349
FXUS62 KRAH 141709
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
110 PM EDT Wed Aug 14 2024

.SYNOPSIS...
High pressure centered over the Great Lakes will shift east and
southeast into the mid Atlantic and the eastern Carolinas through
Friday and then shift offshore Saturday. A cold front will approach
the region from the west on Saturday.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1000 AM Wednesday...

Underneath NW flow aloft, a dry air surface ridge will extend south
into the area today, resulting in comfortable conditions for mid
August standards. Highs this afternoon in the lower to middle 80s,
with dewpoints further mixing out down into the lower/mids 60s, with
even some upper 50s possible.

Amidst weak instability, weak/channeled vorticity disturbances make
trigger some isolated weak convection, mostly in the way of showers
later this afternoon before dissipating.

Tonight, with generally clear skies and calm winds, lows should
manage to dip some 2-6 degrees below normal in the upper 50s in
outlying areas to low to mid 60s elsewhere. This will certainly be a
comfortable night we have not seen in some time.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 220 AM Wednesday...

Ridging aloft over the Midwest and OH valley will gradually pivot
east into the Mid-Atlantic as an upper trough tracks into the Great
Lakes region. High pressure will continue to nose down into our area
from the northern Mid-Atlantic. Temperatures will be perhaps 1-2
degrees warmer than Wed owing to a slight rise in low-level
thicknesses, in the low to mid/upper 80s. This is just below
average. We will again see some afternoon fair weather cumulus.

The aforementioned trough will combine with low to mid-level WAA
across the TN/OH valleys Thu night, increasing some mid/high clouds
across the western Piedmont. The WAA will likely generate some
upstream convection as far south as the TN/KY region, but it will
not reach us due to high pressure and its stability. Lows should be
comfortable again, ranging from the low to middle 60s, lowest in the
Coastal Plain.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 400 AM Wednesday...

Dry WNW flow aloft will continue to dominate on Friday, as ridging
pivots farther east across the Carolinas and surface high pressure
extends down the Eastern Seaboard, which will help keep what is then
likely Hurricane Ernesto well to our east over the Atlantic. Enough
mixing of the dry air aloft will likely help keep dew points in the
mid-60s in the afternoon. As troughing extends down from the Great
Lakes to the TN Valley, guidance shows it pushing the ridging far
enough east for some increased moisture to spill over the
Appalachians. This may result in isolated showers or storms making
it as far east as the NW Piedmont, so carry slight to low chance
POPs there on Friday.

As the trough and associated cold front push farther east into the
Appalachians on Saturday, SW flow will increase moisture and
instability across all of central NC, with 1000-2000 J/kg of MLCAPE
and PW values reaching or even exceeding 2 inches. This looks to be
the day with greatest confidence in precipitation during the
extended period, which is backed up by the latest ensemble
probabilities. Mid-level flow doesn`t look terribly impressive,
around 20-30 kts, but a few strong to severe storms still can`t be
ruled out. Low chance POPs continue on Sunday, highest east, as the
surface trough works it way through central NC. However, drier air
beginning to work in from the west at that point may decrease
shower/storm chances a bit compared to Saturday.

Guidance depicts below-normal PW values in place by Monday and
Tuesday behind the passage of the trough/front, as the low-level
flow turns W/NW. With the mid/upper trough axis near or over the
area, diurnally-driven slight to low chance POPs linger, but
coverage does not look too impressive, and guidance actually depicts
weak mid-level height rises. The ECMWF had been depicting a
slower/wetter solution, but the 00z run looks more like the GFS with
bringing the cold front through our area over the weekend instead of
stalling it out.

The frontal passage may be more like a trough than an actual cold
front, as temperatures should be pretty consistent through the
extended period and within a few degrees of normal. Forecast highs
are in the mid-to-upper-80s each day. Lows will be in the upper-60s
to lower-70s each night, maybe a bit cooler by early next week as
drier air moves in.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 110 PM Wednesday...


VFR conditions should persist for much of today with scattered to
broken strato-cumulus in the 4-5 kft range. Centered underneath the
surface ridge axis, light NELY winds should decouple overnight.
Model guidance suggests the potential for another night of fog and
associated sub-VFR restrictions, mainly at KRDU at KRWI. Confidence
was too low to mention at the other terminals. Any fog that does
develop should quickly dissipate Thursday morning. Winds will remain
light on Thursday and are expected to become E-SELY late in the day.

Outlook: Mostly dry, VFR conditions are expected across the area
into Friday. A slow moving cold front will approach this weekend,
producing at least scattered chances of showers/storm over the
weekend and lingering into Monday as the front finally moves
through the area.


&&

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

&&

$$
SYNOPSIS...CBL/Kren
NEAR TERM...Kren
SHORT TERM...Kren
LONG TERM...Danco
AVIATION...CBL