089
FXUS62 KRAH 080429
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1230 AM EDT Mon Jul 8 2024

.SYNOPSIS...
A weak frontal zone extending from Chesapeake Bay through the
Piedmont of the Carolinas will weaken further today before
dissipating tonight. Mid and upper level high pressure will build
across the area through mid week, before another cold front
approaches Wednesday night. This front will then stall out and hold
over the western and central Carolinas through Friday.

&&

.NEAR TERM /OVERNIGHT/...
As of 928 PM Sunday...

The convection has mostly ended across central NC with some
lingering rain patches attm, as the sfc front has slipped south and
now extends from approx the CLT region ENE to KGSB and then north to
the ORF area. Cooler sfc air behind the front is evident in latest
sfc obs with readings in the lower 70s and even some upper 60s temps
currently across our northeast Piedmont and northern Coastal Plain
zones, with mid-upr 70s across much of the rest of central NC except
some lingering 80s readings near the SC border. Will make a few
tweaks to forecast temps overnight to account for current trends.

Otherwise, the rain should gradually taper off after 06Z tonight as
both instability and larger-scale forcing wanes. Until then, in
additions to some lingering patchy rain, we can`t completely rule
out a few widely sct tstms across our southern-most zones where the
front hasn`t yet cleared the area. And it`s also worth noting that
several MCVs across the Carolinas and Southeast states...as noted in
current water vapor imagery, including one notably just west of the
CLT area, appear to be drifting slowly to the southeast...and thus
should have limited impact on our weather overnight as they should
stay south of our area.  Finally, the latest HRRR suggests some
stratus will continue to develop and expand overnight across much of
the Piedmont region, perhaps extending all the way toward I-95...
this stratus formation occurring over areas that received the
heavier rain earlier today.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
As of 250 PM Sunday...

* Continued shower/thunderstorm chances, albeit it with lower areal
  coverage
* Brief periods of heavy rain likely the primary threat with any
  storms that develop

We should have a very similar synoptic setup across the area
tomorrow with PW`s still running around 2 to 2.2". The presence of a
stalled surface boundary may be lacking though and with only a lee
trough and sea breeze to contend with, the overall triggering
mechanisms for convection may ultimately be the limiting factor.
Storms are once again favored across the western Piedmont along with
the Sandhills/southern Coastal Plain, with lesser chances elsewhere.
Storms are likely to be outflow dominant and pulse-type in nature
given very weak steering flow around 15kts or less. While wet
microbursts would be a possibility with any storms that approach
severe limits, locally heavy rainfall from slow moving/training
storms would likely be the primary threat tomorrow.  However given
relatively limited areal coverage, we shouldn`t need any flood
watches. PoPs in the 20-40 percent range area-wide are the general
consensus from the NBM, HREF, and other global models and this seems
reasonable at this point.

Temps will be on par with today`s values with highs in the upper
80s/lower 90s with lows falling into the lower 70s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 250 PM Sunday...

* Typical summer pattern through the weekend
* Some storms possible Tuesday/Wednesday, becoming more numerous
  late in the week

Precip chances look to decrease on Tuesday as an offshore upper low
off the NC coast dives southwestward toward Florida. In its wake,
mid level heights appear to increase by a few meters and this may be
enough to further inhibit storm development across the area. While
similar PW`s will be in place area-wide, very limited forcing and
instability outside of an area near a lee trough across the western
Piedmont should keep storms isolated/widely scattered in nature.

Meanwhile, the remnant circulation and moisture associated with T.C.
Beryl will be drawn inland and absorbed into a longwave trough
approaching the western Great Lakes later this week. This will spawn
a relatively deep surface cyclone that will track northward across
the Great Lakes into southern Ontario. An attendant surface boundary
will make an eastward run at the mountains, but likely stall/wash
out before it makes it across. However the remnant boundary and/or
lee troughing will likely result in an area of enhanced surface
convergence which will be stall out and be slow to exit the area.
Nearly all global models suggest a plume of increased PW`s will be
drawn inland from off the SE coast on Wednesday, interacting with
and serving as a necessary ingredient for increased shower and
thunderstorm coverage to close out the week. There is a general
consensus among the ensembles that Thursday and Friday could be
particularly active as a weak surface low develops along the stalled
surface boundary to our south and tracks through central NC. Looking
at the 100 member grand ensemble of the Canadian, GFS, and EC
ensemble forecast systems, nearly 80 percent suggest precip across
the area on Thursday and nearly 90 percent on Friday, which is an
unusually high amount of agreement for this time of year at this
lead time. Of course exactly how much rain will fall, and exactly
where the surface boundary and low track set up, is still TBD but
the trend of increasing late-week PoPs will continue. Precip chances
should remain elevated (although slightly lower as compared to
Thursday/Friday), as we get into the weekend.

Temperatures this week should be within a few degrees of normal.
Through mid week with mid level ridging sneaking in from the east,
temps should make a solid run into the mid 90s area-wide and it is
on these days (Tuesday and Wednesday) where heat indices could make
a return to dangerously high values. However increased cloud cover
and precip chances will knock readings back into the mid/upper 80s
Thursday, especially Friday, and possibly into Saturday as well
before returning to normal by Sunday. Lows throughout the period
generally upper 60s to mid 70s.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 1230 AM Monday...

Confidence is high in widespread sub-VFR stratus (mostly IFR/LIFR)
and areas of mostly MVFR fog persisting across much of central NC
until mid morning, particularly affecting INT/GSO/RDU, with slightly
lower confidence at RWI/FAY. Patchy rain will dwindle but linger
over the far SW edges of the forecast area through daybreak, however
much of the area will stay dry through mid morning. IFR clouds will
be slow to improve, likely rising to MVFR between 14z and 16z
(slowest in the W Piedmont) and to VFR by 18z. FAY is likely to see
MVFR/IFR cigs lasting a shorter time, 10z-14z, with 08z-14z at RWI.
Scattered showers and storms are expected today, through the central
sections (RDU) late morning/early afternoon then over the NW and SE
areas (INT/GSO and FAY) mid afternoon through early evening, with
storms likely to develop over the higher terrain and drift into the
Triad, and along an inland-moving sea breeze toward FAY. Overall
coverage is expected to be lower than over the last two days, and
showers and storms should start to decrease and diminish by mid to
late evening. Periods of sub-VFR cigs/vsbys and gusty/erratic winds
are possible in and near any storms today. Outside of any storms
today/tonight, surface winds will be light and variable, mainly from
the S (SE through SW).

Looking beyond 06z Tue, there is a chance for sub-VFR cigs/vsbys
early Tue morning, mainly across the S, but should be less coverage
than this morning. A general pattern of scattered to numerous
showers and storms primarily each afternoon through evening will
continue through Fri, with the highest chances late Wed night
through Fri, and at least some chance of early-morning sub-VFR
clouds/fog each day. -GIH

&&

.CLIMATE...
Record High Minimum Temperatures:

July 7:
KGSO: 73/2019
KRDU: 77/1900
KFAY: 78/2017

July 8:
KGSO: 76/2010
KRDU: 78/1986
KFAY: 79/2012

July 9:
KGSO: 76/1987
KRDU: 74/2014

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...np
SHORT TERM...DL
LONG TERM...DL
AVIATION...Hartfield
CLIMATE...RAH