298
FXUS61 KPBZ 301728
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
128 PM EDT Sun Jun 30 2024

.SYNOPSIS...
Isolated showers and storms will continue to move ahead and
along a cold front early this morning into early afternoon.
Building high pressure will return comfortable dry weather for
the first half of the week before an unsettled pattern takes
hold to close out the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Isolated showers and thunderstorms are possible with a passing
  cold front.
- Cooler and drier weather expected tonight behind the front.
-------------------------------------------------------------------

The cold front continues sagging south across the area in an
environment in which instability is plentiful with up to 1500 J/kg
MLCAPE, EBWD of 30-40 knots, and DCAPE up to 1100 J/kg. However,
updrafts are struggling with vertical extent as low and mid level
lapse rates are poor, and storms are really only growing closer to
the higher terrain where orographic influences may be providing an
extra nudge. A good amount of mid-level dry air has started to work
in as noted on the 12 PIT sounding, so despite the arrival of better
forcing, updrafts may be entraining dry air. With warm rain
processes still dominant, any shower or storm will produce a quick
burst of heavy rainfall with it (earlier storms had 3-4"/hr rainfall
rates). Our window for development will continue over the next
couple hours until the front clears the area, and the highest threat
for any strong storms still appears to be south and east of
Pittsburgh.

Convection promptly ends with the passage of the front. We then
finally get a push of drier air (dew points in the 40s upstream) as
high pressure builds across the Great Lakes and reinforces northerly
flow in the wake of the boundary. Clouds will scatter into early
this evening save for north of I-80 where forecast soundings
indicate that lake moisture under northerly flow will remain trapped
beneath increasing subsidence. In addition, a passing upper wave
looks to reinforce cloud coverage further south toward morning on
Monday. Still, overnight lows will be refreshing dipping into the
50s/ (60-80% chance of upper 40s in the ridges and north of I-80).

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
KEY MESSAGES:

- Drier air builds in with cooler temperatures.
-------------------------------------------------------------------

Dry weather and below normal temperatures prevail with high
confidence Monday and Monday night as heights begin to rise and
high pressure builds east. In fact, latest HREF probabilities
show most locations having a <30% chance of reaching 75 degrees,
with the exception being urban areas (e.g., Pittsburgh metro)
and portions of eastern OH south of I-70 where the probabilities
for reaching 75 degrees are closer to 50%. Low temperatures
Monday night dip into the low to mid 50s, roughly 7-10 degrees
below normal for this time of year.

&&

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

- Dry weather continues Tuesday with warming temperatures.
- Showers and thunderstorms expected Wednesday through the end
  of the work week with the return of a more active pattern.
-------------------------------------------------------------------

Good agreement amongst the various ensemble clusters supports dry
weather on Tuesday as ECONUS ridging builds. Temperatures begin to
rebound as flow becomes more south of east and pushes highs back
toward or a couple degrees above normal.

By mid-week, ensembles break the ridge down and shunt it
southward over the Southeast CONUS and Gulf Coast, leaving
zonal flow over the Ohio Valley and lower Great Lakes while
lower heights settle in upstream over the upper Great Lakes and
Midwest. This patten is certainly more active than the first
half of the week, promoting surface low pressure over southern
Ontario that quickly tracks northeastward and leaves a trailing
cold front sagging southward into our area late Wednesday into
Thursday. There is some minor concern at this time that the
zonal flow overtop what appears to be a slowing and
weakening/diffusing cold front could lead to a setup where
multiple rounds of showers and storms develop along said east-
west oriented boundary in a moisture-rich environment (ensemble
mean PWATs surpassing 1.75 inches), leading to training of
thunderstorms and flooding rain potential. It`s too far out to
say any of this with certainty, but I would like to see the
pattern become a bit more progressive to prevent the front from
slowing or stalling over the local area and put these concerns
at ease. Additionally, machine learning continues to highlight
some severe potential with this pattern as the front will
initially be moving into a warm and moist airmass, though weak
flow aloft resulting in limited bulk shear is helping to keep
the overall threat low at this time. Still, this too will bare
watching over coming days.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...

As the front slowly crosses, convection may development towards
LBE and MGW, utilizing some surface heating early this
afternoon. However, confidence is still low that the terminals
will be directly impacted.

Hi-Res guidance suggest VFR conditions will continue to build
between 18Z to 20Z for areas north of PIT. Daytime gusts will
range from 20-25kt with post-frontal mixing of a tight pressure
gradient. Stratocumulus decks may try to fill in late
tonight/early tomorrow monring unde northwest flow; especially
for DUJ/FKL.

.Outlook...
VFR is expected until a slow moving front sets up across the
region Wednesday and Thursday.

&&

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

&&

$$

SYNOPSIS...MLB
NEAR TERM...MLB
SHORT TERM...Cermak/MLB
LONG TERM...Cermak/MLB
AVIATION...Hefferan