Area Forecast Discussion
Issued by NWS Pittsburgh, PA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPBZ 222226
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
626 PM EDT Fri Mar 22 2024

.SYNOPSIS...
Rain is expected to overspread the region tonight through early
Saturday with crossing low pressure. Dry weather is then
expected through early next week under high pressure.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
KEY MESSAGES:

- Rain tonight with crossing low pressure

-------------------------------------------------------------------

Areas north of I-80 have wet-bulbed with rain/snow mix
prevailing as indicated my observations, mpings, and webcams.
Northeast winds at Franklin, PA are still dominating, showing
that the southerly surge of warm air has still yet to be
ingested. This has added some forecast uncertainty into
tonight; current observations north of I-80 are far cooler than
any guidance and the conditions are not initializing well. It
is still more likely than not that snow transitions to rain
before switching back over to snow tomorrow morning with the
surface cold front, but there is still a possibility of no
changeover with the maintenance of northeast flow. Even then,
lingering warm surface conditions will challenge accumulations.


.. Previous Discussion ..

A surface trough was analyzed from southern OH through
southwest PA. Dry air remains in place in the lower levels,
though warm, moist advection should eventually result in dew
points increasing through this evening.

A northern stream trough advancing across the Upper Midwest is
expected to phase with a SE CONUS trough tonight, as a surface
low tracks NE along the East Coast. Rain is expected to
overspread the region tonight, as an inverted surface trough
extends northward across the Upper Ohio Valley region. The
latest mesoanalysis shows 850mb temps still -1 to -3 deg C
across Venango and Forest counties. A brief period of snow, or
rain/snow mix, is possible at the onset of the precip this
evening in that area, before enough warm advection occurs to
change the precip to rain. The region will also be under the
entrance region to an upper jet, enhancing ascent. Rainfall
amounts are expected to range from 0.25 to 0.5 inches west of I
79, with 0.5 to 0.75 east of I 79. NBM probabilities of 0.5
inches are highest (50-60%) north and east of PIT.

The inverted surface trough/cold front will shift east of the
area toward morning, as the surface low continues its track
along the East Coast. The rain could mix with or briefly change
to snow north of PIT, though most of the moisture and ascent
should be exiting the region as colder air moves in.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
KEY MESSAGES:

- Precipitation ends Saturday as low pressure exits
- Dry weather is then expected through Monday under high
  pressure
- Warmer temperatures Monday

-------------------------------------------------------------------

Rain will end from west to east Saturday as the surface low
tracks NE the East Coast, and the surface trough/cold front
exits the Upper Ohio Valley region. A brief mix or changeover to
snow is possible north of PIT and in the ridges, though no
accumulation is expected. North wind is expected to gust to
30-35 mph during the day, with a tight pressure gradient between
the East Coast low and high pressure to our west.

Shortwave ridging is then expected to build across the Upper
Ohio Valley region through Monday, with dry weather expected.
Seasonable temperatures are expected Sunday. A warming trend is
expected by Monday as the ridge axis shifts east of the area,
and the flow veers to the south. Highs are expected to be 10 to
15 degrees above average by Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
KEY MESSAGES:

- Rain chances return Tuesday and Wednesday with a cold front
- Mainly dry and seasonable to end the week

----------------------------------------------------------------

Model ensembles indicate a trough across the central CONUS will
advance slowly eastward toward the Upper Ohio Valley region
Tuesday and Wednesday. Increasing rain chances are expected as
the trough and its associated surface cold front track east
across the area. The front is expected to move east of the area
by Thursday, though some uncertainty exists in how far east it
will progress before a wave of low pressure tracks north along
it. Maintained slight-low chance pops due to the uncertainty.

High pressure is expected to build across the region Thursday
night and Friday, with dry and seasonable weather expected.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions will persist through the afternoon before
deterioration tonight. Middle clouds, associated with an
advancing warm front, will dominate initially. Some radar
returns are evident across the Middle Ohio Valley and heading
northeastward. However, a dry boundary layer will keep much of
the rain from reaching the ground until 23Z/00Z in most cases.
Generally light east to southeast wind will continue, save for a
few gusts approaching 20 knots along west-facing slopes, thanks
to downsloping.

Hi-res model timing still brings precipitation in earnest after
00Z, with rainfall becoming more widespread after 06Z,
especially east of an advancing cold front in southwest PA and
northern WV. Ceilings will slowly deteriorate through MVFR to
IFR as a result. Initial IFR NBM probabilities through 06Z are
50% or greater to the northwest of PIT, and have such ceilings
in the ZZV/FKL TAFs first as a result. Probabilities then
increase above 50% for the vast majority of the region by 12Z,
along and just behind the front, and have dropped ceilings below
1000 feet areawide by then. Visibilities do not seem to be as
impacted in the model probabilities, and have kept the majority
in the 3-5 mile range through the event. Expect a wind shift to
north and northwest with overnight FROPA.

Rain departs with the front from west to east after sunrise, and
better mixing behind the boundary will allow visibility to
improve to P6SM. Ceilings will be slower to recover, with most
remaining at MVFR through 18Z. However, ZZV could achieve VFR by
18Z, with NBM probabilities of such around 30-40 percent by
that time. Wind will become gusty with daytime heating, with
peaks of 15 to 25 knots possible.

.Outlook...
Wind gusts will continue to increase Saturday afternoon as
mixing taps into elevated wind aloft in the cold advection
regime in the wake of the front. Probabilities for gusts >25
knots sit at 70-90%. Gusts will diminish overnight Saturday
night.

VFR conditions then continue through Monday as high pressure
moves across the area. Restriction potential returns Tuesday
with an approaching cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$

SYNOPSIS...WM
NEAR TERM...WM/Milcarek
SHORT TERM...WM
LONG TERM...WM
AVIATION...CL


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.