503
FXUS61 KPBZ 061753
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
153 PM EDT Mon May 6 2024

.SYNOPSIS...
Probability of rain showers and isolated thunderstorms increase
for areas south of Pittsburgh after 4pm this evening with an
approaching disturbance. Fog potential returns early Tuesday
morning for portions of the region. Severe weather potential
increases Tuesday evening, after 6pm and could last into the
overnight hours.

&&

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

- Rain and thunderstorm chances increases this evening.
  Lightning and areas of heavy rainfall rates will be the main
  concern.

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A stationary boundary is currently straddling along I-70 early
this morning. Clouds will continue to stream through the
region as a shortwave trough enters the Appalachians. As the
shortwaves tracks through central West Virginia, showers and
isolated thunderstorms will likely develop for areas south of
Pittsburgh. Storms are not expected to be organized with
marginal shear (effective shear less than 30kts) despite MLCAPE
ranging between 900J/kg to 1100J/kg on sampled soundings near
MGW. There was a noted layer of drier air on the KPIT morning
sounding (between 700mb to 500mb) that would have been good for
downdraft potential, however that layer of drier will likely
dissolve this afternoon with a flux of mid-level moisture.

Like yesterday, with very saturated environment (PWATS values
ranging between 1.30 to 1.45) and marginal shear, isolated
storms can prompt heavy rainfall rates. Urban areas will likely
be the places of interest today for any lingering or back-
building storm due.

Probability of fog (less than a half a mile in visibility)
ranges from 45% to 65% for areas south of I-70 during the
overnight time period. Weak moisture boundary layer convergence
will likely cause probabilities to increase and isolated areas,
and could create visibility issues for travelers. A Special
Weather Statement or Dense Fog Advisory may need to issued for
forecast zones south of Pittsburgh in the next 12 to 18 hours.

&&

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

-Warm front will bring the next risk for showers and storms
 late Tuesday and Tuesday night.
- Ridging over the Great Lakes is expected to reduce
  precipitation chances briefly Wednesday.

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An ejecting trough out of the Rockies, that will eventually
move over 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 late Tuesday and Tuesday night under a destabilizing
airmass and effective shear rapidly increasing from 20kts to
50kts. 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.

A break in the activity is possible Wednesday with weak ridging
aloft.

&&

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


- 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.
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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 /18Z MONDAY THROUGH SATURDAY/...
Any MVFR cigs are expected to improve to VFR this afternoon amid
dry advection. A crossing shortwave will trigger additional
showers and possibly a thunderstorm primarily south of I-80 later
this afternoon and evening.

Winds remain light through the period.

.Outlook...
An active pattern will keep periods of precipitation and related
restrictions through much of the week.

&&

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

&&

$$

SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...Hefferan/22
LONG TERM...Hefferan/22
AVIATION...88