597
FXUS61 KRNK 051356
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
956 AM EDT Fri Jul 5 2024

.SYNOPSIS...
High pressure offshore will continue to keep muggy conditions
around through tonight, with heat indices exceeding 100 degrees
in the Piedmont. A front is going to reach Ohio/TN Valleys this
afternoon and several impulse will lead to scattered to numerous
thunderstorms. This front will pass across the Mid-Atlantic by
Saturday night into early Sunday. Spotty showers and
thunderstorms will remain in the forecast for early next week as
an upper level trough develops over the central United States.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 945 AM EDT Friday...

Key Messages:

1) Heat Advisory remains in effect this afternoon/evening for
our foothill and piedmont including Roanoke/Lexington, VA.

2) Strong to severe storms possible this afternoon with the main
threat being damaging winds. Greater chances in the mountains.


Expect an unstable/humid airmass this afternoon. With plenty of
sunshine this morning, SBCAPEs are forecast to reach 2000-3000
J/kg by mid afternoon across southern VA into NC. There is a
convective system moving across central KY into Mid TN this
morning with an associated MCV. This piece of energy should
reach our mountains by mid afternoon and push into the piedmont
by later in the afternoon. Enough instability and high pwats to
bring a damaging wind threat for any storms that form or move in
this afternoon. Majority of convective allowing models have
storms arriving in our mountains between noon-2pm, then better
chances will be in the 3pm-9pm time frame. Better coverage still
looks across our mountains of SW VA/southern WV into NC, with
less in the piedmont.

No changes to heat headlines.

Previous discussion...


A blocking high stretched from the central Atlantic and into
Africa, and was keeping low pressure in the western Atlantic
from progressing east. This in turn has resulted in slow
movement of the weather pattern affecting much of the eastern
CONUS. Within this broad trough, additional bands of PVA
arriving today will provide lift for convection. Surface low
pressure and associated fronts will near from the west but not
cross until sometime Saturday, but we still have a lee trough in
the area today to provide some focus. Showers and thunderstorms
will develop over the southern Blue Ridge and also arrive from
the west around late morning to noon. Instability will be a
little better than yesterday, and shear will also be improved.
Shear will be marginal and likely not enough for supercells,
but we should see good coverage of multicells producing heavy
rain and also some instances of damaging winds this afternoon
and evening.

Today will be slightly hotter and a bit more humid in spots
compared to yesterday, but overall pretty similar. Current dew
points were in the upper 60s to lower 70s, and southerly winds
today will keep transporting Gulf of Mexico moisture to the
Blue Ridge where it will interact with a lee trough. The 04/12Z
and 05/00Z RNK soundings both had PWATs of 1.72", and this
number beat the old record of 1.71" for that date set in 2013.
NAEFS situational awareness table as well as the ECMWF Extreme
Forecast Index and Shift of Tails point towards continued
anomalous warmth and humidity today. PWATs will likely top
2.20" for parts of the Piedmont, and almost 2" for the
mountains.

Temperatures top out in the mid 80s to low 90s for the mountains,
and the mid to upper 90s for the Piedmont. Lynchburg and Roanoke
will be closest to meeting or exceeding their daily high records;
see Climate section below. A Heat Advisory has been expanded
slightly, and is now in effect for parts of north and north
central NC, the Roanoke area, and parts of Southside VA and the
Piedmont, based on calculated heat indices as high as 109.
Please use caution if working or spending time outside, drink
plenty of water, and do not leave children or animals unattended
in cars.

Overnight, shower and storm coverage gradually shrinks to just
include the western mountains, as a cold front finally arrives
on our doorstep. from the northwest overnight. Expect another
humid and warm night, with widespread fog, some of it dense.

Confidence in the near term is high.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
As of 200 AM EDT Friday...

Key Messages:

1. Good chances for storms producing heavy downpours with a slow
moving frontal passage Saturday.

2. Temperatures cool off a bit this weekend.

A cold front will be located over the foothills Saturday morning
with convection starting by noon. This front will continue its
slow track across the area, moving over the piedmont in the
evening. With ample moisture and modest instabilities, strong
storms with heavy downpours are possible towards Southside VA
and northwest NC piedmont. By Sunday morning, this front should
be in the coastal piedmont where it will stall and washout.

High temperatures Saturday will range from the low to mid 80s
across the mountains and low 90s in the foothills and
piedmont. Mostly dry weather is expected Sunday which will have
temperatures a few degrees warmer than Saturday.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 210 AM EDT Friday...

Key Messages:

1. Warmer than normal temperatures with daily storms early next
week.
2. Trending cooler and possibly drier by mid week.

An upper level disturbance will approach the Carolina coast
Monday, bring Atlantic moisture into the area.
Diurnal/orographically driven showers and thunderstorms are
expected during the afternoon and evening, mainly along and east
of the Blue Ridge. Models have a cold front moving across the
region Tuesday afternoon into Tuesday night. High pressure
builds in behind the front, keeping most of the area dry going
into next weekend. It is still summer, so can not rule out a few
hit and miss thunderstorms Thursday and Friday afternoon.

Warmer than normal temperatures expected Monday into Wednesday.
Near normal temperatures possible Thursday and Friday.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
As of 950 AM EDT Friday...

Mainly VFR through this afternoon, except when any storms move
over a TAF site. Best chance of TSRA noon-2pm along the
southern Blue Ridge and BLF, then expanding east to the
remainder of the TAF sites by 22z, though less coverage in the
piedmont (DAN/LYH). Coverage will be more expansive south of a
BLF-ROA line.

Tonight, SHRA/TSRA will continue to affect mainly BLF and LWB as
a front nears. Expect another night of widespread fog and
stratus, as low as LIFR.

Average confidence in the above forecast.


AVIATION OUTLOOK...

Saturday and Saturday night, a front will cross the area,
bringing additional SHRA/TSRA/fog with possible MVFR or lower
conditions. Sunday, the remaining SHRA/TSRA will only affect
DAN and perhaps LYH, but fog is expected in locations where it
rained Saturday, and some of this may be dense.

For Monday, the probability for scattered SHRA/TSRA/MVFR
conditions will be mainly confined to the afternoon and
evening. On Tuesday and Tuesday night, another front arrives
from the west, spreading SHRA/TSRA to the entire area, along
with reductions in conditions.

&&

.CLIMATE...
As of 300 AM EDT Friday...

Record highs and warmest lows temperatures for July 5th.

Friday 07/05/2024
Site  MaxT Year  HiMin Year
KBLF    93 1948    71 1969
KDAN   103 1919    76 1926
KLYH    98 2012    75 1900
KROA   100 1999    76 2012
KRNK    94 1930    78 1949

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Heat Advisory until 8 PM EDT this evening for VAZ022>024-
     032>035-043>047-058-059.
NC...Heat Advisory until 8 PM EDT this evening for NCZ003>006-020.
WV...None.

&&

$$

SYNOPSIS...NF/SH/WP
NEAR TERM...SH/WP
SHORT TERM...RCS
LONG TERM...RCS/WP
AVIATION...NF/SH
CLIMATE...RCS/SH