294
FXUS62 KRAH 172245
AFDRAH

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

.SYNOPSIS...
Deep high pressure will extend across the Carolinas through
Saturday. A series of upper level disturbances will track east and
southeast through the Mid Atlantic region Friday through early next
week, 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 given DCAPE values around 800-900
J/kg, still can`t entirely rule out a damaging wind gust mainly
across the 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 340 PM Thursday...

...A Heat Advisory is in effect from 11 AM to 8 PM Friday for the
eastern Piedmont, Sandhills, and Coastal Plain...

The mid/upper high to our south will drift even farther west on
Friday and Friday night to become centered over FL, resulting in
continued WSW flow across central NC. The environment will again be
moist and unstable, with PW values near and exceeding 2 inches along
with MLCAPE over 2000 J/kg. The main difference from today will be
the presence of a more potent shortwave that tracks SE from WV/VA
into NE NC on Friday afternoon and evening. This will result in
better forcing for more widespread showers and storms, which may
reach the northern Piedmont and northern Coastal Plain during this
time. Thus expect convective development to mainly be focused there,
with more isolated coverage in the south which will feel more drying
influence from the ridge. While still marginal, guidance shows 0-6
km bulk shear values of 20-25 kts are possible across our northern
counties, which may be enough to support isolated damaging wind
gusts with any storms. There is also where isolated to scattered
flash flooding will be possible, particularly the northern Coastal
Plain where LPMM from the 12z HREF depicts isolated pockets of 1-3
inches can`t be ruled out on Friday evening. However, these areas
haven`t been as saturated from recent rainfall compared to farther
west, and the heavy rain signal in guidance is stronger to the north
and east of our area. So opted against a Flood Watch at this time,
but we will certainly continue to monitor. Showers/storms will
diminish and move out of our region overnight Friday night.

The other threat on Friday will be the excessive heat, as high
temperatures in the lower-to-mid-90s are expected. Even with good
mixing, dew points in the lower-to-mid-70s will result in heat
indices as high as around 107F in the afternoon across the eastern
Piedmont, Sandhills, and Coastal Plain. So a Heat Advisory is in
effect there from 11 AM to 8 PM. Be sure to stay hydrated and take
frequent breaks from the heat if spending a lot of time outdoors.
Lows Friday night will again not provide a lot of relief, ranging
from lower-70s north and west to mid-to-upper-70s south and east.

&&

.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 /23Z THURSDAY THROUGH TUESDAY/...
As of 645 PM Thursday...

Convection continues to diminish in both coverage and intensity
with mostly dry conditions expected shortly after sunset.

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, particularly 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...Danco
LONG TERM...CA
AVIATION...CBL