373
FXUS62 KRAH 021039
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
635 AM EDT Fri Oct 2 2026

.WHAT HAS CHANGED...

* Will issue a Dense Fog Advisory for this morning much of the
  southern and central Coastal Plain, Sandhills and southern/eastern
  portions of the Triangle area.

&&

.KEY MESSAGES...
As of 345 AM Friday...

1) Dense fog is expected into mid morning hours across the southern
and central Coastal Plain, Sandhills and southern/eastern portions
of the Triangle area.

2) Saturday will mark a transition to cloudy, much cooler, and wet
conditions that will continue in cold air damming through the
weekend.

&&

.DISCUSSION...
As of 345 AM Friday...

KEY MESSAGE 1... Dense fog is expected into mid morning hours across
the southern and central Coastal Plain, Sandhills and
southern/eastern portions of the Triangle area.

A return flow transporting shallow moisture with dewpoints in the
lower to mid 60s north into the region will continue to support an
expanding region of dense fog across southeastern NC. The fog will
continue to spread north through daybreak and will likely advance as
far north and northwest as portions of Lee, Wake, and Nash counties.
The most widespread fog with the lowest visibilities will be focused
near and east of Interstate 95 where visibilities will be reduced at
times to one quarter mile or less. The fog will slowly lift and
erode and conditions should improve notably by 9 or 10 am.


KEY MESSAGE 2... Saturday will mark a transition to cloudy, much
cooler, and wet conditions that will continue in cold air damming
through the weekend.

On the nwrn periphery of a strong sub-tropical high over the swrn N.
Atlantic, a positively-tilted srn stream trough/shear axis, and
related convectively-amplified mid-level disturbances, will progress
across the OH Valley and Middle Atlantic today and the Southeast
this weekend. It will do so ahead of a broad nrn stream trough that
will amplify across ern Canada and the Great Lakes this weekend,
with related cyclone development likely from near James Bay into QC
by 12Z Mon. In the tightening height gradient between the troughs
and branches of the westerlies, the models depict the development of
a wswly to swly upr level jet streak from the lwr MS Valley to the
Middle Atlantic, though there is large model spread in its placement
and orientation and related influence to vertical motion via both
upr-level divergence and lwr-level convergence and Fgen within its
entrance region.

At the surface, high pressure extending from near Bermuda to the
Southeast will be displaced by a wavy synoptic frontal zone, or a
couple of closely-spaced ones, forecast to settle swd and across
cntl NC on Sat. The front(s) will likely stall and become quasi-
stationary from SC to southeastern NC Saturday night, then perhaps
retreat slightly nwwd across ern NC with the passage of a weak
frontal wave Sun into Sun night. A following, ~1028-1030 mb cP high
will progress across and offshore sern Canada this weekend, while
extending swd across the Middle Atlantic and Carolinas. Though
progressive, the high will be favorably strong and located for cold
air damming to develop over the srn Middle Atlantic and Carolinas.

Convective allowing models depict an area of scattered to locally
numerous convection developing along the cold front from late Sat
morning through Sat evening over roughly the srn half of NC. Weak
mid-level lapse rates (generally less than 5.25 C/km) will yield an
only weakly unstable environment with diurnal heating ahead of the
front, however. North of the front, patches of mixed character
rain/showers will be possible amid moistening mid-levels and very
weak elevated instability, atop developing and deepening nely flow
within the building surface ridge and cold air damming.

Rain will become more-widespread, steadier, and increase in
intensity Saturday night and Sunday, in a regime of strengthening
isentropic upglide across the surface frontal zone and atop the CAD
high. Although the models continue to vary in storm total rainfall
amounts and their placement, it remains likely that a relatively
widespread, soaking rain (with amounts generally between one and two
inches) will result over cntl NC by the end of the weekend. Given
the likelihood of CAD, forecast high temperatures and diurnal ranges
for Sat night-Sun night have continued to trend lower.

A reinforcing cold front and following cP/Canadian surface high will
progress across the srn Middle Atlantic early next week, with
following cool and dry fall conditions for cntl NC through at least
mid week.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 635 AM Friday...

24 hour TAF period: Areas of dense fog and some stratus with LIFR
and IFR VSBY and CIG restrictions will continue across the Coastal
Plain, Sandhills along with southern and eastern portions of the
Triangle area this morning. The fog has resulted in several hours of
LIFR conditions at the KFAY and KRWI terminals with the fog and
stratus near but just a few miles southeast of the RDU terminal.
Elsewhere, VFR conditions are generally expected across central NC
with just a few localized spots of fog.

The fog will persist for a few more hours and it should not expand
much more to the north or west over the next few hours. The fog and
stratus will slowly lift and burn off an hour or two after sunrise
with some lingering MVFR restrictions possible at the KRWI and
especially KFAY terminals through 14 or 15Z. Otherwise, fair weather
with mainly clear skies mixed with some high cirrus clouds and a few
fair weather cumulus clouds are expected today. Fair weather
continues into the overnight with mid and high clouds increasing.
Low level moisture ahead of an approaching cold front will result in
an increase in low clouds across the north and northwest late
tonight and a rogue shower is possible mainly near the VA border.

Light southwest winds at 3 to 6 kts this morning will increase and
range at 6 to 10 kts this afternoon and evening with a few gusts to
around 15 kts.

Outlook: Widespread adverse aviation conditions in clouds and rain
with associated sub-VFR restrictions are expected across the entire
region from Saturday into Sunday night. A drier air mass will build
into the region on Monday with a return to fair weather and VFR
conditions expected for the second half of Monday through mid week.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EDT this morning for NCZ027-028-
041>043-075>078-084>086-088-089.

&&

$$

DISCUSSION...Blaes/MWS
AVIATION...Blaes