523
FXUS61 KPBZ 011506
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1106 AM EDT Mon Jul 1 2024

.SYNOPSIS...
High pressure will provide dry and comfortable weather for the
first half of the week before an unsettled pattern takes hold to
close out the week.

&&

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

- Dry and comfortable today.
- Temperatures below normal.
-------------------------------------------------------------------

For a mid morning update, only needed to make some minor
adjustments to cloud cover and dewpoints, with slightly higher
values being observed than forecast. Expect the drier air aloft
to mix and bring those values down as we warm through the
afternoon. Otherwise, no other changes are necessary at this
time.

Previous...Slow height rises aloft and building high pressure
will provide dry and comfortable conditions with lots of
sunshine. With a cool northwest flow aloft, temperatures will be
below normal.

&&

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


- Dry weather through Tuesday and most of Wednesday.
- Temperatures warm both days with above normal readings
  returning on Wednesday.
-------------------------------------------------------------------

Building 500mb ridge is anticipated on Tuesday as well as warm
air advection. Surface high pressure will drift across the
region. All of this will mean another quiet weather day with
temperatures warming to near or just above normal.

Ridge will slowly break down on Wednesday, as a shortwave
trough digs into the upper Midwest and pulls a surface cold
front eastward. Even though the ridge will be flattening, warm
air advection is expected to continue pushing highs toward 90
degrees. Still some timing issues on how quickly activity may
reach the western half of the region ahead of the cold front.

NBM begins to introduce probabilities for measurable
precipitation Wednesday afternoon. The high probs (30-40%) are
mainly over Ohio and NW PA. Current rainfall amounts Wednesday
afternoon look light on the NBM, however this activity will be
convective in nature, so it will be helpful to get a look at the
CAM models as Wednesday gets closer.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
KEY MESSAGES:

- Showers and thunderstorms possible Wednesday night continuing
  through the end of the work week with the return of a more
  active pattern.
-------------------------------------------------------------------

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 Wednesday night 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. Still a bit too far out to dive into certain
specifics, but will have to keep an eye on the pattern evolution
and potential for an unsettled July 4th holiday. Machine
learning continues to highlight some severe potential with this
pattern as well 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.

Ensembles then signal an upper wave diving through the Great
Lakes to close out the week, though uncertainty comes into play
with how deep the trough is and subsequently how strong the
surface low is and where it tracks. Consensus is to our north
and dragging a cold front through sometime early in the weekend,
but details remain fuzzy.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Lingering low and mid cloud deck over the high terrain and north
of I-80 this morning should lift and dissipate with the onset of
morning heating/mixing. Areawide VFR prevails thereafter. North
winds around 7-10 knots expected much of the day with infrequent
gusts to 15 knots possible during late morning and early
afternoon. Winds settle tonight, but dry air and increasing
high clouds should help mitigate impactful fog development.


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

&&

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

&&

$$

SYNOPSIS...22/34
NEAR TERM...34
SHORT TERM...22
LONG TERM...Cermak/MLB
AVIATION...Cermak/Milcarek