FXUS61 KRNK 200121

Area Forecast Discussion
National Weather Service Blacksburg VA
921 PM EDT Thu Oct 19 2017

A large area of high pressure will remain over the eastern part
of the country this week before slowly sliding off the coast on
Saturday. This will keep skies mostly sunny and allow
temperatures to warm to above normal levels. Early next week, a
strong cold front and deep upper trough will approach from the
Midwest bringing widespread rain showers followed by much cooler


As of 910 PM EDT Thursday...

Other than for some passing thin cirrus from the north around
upper ridging west of the mountains, expecting another clear and
cool overnight under surface high pressure. However temps and
dewpoints are again a bit higher which should help alleviate
much of the frost threat by dawn despite continued good
radiational cooling. Still appears that some of the deeper
valleys could again see a late night coating of frost so
included a bit more in spots out west. Also nudged lows down
some given such dry air in place, which puts most of the
mountains down in the 30s, with upper 30s/lower 40s east.

Previous discussion as of 220 PM EDT Thursday...

Our string of pleasant fall weather will continue through the
end of the workweek as a large area of high pressure remains in
place across the eastern US. Temperatures tonight will be a bit
warmer than last night and with dew points creeping up coverage
of valley fog may be greater. Look for lows generally in the
mid 30s to around 40 degrees with some cooler readings in the
valleys and some spotty frost. Friday will be sunny and pleasantly
warm with above normal temperatures as highs reach the middle
and upper 70s east of the Ridge, low/mid 70s to the west.


As of 230 PM EDT Thursday...

Big ridge of high pressure over the southeast Friday night exits to
the east Saturday night as upper trough digs over the central U.S.
Still looking at dry weather with increasing temps through the
period. Clouds increase by late Saturday into Saturday night as the
low level flow turns more south to southwest.


As of 230 PM EDT Thursday...

The forecast has changed a little compared to 24 hours ago, namely a
slower onset of showers as models are trending slower as the upper
pattern becomes more amplified.

Sunday into Sunday night is going to be mainly dry and milder, but
cannot rule out some showers forming in an upslope se flow over the
NC mountains/far SW VA Blue Ridge late Sunday night.

Monday, low pressure along the main front moves from the MS/AL
border north to Ohio. Should see an uptick in threat of showers
mainly in the mountains to foothills. Still mild/warm with highs
ranging from the mid to 60s to around 70 west, to lower to mid 70s

Appears differences in models remains beyond Monday but overall
looks like colder air will be somewhat delayed and holding onto
front in the area Tuesday with best chance of showers late
Monday night through the day Tuesday.

Euro solution more phased at 5h than GFS but still suggests front
shifting east by Wednesday morning with less of a breeze than it
looked like yesterday, but still looking at some gusty conditions Wed
but more in the 15-25 mph range, mainly in the mountains/foothills.

Rain cooled air will bring temperatures back down to normal Tuesday
with highs from the 60s west, to around 70 east. Some upslope and
upper trough induced showers across the west starting late Tue night
into Wednesday as temperatures drop into the mid to upper 30s
mountains Tue night with 40s elsewhere, and only rising to the 50s
Wednesday west, to the lower to mid 60s east.

Looks drier after Wednesday with high pressure sliding in from the
Gulf Coast states and upper flow turning more west.


As of 655 PM EDT Thursday...

High pressure will remain in control of our weather this TAF
period with VFR flight conditions and light winds expected,
with the exception of IFR conditions in nocturnal fog/stratus
developing in the valleys. Expect KBCB and KLWB are most likely
sites for IFR conditions in fog/stratus, and with increasing
dew points coverage/duration look to be a bit greater than last
night. Will continue and go with prevailing IFR/LIFR these
sites for a couple of hours around daybreak.

Extended Aviation Discussion...

High pressure will remain over the region through Sunday with
generally VFR conditions expected, outside the usual late
night/early morning patchy river and mountain valley fog.
A deep upper trough and associated strong cold front will move
into the region from the west by Monday promising a period of
sub-VFR conditions in rain/showers along with increasing wind.
Colder, blustery, unsettled weather with perhaps largely MVFR
conditions across the mountains will linger through the later
half of next week as an upper trough cuts off across the central




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