823
FXUS62 KRAH 171105
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
705 AM EDT Mon Aug 17 2026

.WHAT HAS CHANGED...

* No significant changes

&&

.KEY MESSAGES...
As of 400 AM Monday...

1) A Heat Advisory is in effect from 11 AM to 8 PM today from the
Triangle region to the south and east.

2) There is a threat for isolated to scattered strong to severe
storms today, with a Slight (level 2 of 5) risk in much of the
Piedmont and a Marginal (level 1 of 5) risk elsewhere. Damaging
winds are the primary threat.

3) Heat will linger through Thu, followed by more- seasonable
temperatures and above average probabilities of rain/convection late
week through at least the first half of the weekend.

&&

.DISCUSSION...
As of 400 AM Monday...

KEY MESSAGE 1... A Heat Advisory is in effect from 11 AM to 8 PM
today from the Triangle region to the south and east.

Another hot day is in store today across central NC, although there
remains some uncertainty on how lingering cloud debris from a
decaying MCS currently over southern VA may affect temperatures
particularly in the east. Brought down forecast highs a hair as a
result, but they are still in the mid-to-upper-90s. Dew points
should also be a little less oppressive than they were yesterday,
mostly lower-to-mid-70s but possibly even some upper-60s by the
afternoon, as the low-level flow turns WNW and some drier air mixes
down. This still yields heat indices in the 105-109 degree range for
much of the area outside of the NW Piedmont and our VA border
counties, so maintain the Heat Advisory there from 11 AM to 8 PM.
The NWS Experimental HeatRisk continues to be Major (level 3 of 4)
across just about all of central NC, suggesting the heat will affect
anyone without cooling/hydration.


KEY MESSAGE 2... There is a threat for isolated to scattered strong
to severe storms today, with a Slight (level 2 of 5) risk in much of
the Piedmont and a Marginal (level 1 of 5) risk elsewhere. Damaging
winds are the primary threat.

Yet another upstream MCS currently over southern IL/IN and northern
KY will track ESE into the southern Mid-Atlantic through tonight. At
the surface, low pressure will slowly track along the northern Mid-
Atlantic and southern New England coast, as a cold front moves
across the OH/TN Valleys and northern Mid-Atlantic. Ahead of this
front, a warm unstable air mass will again be in place, with 1500-
2500 J/kg of SBCAPE and PW values in the 1.75-2.25" range (100-125%
of normal). While CAMS are very limited at best with convective
coverage early this afternoon, wouldn`t be surprised if some
isolated showers and storms develop over the Piedmont with the lee
trough.

A better chance of storms comes from late afternoon into the
evening, from about 21z to 03z, particularly over the northern
Piedmont, as the MCS approaches. Deep-layer shear of 20-30 kts,
DCAPE around 1000 J/kg and steep low-level lapse rates may support a
damaging wind threat. Thus SPC has much of the Piedmont in a Slight
(level 2 of 5) risk for severe storms with a Marginal (level 1 of 5)
risk for the rest of central NC. However, think this is a low-end
Slight risk given potentially unfavorable diurnal timing and really
depends on how quickly the convective complex can get here before
daytime heating is lost, which CAMS disagree on. They do generally
agree it will weaken in intensity through the evening as it pushes
east into the northern Coastal Plain, as any severe threat comes to
an end.


KEY MESSAGE 3... Heat will linger through Thu, followed by more-
seasonable temperatures and above average probabilities of
rain/convection late week through at least the first half of the
weekend.

A sub-tropical ridge now over TX will retrograde into the Southwest
and Four Corners while amplifying sharply through the Rockies
through the week, while a downstream trough will amplify across the
ern US. Although the models strongly indicate a cyclone will develop
within that trough over the Great Lakes and vicinity by the end of
the weekend, there remains large model spread in its depth and how
quickly it will lift through ern Canada through early next week.
Related falling heights, and moist and unseasonably strong swly flow
east of the trough axis, will favor both less hot temperatures and
also above average probabilities of convection, some probably
severe, late Thu-Sat.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 700 AM Monday...

24-hour TAF period: Mainly VFR conditions will prevail across
central NC through this morning. Some patchy visibilities around 2-5
SM are currently observed, so keep TEMPO groups for MVFR
visibilities at all terminals through 13z.

A complex of showers and storms will move into the NW Piedmont in
the late afternoon or early evening hours today, potentially
spreading east through the rest of the evening and early overnight
hours. However, high-res guidance generally shows the convection
weakening with time especially once daytime heating is lost. The
best chance for gusty winds and sub-VFR restrictions is at INT/GSO,
followed by RDU and then RWI. It appears likely the showers and
storms will stay north of FAY, so don`t have any mention in the TAF
there, but it still can`t be entirely ruled out. Outside of any
storms, WNW winds may still briefly gust up to 15-20 kts at times in
the afternoon.

Looking beyond 12z Tue: The better chances of storms should shift to
mainly south and southeast of the terminals for Tue-Thu. Higher rain
chances are expected areawide Fri ahead of an approaching upper
level low pressure trough. Outside of storms, generally VFR
conditions are expected, although a few hours of patchy early-
morning sub-VFR fog/stratus may occur each day, with the highest
chances in areas that see rain.

&&

.CLIMATE...

Record High Temperatures:

August 17: KGSO: 99/1988 KRDU: 99/1997 KFAY: 104/1954

August 18: KFAY: 98/1988

August 20: KFAY: 102/2007


Record High Minimum Temperatures:

August 17: KGSO: 75/2010 KRDU: 76/2024 KFAY: 78/2007

August 18: KGSO: 75/2017 KRDU: 77/1995 KFAY: 78/2021

August 19: KRDU: 77/1988 KFAY: 76/1940

August 20: KRDU: 75/2007 KFAY: 78/2005

August 21: KRDU: 76/2009 KFAY: 77/2005

August 22: KFAY: 75/2018


&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 8 PM EDT Monday for NCZ024>028-040>043-
073>078-083>086-088-089.

&&

$$

DISCUSSION...Danco/MWS
AVIATION...Danco/Hartfield