Area Forecast Discussion Issued by NWS Pittsburgh, PA
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000
FXUS61 KPBZ 180717
AFDPBZ
Area Forecast Discussion
National Weather Service Pittsburgh PA
317 AM EDT Mon Mar 18 2024
.SYNOPSIS...
Scattered snow showers are expected on and off through Tuesday
morning with a crossing upper trough. Dry weather is then
expected as temperatures will gradually warm mid to late week.
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.NEAR TERM /UNTIL 6 AM THIS MORNING/...
KEY MESSAGES:
- Lake enhanced showers continue mainly north of Pittsburgh
- Colder temperatures arrive tonight, especially over the
southern half of forecast area
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No changes needed for the early overnight update...
Deep and cold trough over the Great Lakes will gradually move
south overnight. 500 mb heights will fall another 70 meters or
so as a result. The column will continue to cool and especially
the boundary layer, with 850 mb temps falling from about -4C
this evening to -11C in the PIT area by 12z Monday.
Coverage of snow showers has become more sparse into the early
overnight with the loss of diurnal heating. However, the loss
of insolation has promoted some minor accumulation in the
more moderate snow showers as seen on area webcams, especially
along and north of I-80. A light dusting to perhaps a brief half
inch is possible for those locations.
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.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
KEY MESSAGES:
- Cold and unstable under upper trough with showers of snow and
graupel.
- Potential for light snow accumulation, mainly north of I 80
and in the higher terrain
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Upper trough will start the day over northwest Ohio and Lake
Erie, moving to western PA and WV by the late afternoon.
Strongest height falls of 150 meters will be over VA.
A very cold and unstable airmass is expected given we have mid
March sun angle. 850 mb temps will be around -10C, 700 mb -18C,
and 500 mb dropping to around -35C. RAP soundings show moist and
unstable situation with diurnal heating under trough with
increasing moisture and even 100-300 j/kg of CAPE. Cloud tops
will be in the -20 to -25C range, so vigorous convective snow
showers are expected which certainly could produce brief heavy
snow bursts and graupel. Accumulations outside of ridges will be
limited by March sun angle. However, with convection continuing
into the evening, there is certainly the potential for
accumulations north of I-80 and over the ridges Monday night.
CIPS analogs indicate that the WV ridges have a 30-50% chance of
4" or more in patterns like this. At this point expect 2-3" in
those areas so expect a sub-advisory event especially during the
daylight hours.
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.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
KEY MESSAGES:
- Near normal temperatures expected Tuesday through Friday
- Mainly dry weekend with moderating temperatures
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As heights gradually rise and flow turns from northwest
to westerly aloft, a low pressure area over the Great Lakes
will skirt mainly north of the forecast area as it heads toward
Ontario/Quebec/New England Tuesday into Wednesday. Certainly
could be snow in the northern half, especially Tuesday morning,
but the system will have limited moisture so the precipitation
shield is more likely to impact New York and far northern PA.
Flow gradually tilts from westerly to southwesterly as the week
progresses with gradually rising heights and moderating
temperatures. While near normal readings are expected most of
the week, moderation begins over the weekend with highs in the
50s Saturday and Sunday.
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.AVIATION /07Z MONDAY THROUGH FRIDAY/...
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Advancing plumes of lake enhanced moisture have created periods
of MVFR conditions for numerous TAF sites early this morning.
Areas as far south as HLG have been experiencing brief periods
of 1.5kft to 3kft cigs. TEMPOs were added to BVI, LBE, HLG, PIT,
and AGC. Meanwhile, MVFR conditions are likely to prevail for
FKL/DUJ in close proximity to Lake Erie moisture and advancing
cold air.
A passing shortwave over the Great Lakes after 15Z will likely
increase the potential for a new wave of snow showers. MVFR is
likely for terminals north of PIT. However, with sfc heating and
linger drier air within the boundary layer, cigs may not drop
until after 23Z Monday for terminals south of FKL/DUJ.
Probability of wind gusts above 20kts throughout daylight hours
of the TAF period remain high with deep mixing prompted by cold
advection and a gradient wind associated with a passing trough.
.Outlook...
MVFR conditions may linger into Wednesday with a new shortwave
and burst of colder air from the north. VFR returns Thursday as
high pressure builds over Ohio.-- End Changed Discussion --
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.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.
&&
$$
SYNOPSIS...Rackley
NEAR TERM...Craven/Rackley/MLB
SHORT TERM...Craven
LONG TERM...Craven
AVIATION...Hefferan