-- Discussion containing changed information from previous version are highlighted. --
341
FXUS61 KRNK 170823
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
423 AM EDT Mon Jun 17 2024

.SYNOPSIS...
High pressure will cover the region through the end of the week.
This will result in unseasonably warm temperatures and a limited
chance of showers and thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM EDT Monday...

Key messages:

- Warm and humid today.

- Widely scattered & disorganized showers and thunderstorms will
develop this afternoon, mainly across the mountains.

- Potential exists for locally heavy rain where showers and storms
do occur.

Starting the morning off with abundant cloud cover given light
southeasterly winds bringing Atlantic moisture into the region.
This is taking place under a strengthening upper level dome of
high pressure centered over central North Carolina. Cloud cover
and increasing moisture are helping to limit cooling compared
to previous nights, and expect overnight lows for most of our
area will hold in the mid to upper 60s.

Southeasterly windflow will continue to draw abundant Atlantic
moisture to support the development of showers and thunderstorms
across the mountains today. Latest weather model data
suggests that precipitable water values west of the Blue Ridge
will rise into the 1.3 to 1.5 inch range, which is above average
for mid-June.

The main challenge is where rainfall will occur today as the
upper high shifting more overhead would act to suppress shower
and thunderstorm development. But strong daytime heating will
overcome that in spots given the abundant moisture, and
therefore expect hit-and-miss & disorganized showers and storms
will develop during mid-afternoon into the evening across the
mountains, though timing and location of development is
difficult to determine. May see some of this activity spill east
of the Blue Ridge across the foothills, but believe the
Piedmont will remain mostly dry given lower moisture and less
energy for the storms to work with. Movement of this activity
will be slow, so a few locations may receive localized downpours
of an inch or more over a short period of time. Most shower and
thunderstorm activity will diminish toward sunset, though a few
may linger through midnight before finally fading away.

High temperatures will hold mainly in the low to mid 80s across the
mountains given partly to mostly cloudy skies. Areas of the Piedmont
west of Highway 29 will hold in the upper 80s, while low 90s can be
expected further east. Lows tonight will fall back into the mid 60s
to near 70.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --
As of 330 AM EDT Monday...

Key Messages:

1) Mainly dry through the period.

2) Hottest temperatures stay well to our north until the
weekend.

There has been a lot of attention in recent days given to hot
temperatures expected through this work week. However, at least
through this time period, the hottest temperatures will remain
well to our north. A 590+dm subtropical ridge will drift north
of the forecast area toward the PA/NY region early this week and
intensify to around 598dm, typically one of the highest 500mb
heights seen throughout the year. A large blob of hot 20+C
850mb temperatures will focus under the high from OH across
PA/NY and into New England through the mid part of the week.
Meanwhile, with our region being located on the southern side of
this upper ridge, a mid-level easterly maritime flow will
develop advecting cooler air into the region from the western
Atlantic. Through at least midweek, 850mb temperatures in our
region actually drop back toward the +15C level as this cooler
air spreads into the region from the east. This pattern will
hold through Thursday. The western and northwestern parts of the
forecast area will remain the warmest aloft under this
scenario, but given this area is higher elevation, it will still
result in maximum temperatures remaining in the 80s, with even
some upper 70s at elevations above 3000 ft. A bit above normal,
but not a heat wave by any means. In addition, dewpoints
actually drop Tuesday-Wednesday as the surface flow trends more
toward the northeast bringing lower dewpoints into the region.
After Monday, dewpoints will trend downward as much as 10
degrees in the Tue-Thu time frame, falling into the lower 60s,
even across the Piedmont. This will further alleviate any heat
concerns and allow nighttime temperatures to fall into the very
pleasant 58-65 range at night, depending on elevation and
urbanization. Bottom line, Tue-Thu will see warm afternoons
mostly in the 80s with a few lower 90s through Thursday, with
nighttime temperatures mostly in the 60s, even some 50s in the
higher terrain. Heat indices reach values no higher than the
90-95 range anywhere through Thursday.

On the other hand, it will be dry and any drought conditions
within the CWA will be exacerbated this week with the
combination of warm temperatures and no rainfall. Shallow rooted
plants and grasses will become increasingly moisture stressed in
areas that do not see receive rainfall Monday or Tuesday. The
low-level maritime easterly flow and general high pressure
aloft will result in a very stable atmosphere. The drier air
spreading into the region from the northeast will further act
to suppress precipitation development.

On Tuesday, the western periphery of the building high to our
north and the associated short wave that will drive scattered
thunderstorms across the mountains Monday will still have enough
influence in the northwest part of the CWA, roughly northwest
of a JGX-BLF-SHD line, to result in isolated to widely
scattered thunderstorms again during the afternoon, but
coverage will be far less than Monday at best. Elsewhere, no
precipitation is expected through the period and the entire
forecast area, outside of a very isolated pop up
shower/thunderstorm generated by differential heating and
orographic lift, hence < 15% mentionable pop, should remain dry
Wednesday and Thursday.

Conditions have become rather dry in some parts of the forecast
area. Case in point, Blacksburg is now nearly 7 inches below
normal on rainfall and Roanoke is over 4 inches below normal for
the year-to-date, while some spots such as Danville and
Bluefield are actually somewhat above normal on rainfall for the
year-to-date.

In summary, overall a very quiet weather period with
temperatures near to slightly above normal and little to no
precipitation.

/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- Moderate to High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed,
- Low Confidence in Thunderstorm Potential.
-- End Changed Discussion --

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 400 AM EDT Monday...

Key Messages:

1). Hot Saturday,

2). Any Heat Wave should be brief, quickly punctuated by a cold
front and associated widespread showers/thunderstorms over the
weekend.

The strong 598dm subtropical ridge anchored over the PA/NY area
through midweek will begin to sag back to the south by the end
of the week as troughing develops across the Great Lakes. The
upper high will drift over the forecast area Saturday. The blob
of hot 20+C temperatures located over the northeastern U.S.
midweek will sag over our region Friday into Saturday. This will
result in the long advertised hot temperatures finally reaching
our region in earnest. High temperatures in the 90s are
expected across the lower terrain Friday and especially Saturday
with 80s in the mountains. However, it appears that dewpoints
will remain low enough that heat index values Friday and even
Saturday will for the most part remain below 100 degrees.
Nonetheless, it will be hot Friday and Saturday.

The good news is that any true "heat wave" should be brief and
confined mostly to one or two days, namely Fri-Sat. In fact, the
west may already see relief from the hot temperatures as early
as Saturday in the form of showers and thunderstorms. The
aforementioned trough will result in a relatively strong cold
front for late June arriving by the weekend. While it remains to
be seen how far this front will make it given the strong
subtropical ridge anchored over the region, it appears that it
will at least bring scattered to numerous showers and
thunderstorms to the region late Friday into Saturday, possibly
continuing even into Sunday. The increased clouds and
precipitation will result in lower temperatures and the cooler
air behind the front should at least spread toward the I-64
corridor by Sunday. Thus, high temperatures are expected to drop
back into the 80s for much of the region by Sunday, with lower
90s confined mainly to the piedmont.

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- Moderate to High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction, High Confidence in Wind
  Speed,
- Moderate Confidence in Thunderstorm Potential after Friday.
-- End Changed Discussion --

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
As of 230 AM EDT Monday...

Starting the morning off with light southeasterly windflow that
is carrying Atlantic moisture into the lower Mid-Atlantic.
Cloud cover is widespread, with MVFR/IFR ceilings observed along
and west of the crest of the Blue Ridge, while low-end VFR
ceilings are reported across the Piedmont.

For today, ceilings will lift after sunrise given another day of
strong heating, though expect pockets of MVFR ceilings will
remain across the mountains through early afternoon given the
inflow of moist air. By early afternoon, expect the development
of widely scattered, hit-and-miss, disorganized showers and
thunderstorms. These will occur mainly west of the Blue Ridge,
though some may spill over into the foothills during early
evening. Believe the Piedmont area will remain dry. These
storms will be slow-moving, and will have the potential of
producing heavy downpours, which may produce localized reduction
in visibility to less than 1/2SM for brief periods of time.
Most of this activity will begin to diminish toward sunset, but
a few may linger through midnight.

Tonight, expect a return of patchy MVFR/IFR ceilings, with
localized fog for areas that receive significant rainfall.

Confidence in the above aviation scenario is moderate.

EXTENDED AVIATION OUTLOOK...

High pressure will cover the region this week. Aside from some
morning river fog in the mountain valleys, conditions are
expected to be primarily VFR. The chance of showers and
thunderstorms will be low from Tuesday into Friday.

&&

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

&&

$$

SYNOPSIS...NF/WP
NEAR TERM...NF
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...NF