584
FXUS62 KRAH 190018
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
818 PM EDT Fri Jul 18 2025

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

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 815 PM Friday...

The Heat Advisory for today has been allowed to expire as heat
indices across central NC have fallen below 105 degrees. As a
reminder, another Heat Advisory was issued earlier this afternoon
for Saturday and will be in effect from 11 AM until 8 PM.

Previous discussion as of 220 PM follows...

Flash Flood Watch for the northern and much of eastern NC through
400 AM Saturday. Flash flooding is possible, especially along and
north of the Triad and Triangle to Rocky Mount this afternoon and
evening.

Look for the likelihood of at least locally severe storms this
afternoon into the evening, especially over the northern portions of
central NC.

Strong heating (temperatures in the lower to mid 90s) of the very
moist environment (dew points in the mid to upper 70s) will continue
ahead of the advancing short wave that will move east across the mid-
Atlantic states later this afternoon into tonight. There were a few
lingering clouds at early afternoon over central NC; otherwise, it
was nearly full sunshine across the region. Scattered thunderstorms
were already developing at 17z over the Foothills of the northern
and central NC mountains in response to the approaching trough and
strong heating. As the scattered thunderstorms move east into the
Piedmont where the very moist, heated, and unstable atmosphere
exists, expect strong to severe storms to develop with the main
hazard of damaging wind gusts. These storms will likely become
clusters across the Triad between 200 and 400 PM, then shift into
the northern and central Piedmont by late afternoon and the Coastal
Plain this evening. Some of the storms may produce damaging wind
gusts.

There is also a flood risk this afternoon and evening, especially
over north-central and NE portions of the region where it has been
exceptionally wet in the past few weeks. We issued a Flood Watch
through 400 AM to match our neighbors to the north and east and
match with the latest slight risk (level 2 of 4) for flash flooding,
and with areas that are nearly saturated or heavily urban. If
repeated areas are hit, especially over saturated areas of north-
central NC and urban areas, isolated to scattered flash flooding
could result. Rainfall rates in excess of 2 inches per hour are
likely.

The Heat Advisory will continue into the evening or may be trimmed
as thunderstorms overturn the boundary layer.

The convection may persist longer into the evening with some upper
support and on outflows. POP will trend much lower after midnight.
Lows in the lower to mid 70s.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 200 PM Friday...

* Heat Advisory in effect for the Eastern Piedmont, Sandhills, and
  Coastal Plain Saturday from 11 AM to 8 PM. Heat index values
  between 105 and 109 are expected.

* Slight (level 2 of 4) risk of flash flooding possible for the
  northern Piedmont and northern and central coastal plain where
  scattered to numerous slow moving storms are likely.

A similar pattern of slow moving afternoon showers and storms will
persist on Saturday. Convection is expected to initiate over the
mountains Saturday afternoon and move eastward into the region as
well as forming on residual outflow boundaries left from convection
that occurs Friday afternoon. Shear values look to be less than 20
kts, limiting severe potential, however a few stronger to severe
storms cannot be ruled out in the afternoon and evening hours. The
main hazard with these storms should be the flooding potential, as
weak cloud-layer flow as well as plenty of moisture are expected. If
storms stall or train over urban areas or areas with already moist
soils, flash flooding will be possible.

High temperatures Saturday afternoon will peak in the low to mid
90s, with the warmest temperatures in the south and east. This will
combine with high humidity values to raise heat indices into the
upper 90s to mid 100s. Thus, a Heat Advisory has been issued for the
Eastern Piedmont, Sandhills, and Coastal Plain from 11 AM to 8 PM.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 305 PM Friday...

A broad mid/upper trough over the Northeast US and Mid-Atlantic
associated with a low over eastern Quebec will push east into the
Atlantic on Sunday and Sunday night. Weak subsidence and mid-level
height rises behind a departing shortwave rounding the base of the
trough will result in lower shower and storm chances on Sunday
across central NC. But 2000-3000 J/kg of MLCAPE and a moist air mass
(PW values 2+ inches) mean isolated convection will still be
possible. The highest POPs (still only around 30%) are focused in
the NW with terrain convection spilling into the Piedmont and the SE
with the sea breeze. The bigger story will be temperatures, as good
sunshine and lower precip chances will help them rise even a bit
higher than Saturday, with highs ranging from lower-90s in the far
north to upper-90s in the far south. With dew points in the 70s,
heat indices are likely to reach as high as the 105 to 109 range
from the Triangle south and east, and another Heat Advisory may be
needed. Any convection will quickly diminish after dark with lows
Sunday night mostly mid-to-upper-70s.

Monday will feature the best precipitation chances of the period, as
a series of upper impulses moves across the area in the NW flow
between the trough just east of the Mid-Atlantic coast and building
ridge from the Deep South into the Central Plains. At the surface,
low pressure over the Canadian Maritimes will send down a backdoor
cold front that reaches the southern Mid-Atlantic on Monday night.
Lift from these features combined with moderate to strong
destabilization will result in more widespread showers and storms on
Monday afternoon and evening, with perhaps some lingering into
Monday night as the front moves through our region. Isolated flash
flooding can`t be ruled out where storms train and in urban areas.
We also get into the SW periphery of the belt of stronger NW mid-
level flow, perhaps up to 25-30 kts, so there could be a threat of
severe storms. Monday`s highs will be in the upper-80s to mid-90s
with lows in the upper-60s to mid-70s.

The ridge will build farther north and east into the OH Valley and
Upper Great Lakes on Tuesday, weakening the mid-level flow across
central NC. Meanwhile drier air and below-normal PW values will
start to filter in behind the backdoor front which settles SW of
central NC. There is still some uncertainty on where the front will
be, but guidance has been trending faster with its passage, so
wouldn`t be surprising if Tuesday ends up largely dry. The best
chance for any convection will be in the SW in closest proximity to
the front. Precipitation chances are very little if any on Wednesday
and Thursday with cooler more stable NE flow from surface high
pressure east of New England and the mid/upper high centered over
the TN Valley. The best chance would be in the NW with terrain
convection and the SE with the sea breeze. Moisture may begin to
increase again on Friday as a Bermuda surface high begins to set up
with southerly flow returning. Temperatures will slowly increase
from Tuesday through Friday as cooler air from the high gradually
erodes. The "coolest" day looks to be Tuesday with highs in the mid-
to-upper-80s and lows in the mid-60s to lower-70s, increasing back
to highs in the lower-to-mid-90s and lows in the lower-to-mid-70s by
Friday.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
As of 659 PM Friday...

Prevailing VFR conditions are ongoing outside of scattered
convection resulting in MVFR to IFR vsbys elsewhere from the TAF
sites. Outflow boundaries may collide near the northern 4 TAF sites
with scattered showers/storms possible at any of them. Handled
initially with PROB30s given low confidence and struggling model
support, but may need to be increased to TEMPOs shortly as it
becomes clear where storms will develop. MVFR to IFR stratus will be
possible at RWI and RDU with less confidence at FAY. The Triad
terminals may see some shallow fog and/or very low stratus around
daybreak, but confidence again remains low since they have missed
out on the rainfall thus far this evening. Afternoon showers/storms
will again be possible Sat afternoon with perhaps greatest coverage
from the Triad terminals to RDU.

Looking beyond 00z Sun, The threat for diurnal showers/storms and
early morning sub-VFR fog and stratus will continue through early
next week. A frontal passage Mon into Tues will bring a wind shift
out of the north and brief relief from this pattern with less
convective coverage and relatively drier air filtering in from the
north expected into the midweek.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 4 AM EDT Saturday for NCZ007>011-021>028-038>043-
076>078.
Heat Advisory from 11 AM to 8 PM EDT Saturday for NCZ008>011-024>028-
040>043-073>078-083>086-088-089.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Badgett/Swiggett
SHORT TERM...Helock
LONG TERM...Danco
AVIATION...Swiggett