Garner, North Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

229
FXUS62 KRAH 201838
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
235 PM EDT Thu Aug 20 2026

.WHAT HAS CHANGED...

* Slight risk of severe thunderstorms has expanded to the southwest
  across much of the forecast area this afternoon/evening.

* Marginal risk of severe thunderstorms has expanded to the north
  across the entire forecast area Friday.

* Widespread heavy to torrential rainfall continues to be expected
  on Friday. Rainfall totals increased to 1-3" over a large area
  with localized amounts of +5 inches possible.

&&

.KEY MESSAGES...
As of 235 PM Thursday...

1) There will be two potential rounds for severe weather today, one
round through the afternoon across eastern counties, with a second
round during the late afternoon and evening focused (but not limited
to) western counties.

2) Today will be the last day in this stretch with above normal
temperatures before the air mass moderates, bringing temperatures
closer to normal.

3) Widespread heavy to torrential rainfall Friday afternoon through
the early overnight hours increase the risk for scattered flash
flooding, especially in urban and poor drainage locations.

&&

.DISCUSSION...
As of 235 PM Thursday...

KEY MESSAGE 1... There will be two potential rounds for severe
weather today, one round through the afternoon across eastern
counties, with a second round during the late afternoon and evening
focused (but not limited to) western counties.

While scattered thunderstorms were expected to develop along the I-
95 corridor this afternoon, the convective temperature was reached
slightly earlier than expected, resulting in a scattered line of
thunderstorms along the I-95 corridor that has prompted Severe
Thunderstorm Warnings and continues to move slowly to the east.
Although there is a threat for large hail to the northeast of the
Triangle, the primary threat will come from damaging winds - so far,
all reports received had been from wind damage. Current MUCAPE
values are between 1500-2500 J/kg, although effective wind shear
remains less than 30 kt. Another line of showers and thunderstorms
is expected to develop late this afternoon along the east side of
the Appalachians and move into the area around sunset, providing the
primary threat for damaging wind across the western part of the
forecast area. Despite occurring at a less favorable time of day in
terms of heating, many members of the 12Z HREF show better
organization with the evening convection and show the potential for
it to make its way across the forecast area, reaching the I-95
corridor by late evening. The primary threat for severe weather with
the second line would also be from damaging winds, and should come
to an end shortly after midnight.

Key message 2... Today will be the last day in this stretch with
above normal temperatures before the air mass moderates, bringing
temperatures closer to normal.

A heat advisory remains in effect for the majority of the forecast
area through 8pm. Heat index values remain at or above heat advisory
criteria through much of the area where thunderstorms have not
occurred. As of 2pm, the temperature was 95 degrees at RDU which had
remained dry, but approximately 10 miles southeast at the NWS
Raleigh office, which had about a third of an inch of rain, the high
temperature reached 95 before the temperature fell to 73 degrees. In
this sense, the area reaching heat advisory criteria will not be
uniform.

KEY MESSAGE 3... Widespread heavy to torrential rainfall Friday
afternoon through the early overnight hours increase the risk for
scattered flash flooding, especially in urban and poor drainage
locations.

A slow moving and baggy trough will largely remain in place over the
eastern CONUS with a weakening within the trough axis extending down
into the panhandle of FL. Weak high pressure is expected to build
over southern Ontario and extend down through the Mid-Atlantic and
push a weak cold front into the Carolinas by Fri morning. This
frontal boundary will likely remain in place through the morning and
into the afternoon as the disturbance over FL lifts north-northeast
and into the Carolinas by the afternoon hours.

A weak area of low pressure is expected to develop over the Midlands
of SC as the disturbance begins to approach the synoptic boundary at
the surface. This should act to focus low-lvl convergence and
provide the initiating boundary for convection to develop late
morning into the early afternoon. Surface dew points in the low/mid
70s are expected south of this boundary and will likely support at
least 1500-2500 SBCAPE. Tall and "skinny" CAPE profiles within an
air mass characterized by PWAT of 2-2.3" and slow corfidi vectors
will promote a highly favorable environment for torrential rainfall
with a conditional risk for training, slow moving storm clusters
surrounding meso-highs produced from prior convection.

HREF and REFS LPMM fields show the potential for a corridor of
widespread 1-3", surrounding the area of the frontal boundary, with
localized amounts of +5". This corridor will be highly sensitive to
where the boundary ends up Fri afternoon, which could be further
complicated by more widespread convection this afternoon (Thurs
8/20) that may affect the placement and degree of destabilization of
the warm sector on Fri. Another potential mitigating factor for
greater coverage of the higher-end totals will be that instability
may be too strong during the afternoon and provide strong outflow
that rapidly spreads away from the initiating boundary and results
in more progressive storm clusters. Even so, impressive rain rates
of 2-4"/hr will still drive a concern for poor drainage and urban
flash flooding, which may occur quickly.

Loosely organized storms within 20-30kt of 0-6km shear may support
some organization along common cold-pools to increase the risk for
damaging straight-line winds, but given the widespread nature of
convection expected along the initiating boundary, wet-microburst
within and surrounding storm collisions will be more likely and
support 40-60 mph wind gusts and isolated instances of hail.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 135 PM Thursday...

TAF period: While scattered thunderstorms were expected this
afternoon, they were not expected to begin quite as early as they
have. As of 1730Z, the line is between RDU/RWI and to the west of
FAY. The inherited TEMPO groups should cover the thunderstorms that
move into RWI and FAY, the thunderstorms should remain just east of
RDU. Another line of thunderstorms is expected to develop later this
afternoon into the evening, and have gone with prevailing
precipitation at INT/GSO/RDU during the evening. There is less
confidence in these showers reaching FAY/RWI, so have continued a
VCSH mention (and PROB30 for TSRA at RWI). While the precipitation
should come to an end after midnight, an area of MVFR/IFR stratus is
expected to develop over VA with a cold front and move south into NC
shortly before dawn. Guidance is unsure as to whether the ceilings
will be just above or below 1000 ft; in addition, FAY had LIFR
ceilings this morning, and even if the VA stratus does not make its
way south to FAY, the saturated air mass should allow for
restrictions to develop there once again.

Outlook: While Friday morning should be dry, widespread showers and
isolated thunderstorms will develop Friday afternoon and evening,
and restrictions are expected at all sites, especially with moderate
to heavy rain forecast. Moderate/heavy rain will continue at all
terminals Friday night, then primarily shift to FAY/RWI on Saturday.
Drier conditions with less flight restrictions are expected for
Saturday night through Tuesday.

&&

.CLIMATE...
Record High Minimum Temperatures:

August 21: KRDU: 76/2009 KFAY: 77/2005
August 22: KRDU: 74/2017 KFAY: 75/2018

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for NCZ024>028-040>043-
075>078-084>086-088-089.

&&

$$

DISCUSSION...Green/Swiggett
AVIATION...Green