Area Forecast Discussion
Issued by NWS Blacksburg, VA

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899
FXUS61 KRNK 190604
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
204 AM EDT Thu Oct 19 2017

.SYNOPSIS...
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 bring us pleasant fall weather through the
weekend. Our chances for rain will then start to increase on
Monday as a strong cold front approaches from the west.

&&

.NEAR TERM /THROUGH TODAY/...
As of 840 PM EDT Wednesday...

Weak upper disturbance passing across will bring a period of
high clouds overnight but expecting most of this to remain thin.
Otherwise high pressure to linger across eastern sections
through daybreak allowing for another mainly clear and cool
overnight. With temps and dewpoints running slightly higher this
evening, appears main threat for frost will be mostly in the
western valleys and eastern outlying areas. However frost should
remain a bit more patchy tonight espcly after seeing warmer
temps this afternoon and possible river valley fog again overnight.
Thus will continue to run without any headlines overnight.
Otherwise only small adjusts to temps with lows mainly 30s to
around 40 except for isolated 20s in the deeper valleys.

Previous discussion as of 250 PM EDT Wednesday...

More pleasant fall weather is on tap through tomorrow as a large
area of high pressure remains in place across the eastern US.
Temperatures tonight will be a bit warmer than last night with
mid/upper 30s east of the Blue Ridge, low/mid 30s west with cooler
readings in the valleys and some patchy frost and fog once again.
Lots of sun with some high clouds for Thursday with highs in
the middle 70s east to upper 60s/lower 70s west.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
As of 257 PM EDT Wednesday...

Surface high overhead Thursday night will slowly lift northeast to
off the mid-Atlantic coast by Friday into Saturday as upper pattern
amplifies with 5h ridge over us keeping us dry with warming trend.
Ridge axis moves offshore by late Saturday allowing some mid/upper
level clouds to increase by Sat night.

Lows Thu night will range from the upper 30s to lower 40s over most
of the area, with some mid to upper 40s urban areas and well mixed
ridges.

Highs about 5-10 degrees above normal Friday under sunny skies in
the 70s.

Slightly milder Friday night with 40s CWA wide.

Same temps again Saturday and milder Sat night with lows in the mid
40s to around 50.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 157 PM EDT Wednesday...

Major amplification of the upper pattern this period, though still
differences in speed of the sfc front and upper trough. The 00z
ECMWF more progressive than the 12z GFS. Allowed for a little faster
than the GFS but given the highly amplified nature things could be a
little slower.

With this in mind should see warmer and more humid conditions ahead
of the front Sun-Mon with rain chances arriving Sunday night with
more showery coverage Mon-Mon night. Some stability indices suggest
slight potential for thunder Monday. Arrival of cooler air as upper
flow deepens over the central Appalachians. A bit of a winter like
setup Tue-Wed with upslope showers. Colder air with the trough may
allow for snowflakes in the higher ridges late Tuesday with
brisk/breezy conditions Wednesday.

Highs in the 70s Sunday and Monday (though Monday could be cooler if
rain comes in faster), drops to highs in the 50s, maybe even 40s by
Wednesday.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 200 AM EDT Thursday...

High pressure will remain across the region at the surface
through the period. A weak upper trough will pass over the area
tonight associated with patchy cirrus through the early morning
and a wind shift more to the west after sunrise. Other than
patchy MVFR to potentially IFR/LIFR BR/FG at LWB and BCB,
conditions are expected to remain VFR and largely SKC through
the TAF valid period.

Winds calm most locations through daybreak becoming generally
SW-WSW 4-6kts after 14Z.

High confidence in ceilings through the TAF valid period.
High confidence in visibilities through the TAF valid period,
except medium confidence LWB/BCB 10Z-13Z this morning.
Medium confidence in wind direction, high confidence in wind
speed through the TAF valid period.

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
Appalachians.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...MBS
NEAR TERM...JH/MBS
SHORT TERM...WP
LONG TERM...WP
AVIATION...JH/RAB



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