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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 240507
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
107 AM EDT Sun Jun 24 2018

.SYNOPSIS...
Low pressure aloft will pass north of the region Sunday into
Sunday night allowing a weak surface boundary to shift south
across the area by Monday.  High pressure aloft will build over
the eastern U.S. during the later half of the week resulting in
hotter and humid conditions along with the threat of diurnally
driven showers and storms.
&&

.NEAR TERM /THROUGH TODAY/...
As of 945 PM EDT Saturday...

No major updates with this forecast adjustment. Have only
tweaked hourly temperatures and dew points to reflect the latest
conditions and expected trends through midnight. Also, made
minor adjustments to the sky cover to reflect even less coverage
prior to the arrival of the activity currently making gradual
progress eastward through far southwest Virginia.

As of 645 PM EDT Saturday...

Very little remains in the way of showers across the region.
This trend should continue as we approach sunset and the loss of
the daytime heating. Additional showers will be possible later
this evening as a disturbance moves into eastern Tennessee. The
western quarter of the region may see isolated to scattered
showers after midnight through daybreak Sunday.

As of 300 PM EDT Saturday...

Water-vapor imagery shows a mid-level trough over the Ohio Valley
rotating eastward towards the Mid-Atlantic region this afternoon
into tonight. The upper low will lift out across the northeast U.S.
by Monday. SPC Mesoscale analysis at 18z showed that CAPEs have
rebounded top 1k to 2k J/Kg east of the Blue Ridge. Lis this
afternoon vary from minus one to minus three across eastern half of
our Forecast area. The HRRR and HiResW-ARW-east showed scattered
showers and thunderstorms developing this afternoon and moving east
across our region into tonight. The latest day one convective
outlook keeps a marginal threat of severe weather across eastern
portions of forecast area. There is a small window for an isolated
pulse severe thunderstorm in the east. However, the best instability
will be pooled across the coastal plain to our south and east. With
the loss of solar heating this evening expected scattered convection
to diminish and tapper off into tonight. Once again expect areas of
low clouds and fog to form overnight into Sunday morning. Low
temperatures tonight will range from around 60 degrees in the
mountains to around 70 degrees in the piedmont.

Quasi-zonal mid-level height regime will govern conditions aloft
across the East. Airmass should become moderately unstable which
should lead to the development of scattered showers and
thunderstorms Sunday afternoon. A couple of weak shortwave rotating
across our area should enhance thunderstorms formation.  SPC does
have the far western portion of the CWA in a 5%/Marginal Risk of
severe weather on day two convective outlook, which seems
reasonable. High temperatures on Sunday will vary from the lower 70s
in the northwest mountains to the lower 90s in the piedmont.

/Confidence Levels/
Temperatures...High
Precipitation Chances... medium
Winds...Medium

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
As of 200 PM EDT Saturday...

Sunday afternoon and evening thunderstorms will gradually fade away
overnight as a weak front tracks across the region Sunday night into
Monday. Stable air behind the front will keep thunderstorms chances
low Monday, while temperatures will again warm above normal.
Temperatures Monday will range from the low to mid 80s west of the
Blue Ridge to near 90 east.

North to northeasterly flow Monday night into Tuesday will bring a
brief break from the heat as a wedge of high pressure skirts over
the Mid Atlantic states and south-central Appalachains. Temperatures
will range from the mid 70s to lower 80s west and low to mid 80s
east. The wedge will slowly erode over the mountains during the day
Tuesday as a cold front approaches from the west. Areas outside of
the wedge may see a few thunderstorms develop in the afternoon, then
fade during the evening hours. Areas that typically erode outside of
the wedge first are the Mountain Empire of southwest Virginia west
to the Bluefield-Richlands area. Greenbrier Valley may also come out
of the wedge late Tuesday, depending on if the front is still over
the Midwest or in the Ohio Valley. As the front continues to
approach the area Tuesday night, the wedge will erode over the
mountains, but remain entrenched across the foothills and piedmont
counties into Wednesday morning.


/Confidence Levels/
Temperatures - High
Precipitation Chances - Medium
Thunderstorm Chances - High

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 220 PM EDT Saturday...

The GFS is quick to remove the wedge Wednesday morning, while the
ECM hangs on to it over the piedmont into the early afternoon. In
either case, scattered showers and thunderstorms will form over the
area as the wedge erodes, it is just a timing issue. As the front
tracks over the region Wednesday, more numerous showers and
thunderstorms will over take the area. The front stalls over the
piedmont overnight which may keep lingering showers in the area into
the early morning hours Thursday. The front is expected to move east
during the day Thursday with only an isolated chance for afternoon
thunderstorms in the afternoon. Temperatures Wednesday and Thursday
will run close to normal levels.

A heat dome of high pressure over the southern Plains early in the
week will move over the East Coast next weekend. Temperatures will
once again run warmer than normal, ranging from the mid 80s to lower
90s across the mountains and mid to upper 90s east. Scattered
thunderstorms are also expected to develop each afternoon and
evening.

/Confidence Levels/
Temperatures - Medium to High
Precipitation Chances - Low to Medium
Thunderstorm Chances - Low to Medium

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
As of 115 AM EDT Sunday...

Another round of showers with a weak impulse aloft approaching
from the west will likely affect the KBLF-KLWB vicinity in the
next hour before heading east and fading upon crossing the Blue
Ridge. Therefore will include either a VCSH or TEMPO mention
across the western sites to start. This may also cause ceilings
to fall to below VFR levels espcly in the wake of the showers at
KBLF with overall VFR expected from the Blue Ridge east.
Patchy IFR/MVFR fog is possible late tonight into early Sunday
morning in the mountain and river valleys.

During Sunday, look for showers and storms to increase across
the entire region, especially in the afternoon, as low
instability increases once again thanks to surface heating and
an upper level disturbance will approach from the Ohio Valley.
Coverage remains highly uncertain with guidance showing
differing locations of where more organized clusters may reside.
Since appears the mountains again likely have the best shot at a
shra/tsra included another VCTS or VCSH mention this afternoon
with west/northwest flow likely making for less coverage out
east where will leave out mention. Otherwise will be on the
breezy side with westerly flow at 10-18 kts with gusts to 25 kts
possible.


.Extended Aviation Discussion...

A cold front may linger near southern sections Sunday night into
Monday with added showers/storms possible as another wave rides
down the boundary on Monday. This likely to result in periods of
MVFR southern sites with VFR across the north. Should finally
see the front get far enough south for mostly VFR conditions
Tuesday. Isolated to scattered MVFR showers and thunderstorms
are possible by Wednesday with more isolated nature to
convection Thursday when should be back to mainly VFR.

&&

.EQUIPMENT...
As of 338 PM EDT Saturday...

The NOAA weather radio transmitter in Hinton, West Virginia that
is WXM72 and broadcasting at a frequency of 162.425 MHz is off
the air. Parts are on order to repair the transmitter, but there
is no known time of restoration. We apologize for any
inconvenience.

&&

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

&&

$$
SYNOPSIS...JH/KK
NEAR TERM...DS/KK
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...DS/JH/KK/NF
EQUIPMENT...