672
FXUS61 KPBZ 051802
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
202 PM EDT Fri Jul 5 2024

.SYNOPSIS...
Shortwave passage will create periods of moderate rain showers
with low probability thunder through tonight, along with a non
zero damaging wind and flood threat. Dry weather returns
Saturday through Monday with temperature rising well above
normal by Monday afternoon.

&&

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

- A conditional threat exists for damaging wind and localized
  flash flooding this afternoon and evening.
- Uncertainty exists in convective and instability development
  to create hazard risk.

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2pm update...
Prior thinking is seemingly playing out with showers and
isolated thunderstorms continuing to track ENE ahead of the
shortwave, with our region pegged for the weaker storm returns.
Given the low probability of storm development, the severe
threat has an even lower probability of developing, especially
as dry aloft will completely erode behind the initial line of
convection.

Rest of the Discussion...

A weak shortwave and surface trough are expected to lift
northeast through the Ohio River Valley through tonight, though
the trough axis may linger southeast of the region into
Saturday. Satellite and radar imagery show ongoing convection
about to enter eastern Ohio where surface and elevated
instability remains limited. This highlights a the conditional
severe weather threat today: both the 12z sounding at KPIT and
KILN show notable warm air aloft that is capping available
instability. Given area cloud cover and increasing mid to high-
level clouds moving NE off the convection, there is greater
probability the severe threat doesn`t materialize before
nocturnal stabilization occurs. If convection can manage to
develop ahead of the initial wave, a damaging wind threat does
exist due to elevated PWAT values, increasing shear, and around
1000 J/kg DCAPE. The combination of instability/dry air is best
maximized through 21z around the Morgantown area, so that is the
most likely location for any severe threat.

The shortwave will more notably pass between 00z-06z, which may
yield a greater uptick of storm development across western PA
but with a lower probabilistic severe environment. Flash
flooding will remain possible as high PWAT persist, but strong
enough steering flow and relatively dry antecedent conditions
should keep risk low.  Passage of the surface trough and upper
wave will diminish precipitation chances west to east and offer
a slight reprieve from the warm, muggy conditions.

&&

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

- Dry and more seasonable weather returns on Saturday.
- Rising temperature likely through Monday as dry weather
  persists.

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Drier southwest flow and ridging at the surface will support dry
weather Saturday. Lingering morning stratus clouds are expected
to break up with a scattered to broken cumulus field developing
in the late morning to early afternoon; weak cool advection plus
the cloud cover should aid temperature returning to more
seasonal values. More notably for some, drier air will mix to
the surface and bring relief to the region from the multiple day
experience of humid conditions.

Return flow as high pressure settles over the Atlantic will
support rising temperature Sunday into Monday as the next upper
trough system develops over the Central Plains. Heat risk
concerns return as a result, though probabilities of seeing heat
indices above advisory criteria remain low.

&&

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

- High probability for dry weather and slightly above average
  temperature the rest of the weekend.
- Unsettled weather returns Tuesday through at least mid-week.

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

Ensemble consensus continues to favor an Upper Midwest trough
lifting through the Great Lakes region Tuesday into Wednesday
morning with a weak surface trough. Moist advection ahead of the
wave is likely to foster a warm, humid environment translating
to likely showers and thunderstorms ahead of the feature.
Environmental conditions remain varied, but with ensemble means
showing near 90F highs and 70F dewpoints, there appears to be at
least a low probability for flash flood risk and potential other
severe hazards.

Variations become post-shortwave passage depending on high
pressure strength to the north as well as potential pattern
impact from the remnants of Hurricane Beryl. The main takeaways
for the long range period is that 500mb mean heights suggest a
continuation of near to above normal temperature and
precipitation chances tied to shortwave movement.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Scattered showers and thunderstorms will be possible late
afternoon / evening with a shortwave and ahead of a crossing
front. Have used a PROB30 for KMGW, but removed mention
elsewhere with low confidence in timing or location.

Cigs should lower into MVFR/IFR again overnight with lingering
moisture, eventually lifting Saturday morning as drier air moves
in behind the front.

.Outlook...
VFR conditions should persist through the weekend with high
pressure. The next chance for widespread restrictions will be
with our next system Tuesday.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...88