-- Discussion containing changed information from previous version are highlighted. --
293
FXUS61 KPBZ 170248
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1048 PM EDT Mon Sep 16 2024

.SYNOPSIS...
Approach of a coastal low will raise precipitation chances mid
week but mainly favor areas southeast of Pittsburgh while having
a low probability of dissipating drought conditions. Above
average temperature is likely for most of the next week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --
KEY MESSAGES:

- Increasing cloud cover and low probability showers expected
  with coastal low approach
-------------------------------------------------------------------

Late Evening Update...
The 00Z PIT sounding continued to show very dry air below 400
mb, with moisture and cirrus above. With the dry air in place,
maintained only slight chance pops late tonight for Tucker
county, as moisture increases on the northern side of the low
centered across the SE CONUS.

Early Evening update...
No major changes needed. Latest hires model
data has slowed the chance for rain late tonight over mainly
Tucker county. The slight chance/chance PoPs were updated to
reflect this.

Previous discussion...
The slow northward movement of a Carolina low and its
associated moisture plume will gradually increase areal
coverage/thickness of cirrus overnight. Upslope flow and
increasing moisture will increase mostly light rain shower
chances for the higher terrain of WV after midnight. Otherwise,
the greater cloud coverage should limit nocturnal cooling.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
KEY MESSAGES:

- Periodic rain chances midweek as coastal low meanders around
  the Mid-Atlantic
- Probabilities remain low in seeing 1" or greater of rainfall
-------------------------------------------------------------------

There remains fairly high consensus for the coastal low to
meander around the Carolinas to Mid-Atlantic vicinity midweek as
its parent trough remains detached from the broader northern
jet streams. Drawing Atlantic moisture around its periphery
will lead to fairly robust cloud coverage across the forecast
area while embedded wave dynamics foster bands of precipitation.

The main question remains the exact low positioning, with two
scenarios (centered along NC coast; centered over central VA) is
the most likely outcomes. The farther southern positioning would
favor accumulating rainfall primarily to just the WV high
terrain, leaving periodic sprinkles for the area Tuesday night
through Thursday. The northern positioning would better bring
synoptic rain bands into the Upper Ohio River valley and offer
periodic wetting rains. Either solution is unlikely to offer a
great deal of hope for easing drought conditions; 72 hour
probabilities for greater than 1" are less than 10 percent
outside of the WV high terrain and even there the percentage is
only 30.

There remains high confidence that the coastal low influence
will begin to wane Thursday night by sagging southeast. Expect
a west to east gradient in changes to both temperature (higher),
cloud cover (lower) and precipitation chances (lower).

&&

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

- Above average temperatures return
- Dry weather next weekend
-------------------------------------------------------------------

Long range ensembles favor a highly amplified pattern of
positively titled ridging over the Great Lakes, a detached
saggy trough near the SE coastline, and shortwave troughs
traversing the northern Rockies. This portends to high
confidence in resumption of above normal temperature and dry
weather for the Upper Ohio River Valley. Variance in this
solution lays in the degree of ridge amplification for the Great
Lakes and/or whether phasing can develop between the sagging SE
CONUS trough and a deeper low near Nova Scotia.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR conditions prevail through the remainder of the TAF period
as high clouds overspread the area ahead of approaching low
pressure. Winds remain out of the east throughout the TAF
period.

.Outlook...
Occasional restrictions and isolated showers are possible
Tuesday through Thursday as low pressure slowly meanders south
and east of the area.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...WM/22/Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Cermak/22/Milcarek