PBZ issues Area Forecast Discussion (AFD) at Apr 18, 3:57 AM EDT472
FXUS61 KPBZ 180757
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
357 AM EDT Fri Apr 18 2025
.SYNOPSIS...
Dry conditions and a warming trend continue today. Shower and
thunderstorm chances return this weekend as frontal boundary
approaches and wavers in the area.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- A warm front crosses this morning, likely in a dry manner
- Temperatures well above normal
-------------------------------------------------------------------
Mid and upper level clouds, spilling over an approaching ridge
will increase mid and upper level cloud coverage this morning, with
coverage lessening this afternoon as the ridge continues to
build across the region. Cannot totally rule out a couple of
sprinkles in a period of isentropic lift, but dry low levels
will likely mitigate any meaningful precipitation.
Strong warm advection and efficient mixing will likely punch up
afternoon high temperatures to 10 to 15 degrees above normal. The
mixing, along with 35 to 40 knots of 850mb flow, will produce wind
gusts into the 20 to 30 MPH range during the afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Rain chances increase overnight
- Marginal chance of severe weather on Saturday
-------------------------------------------------------------------
A surface cold front slowly settles southwest during the
period, increasing rain chances overnight and into Saturday with
seasonally-anomalous precipitable water values of 1.2 to 1.3
inches surge into the Upper Ohio Valley. Rain chances then
continue into Sunday night as the boundary settles through.
With sufficient shear, severe potential will depend on
instability. Latest NBM guidance shows an 80-90% chance of
>250 J/kg, 40% chance of 500 J/kg, and 0% chance of >1000 J/kg
of MUCAPE during the afternoon. Latest CSU-MLP output also paints
a 15% across much of the region Saturday. SPC has maintained a
Marginal Risk for portions of the forecast area. Given the
relatively meager instability and relatively straight
hodographs, isolated strong to damaging gusts should be the
main issues if severe weather occurs. Above-normal temperatures
continue.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
KEY MESSAGES:
- Mostly dry and seasonable Sunday
- Shower chances return for Sunday night/Monday before a dry
midweek stretch
- Mostly above-normal temperatures
-------------------------------------------------------------------
Ensembles generally agree that surface low pressure rides northeast
across the Mississippi into the western Great Lakes by Monday
morning. Combined with southwest flow aloft, this should push the
front back north of the region by then. Then, the cold front of the
occluding system would push through on Monday. This will keep shower
and daytime thunderstorm chances going into the early week period.
While the environment should continue to support deep shear,
buoyancy is more questionable. CAPE values appear a bit more
favorable on Monday, but any severe risk appears low at this
distance. Temperatures remain above-normal through this period.
Dry weather and near to above-normal temperatures appear most likely
for Tuesday and Wednesday as surface high pressure crosses in
increasingly quasi-zonal flow. There is potential for mid-level
shortwave energy to provide the next decent chance of rainfall by
Thursday.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
A warm front will move across the region through early morning,
with areas of mid and high level clouds. A low level jet will
develop across OH and western PA toward daybreak, with LLWS
expected. Surface wind is progged to be light out of the SE,
with 2kft winds SSW at 35-40kt.
The front will exit east by mid to late morning, with surface
wind veering to the SSW. Mixing and a tightening pressure
gradient will then result in gusts from 25-30kt through the
day and evening. VFR will also continue.
Outlook...
Showers, restrictions, and possible thunderstorms are expected
on Saturday into Saturday night as a cold front tracks slowly
SE across the Upper Ohio Valley region. VFR should return
Sunday as the front drops south of the area.
Showers and restrictions are possible Sunday night as the front
moves back north as a warm front.
Showers are likely (with possible thunderstorms) on Monday with
a crossing cold front. VFR returns Tuesday under high pressure.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...CL
AVIATION...WM
Source:
PBZ issues Area Forecast Discussion (AFD) at Apr 18, 3:57 AM EDT---------------
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