850
FXUS61 KPBZ 160522
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
122 AM EDT Tue Jul 16 2024

.SYNOPSIS...
Storm potential continues into tomorrow with mesoscale
convective systems advancing across the Ohio River Valley. A
passing cold front Wednesday will keep storm chances, and bring
temperatures closer to normal. A warming trend is expected into
the weekend.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
KEY MESSAGES:

- Overnight low temperatures will remain above average under a
  ridge.
- Shower and storms may develop after 4am with mesoscale
  convective system (MCS) tracking over the Midwest.

__________________________________________________________________


The threat for showers and storms has decreased for the time
being. However, the threat for additional convection may
increase as a mesoscale convection system (MCS) tracks from the
Midwest and into the Ohio River Valley overnight. Significant wind
damage has been measured and observed over the state of Iowa and
Illinois this evening. Hi-Res models have the squall line
advance into western Ohio between 2am to 3am and could continue
to pose a threat under areas of weak CIN and high buoyancy
(2000J/kg to 2500J/kg).

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
KEY MESSAGES:

- Active weather with several convective rounds presenting
  potential severe hazards until the passage of a cold front on
  Wednesday.

- Continued well above normal temperatures.
  _________________________________________________________________

Uncertainty in the forecast continues as upstream development
will largely dictate our weather until the passage of a
Wednesday cold front. Further rounds of convection are expected
Tuesday afternoon and evening. Damaging wind will continue to
be the primary threat mode on Tuesday, though isolated tornadoes
and large hail could not be ruled out. Once again, the primary
mode of uncertainty will be weak forcing and storm development.
Guidance tends to suggest a weak wave will be the primary mode
of development. f storms remain cold pool- balanced, the
tornado threat may be a bit higher, otherwise, winds will
remain the primary threat in downbursts. This will depend on the
amount to dry air aloft.

A more stout shortwave trough dropping into the Great Lakes on
Wednesday will finally help to push a cold front along for an
eventual Wednesday afternoon/night passage, bringing a more
concentrated precipitation area Wednesday, but then an end to
the convective threat behind it.

Heat and humidity will continue to be part of the story during
the early part of the week. The potential for advisory-level
heat index values of 100 or more on Tuesday depending on
convective extent and timing. The current forecast update
tended towards the higher end of temperature guidance, although
at this time there is only about a 15% chance we exceed
advisory criteria. The only way that we realize that at this
point is mostly clear skies. Guidance still has a large spread
on cloud cover dependent on the progression of the
aforementioned overnight MCS. Will keep an eye on things, but
confidence was too low to issue and products for tomorrow at
this point. Nonetheless, cumulative heat stress will approach
major stage for most, so avoid prolonged exposure to the
elements and stay hydrated.

&&

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

- A drier and cooler pattern will ensue on Thursday and continue
  into next weekend.

-------------------------------------------------------------------

The cold front should complete its passage Thursday morning, perhaps
stalling over the Central Appalachians/Middle Ohio Valley, with
expanding high pressure across the Great Lakes and northeast
CONUS into next weekend. Drier weather and cooler temperatures
are expected on Thursday with a warming trend into the weekend,
though humidity should relax a bit.

The shallow upper troughing in place Thursday and Friday may be
replaced by rising heights Saturday/Sunday in response to increased
troughing over the Central Plains. This could also bring moisture
back from the south, leading to increased diurnal precipitation
chances, mainly southeast of Pittsburgh.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
A portion of the MCS across IN and MI is expected to continue
to turn to the SE overnight toward more favorable theta E values,
while the far northern portion of the line tracks ewd. This
track follows the pattern of the 1000mb-500mb thicknesses.
Included a VCSH mention at FKL around sunrise, as the activity
weakens as it moves east into less instability. Mid/high clouds
will increase through early morning as the remnant clouds from
the MCS track across the Upper Ohio Valley region.

Elsewhere, VFR is expected through much of the day. Mixing will
likely result in SW wind gusts to 20kt by mid morning. CU rule
and model soundings indicate a scattered to broken CU layer will
develop by mid to late morning as convective temperatures are
reached. Models differ on the extent and timing of convective
development through the day. Most guidance indicates a shortwave
will track across the region from late morning through the
afternoon. Included Prob30 for thunder and restrictions at each
airport for the most likely time of occurrence, tied to the
timing of the shortwave passage.

Convection should wane Tuesday evening as instability wanes, and
with a lack of forcing.

.Outlook...
Cig/vsby restrictions are possible Tuesday night/Wednesday
morning with patchy low level moisture in place. Showers and
thunderstorms, and associated restrictions, are likely with the
passage of a Wednesday cold front. VFR returns Thursday through
Saturday under building high pressure.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...CL/Milcarek/88
LONG TERM...CL/Milcarek
AVIATION...WM