PBZ issues Area Forecast Discussion (AFD) at May 31, 9:21 PM EDT144
FXUS61 KPBZ 010121
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
921 PM EDT Sat May 31 2025
.SYNOPSIS...
Dry weather and rapidly rising temperatures are expected through
early next week, as high temperature hits above normal readings
by Tuesday.
&&
.NEAR TERM /THROUGH SUNDAY/...
KEY MESSAGES:
- Low temperatures 10 to 15 degrees below normal, with frost
potential in eastern Tucker County.
- Smoke expected aloft.
-------------------------------------------------------------------
Evening update...The last of the remaining cloud cover is
exiting the forecast area to the east as the low exits to the
northeast. This will lead to mainly clear skies overnight with
the exception of some smoke aloft. This will result in some
frost development. The Frost Advisory for eastern Tucker has
been maintained and is in effect through 8am. Some isolated
instances of frost are possible on the Preston Co ridges.
Heading into the tomorrow, there may be some thick haze from the
smoke aloft from wildfires to the north. This may dampen
temperatures by a degree so have adjusted in the grids. High
pressure and dry weather will be in place.
Previous discussion...The cold front has sunk south of the
Mason- Dixon Line, with only a few showers and thunderstorms
remaining along it in northern West Virginia. The environment
over the next hour does not appear too conducive for strong to
severe storms, with diminishing surface-based CAPE and
increasing dry air aloft, which is helping to limit updraft
strength. Behind the front, cold advection in northwest flow and
upper troughing are supporting some generally light rain
showers/sprinkles underneath a stratocumulus deck. Temperatures
are struggling to remain in the 50s, and have even fallen into
the 40s northwest of Pittsburgh, while ZZV/MGW, where cold
advection is just starting to kick in, remain around 60. With
steeper low-level lapse rates, northwest wind gusts of 25 to 35
MPH continue this afternoon.
Expect a drying trend to take hold by the late afternoon/evening
as increasing dry advection and subsidence will bring an end to
most precipitation by sunset. Clouds will also show a decreasing
trend, with a mostly clear sky by the overnight hours.
Stabilizing low levels will allow wind gusts to taper this
evening, with light wind overnight. The combination of light
wind and decreasing clouds will lead to overnight lows some 10
to 15 degrees below normal. With eastern Tucker County expected
to drop into the mid 30s, and with winds becoming light enough
at least in sheltered locations, a Frost Advisory was issued for
the overnight period.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
KEY MESSAGES:
- Warming trend with predominantly dry weather.
- Showers late Monday couldn't be ruled out northeast of
Pittsburgh.
-------------------------------------------------------------------
The short term flow patter remains high confidence. A eastern
trough will be replaced with ridging, clearing skies Sunday and
leading to a temperature rebound. Heating under subsidence will
lead to well mixed surface profiles, with potentially a weak
subsidence inversion overhead. With clear skies and tapping into
this layer, opted to raise temperatures a couple degrees over
guidance during the day, and lower dew points a hair. This may
still result in below normal temperatures, but the air may feel
quite dry.
Into Sunday night, clear skies are expected to prevail with a
relaxation in winds which may lead to temperatures ending up
near frost criteria north of Pittsburgh with efficient
radiative cooling. NBM probs remain <10%, but temperatures tend
to underpreform in valleys and sheltered areas when all frost
indicators are favorable.
Monday will see continued ridging and a return to near normal
temperatures, though there is some indication smoke aloft may
return which could stave a couple of degrees off highs. With
lower dew points, more dry surface conditions are forecast. A
subset of ensemble members have a fast weak wave northeast of
Pittsburgh which may result in a low probability of cloud cover
and perhaps a quick rain shower, but with surface profiles so
dry, there is also the chance that even with forcing, that
precipitation will not make it to the ground. Stuck with NBM
PoPs for now. Frost concerns are null Monday night with dew
point rises keeping lows well above the 30s necessary for
formation.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
KEY MESSAGES:
- Warm temperatures this week with moderate heat risk by
Wednesday and Thursday.
- Rain and severe chances again late-week.
-------------------------------------------------------------------
Continued ridging is forecast with high confidence. Ensemble
clusters have very little variability around the Pittsburgh
area, with height maxes around 588 dm Late Tuesday into
Wednesday. This would generally translate to a forecast in the
upper 80s for daytime highs. Modeling these ridging patterns in
the east typically come with some issues modeling the extend of
cloud cover and maybe daytime convection; add on there may the
the influence of smoke aloft during this period. This will
create some lower probability "cooler solutions" of low 80s
Tuesday/Thursday with mid-80s Wednesday.
The more high probability scenario is mostly clear and dry
weather under ridging, pushing daytime highs into the mid-to-
upper 80s for this period, with Wednesday likely the warmest
day. Chances of >80F all three days are 80% to 100% apart for
the ridges, and chances of >90F are ~50% for Pittsburgh and
river valleys Wednesday and Thursday, and as high at 80% for the
Ohio River Valley along the Ohio/WV border. Urban effects may
increase these probabilities locally. Combine this with
overnight lows only getting to the upper 60s to low 70s, heat
risk increases to moderate levels Wednesday and Thursday.
Confidence in the forecast is higher Wednesday than Thursday
with some cloud and precipitation timing uncertainty with the
next disturbance.
Precipitation spread is the highest Thursday and Friday,
indicating some subtle differences in timing the next rain
chances. Some severe chances come with this wave, as evidenced
in a 5% to 15% chance within 25miles on the CSU-MLP product.
Chances of rain >1" are low (around 15%) for now, though likely
a tad low due to the aforementioned timing uncertainty. This
should bring some relief, height falls, and a return to more
quasi-zonal flow, with most of the temperature spread next
weekend encompassed in the 70s for highs.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Dry advection and
increasing subsidence with approaching surface high pressure will
allow for a decreasing trend in cloud cover. This will lead to
areawide VFR conditions overnight. Cannot totally rule out patchy
fog in areas that have received rain lately, but dry advection may
mitigate this outcome.
VFR will continue tomorrow under the influence of high pressure
and dry advection. Tomorrow afternoon, gusty conditions (15-20
knots) are expected over western Pennsylvania. Wildfire smoke
is expected to reach our region tomorrow. Currently, this is not
expected to impact visibility at the surface.
Outlook...
Subsidence and dry conditions are likely to persist under
ridge building to start the next week.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...Frost Advisory from 1 AM to 8 AM EDT Sunday for WVZ514.
&&
$$
SYNOPSIS...Frazier/Shallenberger
NEAR TERM...CL/Shallenberger
SHORT TERM...Milcarek
LONG TERM...Milcarek
AVIATION...CL/Lupo
Source:
PBZ issues Area Forecast Discussion (AFD) at May 31, 9:21 PM EDT---------------
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