Scientific Forecaster Discussion
fxus61 krnk 071836
Area forecast discussion
National Weather Service Blacksburg Virginia
136 PM EST Sat Dec 7 2019
a large area of surface high pressure will slide across the
northern mid-Atlantic and into New England this evening...then
off the East Coast Sunday. A period of wet weather is expected
Monday and Tuesday as a cold front moves east from the central
Near term /through Sunday/...
as of 1250 PM EST Saturday...
Surface high pressure will move over New England by this
evening. Once this ridge is in place, colder drier air will
filter into the region overnight with most area seeing starry
skies. The high-resolution models maintain some low level
cloudiness over western NC and into the Grayson Highlands, but
layer should remain relatively shallow and not yielding any
precipitation. That said, some rime icing possible for terrain
which intersects the cloud base but that should be the
extent...otherwise, the only impact would be to keep
temperatures up a few degrees where the clouds persist.
Elsewhere, the surface based inversion should be stronger with
mostly clear skies resulting in a colder night, temperatures
dipping into the 20s.
The parent high pressure will move off the New England coast
through the day Sunday. Winds will veer to the southeast,
possibly allowing Atlantic moisture to produce a few clouds
during the afternoon. However, the moisture fetch off the
Atlantic will not be enough to produce any precipitation.
Temperatures Sunday will be close to normal, ranging from the
40s across the mountains to upper 40s to lower 50s east.
Short term /Sunday night through Tuesday night/...
as of 150 PM EST Saturday...
A longwave trough will travel east through the central Continental U.S.
And should reach the Ohio Valley about Tuesday night. A deep and
moist southwesterly flow will develop across our region in
advance of the upper trough associated surface cold front.
The high center over our region will push east into the
Atlantic Ocean Sunday night. Moisture will slowly return from
the south. During the onset of precipitation Sunday night, there
may be enough cold air for pockets of sleet for the Southwest
Mountains. Little if any sleet accumulation is expected. As the
night progresses, surface temperatures are expected to slowly
rise from south to north across the area. Low temperatures
Sunday night will range from the lower 30s in the mountains to
the upper 30s in the Piedmont.
Cloudy skies with periods of rain will continue Monday into
Monday night/ the best chances of rain will be located across
the northern and western sections of the forecast region. High
temperatures Monday will be mild with readings from the upper
40s in the mountains to the upper 50s in the Piedmont. Low
temperatures Monday night will vary from the lower 40s in the
mountains to the mid 50s in the Piedmont.
The cold front will continue to move east Tuesday into Tuesday
night across the region. In the east, temperatures will continue
to be on the mild side ahead of the front. Western sections of
the area will see quickly falling temperatures in the afternoon,
with the potential for some pockets of a rain/snow mix at the
highest elevations. High temperatures on Tuesday will range from
the upper 40s in the northwest mountains to the mid 60s in the
Gusty northwest winds will usher in colder air across the
region Tuesday night. Rain showers will transition to snow
showers across the mountains, with enough cold air extended far
enough east for a mix of rain/snow showers across the foothills
and western Piedmont regions. Some light snow accumulations are
possible late Tuesday night into Wednesday morning from a
coating to around an inch in the mountains. The European model (ecmwf) was a
little slower in ending snow and snow flurries. Low
temperatures will generally be from the lower 20s in the
northwest mountains to the mid 30s in the Piedmont.
Confidence in this portion of the forecast is moderate.
Long term /Wednesday through Friday/...
as of 150 PM EST Friday...
High pressure from the northern plains will build into our
region early nest week behind the cold front. The cold air mass
will drop our temps to below normal for December, so the end of
the week will be chilly. The high center will move east across
southern New England Thursday into Thursday night and out into
the Atlantic Ocean Friday. Some moisture will push into the
southern portions of the forecast area late Thursday night into
The weather become quite active Friday into Saturday with
cyclogenesis over the northeast Gulf Coast. Rich moisture will
eventually push back into the central Appalachians. There has
been a lack of consistency in the models with track and timing
of the surface low that will bring precipitation around next
weekend. The details on this system will become more clearer
Confidence in this portion of the forecast is low to moderate.
Aviation /18z Saturday through Thursday/...
as of 1222 PM EST Saturday...
High pressure over the northern mid-Atlantic will wedge south
this afternoon into tonight. Cold dry air will help limit any
low clouds and/or fog. However, before the dry air arrives, scattered-
broken low clouds will move south across the area. Ceiling
restrictions will be elevation dependent with higher elevations
being IFR-MVFR through the afternoon. At this time, kblf is
carrying a northwest wind and with low level moisture banked
along western slopes, MVFR ceilings may last into mid-afternoon.
At other taf sites, ceilings are VFR.
Winds will veer to the northeast by this evening. Speeds will
vary between 5-10kts this afternoon with low-end gusts possible
across the Piedmont. Winds will diminish this evening and remain
light into Sunday morning.
Extended aviation discussion...
Confidence continues to increase in poor flying weather for Monday
and Tuesday as a complex low pressure system develops to provide low
ceilings and rain. The cold front from this low pressure system
should cross overhead by Tuesday night to bring gusty northwest
winds for Wednesday.