PBZ issues Area Forecast Discussion (AFD) at Jan 30, 5:32 AM EST065
FXUS61 KPBZ 301032
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
532 AM EST Thu Jan 30 2025
.SYNOPSIS...
Dry weather is expected today under high pressure. Rain returns
tonight and Friday with crossing low pressure. Dry weather then
returns for the weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
KEY MESSAGES:
- Dry and warmer today
----------------------------------------------------------------
Update...
Increased cloud cover over portions of the area this morning
where mid level clouds were seen on the leading edge of warm
advection.
Previous discussion...
Dry weather is expected today as high pressure builds across the
Upper Ohio Valley region. Patchy mid level clouds will exit the
region this morning, before more high and mid level clouds
increase later in the day in warm advection ahead of the next
approaching shortwave/low pressure system. Nudged highs toward
the warmer side of guidance, with strong warm advection through
the day.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
KEY MESSAGES:
- Rain returns tonight and Friday with low pressure
- Flood watch for Laurel Highlands to nrn WV tonight through Sat
- Dry weather returns Saturday
--------------------------------------------------------------------
A central CONUS trough will advance eastward tonight, as a
surface low develops across the Midwest. Moisture and ascent in
warm advection ahead of the trough will overspread the Upper
Ohio Valley region tonight, with rain developing. Temperatures
are expected to remain above freezing overnight, with the area
in the warm sector.
Periods of rain will continue on Friday as the shortwave trough
approaches, and surface low pressure tracks across northern OH
and NW PA. Some areas mainly south of I 70 could see some
enhancement to the rainfall as a low level jet crosses the
region late tonight into Friday. The upper trough axis will
cross the region Friday evening, as the surface low pulls a cold
front across the region as it tracks eastward. Rain should taper
off later in the day as the front crosses, though some patchy
light rain will remain possible Friday night as the front
completes its passage. There could be a brief period of snow
mixing in before the precip ends, though no accumulation is
expected.
Rainfall amounts are expected to range from 0.5 to 1.25 inches,
with the highest amounts south of I 70. A Flood Watch continues
in effect for the Westmoreland county and points to the south,
where a combination of snow melt and rainfall will likely result
in river rises. These rises could also cause ice
movement/breakup, with a possibility of ice jams. Please see the
Hydrology section below for more detailed information.
Dry weather returns Saturday and Saturday night under high
pressure. Most locations south of I 80 are expected to reach the
50s for highs on Friday, with 40s to the north and in the
ridges. Readings return to more seasonable levels after FROPA.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
KEY MESSAGES:
- Mainly dry on Sunday
- Slight chance for rain with a Monday cold front
- Rain and snow chances return Wednesday with low pressure
-------------------------------------------------------------------
Model ensembles indicate a general zonal flow is expected across
the CONUS for much of the long term period, as a trough develops
off the Pacific NW coast. A weak cold front embedded in the flow
is progged to cross the Upper Ohio Valley region on Monday, with
only a slight chance of rain expected. Generally dry weather
returns on Tuesday as surface high pressure builds in.
Low pressure is expected to develop along a stalled surface
boundary across the Mississippi Valley region Tuesday night,
approaching the Ohio Valley region on Wednesday. Rain chances
return with the approach of the low. Some snow is also possible,
depending on the exact track of the low and where the surface
boundary sets up. Stayed close to the ensemble blend to smooth
out some of this uncertainty in the forecast.
Temperatures are expected to average above seasonable levels
through most of the period, with Tuesday being the coldest day
after FROPA.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
General VFR forecast through much of the period. Lingering
stratocu deck will continue to slowly dissipate overnight,
leaving VFR stratocu at FKL,DUJ and LBE for the early portion
of the forecast. An area of higher clouds will drift across the
area late tonight in the northwest flow aloft. Low confidence on
how far south these clouds will make it.
Winds will continue to weaken overnight.
High cirrus clouds will increase from the southwest this
afternoon. Expect restrictions to quickly return from southwest
to northeast this evening as rain and IFR/MVFR cigs overspread
the region.
Outlook...Restrictions and rain on Friday with low pressure. A
warm front returns restriction potential on Saturday.
&&
.HYDROLOGY...
Rainfall amounts between 0.75-1.25 inches falling on a melting
snowpack could contribute to significant rises on area rivers,
especially in the Mon, Yough and Cheat basins. These rises will
certainly disturb areal river ice and could create ice jam
flooding. At this time multiple forecast points are forecast to
hit action stage but none are currently forecast to hit minor
flood stage.
Mon, Yough and Cheat Basins:
These basins are grouped together because their anticipated rain
totals, snowpack and ice coverage are expected to create similar
issues.
Rises on the Upper Mon and Cheat rivers are expected to on the
order of 6-12 feet. These rises will certainly disturb any river
ice and can exacerbate issues seen across these basins. At this
time there are several locations in these basins forecast to reach
action stage.
Rises on the Lower Mon are expected to be on the order of 10-20
feet. This is expected to take all forecast points on the Lower
Mon to action, but not to minor flood.
Rises on the Yough are expected to be on the order of 3-6 feet.
These rises will certainly disturb thick river ice observed along
the river. At this time no points are forecast to reach action
stage but issues due to ice jams can bring flood concerns anyway.
Allegheny, Ohio and Musk Basins:
Upcoming rainfall and current snowpack are lighter in these
basins. However, rain on rotting snow, river ice and the heating
induced snowmelt are likely to cause rises over the next several
days.
Rises on the Allegheny are expected to be on the order of 1-3
feet. These rises could be enough to disturb the current ice
coverage on the river and lead to ice jam flooding. At this time
no points in the Allegheny Basin are expected to reach action
stage.
Rises on the Ohio are expected to be on the order of 5-10 feet.
At this time no points are forecast to move to action stage but
the disturbance of ice may cause issues.
Rises on the Beaver, Muskingum and Tuscarawas rivers are expected
to be on the order of 1-3 feet. At this time no points are
expected to move to action stage. However, these rises are
sufficient to disturb plentiful areal ice coverage and cause
issues.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...Flood Watch from late tonight through Saturday afternoon for
PAZ073>076.
OH...None.
WV...Flood Watch from late tonight through Saturday afternoon for
WVZ509>514.
&&
$$
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...22
HYDROLOGY...
Source:
PBZ issues Area Forecast Discussion (AFD) at Jan 30, 5:32 AM EST---------------
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