PBZ issues Area Forecast Discussion (AFD) at Feb 26, 8:00 AM EST220
FXUS61 KPBZ 261300
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
800 AM EST Wed Feb 26 2025
.SYNOPSIS...
Temperatures will remain above normal through Thursday with
periodic chances for precipitation.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Areas of dense fog possible through mid-morning.
- Possible freezing fog.
- Rain returns this afternoon/evening.
-------------------------------------------------------------------
**UPDATE***
Not much change needed to the ongoing forecast as sfc obs and
satellite imagery still support the previously issued Dense Fog
Advisory for locations north of PGH. Have updated the advisory
to mention isolated areas of freezing fog across northern
counties where sfc temperatures are below freezing.
A SPS was issued to cover more patchy dense fog being observed
across eastern OH and in the ridges of PA, but coverage was not
enough to justify adding to the existing advisory. This fog
should dissipate by mid- morning as low level mixing commences.
Previous discussion follows..
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Have issued a dense fog advisory for counties north of
Pittsburgh through 9am. Fog should quickly dissipate this
morning.
Brief height rises this morning, and weak surface high pressure,
should work to keep much of the area dry this morning. A warm
front, associated with a surface low over the Midwest, will
slowly push northward through the area this afternoon.
Precipitation will begin to develop along and north of the front
as a shortwave trough moves north of the surface boundary this
afternoon. Precipitation will become more widespread this
afternoon as the surface low drifts eastward toward Ohio. Most
of the precipitation should fall as rain. However, colder air
aloft, that has not yet ejected northward, over the I-80
corridor, could allow for a mix of rain and snow or a change
over to all snow. Some of the CAM models are picking up on this
as they are cooling the atmosphere once the precipitation
begins. HREF probs for > 0.1 inches of snow are around 40-60%
over the I-80 corridor this evening. Probs for > 1 inch are
around 40-50%. NBM probs are not nearly as robust during this
time period. Have increased the coverage of the rain/snow for
this evening. For now, will leave out accumulations, as ground
temperatures should remain warm. This will need to be monitored
as the day progresses.
High temperatures today will be tricky and will be dependent on
how fast the warm air advection can eject the colder air aloft.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
KEY MESSAGES:
- Rain continues through Thursday.
- Above normal temperature Thursday.
- Colder on Friday
------------------------------------------------------------------
A surface low will then slowly drag a cold front through the
area late tonight and Thursday morning. Somewhat more
substantial rain is anticipated Wednesday night and Thursday,
but overall amounts should stay relatively light. Probs for >
0.20 inches of rain remain generally low (30-50%) with the
highest of these near over the I-80 corridor.
Rain will taper off Thursday morning behind the cold front,
though cold advection and a weak upper trough will maintain
light rain showers through the day, and eventually scattered
snow showers Thursday evening and overnight. Cold advection
behind the front will drop temperatures through the day, with
highs likely reached early in the day.
The cold air will begin to eject northward Friday morning as a
warm front, associated with a deep surface low over the northern
Great Lakes, swings through during the afternoon. It will take
all day to push the colder air out, so have lowered high
temperatures a bit on Friday. Friday should be dry, although
morning snow showers cannot be completely ruled out over the
ridges.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
KEY MESSAGES:
-Trends favor below average temperature into the weekend with a
passing trough.
- Active weather continues into early weekend, with drier
weather thereafter.
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A series of crossing shortwaves and passing surface low pressure
will mean an active period of weather into the early weekend.
Higher confidence exists that a trough axis will cross the Ohio
River Valley and Great Lakes region on Saturday, ejecting into
the Northeast by Sunday. At the surface, low pressure is likely
to cross near or north of the area. However, uncertainty
remains in the overall depth of the trough axis, and in turn,
expected surface temperatures. For now, it seems more likely
that precipitation into Saturday will begin as rain or snow,
transitioning to all snow as precipitation departs early Sunday.
Probabilities of measurable snow (0.1") in the vicinity of I-80
remain about 30-40%.
Dry weather looks to arrive late weekend into early next week as
high pressure builds back into the area.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
Areas of IFR to LIFR fog this morning impacting several ports
should quickly diminish through mid-morning, with the most
widespread coverage north of KPIT in general. (River valleys as
well)
VFR conditions will then resume by mid to late morning. Mid
level clouds will then increase ahead of low pressure,
advancing eastward from the Midwest. Rain is expected to begin
across areas near and north of a ZZV-AGC-LBE line by mid to late
afternoon, though any restrictions should be minimal. There
could be a rain/snow mix at FKL and DUJ, where MVFR is expected,
until warm advection changes the precip to rain by this evening.
Wind is expected to shift to the SE as the surface low
approaches late this afternoon and evening. A low level jet
will also result in LLWS as it moves over the Upper Ohio Valley
region. MVFR restrictions are also expected to increase from N-S
through the evening as the low approaches and crosses the
region.
Outlook...
Restrictions are likely into Thursday as the surface low and
cold front cross the region. Restrictions will likely continue
Thursday night into Friday in rain/snow under a crossing upper
trough. Restrictions in rain/snow are possible again Saturday
with a crossing cold front before VFR eventually returns Sunday
under high pressure.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 9 AM EST this morning for PAZ007>009-
013>016-022-077-078.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Rackley/22
NEAR TERM...22/88
SHORT TERM...Rackley/22
LONG TERM...Hefferan/Rackley
AVIATION...WM/88
Source:
PBZ issues Area Forecast Discussion (AFD) at Feb 26, 8:00 AM EST---------------
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