376
FXUS61 KPBZ 011855
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
255 PM 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, with periods
of showers and storms, takes hold to close out the week.

&&

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

- Dry and comfortable thru tonight.
- Temperatures below normal.
-------------------------------------------------------------------

High pressure will maintain comfortable - i.e dry and seasonably
cool temperatures, for the remainder of today into tonight.
Diurnal mixing is allowing for the dry air aloft to mix to the
surface, bringing dewpoints into the mid-upper 40`s. Expect
another night, not unlike last night with cool temperatures in
the low 50`s as the surface high remains situated overhead.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
KEY MESSAGES:


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

The broad 500mb ridge centered over the southern states will
build over the region and into New England Tuesday, with the
surface high shifting to the east over time. Winds will veer
more southerly as well, returning warm advection. Both the
higher heights and waa will support a warming trend Tuesday into
Wednesday. Temperatures are currently projected to be close to
seasonal averages Tuesday but will once again rise above average
on Wednesday.

The aforementioned ridge will slowly break down on Wednesday,
as a shortwave trough digs into the upper Midwest and pulls a
surface cold front eastward. NBM begins to introduce
probabilities for measurable precipitation Wednesday evening.
The high probs (30-40%) are mainly over Ohio and NW PA at this
time, expanding south and eastward overnight. Based on the
current timing, models are keeping the bulk of the instability
over Western and Central Ohio, though some instability
(<500j/kg) is present in our eastern Ohio counties. Shear
should be sufficient for storms as well, though the timing of
the front and some lingering warm air aloft may cap things until
late. At this time, SPC has a portion of the region in a
marginal risk, and given the uncertainty, find this to be
appropriate. The primary concern would be wind at this point,
though a secondary concern is heavy downpours as PWAT values
will be increasing through the rest of the week.

&&

.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.
- Showers and storms could pose a heavy rain/localized flooding
  threat Thursday
-------------------------------------------------------------------

Cold front will continue to track southeastward but appears to
stall/become more diffuse with time as it loses its connection
with the associated low shifting into ne Canada. At the same
time, the upper ridge will be flattening across the upper Ohio
Valley, maintaining zonal flow through the end of the week.
Shortwaves passing through this the zonal flow will support
multiple rounds of showers and storms along the east- west
oriented boundary in a moisture- rich environment. At this time,
the placement of the boundary is generally south of I-70 but
there is some uncertainty in it`s exact placement. That being
said, the very moist airmass that will be present across at
least a portion of the region (NBM has a 60-80% chance of PWATs
nearing climatological max of 2 inches for the areas from I-70
south) could lead 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 /18Z MONDAY THROUGH SATURDAY/...
VFR conditions and generally light north to northeast winds
prevail through the TAF period.


.Outlook...
VFR is expected through Wednesday. A slow moving front sets up
across the region Wednesday night into Thursday, bringing
showers and thunderstorms and associated restrictions back to
the local area through the end of the week.

&&

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

&&

$$

SYNOPSIS...34
NEAR TERM...34
SHORT TERM...34
LONG TERM...Cermak/34
AVIATION...Cermak/Timmins