325
FXUS61 KRNK 270025
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
825 PM EDT Wed Jun 26 2024

.SYNOPSIS...
A weak cold front will slowly track south through the Mid
Atlantic and Carolina states through Friday and resulting in
showers and thunderstorms tonight. Another front with
thunderstorms comes across the region Saturday and Sunday. The
humidity will remain high through the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 800 PM EDT Wednesday...

Key Messages:

1) Severe threat low, increasing threat for flooding issues with
more rain expected overnight...mostly over by 4 AM.

2) Additional chance for thunderstorms over the Piedmont
tomorrow with front stalled in the area.

First wave of convection over areas north of Highway 460 has
devolved into a large area of moderate rain over the Greenbrier
Valley and the southern Shenandoah Valley. Rainfall rates of 1-2
inches per hour have been noted and we continue to monitor for
any flooding issues, mainly for Summers and Greenbrier Counties
in WV. Thankfully, precipitation has largely moved out of those
areas, but additional rainfall is expected later tonight ahead
of a SE moving cold front. This activity is expected to push
across the entire area, with periods of rain through about 4 AM
before tapering off.

The severe threat has waned considerably this evening, and at
least through the morning hours, expect the main concern to be
moderate to heavy rainfall as outlined in WPC`s Mesoscale
Precipitation Discussion. The front is expected to stall in
the vicinity, and could be the focus for additional convection
tomorrow afternoon, mainly in the Piedmont.

Rainfall cut temperatures down a good 10-15 degrees over the
course of an hour or two. It will still be muggy overnight with
rain showers and temperatures in the low to mid 60s for the
mountains, and the upper 60s/low 70s for the Piedmont.

Confidence in the above scenario is high.



As of 215 PM EDT Wednesday...

Key messages:

    - Scattered thunderstorms tonight
    - Front may stall on Thursday

Convective temperatures have been reached across much of the
area leading to the development of isolated thunderstorms
along the southern Blue Ridge, through the New River Valley and
in southeast West Virginia. Plenty of instability with
Convective Available Potential Energy in the 800-1500 J/kg range
and downdraft CAPE up to 1200 J/KG. Most likely probability for
wind gusts exceeding 50kts north of Route 460.

Much of thunderstorms will be pulse variety with outflow and
merging cells aiding in triggering storms. A pre-frontal
trough will push through the region tonight followed by the weak
cold front. The surface front advances to the North Carolina
border but the 850 front never making it that far south. This
leaves areas of convergence over Virginia tonight and Thursday.
Thunderstorms will continue overnight and into Thursday morning.


Surface dew points have climbed back into the upper 50s to mid 60s.
This will keep temperatures mild overnight. The cloud cover and any
rain will inhibit heating on Thursday. This will hold maximum
temperatures in the 70s and 80s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 130 PM EDT Wednesday...

Key Messages:

1. Daily chances of showers and thunderstorms through the
period.
2. Near to above normal temperatures.

Lingering showers and thunderstorms may continue overnight
Thursday into early Friday morning, mainly in the eastern
counties of the forecast area, following the passage of a cold
front. Surface high pressure develops over the northeastern US,
building down into the Mid Atlantic behind the front for Friday,
bringing some cooler and drier air to the area. Not expecting
much of a drop in high temperatures with this airmass, but a few
degrees lower than earlier this week, and Friday will likely be
the coolest day of this forecast period. Easterly flow around
the high will bring some moisture into the area from the
Atlantic, and could trigger some afternoon showers and
thunderstorms over the southern Blue Ridge of Virginia and North
Carolina.

Heading into the weekend, ridging aloft develops over the
southeastern states, and 500mb heights increase over the Mid
Atlantic, suggesting a warming trend in temperatures. An upper
trough amplifies over the Great Lakes late in the forecast
period, and a warm front lifts northward over the area through
Saturday, putting the area in the warm sector of the surface
low pressure system, so temperatures and dewpoints will increase
through the day. The cold front approaches the region from the
Midwest, increasing probabilities for more widespread convection
by Saturday afternoon. NBM thunderstorm probabilities range
from 50% to 70% by late Saturday, as dewpoints rise via the
southwesterly flow. However, chances for more organized
convection increase with the passage of the actual front.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 145 PM EDT Wednesday...

Key Messages:

1. Showers and thunderstorms possible Sunday, though
   timing is uncertain.
2. Near normal temperatures, slightly cooler Monday and
Tuesday.

An upper trough digs into the Great Lakes and northeastern US
into Sunday, bringing a surface frontal system through the
eastern states. Ample moisture and warm air ahead of the front
will contribute to increasing instability, which will increase
potential for showers and thunderstorms on Sunday. Better
forcing for storms comes along with the front, and the trough
will bring additional upper level support, and would lead to
more organized convection, though those better dynamics appear
to stay farther north, over the northern Mid Atlantic and
Northeast, at this time. With uncertainty due to model
differences in the timing of the frontal passage, and with the
system still being several days out in the forecast period,
confidence is lower on potential for severe storms. However,
with above normal precipitable water values, storms would have
the potential to produce moderate to heavy rainfall, and though
most of it would be beneficial with the very dry antecedent
conditions across much of the forecast area, there is a marginal
risk for flooding of urban and low lying areas.

Behind the front, high pressure returns to the area for the
beginning of the work week. Temperatures will drop a few degrees
in the cooler and drier airmass over the region, closer to
seasonal normals.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 815 PM EDT Wednesday...

First batch of thunderstorms has morphed into areas of moderate
to heavy rainfall near LWB and north of ROA. Additional rainfall
is expected later tonight ahead of a SE moving cold front. This
activity is expected to push across the entire area, with
periods of rain through about 8Z before tapering off. After 8Z,
we could see a few more hours of light rain, but it remains
broken to overcast, limiting fog. Most likely spot for IFR/LIFR
conditions will be LWB. Otherwise, MVFR ceilings and
visibilities are possible overnight, with improving conditions
to VFR after 14Z.

Additional SHRA/TSRA/MVFR conditions possible tomorrow, mainly
for LYH and DAN, with the front near that area.

Moderate confidence for this TAF forecast.


EXTENDED AVIATION OUTLOOK...

Isolated showers and thunderstorms are possible again each
afternoon and evening Thursday and Friday.

A greater coverage of thunderstorms and associated MVFR flight
conditions, is expected along and ahead of a cold front on
Saturday and Sunday.

Monday is expected to be drier and VFR, with a majority of the
showers and thunderstorms south of the region.

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AS/SH
SHORT TERM...AS
LONG TERM...
AVIATION...AMS/BMG/SH