Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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500
FXUS61 KPBZ 201123
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
723 AM EDT Sat Jul 20 2024

.SYNOPSIS...
Dry weather is expected for most of the area through Sunday
night under high pressure. The exception today is a wave of low
pressure could bring a few showers or thunderstorms to areas
southeast of Pittsburgh. A unsettled weather pattern is expected
next week, with periodic chances for showers and thunderstorms.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:

- Dry for much of the area under high pressure

- Shower/thunderstorm chances SE of Pittsburgh with a wave of
  low pressure

__________________________________________________________________

Made a few minor updates to the early morning forecast update.
Surface high pressure will keep most of the area dry today as it
builds further across the Upper Ohio Valley region. The
exception will be for areas southeast of Pittsburgh, where a
shortwave/vorticity maximum embedded in southwest flow aloft
tracks northeastward from the TN Valley. Most of the upper
support and ascent will stay southeast of our region, though as
convective temperatures are reached, and ascent from the vort
max approaches, scattered showers and thunderstorms should
develop through the day. Instability should be minimal, with MU
CAPEs around 500 j/kg.

High temperatures should be similar, or a couple of degrees
higher, than yesterday`s readings with slightly higher
1000-500mb heights, and warmer 850mb temperatures.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Dry weather expected tonight through Sunday night

- Unsettled weather pattern begins Monday

_________________________________________________________________

The vort max will exit off the Mid Atlantic coast this
evening, with any showers/storms SE of PIT quickly ending.

Ridging, ahead of a Central CONUS trough, will build across the
Upper Ohio Valley region tonight through Sunday night. This
will maintain (or return) dry weather across the region, along
with some increase in temperatures.

An unsettled weather pattern begins on Monday, as the Central
CONUS trough begins to drift eastward. Moist advection and
a shortwave embedded in southwest flow aloft will return
scattered showers and thunderstorms to the region on Monday,
continuing Monday night. The Storm Prediction Center has the area
included in a general thunderstorm outlook, and this seems
reasonable given limited instability.

Temperatures are expected to continue to run above average, with
dew points increasing back into the 60s by Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Periodic shower and thunderstorm chances increase through the
  week
- Above average temperatures expected

________________________________________________________________

Model ensembles indicate the Central CONUS trough will continue
a slow eastward drift through the week, approaching and crossing
the Upper Ohio Valley region by late week. Continued moist
advection and shortwave embedded in southwest flow ahead of the
trough, and the late week passage of the trough, will maintain
periodic shower and thunderstorm chances through late week. A
diurnal trend in the POPs is forecast with daytime instability.

Temperatures are expected to average near, to a few degrees
above, seasonable levels through the period.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
VFR expected through the TAF period with light to variable
winds and mainly streams of broken to overcast cirrus.

Closer proximity to shortwave movement will create isolated to
scattered showers around and east of MGW through this afternoon.
Probability of lightning remains low (less than 30%) given
excessive cloud cover in the area. Reduction in area cloud cover
is likely overnight as trough positioning pushes the moisture
plume farther east.

.Outlook...
VFR is expected through the Monday under the influence of high
pressure, though probabilities increase for isolated to
scattered afternoon storms Monday mainly along the WV higher
terrain and Laurel Highlands.

Scattered shower and thunderstorm chances are expected Tuesday
through Thursday with the slow approach of an upper level trough
from the west. Current probabilities favor afternoon to evening
storm timing, with lower risks during the overnight to morning
hours.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$

SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...Frazier