Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Blacksburg Virginia
656 PM EDT Tue Jun 25 2019
high pressure will settle across the region overnight and remain
through late in the week. The next chance for widespread
showers will be associated with a cold front that arrives later
in the weekend.
Near term /through Wednesday/...
as of 210 PM EDT Tuesday...
The cold front has moved to the coast with high pressure
building over the mountains this evening. This ridge is not
deep, but with wet soils some Mountain Valley fog is possible
during the early morning hours Wednesday. With high pressure at
the surface and zonal flow aloft, Wednesday will be rain-free
with afternoon temperatures ranging from the 80s across the west
and near 90f east of the Blue Ridge.
Short term /Wednesday night through Friday night/...
as of 330 PM EDT Tuesday...
An upper level ridge and surface high pressure will support
northwest windflow across the area, which is expected to cap the
atmosphere during the middle of this week. This will make
getting a shower or thunderstorm to develop on Thursday quite
difficult, with best chances of very isolated activity occuring
along the crest of the Blue Ridge with afternoon heating.
Better coverage of showers/storms is expected on Friday upper
level ridging develops across the central United States, while
surface high pressure pushes east, allowing winds to swing more
southerly. May see showers and storms fire along the crest of
the Blue Ridge with afternoon heating, followed later in the day
possibly by more organized thunderstorm activity moving into
the area from the northwest associated with a strong upper level
disturbance. Will keep an eye on the development of this
scenario in the coming days.
Long term /Saturday through Tuesday/...
as of 345 PM EDT Tuesday...
Expect upper level ridging across the central United States
toward the end of the week, resulting in northwest windflow
aloft across the mid-Atlantic. Given strong heating on Saturday
and Sunday, will have to keep an eye on any disturbances
approaching from the Great Lakes region, which could trigger a
line of strong thunderstorms. Confidence on timing, track and
even development of these storms is low that far into the
future. Chances for thunderstorm activity do increase Sunday
night however as a cold front is expected to approach from the
north, with the front possibly entering and stalling across our
area on Monday.
Aviation /00z Wednesday through Sunday/...
as of 650 PM EDT Tuesday...
Widespread VFR conditions will prevail through this evening with
a canopy of mainly mid/high clouds around before high level
moisture pushes south later this evening. This as ongoing
northwest winds slowly diminish to less than 10 kts overnight
including near calm in the valleys late.
Late tonight, areas of IFR cigs and visibilities are also expected,
especially at the Mountain Valley taf sites (klwb and kbcb) as
light winds and a moist ground help generate fog and stratus in
some places. However this remains low confidence given ongoing
clouds and light mixing, but enough potential to keep in some
mention espcly at the more typical foggy locations.
The combination of a weak surface ridge and zonal flow aloft will
allow for VFR again on Wednesday after any early fog/clouds
fade. Again likely to see some scattered/broken cumulus over the
mountains but mainly above 4-5k feet. Winds will turn more west
to southwest but remain in the 5-15 kt range Wednesday
Extended aviation discussion...
High pressure is expected to take up residency over the region
into Friday. For the most part, VFR conditions are expected
outside of late night/early morning fog. Also, as we approach
the weekend showers and storms will be on the increase, and
these too may bring some temporary reductions to visibility and
Late Friday into Saturday, the chances of sub-VFR conditions
increase espcly across the mountains with heating of low level
moisture aided by orographics. The arrival of a backdoor cold
front late in the weekend should allow for an increase in
coverage of showers and storms by Sunday afternoon.