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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 250128
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
928 PM EDT Sat Oct 24 2020

.SYNOPSIS...
A cold front moves south across the Carolinas tonight into
Sunday, with high pressure wedging south into our area into
early next week. Another front moves in midweek. Temperatures
for Sunday will back below normal and rain is expected tonight
into early Sunday night. Temperatures moderate early next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 900 PM EDT Saturday...

Strong short wave lifting northeast to east-northeast out of
Georgia, centered near ATL this evening. Vigorous, highly
kinematic system that will bring a good dousing of rain to the
southeastern parts of the CWA, far less to the northwest part of
the CWA. The main emphasis will be across central/eastern NC,
SC, and eastern GA overnight. The system will track east of the
area by late Sunday, but leaving behind a wedge of cool air, low
clouds, and drizzle/fog overnight into Monday morning before the
situation improves.

WPC concerned about rainfall over the next few hours across the
NC Piedmont especially as well as back into western NC and
points south. MPD was issued and included our southern tier of
mainly NC counties for 1-2 inches of rainfall over the next
couple of hours. This precipitation is riding along the
remnant/wedge developing frontal boundary.

As of 155 PM EDT Saturday...

Frontal boundary stretching from the mid-Atlantic to the west of the
Blue Ridge in NC slides southeast tonight slowly and will take on a
west-east orientation as it becomes parallel to the upper flow. A
shortwave works northeast through the Carolinas late tonight into
Sunday pushing offshore by late in the day Sunday.

As for the weather, will see showers form along/ahead of the front
heading into mid to late afternoon from the NC mountains into the
foothills of VA, but appears showers will be weak early on. Better
instability where more sunshine occurred lies east of the Blue Ridge
and south of the Roanoke River/U.S. 460 corridor. Allow for isolated
thunder in the piedmont, and as far west as the NC mtns late this
afternoon.

Expect rain to increase in coverage ahead of the shortwave later
this evening and overnight, as best isentropic lift becomes
coincident with upper forcing. Went with likely pops along/east of
the Blue Ridge, with lower threat west. Rainfall amounts are
actually sliding upward per latest models along and east of the
southern Blue Ridge with up to three-quarters of inch possible
tonight into early Sunday, with a quarter inch or less west.

High pressure to the north wedges southward into the area Sunday and
will lean toward cooler temps and non-diurnal temperature curve,
with clouds likely to hinder temps from rising much during the day.
Exception may be southwest of a Bluefield to Marion line.

Temperatures Sunday may not get out of the 40s north of U.S. 60, in
the higher elevations, and even Lynchburg. Most will stay in the
50s, with 60s southwest a line from Bluefield to Wilkesboro, except
the Blue Ridge.

Forecast confidence is good for rain threat at least tonight-Sunday,
lower on thunder threat and highs Sunday.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 210 PM EDT Saturday...

Deeper moisture heads out Sunday night into Monday but wedge remains
and look for patchy light rain/drizzle and fog for most Sunday night-
Monday morning. Should see flow turn more south Monday afternoon but
models are still showing residual low level moisture hanging tough
most of the day east of the Blue Ridge. Forecast confidence is lower
for sky cover and temperatures Monday but lowered highs in the
piedmont a few degrees, but will still be milder Monday compared to
Sunday with highs in the 60s.

Upper ridge across the southeast remains in place with trough axis
across the Great Lakes/Midwest. A fast flow aloft will exist over us
Tuesday and frontal boundary works in but with west flow will likely
see limited shower threat. Temperatures continue to warm above
normal, with mid to upper 60s west on Tuesday to mid 70s east.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 1245 PM EDT Saturday...

The models continue to advertise a closed upper level low crossing
over the southern Plains on Wednesday with a tropical area of low
pressure coming northward from the Gulf of Mexico. Any tropical
moisture would get wrapped into a low pressure system over the
Mississippi River Valley by Wednesday night and head toward the Mid
Atlantic. Thus, confidence continues to rise for a rather wet
Thursday. Periods of moderate to heavy rain are possible, but it is
way too early to tell what if any hydro impacts may occur due to
most of this month being quite dry and also the considerable model
discrepancies with the track of the low pressure system.

While there are some notable timing differences among the models
regarding when the bulk of the moisture should exit off the East
Coast, it seems that lingering showers could persist through
Thursday night and Friday. The closed upper level low could pass
overhead by Friday afternoon as well to keep the shower chances
ongoing. Eventually, high pressure will build over the Appalachian
Mountains during Friday night into Saturday morning. Drier and
cooler conditions should take hold for the start of the weekend.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
As of 800 PM EDT Saturday...

Poor aviation conditions expected through the TAF valid period
as a wedge develops north of a stalled frontal boundary to our
south and a vigorous short wave aloft tracks across the region
from GA and SC overnight into Sunday. Showers and isolated
thunderstorms this evening will give way to more widespread
light rain and eventually drizzle/fog through the day Sunday.
Mostly IFR-LIFR ceilings are expected through the TAF valid
period once they settle in overnight and early Sunday, going
nowhere after that until the wedge breaks Monday morning.
Visibilities mainly MVFR through the day Sunday with pockets of
IFR-LIFR in DZ/FG overnight Sunday into Monday morning. Rain
will be most prevalent with periodic heavier showers east-south
of the Blue Ridge mainly after 04Z Sunday. Lighter rain or
drizzle expected to the northwest. Winds will become northeast
to east 5-10kts late tonight/early Sunday with low end gusts
expected mainly east of the Blue Ridge.

/Confidence in Forecast Parameters/
-Moderate to High Confidence in MVFR-IFR or worse ceilings
through the TAF valid period,
-Moderate Confidence in MVFR or worse visibilities mainly after
04Z Sunday in -RA, -DZ, and BR/FG through the TAF valid period.
-High Confidence in winds becoming NE-E 6-12kts with low end
gusts overnight/early Sunday.
-Low Confidence in isolated thunderstorms this evening.

.Extended Aviation Discussion...

A cool air wedge will remain in place until Monday morning when
it is expected to erode. Sub-VFR conditions are likely continue
until at least early Monday and when the wedge breaks. Aviation
conditions will finally improve Monday afternoon as the wedge
breaks.

A period of mostly VFR to MVFR conditions is expected Tuesday-
Wednesday before a stronger front arrives from the west possibly
combined with the moisture from what is currently T.D. #28 and
expected to become T.S. Zeta in the next day or so.

&&

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

&&

$$
SYNOPSIS...AMS/WP
NEAR TERM...RAB/WP
SHORT TERM...WP
LONG TERM...PW
AVIATION...AMS/RAB/WP