PBZ issues Area Forecast Discussion (AFD) at Oct 12, 1:48 PM EDT459
FXUS61 KPBZ 121748
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
148 PM EDT Sat Oct 12 2024
.SYNOPSIS...
Mostly dry and relatively warm weather will continue before shower
and thunderstorm chances return later this afternoon through
Sunday night with crossing low pressure. Much cooler and
unsettled weather is then expected through Wednesday with a
series of crossing disturbances.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Largely dry weather today with increased cloud coverage.
-------------------------------------------------------------------
A cold front will drop southward across the region today with
increased cloud coverage and isolated, light rain along the
front before stalling across OH into southern PA.
Little upper support for ascent looks to be associated with the
front, so minimal rain is expected for most areas, with only
light precipitation along the front. High temperatures are
expected to top out around 5 degrees above average for this
time of the year.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
KEY MESSAGES:
- Showers and possible strong thunderstorms through Sunday
evening
- Much cooler with scattered showers through Sunday night
through Monday night
-------------------------------------------------------------------
A digging shortwave trough is progged to track from the Upper
Midwest tonight, as surface low pressure develops in response
across IL and IN, SE of the trough. This low will pull the
stalled cold front back north as a warm front later tonight into
Sunday morning as it tracks eastward. With increasing moisture
and ascent, enhanced by an approaching low level jet, showers
are likely north of PIT, with lower shower chances to the south,
south of the front. A thunderstorm will also be possible with
the low level jet, and minimal elevated instability (Showalter
indices of 0 to -1 across NW PA through OH.)
The digging shortwave will continue to advance across the
Midwest and Great Lakes region Sunday, as the surface low tracks
across OH through PA. The low will pull a cold front across the
region during the afternoon and early evening hours.
Wind profiles increase through the day Sunday with an
approaching jet. Gusty winds around 30-35mph are possible with
mixing during the afternoon. A narrow band of instability is
progged to develop just ahead of the cold front during the mid
to late afternoon, with mean MU CAPE values around 500 j/kg
generally S-SE of PIT. 0-6km shear is expected to increase to
between 40 and 50kt at the same time. Model soundings indicate
a mid level cap as well, eroding as FROPA occurs. This cap
should help limit thunderstorm development, though a broken
line of showers and embedded thunderstorms are expected along
the front. More convectively enhanced showers or organized
thunderstorms could tap the increased wind field aloft,
resulting in a potential for damaging wind gusts S-SE of PIT.
The Storm Prediction Center has placed this area in a Marginal
Risk (level 1 out of 5) for severe storms Sunday afternoon and
evening. Will highlight this potential in the Hazardous Weather
Outlook.
Showers and thunderstorms will taper off Sunday evening after
FROPA. Showers should increase in coverage again late Sunday
night and Monday as the initial upper trough axis crosses the
region, and cold advection occurs. The trough is progged to
deepen into a closed low across eastern Canada later Monday and
Monday night, as additional shortwaves rotate around it. This,
and cold NW flow off of the Great Lakes, will maintain scattered
to numerous showers across the region through Monday night. A
few snow flakes could also mix in across the higher terrain
areas, as 850mb temperatures drop to around -2 deg C.
Gusty winds are expected through much of the period, generally
ranging from 20-30mph.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
KEY MESSAGES:
- Cooler and unsettled weather through mid week
- Dry and warmer toward late week
-------------------------------------------------------------------
Model ensembles indicate the upper low will remain across the NE
CONUS through midweek, before opening into a trough and exiting
eastward later Wednesday. Continued cold NW flow off of the
Great Lakes, and shortwaves rotating around the low, will
maintain scattered showers across the region. Temperatures at
850mb are progged to range from -2 to -4 deg C through midweek,
and some snow could mix in at times across the higher terrain
areas of the Laurel Highlands and WV.
A ridge, between the exiting trough the the east, and a western
CONUS trough, will build across the region by late week. This
will result in dry and warmer weather returning to the region.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Light rain associated with a weak cold front has mostly
dissipated south of Pittsburgh this afternoon. However latest
radar imagery shows increasing coverage of showers across
central Ohio moving to the east. Uncertainty remains with
coverage over our area this afternoon as the front lifts
northward. Probabilities remain low enough to preclude mention
at any terminal for now. Rain chances will increase after 06z
tonight, with primary focus along a boundary across the I-80
corridor Sunday morning. More widespread coverage along the
front is possible Sunday afternoon, but uncertainty remains high.
Southwesterly winds will gust in excess of 20 kts on Sunday.
.Outlook...
Rain chance with restrictions are possible into Sunday night as
low pressure crosses the region. Building high pressure mid-week
should return dry weather and low restriction chance into the
weekend.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...WM
NEAR TERM...WM/88
SHORT TERM...WM/88
LONG TERM...WM
AVIATION...Rackley
Source:
PBZ issues Area Forecast Discussion (AFD) at Oct 12, 1:48 PM EDT---------------
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