Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 211742
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
142 PM EDT Thu Sep 21 2017

.SYNOPSIS...
High pressure will cover the region today through Saturday. A
cold front will approach the Mid Atlantic region the middle of
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 125 PM EDT Thursday...

An upper level ridge will remain stationary over the Midwest but
will expand in areal coverage to include the south-central
Appalachains this afternoon into Friday. As this ridge expands, it
will nudge an upper level trough south into North Carolina tonight.
While this trough remains in our vicinity, scattered afternoon
showers are possible, mainly across the mountains and south of hwy
460. These showers will fade with loss of heating this evening.

Surface high pressure will build in overnight, decreasing
chances and areal coverage of showers Friday afternoon to the
North Carolina High Country. Any afternoon showers today and
Friday will remain light with less than a tenth of an inch of
rainfall. Patchy dense fog is highly likely in mountain valleys
for Friday`s morning commute.

Area remains under high pressure with little to no change in air
mass. Temperatures will stay above normal today and tonight.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 142 PM EDT Thursday...

Upper ridge will remain just to our northwest through the weekend.
The center of the ridge will build northeast and be located over
Pennsylvania.

At 17Z, Hurricane Maria was located near 20.4 N, and 69.4 W.
Maria was moving toward the northwest near 9 mph. Data from an
Air Force Reserve reconnaissance aircraft indicate that maximum
sustained winds remain near 120 mph with higher gusts. Maria is
expected to turn toward the north-northwest Friday, then
northward into the weekend.

Summerlike conditions will continue into the weekend with 850mb
temperatures around plus 16 to plus 18.  It will be a real nice
weekend for outdoor activities with mild temperatures and
comfortable humidity levels.

Any isolated shallow convection Friday afternoon will diminish
quickly Friday evening with the loss of solar heating. Clear to
partly cloudy conditions will result in good radiational cooling.
Added some patchy valley fog to ISC grids. Low temperatures
Friday night will range from the lower 50s in the mountains to
the lower 60s in the Piedmont.

Under plenty of sunshine, High temperatures Saturday will vary from
the mid 70s in the west to the mid 80s in the east. Mostly clear
conditions will continue Saturday night with lows from the the lower
50s in the mountains to the lower 60s in the piedmont. Sunday will
feature bright sunshine with high readings from the mid 70s in the
mountains to the mid 80s in the piedmont. A good night to keep the
window open Sunday night with low values from the lower 50s in the
west to the lower 60s in the east.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 142 PM EDT Wednesday...

Models showed good large-scale agreement across CONUS through
medium range. The amplified weather pattern continues across
the country with an active tropics in the western Atlantic
ocean. Model ensembles and consensus from NHC keep Maria east of
the mainland. See latest NHC advisory for position and track.

The trough across the central U.S. and associated cold front
will slowly travel eastward. The strong upper level ridge should
hold across our area. Operational models showed the potential
for some clouds and possible showers to flirt with our piedmont
counties Tuesday afternoon with Maria interacting with coastal front
and trough. Hard to tell how far west any moisture really
pushes. 12z run looked less impressive with moisture and qpf.
Interesting to note the weak shortwave rotating around the upper
ridge across southeast portions of forecast area. A cold front
will weaken as it moves east and travel through the eastern U.S.
Thursday into Friday.

Temperatures remain above normal during extended period with lows
generally in the upper 50s to around 60 in the west, to lower to mid
60s in the east. High temperatures will range from the mid 70s to
around 80 in the west, to lower to mid 80s in the east. The
strength of the subsidence with Maria and amounts of cloud
cover will greatly impact the temperatures.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 130 PM EDT Thursday...

A departing upper level trough sinking south into North Carolina
may generate scattered showers and an isolated thunderstorms this
afternoon. Areal coverage will be too limited to add to the TAFS at
this time and the best probability of precipitation will be south
and west of KROA, KBCB, and KBLF. Just like the last several
mornings, patchy dense fog is highly likely in mountain river
valleys (KLWB/KBCB). Fog should lift by 14Z/10A.

Extended Aviation Discussion...

Overall persistence forecast to prevail for the rest of the week.
Strengthening high pressure remaining in place between exiting Jose
offshore and a weak cold front approaching from the west. This
should maintain good flying weather outside of isolated diurnal
showers and thunderstorms. Dry weather is expected Friday through
Monday.

&&

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

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...KK
LONG TERM...KK
AVIATION...AMS/DS



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