and
dry advection aloft work to erode stratocu and midlevel decks.
Flow is expected to turn more northwesterly to northerly as the
upper trough axis crosses after 04z. Cold advection plus lake
enhancement may trigger scattered to broken stratocu through
12z Thursday across western PA, with probabilities for MVFR cigs
approaching 50% at FKL/DUJ.
High pressure and waning flow aloft will result in clearing
skies and falling wind speed Thursday afternoon and evening as
VFR conditions continue.
.Outlook...
VFR under high pressure will dominate until the next fast-moving
upper trough crosses around the start of the weekend which may bring
additional restrictions in rain showers Friday night into Saturday
morning.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Hefferan/CL
NEAR TERM...Hefferan
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...Frazier
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 23, 7:51 PM EDT---------------
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