Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
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FXUS61 KRNK 271722
Area Forecast Discussion
National Weather Service Blacksburg VA
122 PM EDT Thu Oct 27 2016
A weak cold front will approach the region from the west this
morning before passing across the area later today into this
evening. High pressure follows the front Friday bringing a return
to drier and milder weather into Saturday. Another weak cold front
will dip south through the Mid-Atlantic region later Sunday into
.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM EDT Thursday...
Surface wave passing to the north will gradually propel a weak cold
front into the mountains later this afternoon and across the Blue Ridge
this evening. Moisture ahead of the boundary remains quite limited with
dewpoints in the 30s/40s under westerly flow aloft. This again spells
concern for coverage of showers with the front later today as best
dynamics pass north while much of any initial lift will go to basically
moisten the column. Models remain quite limited in producing much QPF
outside of the far north/northwest with the GFS wetter with a pre-
frontal convergence axis this afternoon before the actual front
arrives this evening. This tied to a stronger lead shortwave rounding
the base of the upper trough which looks overdone. Latest ECMWF on
the other hand quite spotty with showers in having only a few
hundredths mainly east of I-81 and a tenth or two to the west.
However despite limited deep return moisture with only subtle backing
seen aloft today, lapse rates look rather steep and with progged
theta-e ridging and weak diffluence aloft, still appears a couple
bands of broken showers possible. This mainly within a possible
pre- frontal band over the west that will attempt to shift into
southeast sections late, and with the actual front crossing the
western ridges by early evening. Isolated thunder cant be totally
ruled out mainly far north per upper support, and over the far
south where guidance shows some weak late day instability, but
quite iffy given limited moisture recovery at this point.
Thus keeping pops mainly chance while cutting back on thunder and
allowing some sunny breaks espcly east this morning and perhaps at
times over the west if showers are slower to develop. Also leaned a
little more toward the milder Met mos today given warmth aloft and
westerly flow which with some breaks could allow readings to jump well
into the 60s to near 70 southeast.
Front should finally clear the area overnight allowing drying aloft to
kick in as northwest flow aloft increases. This should shut off most
lingering shower chances during the evening with downslope clearing
taking shape out east. However low level moisture within the
northwest trajectory likely to aid low clouds and possibly spotty
drizzle western slopes after midnight with low clouds likely
spilling out toward the Blue Ridge overnight. Thus becoming mostly
clear east to partly cloudy Blue Ridge to remaining mainly cloudy
far west. Cool advection bleeding into the west should allow lows
to drop off into the 40s west of the Blue Ridge with overall low/mid
50s east given best cooling aloft to the north and west.
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 330 AM EDT Thursday...
After a vigorous short wave exits New England on Friday, the upper
level pattern will trend to a progressive quasi-zonal regime through
the weekend. Anything resembling cold air will remain bottled up to our
north and with high pressure at the surface taking up a position over
the southeast we will have a steady warming trend with temperatures
well above normal through the weekend. By Sunday a low will be sliding
by to our north and slowly pushing a weak frontal boundary into the
region. This may bring a shower to the far north from Greenbrier county
WV through the Alleghany Highlands and down the western slopes of the
Appalachians later on Sunday into Sunday night, but any precipitation
looks to be meager and the majority of the area will see no
precipitation at all. It also looks to be a bit breezy mainly Saturday
night and Sunday.
High temperatures on Friday will generally be in the upper 60s/lower
70s east of the Blue Ridge to low/mid 60s west. However by Sunday highs
will be close to 80 for some locations east of the Ridge with low/mid
70s west, which will be a solid 10 degrees above normal.
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM EDT Wednesday...
Above normal temperatures will continue into the medium range with
Southeast ridging. Several shortwaves will rotate across the northern
Tier of the CONUS in the fast upper flow. High pressure will build
south into our region for Monday into Wednesday.
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 125 PM EDT Thursday...
Some showers and cloud cover is in place over the region associated
with an upper level disturbance. A weak cold front is also expected
to cross the area during the TAF period. Winds are expected to be
relatively light with the exception of some gusts at BLF. For the
short term, conditions will remain VFR with some low to mid level
cigs. Areas east of the mountains can expect to remain VFR through
the forecast. Those locations at elevation can expect at the minimum
MVFR conditions overnight. BLF should see a lower cloud deck
moving overhead this evening which will cause vis restrictions. This
will persist until after sunrise until enough heating takes place to
burn the deck off. Some guidance suggests that visibility at LWB
could become IFR late tonight, however, enough uncertainty exists as
to just as far the temp will drop this evening that it was left as a
tempo group. Any chances for fog will diminish shortly after sunrise.
Afterward, high pressure will dominate the region and VFR conditions
Extended aviation discussion...
VFR conditions should persist through the next several days as high
pressure becomes the dominant feature for the region. Some
possibilities for MVFR and perhaps a shower exist for Sunday ahead
of another weak front, but models seem to be in disagreement with
placement and this feature may very well miss the region to the