PBZ issues Area Forecast Discussion (AFD) at May 9, 7:40 AM EDT528
FXUS61 KPBZ 091140
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
740 AM EDT Fri May 9 2025
.SYNOPSIS...
Lingering light rain expected east and southeast of Pittsburgh
this morning. Drier weather returns early afternoon and
continues into the weekend with a warming trend continuing
through next week. Rain chances return by the middle of next
week.
&&
.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:
- Light rain continues early this morning southeast and east of
Pittsburgh
- Drier conditions expected early afternoon
- Below average temperatures expected
-------------------------------------------------------------------
A stalled upper level low remains positioned north of New York
early this morning. Mid-level water vapor satellite depicts a
surge of drier air tracking across Lake Erie and into eastern
Ohio/western Pennsylvania, clearing clouds and rain chances for
a large portion of the area. For the ridges, shallow light rain
showers are noted on the radar in the vicinity of a cold front;
dew points still range in the mid to low -50s in eastern
Tucker/Preston while areas north have dropped in the low-40s
and 30s.
Probability of measurable rain along the ridges is still
slightly elevated through late morning before the cold front
makes a complete passage of the region. Increasing mid to low
level subsidence will likely decrease rain chances and clear
clouds between 11am to 1pm.
With 850mb temps ranging between 0 to 2 degrees Celsius under
north/northeast flow, temperatures will trend below average by
10 degrees. With some areas struggling to reach 60 degrees north
of Pittsburgh.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Frost Advisory in effect 2am to 8am Saturday for portions of
the region
- Dry with increasing temperatures through the weekend.
-------------------------------------------------------------------
The combination of light winds, clear skies encouraging
radiational cooling, and 850mb temperatures between 0 to 2
degrees Celsius is expected to bring near-freezing conditions
to several forecast zones. Given that the growing season is
underway based on accumulated growing degree days, a Frost
Advisory has been issued for the ridges of Pennsylvania and West
Virginia, as well as areas north and west of Pittsburgh. High-
resolution ensemble models indicate a 60% to 80% probability of
temperatures falling below 35 degrees.
Below average temperatures come to end after sunrise Saturday
as a ridge axis builds over the Midwest. Temperatures are
expected to be near seasonable with dry and clear conditions.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Warming trend continues through next week.
- Next rain chances return Tuesday
- Potential for strong to severe thunderstorm Thursday/Friday
-------------------------------------------------------------------
Dry conditions and above-average temperatures are expected
Sunday and Monday as a ridge axis shifts over the Great Lakes.
Mid- and upper-level clouds will gradually increase on Monday,
especially from the south, as a cutoff low progresses out of the
Mississippi River Valley.
Despite increasing cloud cover, soundings suggest low-level dry
air will persist through late Monday into early Tuesday, likely
delaying the onset of precipitation until after sunrise. With
southeast flow supporting weak low-level moisture advection, the
chances of thunderstorms before sunrise have been removed. By
Tuesday afternoon, warm advection and a deepening southerly flow
should enhance moisture transport, allowing for the development
of a few non-severe thunderstorms.
Thunderstorm potential continues into Wednesday, with forecast
instability values ranging from 400J/kg to 900J/kg. However,
with effective shear remaining below 15kts and DCAPE values
under 500J/kg, strong downdrafts and damaging wind gusts appear
unlikely. Lightning will likely be the primary hazard.
The best chance for more organized convection capable of
producing strong to severe storms appears to be Thursday and/or
Friday. A developing low pressure system over the Dakotas is
expected to track into the Great Lakes, increasing the
probability of favorable severe weather parameters. Joint
probabilities of 0-500mb effective shear >=30kts and MUCAPE >=
500J/kg reach around 30% over the Ohio River Valley region
during this time period and have been consistent with a number
of model runs.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
MVFR CIGs are beginning to degrade and retreat eastward this morning
along our southern/eastern borders as an upper-level low departs the
region. CIGs will lift across much of the area as mixing picks up by
mid-morning leading to area-wide VFR by afternoon. Northerly winds
are expected to pick up through the daylight hours but low speed
shear likely leads to a sustained 10-12KT wind versus a gusty one.
Outlook... High pressure building into the region will allow VFR
conditions to persist through early Monday evening.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Frost Advisory from 2 AM to 8 AM EDT Saturday for PAZ007>009-
013>015-074-076-078.
OH...Frost Advisory from 2 AM to 8 AM EDT Saturday for OHZ039>041-
049-050.
WV...Frost Advisory from 2 AM to 8 AM EDT Saturday for WVZ510>514.
&&
$$
SYNOPSIS...Hefferan
NEAR TERM...Hefferan
SHORT TERM...Hefferan
LONG TERM...Hefferan
AVIATION...AK/Rackley
Source:
PBZ issues Area Forecast Discussion (AFD) at May 9, 7:40 AM EDT---------------
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