209
FXUS61 KPBZ 060026
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
826 PM EDT Sun May 5 2024

.SYNOPSIS...
Showers and thunderstorms will continue to impact the region
through the late evening. A few storms could be severe and
produce strong wind, hail, and heavy rainfall. Wet, warm
conditions are anticipated to continue throughout the week as an
elongated trough builds to our west and deep southwest flow
remains.

&&

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

- Localized flooding concerns remain from evening heavy rain.
- All other hazards will continue to diminish.
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Outflow collisions led to stalled thunderstorms over far
northeastern Washington County, prompting a flash flood warning
until 1030pm EDT. Those same thunderstorms will see greater
eastward progression the rest of the evening following a weak
crossing upper level shortwave.

The rest of the overnight period will be primarily dry given
loss of diurnal heating and waning upper level support. Slow
progression of a surface boundary may still spark an isolated
shower (low probability thunderstorm), with most convection
dying off by midnight. Localized fog may become a bit of concern
in rain-soaked areas due to the influx of boundary layer
moisture and precipitation-cooling. But the likelihood of
widespread fog remains low as area cloud cover will persist to
limit radiational cooling of surface. Temperature is expected to
remain above the daily average with little change to the
airmass.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

- Temperatures will remain above normal Monday.
- Convection will likely redevelop south of I-70 Monday
  afternoon/evening, along a stalled frontal boundary as a low
  pressure system passing to our south.

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After dawn, Hi-Res model guidance suggest that the frontal
boundary will likely stall near or south of I-70. A passing
shortwave out of the Mississippi River Valley will near West
Virginia Monday afternoon, showers and storms will redevelop
south of Pittsburgh along the weak frontal boundary. Probability
of precipitation will remain low between Pittsburgh and I-80,
likely due to ridging over the Great Lakes filtering drier air
from the north.

The probability of severe storms will remain low despite MUCAPE
ranging between 700J/Kg to 1000J/kg during peak heating. Bulk
wind shear will only range between 20kt to 25kts and downdraft
potential will be low given shallow layers of potential dry air
available aloft.

A ejecting trough out of the Rockies into the northern Plains
and ridging over Florida will reinforce a surge of moisture into
the Ohio River Valley Tuesday under southwest flow. Severe
storms have the potential to develop Tuesday afternoon/evening
under a destabilizing airmass and effective shear rapidly
increasing from 20kts to 50kts just before sunset. The Storm
Prediction Center has noted the severe potential with issuing a
Slight/Marginal Risk for portions on Day 3. Based on model
soundings and hodographs, hail and damaging winds will likely
be the biggest threat.

&&

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

- Ridging over the Great Lakes is expected to reduce
  precipitation chances briefly Wednesday.
- A new disturbance is expect to return showers and
  thunderstorms late Wednesday night into early Thursday
  morning.
- Ensemble models suggest a very wet pattern into the weekend.
-------------------------------------------------------------------

An active weather pattern will remain in place for our region,
with decent daily precipitation chances through the weekend.
Therefore, flooding concerns will need to be monitor in the long
term.

The potential of a period of severe weather Wednesday
night into early Thursday with a passing disturbance will need
to be monitored closely. Organized convection could be
initiated if sufficient moisture advances north into the Ohio
River Valley. Confidence is high that the wind shear will be
available, it is a matter of destabilization that could pose a
problem for severe convection development.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Expect some lingering showers and thunderstorms impacting
terminals through the first 6 hours of the TAF period.
Especially PIT, AGC, and LBE. These will drop cigs and vis
through the evening hours at times. Cigs will become variable
through the evening, but as the thunderstorms and showers
dissipate through the overnight, expect some low cigs and vis
throughout the area late tonight behind the weakened cold front.
In fact, NBM probs in DESI show a near 90% chance of IFR
conditions across the area overnight.

Some improvement is possible tomorrow towards the end of the TAF
period as dry air begins to push into the northern areas. Winds
will be light at times but may increase to 10 to 15 knots from
the west northwest tomorrow afternoon.

.Outlook...
Some improvements to the restrictions are expected Monday with
influence of high pressure to the north, but shortwave movement
across the TN River Valley may maintain some
restriction/precipitation chances for southern terminals.

The rest of the week will remain active with varying periods of
precipitation and restrictions amid low pressure passage.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Frazier
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...Shallenberger