-- Discussion containing changed information from previous version are highlighted. --
109
FXUS61 KRNK 181048
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
648 AM EDT Tue Jun 18 2024

.SYNOPSIS...
High pressure will cover the region through the end of the
week. This will result in unseasonably warm temperatures and
mainly dry conditions. Any rainfall is expected to be isolated.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 230 AM EDT Tuesday...

Key Message:  Less shower activity today.

High pressure is building inland from the western Atlantic.
Subsidence is expected to become more pronounced as temperatures
warm aloft. Drying will also take place aloft, limiting CAPE,
and precipitation chances decreasing. Can`t rule out some
isolated shra/tsra west of the Blue Ridge but overall trend is
expected to be down compared to Monday. As the airmass dries
from top down, surface dewpoints will also begin to come down,
lowering over the piedmont today, then across the mountains
Wednesday. In general expecting afternoon dewpoint temperatures to
range from the lower 60s over the piedmont to near 70 along the
Blue Ridge. Shave off another 5 degrees by Wednesday.
Temperatures will not necessarily be any cooler, with highs 4 to
8 degrees above the seasonal norm, ranging from the mid 80s to
lower 90s. With dewpoints coming down, hopefully tonight will
not feel as muggy. Lower dewpoints should also allow the air
temperature to be a few degrees lower as well.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 415 AM EDT Tuesday...

Key Messages:

1). Little to no precipitation for the Piedmont through the
period.

2). Isolated afternoon thunderstorms possible across the
Western mountains mainly Thursday and Friday.

2). Temperatures warming a couple of degrees each day through
the period.

3). Hottest temperatures expected to arrive at the end of the
week.

The dominant weather feature through the period will be a strong
subtropical 598dm upper ridge anchored the first half of the
week to our north generally over the PA/NY region. Associated
with the core of the upper ridge is a large blob of unusually
hot air for the northeastern U.S. where 850mb temperatures
average in the +20C to +24C range. The upper ridge will
gradually sag southward through the later half of the week into
the first part of the weekend as upper troughing begins to
develop across the Great Lakes. As this occurs, the blob of hot
air to our north will relocate over our area in the Friday to
Saturday time frame. For Tuesday into Wednesday, however, that
is prior to the upper ridge drifting back to the south, easterly
flow on the bottom/south side of the upper high will allow
cooler maritime air from the western Atlantic to flow into the
region. This will temper the heat keeping heat index values
below 100 degrees. The lower dewpoints associated with this
easterly flow will also allow the nights to cool more than for
our neighbors to the north. Maximum temperatures will top out
mostly in the 80s west to lower 90s east Wednesday through
Thursday creeping 2-4 degrees higher by Friday and Saturday. Low
temperatures will range from the upper 50s to lower 60s in the
higher terrain to upper 60s to around 70 in the larger urban
areas such as Roanoke. These readings will also creep upwards a
few degrees by the end of the week as the air mass warms through
this time frame,

With regard to precipitation, don`t expect much during this time
frame. The disturbance that brought scattered showers and
thunderstorms to the region Monday afternoon will be long gone
and the upper high with warm air aloft combined with the lower
dewpoints and dry air at the surface will result in a rather
stable atmosphere despite the hot surface temperatures. Any
precipitation would be confined to very isolated pop up
afternoon/early evening showers and thunderstorms driven
entirely by differential heating and orographic lift, hence the
western mountains.

/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- High Confidence in Low Pops Through the Period,
- Moderate Confidence in Wind Direct, High Confidence in Wind
  Speed,
- Low Confidence in Thunderstorm Potential.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 500 AM EDT Tuesday...

Key Messages:

1) Hot temperatures peak Saturday ahead of a cold front.
Temperatures slightly cooler for early next week.

2) Increasing chances for showers and thunderstorms over the
weekend.

As the aforementioned upper trough developing over the Great
Lakes deepens late week into the weekend, a west-east oriented
cold front will sag southward into the Mid-Atlantic and central
Appalachian region. Showers and thunderstorms will be on the
increase as a result of the frontal boundary and cooling
temperatures aloft. However, the big question at this point is
how far south will the front track before it washes out as it
encounters the continuing strong upper ridge, which by the
weekend will be centered just barely to our south. Latest model
trends have become less encouraging about the front tracking far
enough south for the region to see any bonafide relief from the
hot temperatures. The main relief from the hot temperatures will
come in the form of scattered showers and thunderstorms.
Dynamics are weak, but enough forcing should be available with
the upper trough to our north and the frontal boundary drifting
into the region for chance to high chance pops for the weekend
into Monday.

Saturday will see the hottest temperatures with 90s for all
areas east of the Blue Ridge and 85-90 for most areas west of
the Blue Ridge, except 80-85, even a few upper 70s, for
elevations above 3000 ft. Low temperatures will be mostly in
the mid 60s to lower 70s by the weekend. Dewpoints/humidity
levels will also be on the increase ahead of the front which
will offset the cooling effect of the showers and thunderstorms
by increasing the humidity levels. Heat indices will top out
around the 100-degree mark Fri-Sun in various pockets across the
piedmont, and especially for larger urban areas like Roanoke
and Lynchburg. Will continue to highlight this concern in the
HWO.

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- Moderate Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed,
- Moderate Confidence in Thunderstorm Potential.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
As of 645 AM EDT Tuesday...

For today...areas of fog and stratus are expected along and
west of the Blue Ridge this morning with potential for IFR west
of ROA. By 14z/10AM, any fog and stratus should dissipate.
After 14Z/10AM daytime heating will result in SCT-BKN cumulus.
Afternoon deep convection is expected mainly along and west of
the Appalachian divide. Warming and drying aloft is occurring
east of the mountains and this will inhibit deep convection east
of the mountains today.

Winds are expected to be out of the southeast...under 10 kts.


EXTENDED AVIATION OUTLOOK...

Wednesday through Saturday...High pressure will cover the
region. Aside from some morning river fog in the mountain
valleys, conditions are expected to be primarily VFR.
Little or no chance for rain is expected through Friday...
then increase for the weekend.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...PM