PBZ issues Area Forecast Discussion (AFD) at Apr 14, 4:07 PM EDT282
FXUS61 KPBZ 142007 AAA
AFDPBZ
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
407 PM EDT Mon Apr 14 2025
.SYNOPSIS...
A strong cold front will bring the chance for strong to severe
storms late this afternoon and evening, mainly south of
Interstate 70. Gusty winds and showers are possible on Tuesday,
with snow showers expected Tuesday night into Wednesday. Most
light snow accumulation will be in the mountains and north of
Pittsburgh.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
KEY MESSAGES:
- Severe storms possible this afternoon and evening, with the
best chances south of I-70.
- Storms quickly exit early overnight.
-------------------------------------------------------------------
Late afternoon update...PoPs have been refreshed using the
latest hires model guidance. Convection is blossoming over
southwest Ohio, however it's movement is keeping the trajectory
of the storms well south of the forecast area for now. A watch
has been issued for portions of the region, south of I-70, with
the highest threat south of the Mason-Dixon line. The watch
will go through 11pm.
Previous discussion...
Strong warm advection continues to drive area temperatures
above guidance, with much of the region at or nearing 70F. Dew
points remain on the lower side of guidance -- mid 40s to near
50. This strong warm advection, and some clearing of clouds
south of I-70 have helped build instability over the area.
Latest HREF guidance continues to show a 50-70% chance of 700
J/kg south of Pittsburgh.
Low pressure will cross the upper Great Lakes through tonight,
with adjacent triple-point sfc low over the lower Great Lakes.
While instability builds over southern portions of our area, the
main forcing still looks to be farther south in the Charleston,
WV CWA. Still, shear is more than sufficient to support a few
severe storms (likely supercells) across northern WV and
possibly southern PA, especially if any discrete cells are able
to develop ahead of more messy linear convection.
Analogs have been consistent with showing a hail threat, though
winds remain just as concerning with an expected storm motion of 40-
50 mph. Despite the presence of up to 30kts of shear in the 0-1km
layer, tornadoes remain a secondary threat due to a lack of low-
level hodograph curvature and uncertainty regarding low-level
instability and storm mode (squall line vs. discrete supercells).
That said, the tornado threat is certainly not zero with SPC
maintaining the 5% tornado potential, but this too has been
pushed south a bit. The best chances residing along and south
of the I-70 corridor. Flooding concerns remain low with fast
storm motion and low training potential. Hence, WPC has
introduced a Marginal Excessive Rainfall threat but this was
shifted south into WV with only a few WV counties encompassed
from the PBZ forecast area.
There is still some timing uncertainty with the storms, but most of
that is encompassed within a late afternoon/evening timeframe. With
the amount of shear available, it will not take a lot of instability
to create significant impacts. SPC maintained a Slight Risk for
severe south of I-70, and has introduced an Enhanced Risk to our
south, just brushing the WV ridges. Severe chances quickly end
behind the cold front, which pushes through late tonight.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
KEY MESSAGES:
- Gusty winds on Tuesday with a Wind Advisory for east Tucker.
- Light snow forecast Tuesday night for some.
-------------------------------------------------------------------
The more robust push of cold air advection behind tonight's
front will occur Tuesday morning. Along with colder
temperatures, this will force near-saturating and help
destabilize the low-levels aloft. With afternoon surface
heating and enhanced mixing, surface gusts may tap into an 850mb
jet of 40-60kts, bringing widespread gusts of 35-45 mph Tuesday
afternoon/evening. Gusts will peak in eastern Tucker county,
where gusts to 55 mph are expected; a Wind Advisory remains in
effect there Tuesday morning through early Wednesday afternoon.
Gusts across the rest of the ridges look to remain just below
advisory-level (46+ mph), with HREF probabilities higher on the
CTP side of the ridges. Still, will continue to evaluate the
possible need for Advisory expansion.
Moist and unstable conditions on Tuesday afternoon, coincident
with a mid-level shortwave passage, will aid widespread rain shower
development. Low freezing levels of 4-6 kft and sufficient lift
will also allow for small graupel/hail development with any
deeper showers.
With showers and continued cold advection, afternoon high
temperatures will top out below average in the 40s and 50s. As
temperatures fall Tuesday night, meager instability will be
maintained which may lead to snow development. Most ensembles
maintain at least a light coating in the I-80 corridor north of
Pittsburgh and high terrain Tuesday night into Wednesday
morning. As a worst case scenario, an inch or two is possible
in eastern Tucker and north of I-80, which may allow for a few
slick spots for the Wednesday morning commute. Ensembles
continue to highlight at least some accumulation in the northern
counties but also the ridges.
Surface high pressure will extend up the Mississippi Valley
Wednesday with ridge axis across the upper Midwest. Low pressure
continues to shift over the Northeast US and Quebec. This
continued tight pressure gradient will maintain gusty winds once
again across the ridges, maxing out over eastern Tucker County.
The Wind Advisory remains in effect through early Wednesday
afternoon.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
KEY MESSAGES:
- Gusty winds linger into Wednesday for high terrain.
- Forecast uncertainty grows next weekend.
-------------------------------------------------------------------
High pressure will keep the region dry for Thursday.
Temperatures will be around normal for this time of year as
highs are expected to cross 60 degrees across much of the area.
This day will also have the potential of low RH during the
afternoon. Uncertainty is maintained in the forecast beyond
Thursday with two clusters (65% of ensemble membership) tending
toward quasi- zonal flow, and another two clusters showing more
pronounced eastern troughing with embedded shortwaves, which
would tend a bit wetter and cooler (35% of ensemble membership).
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
High confidence forecast (80-90%) of VFR weather outside the
window between 21Z-02Z when showers and storms are forecast.
A cold front will cross this evening and out ahead of it will be
showers and storms. Timing remains consistent with eastern Ohio
around 21Z-23Z and western PA / northern WV 22-02Z. A brief
wind gust above 40 kts is possible if an airport gets hit with a
storm directly. The highest probability of MVFR or lower VIS is
10-15% south of the Mason-Dixon Line, while a much higher
chance of CIGS falling below VFR area wide /35%-45%/.
In wake of the cold front later this evening, VFR flight
conditions are expected. Wind will shift to the west with
sustain speeds around 12kts through the overnight hours. Wind
will be the primary impact Tuesday with a 90% chance of sustain
speeds above 15 kts /probably closer to 20kts/ at all airports.
Gusts could reach 40-45 knots, especially at hilltop airports
like AGC and HLG.
Scattered showers will be around Tuesday with coverage ramping
up during the daylight hours. A brief drop to MVFR CIGS as they
pass.
Outlook...
Dry weather returns Wednesday and Thursday with building high
pressure before another round of showers and storms (and
restrictions) on Friday.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...Wind Advisory from 10 AM Tuesday to 2 PM EDT Wednesday for
WVZ514.
&&
$$
SYNOPSIS...Rackley
NEAR TERM...Rackley/22
SHORT TERM...Rackley
LONG TERM...Rackley/Shallenberger
AVIATION...McMullen
Source:
PBZ issues Area Forecast Discussion (AFD) at Apr 14, 4:07 PM EDT---------------
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