579
FXUS62 KRAH 171903
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
302 PM EDT Thu Jul 17 2025

.SYNOPSIS...
A series of upper level disturbances will track east and southeast
through the Mid Atlantic region from Saturday night through Monday,
as a backdoor cold front approaches from the north.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 300 PM Thursday...

Water vapor imagery depicts the subtropical high centered east of FL
which is extending farther west compared to yesterday. This is
shifting the mid-level flow to a more westerly direction and the low-
level flow to more west-southwest, which is allowing scattered
showers and storms developing over the Mountains/Foothills of
western NC near a weak surface trough to spill into the western and
northern Piedmont of central NC this afternoon. Convection is also
developing along the sea breeze near the immediate NC/SC coast, but
the WSW flow should keep it pinned fairly close to the coast,
perhaps reaching our far SE (mainly Sampson County). While there is
a lack of strong upper forcing or significant boundaries, dew points
in the mid-to-upper-70s are allowing for strong instability to
develop with MLCAPE values of 3000-3500 J/kg according to the latest
SPC mesoanalysis. PW values are also in the 2 to 2.2 inch range.

The slow-moving nature of the storms means there is a risk for
isolated flash flooding over the northern Piedmont, particularly in
urban areas around the Triad which are already quite saturated from
recent rainfall. Weak shear will limit severe potential and storms
will be of the pulse variety, but still can`t entirely rule out a
damaging wind gust mainly across the far northern Piedmont where
there is a marginal (level 1 of 5) risk of severe from SPC. The
closer proximity of the ridge and drier WSW flow will limit
convective development in the Sandhills and central/southern Coastal
Plain, with only isolated coverage at best expected there.
Convection will quickly diminish after dark with loss of daytime
heating.

Today`s highs will be in the upper-80s far north to lower-90s
elsewhere, and the humid air mass is yielding heat indices in the
low-100s for many spots outside of the NW Piedmont. The moisture
will also keep lows quite mild tonight, in the mid-to-upper-70s.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 138 AM Thursday...

Temperatures will increase some on Friday, with most guidance in
good agreement for highs to reach the mid 90s. Dew points will
struggle to mix out, and as such we may reach Heat Advisory criteria
over portions of our CWA. Best chances would be from Raleigh ->
south and east.

Convection wise, models are hinting at a bit stronger short-wave
moving across the Mid-Atlantic Friday afternoon and evening. This
will likely trigger widespread convection along the Blue Ridge
Mountains which will then propagate across the VA/NC Piedmont. The
HREF is depicting ~30 to 35 kts of shear across the Mid-
Atlantic/Chesapeake vicinity. While shear looks to be weaker with
southward extent, the HREF depicts 20 to 25 kts of shear potential
across the NC/VA border. As such, a few storms could be strong to
severe with damaging wind being the biggest potential hazard. It`s
worth noting that the AI/ML guidance also have relatively higher
probabilities over our northern areas for severe weather potential.
So while the shear looks modest at best, there is a signal there in
the guidance worth keeping a close eye on.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 230 PM Thursday...

* Heat continues Saturday, with heat index values as high as 105-109
  possible from the Triangle to southeast. Heat Advisory is likely.

* High confidence for scattered thunderstorms Saturday/Sunday
  afternoon and evenings with heavy rainfall possible.

*There is a Slight/Marginal risk for Flash Flooding across the
region on Saturday.

Over the weekend, a strong upper level ridge over the Southeast will
shift slowly westward into the Gulf Coast and builds across the
Midwest by Monday.  Meanwhile at the surface, a Piedmont trough will
linger across central NC Saturday and Sunday increasing the chance
for afternoon/evening thunderstorms. Thunderstorms are expect to
develop west to east with slow movement, thus resulting in possible
flash flooding. While the highest chance for strong storms and flash
flooding will be across the northern Piedmont, areas to the south
could see some isolated slow moving storms as well along with some
isolated flash flooding. WPC has the CWA split on Saturday, with the
northern half in a slight risk for flash flooding and the southern
half in a marginal risk.

Ahead of the storms, warm southwesterly flow and dew points in the
mid/upper 70s will enhance heat indices well into the low 100s for
areas along and east of the US1 corridor. High temperatures on
Saturday and Sunday will range from the low 90s NW to upper 90s SE.
A heat advisory will be likely for areas around the Triangle and
southeast for Saturday and possibly Sunday as well.

By Monday, the Piedmont tough will weaken as a backdoor cold front
drapes down into the Mid-Atlantic region. While I suspect the front
to dissipate before it gets into NC, another round of isolated to
scattered storms is possible Monday afternoon and evening. As the
trough finally lifts to the north early next week, the upper level
ridge will dominate the region through much of the week. Chance of
precip is lower each day through Thursday, however diurnally driven
afternoon showers and storms are still possible. Temperatures become
near normal mid to late week with highs ranging from the mid 80s to
low 90s.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 100 PM Thursday...

Scattered showers and storms developing along a weak lee-side
surface trough across western NC will continue into the early
evening before dissipating after sunset. Brief periods of MVFR to
IFR restrictions are most likely at KGSO, KINT, with possible
impacts at KRDU and KFAY.

Overnight into Friday morning, model guidance suggests a lower
potential for sub-VFR restrictions due to stratus. However, favoring
persistence and RAP soundings, a TEMPO group for MVFR ceilings has
been included at KRDU, KFAY, and KRWI between 10-14z Fri.

Any sub-VFR ceilings that do develop should lift to VFR by mid to
late morning Friday owing to daytime heating and mixing.  By Friday
afternoon and evening, a series of upper disturbances riding the
periphery of the ridge will likely support scattered to numerous
showers and storms, mainly across northern portion of the forecast
area Friday afternoon and evening.

Outlook: Higher storm coverage is expected again expected Sat
afternoon through Sat night. Daily thunderstorm chances will
continue into early next week, along with patchy late night and
early morning fog and stratus that may result in periods of sub-VFR
restrictions.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Danco
SHORT TERM...Luchetti
LONG TERM...CA
AVIATION...CBL