093
FXUS62 KRAH 151040 CCA
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
640 AM EDT Thu Aug 15 2024

.SYNOPSIS...
High pressure will persist over the Carolinas today then shift
offshore by late Friday. A cold front will approach the region from
the west on Saturday.

&&

.NEAR TERM /TODAY and TONIGHT/...
As of 640 AM Thursday...

A dry and tranquil weather pattern... featuring NW flow aloft, sfc
high pressure over our region, and high PWAT airmass suppressed well
to our south... is in place over central NC attm and will remain
through the near term.  Highs today will be near or a couple deg
below climo... mid to upper 80s.  Lows tonight in the 60s under some
passing mid and high clouds as the upper ridge axis builds toward
our region.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 311 AM Thursday...

The sfc ridge axis will move offshore early in the day with
increasing southerly low level flow by late in the day.  A short
wave trough that is crossing the Midwest region today will move
across the western Great Lakes on Friday, with lowering heights to
our north.  A band of showers/tstms ahead of the trough axis will
cross the Ohio Valley early in the day, then the mountains during
the afternoon.  As this band of showers moves east of the mountains
toward the drier antecedent air over central NC, its possible that a
couple of the showers/tstms may hold together, reaching our Triad
zones before dissipating.  Thus, will continue to advertise slt
chance PoPs for our Triad zones later in the day and into the
evening. Otherwise, the rest of central NC should remain dry on
Friday with highs a couple degrees warmer than today, and a slight
uptick in humidity as the southern flow increases late.  Lows Friday
night in the upper 60s to around 70 under partly cloudy skies.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 400 AM Thursday...

A surface low will slowly drift east from MI into Lake Huron and SE
Ontario on Saturday and Saturday night. An associated prefrontal
trough will be over central NC, with the actual cold front still
moving from the OH Valley into the Appalachians. Timing of this
frontal system has slowed down somewhat compared to yesterday, so
POPs have come down a bit during the day and are mainly focused in
the NW. While moisture doesn`t look too impressive, there still
could be enough instability (1000-2000 J/kg of CAPE) and forcing
from the mid/upper trough to our west and surface trough in place to
bring scattered showers and storms to central NC, especially by the
evening hours when POPs are in the 30-40% chance range. Some rain
chances may linger into the overnight hours.

The best coverage for convection across the whole region now looks
like it may come on Sunday, when shortwave energy diving down from
the NW deepens the mid/upper troughing in place to our west,
increasing SW flow and height falls across the area. Meanwhile a
cold front will approach and slowly move across central NC on Sunday
evening/night. Latest ensemble probabilities indicate a 70-80%
chance of measurable precipitation on Sunday afternoon/evening, but
don`t have enough confidence to go too high with POPs yet, capping
them at 40-50%. Mid-level flow is looking more impressive on the 00z
guidance, in the 30-40 kt range, so some strong to severe storms
can`t be ruled out. Rain chances should end from NW to SE on Sunday
night behind the cold frontal passage.

A drying trend will then set up from Monday through Wednesday.
Surface high pressure will build down from the Great Lakes and
Northeast US as the cold front stalls near the coast. The mid/upper
trough axis will initially be over us on Monday, then push east near
the coast, bringing NW flow aloft that brings below-normal PW values
and helps dew points mix out well into the 60s on Tuesday and
Wednesday. In fact, some guidance even shows some 50s dew points on
these days. After slight to low chance POPs on Monday, convection
will get even more isolated on Tuesday and Wednesday, with only
slight chance POPs in the east and southeast in closest proximity to
the front.

Temperatures will be on a gradual downward trend through the period
as the cold front moves through. Forecast highs are in the mid-to-
upper-80s (near normal) on Saturday, decreasing to lower-to-mid-80s
(slightly below normal) by Tuesday and Wednesday. Forecast lows
similarly drop from lower-70s on Sunday morning to 60s by Tuesday
and Wednesday mornings.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
As of 640 AM Thursday...

Through 12Z Friday:  Scattered patches of IFR fog and stratus are
being reported at this time across central NC.  That will lift and
burn off within the next 2 hours, then we can expect VFR conditions
through the rest of the 24 hour TAF period, along with light N-NE
sfc winds that will become variable late in the day.

After 12Z Friday: 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...np
NEAR TERM...np
SHORT TERM...np
LONG TERM...Danco
AVIATION...np