Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/08/20

Area Forecast Discussion

National Weather Service Pittsburgh PA

 646 PM EST Fri Feb 7 2020

.SYNOPSIS...
Crossing upper disturbances will support periods of snow showers
through Saturday, with generally light accumulation expected. A
gradual warm up is then expected into early next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
No major changes were made to the evening forecast as residual snow
showers continue. The Winter Weather Advisory will be allowed to
expire.

Previous: A crossing shortwave embedded within broad upper troughing
will support snow showers through tonight. Sufficient moisture
lingering through the dendritic growth zone as observed in recent
AMDAR soundings out of KPIT, combined with low-level instability and
potential lake- enhancement may lead to heavier bursts of snow
showers with reduced visiblity and gusty wind.

This profile is especially evident in the ridges, where accumulating,
upslope snow will continue before waning late tonight as wind backs
to wly.

Elsewhere, dry advection in sfc ridging should generally hamper snow
efficiency later tonight as moisture depth through the boundary
layer decreases, with snow showers becoming more isolated in nature.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/...
Deep troughing across the Great Lakes should flatten in response to
an upstream Pacfic NW low, with rising heights yielding a more quasi-
zonal flow and gradual temperature moderation.  A weak shortwave
trough embedded within the flow will cross the region Saturday,
invigorating snow/rain as it passes. Given weak forcing for ascent,
snowfall accumulations should be minor.

In the system`s wake, high pressure will build into the region as a
strong wave digs swd along the west coast. The downstream effect will
be increasing heights in the ern CONUS and an attendant modest warm-
up early next week.

As swly flow increases in advance of the wrn trough, a shortwave
trough and advancing cold front will focus precipitation development
in the region Sun night and Mon. Warm air aloft will be more than
ample to ensure all rain during this time, with any changeover to
snow limited to lingering precipitation immediately behind the cold
front.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Although flow on the whole will be zonal through the remainder of the
week, several waves embedded in the nrn stream flow will graze the
Ohio Valley through the week, suggesting the potential for active but
low-impact wx.

Considerable differences exist between the ECMWF and GFS by late next
week, with the latter considerably colder and suggesting lake-
enhanced showers while the former suggests warm advection and a
warm-sector system on Thu.

At this time, PoPs and temperature have split the difference until
the forecast details can become in better agreement.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
MVFR cigs and lcl IFR in shsn can be expected early this evening via
shrtwv/upr trof spprt and upsloping lake mstr. Initially steep llvl
lapse rate wl also maintain 20 to 25 kt gust potential.

Brief shrtwv ridging should spawn improvement aftr dark with
mid-lvl-blanketed VFR anticipated, but condition deterioration back
to MVFR, with lcl IFR in shsn is progged once again with a Saturday
disturbance.

.Outlook...
Restrictions are again likely with the crossing of low pres late Sun
and Mon.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Winter Weather Advisory until 7 PM EST this evening for MDZ001.
OH...None.
PA...Winter Weather Advisory until 7 PM EST this evening for PAZ074-076.
WV...Winter Weather Advisory until 7 PM EST this evening for WVZ510>514.

&&

$$