605
FXUS62 KRAH 071427
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1025 AM EDT Sun Jul 7 2024

.SYNOPSIS...
A weak frontal zone extending from the Chesapeake Bay into the
Piedmont of the Carolinas will linger and weaken before dissipating
by Tuesday. Mid and upper level high pressure will then build across
the area before another cold front approaches late in the work week.
&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1025 AM Sunday...

* A notable change in the weather pattern and sensible weather for
  today with more cloudiness and cooler temperatures than the past
  few weeks.
* Scattered to numerous showers and storms are expected although a
  fair amount of uncertainty in how convection will evolve today.

The latest surface analysis shows a cold front extending from the
DelMarVa peninsula southwest across southeastern VA into the
northwestern Piedmont of NC and into far upstate SC. The air mass
across central NC is very moist with PW values of 2.0 to 2.3 inches
this morning with the KGSO RAOB observing 2.12 inches. Southeast of
the front, dew points range in the lower to mid 70s with an axis of
upper 70s extending along the Coastal Plain. Northwest of the front,
a light northeast wind is observed in the Triad and in the VA border
counties.

Further aloft a 594dm mid and upper level anticyclone is centered
over the eastern Gulf of Mexico, sandwiched between Beryl and the
closed mid/upper level low east of the Carolinas. The mid and upper
flow across NC will be rather light today and from the west and
southwest. There are a few disturbances in the general flow, most
prominently is one moving across eastern NC this morning and perhaps
a few others moving into NC from the southwest late this afternoon
and this evening.

Satellite imagery and surface observations note a good deal of
cloudiness across central NC this morning with areas of MVFR/IFR
ceilings. With heating, expect some additional breaks in the
overcast to develop which will subsequently be followed by
stratocumulus and cumulus cloud growth, all of this will result in
partly to mostly cloudy skies this afternoon and evening.
Particularly challenging today will be the evolution of convection,
especially where it will develop and how it evolves. The frontal
zone should serve as a natural focus for storm initiation as will a
myriad of boundaries across the area including differential heating
areas from breaks of sunshine and gradients of different rainfall
amounts from yesterday. Convection allowing models provide vastly
different solutions which is not surprising given the weak forcing
and numerous mesoscale features present. Expect convection to
gradually ramp up over the next handful of hours, especially after 1
and 2pm with coverage and intensity peaking between 3 and 6pm and
then a gradual decline into the mid and late evening. With a couple
of upstream disturbances posed to move near the area tonight,
wouldn`t be surprised to see a rogue shower or storm overnight.

The main weather hazard today will be slow moving convection in a
moist and weakly to moderately unstable environment will be produce
some locally heavy rain. Highs today will be tempered by cloudiness
and a slightly cooler air mass and generally range in the upper 80s
to lower 90s, coolest in the Triad behind the front and warmest
across the southeast, ahead of the front and in a warmer atmosphere
that did not experience much rain. It will remain warm and muggy
tonight with lows in the lower to mid 70s. -Blaes
&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 330 AM Sunday...

Our overall pattern remains much the same, although there are signs
that convection coverage may be a bit lower than Sat and today. The
frontal zone to our NW will have largely dissipated or morphed into
a very weak lee trough, keeping high surface dewpoints and near to
above normal temps over the area. Models generally agree in taking
the mid-upper low off the Carolinas slowly SSW toward the N Bahamas
Mon/Mon night with rising mid level heights over GA/SC/NC, while the
high PW axis sitting across central NC decreases about a quarter to
a third of an inch. SBCAPE is again expected to peak in moderate
territory but with the higher values shunted to our NW. The mid-
upper level flow remains quite weak, yielding poor deep layer shear,
hindering storm organization once again. Will have pops just
slightly under today, peaking at good chance to likely in the
afternoon and decreasing in the evening. Once again expect highs in
the upper 80s to mid 90s, followed by lows in the 70s. -GIH

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 255 AM Sunday...

Tuesday and Wednesday: Beryl is forecast to become ingested within a
trough digging into the central/southern Plains Tues and lift into
the Mid-MS Valley Wed evening with a transition into an asymmetric
cold core cyclone. Closer to home, a continued hot/humid airmass
will be in place as central NC is situated within a weakness in the
mid-level flow with little synoptic forcing for ascent. This will
favor near climo rain/storm chances with pulse, classic summer-type,
storm mode. Storm depth/strength may be less than previous days with
less instability (500-1500 J/kg SBCAPE) and an upper level
anticyclone centered over central NC. Well above normal deep layer
moisture and slow storm motions will still pose an isolated risk for
flash flooding, mainly in urban and poor drainage locations Tue and
Wed. Temperatures will remain hot/humid and average 5-10 degrees
above normal. Highs with range from the low/mid 90s with lows in the
mid/upper 70s. With heat indices still expected to reach 100-105 and
with little recovery overnight, anyone without effective cooling
and/or adequate hydration may experience heat related illnesses.

Wed night through Friday: The extratropical cyclone associated with
Beryl merging with the synoptic trough is forecast to lift through
the Mid-MS Valley through the Ohio Valley and towards the Great
Lakes region by Wed night into early Thurs morning. Ensemble
guidance suggests a unseasonably deep cyclone should evolve (40-60%
of members indicating < 1010mb and 20% < 1005mb) by early Thurs with
a low-level convergence axis and surface cold front should push into
the central Appalachians, and perhaps the Piedmont of central NC
into the mid week, which will provide a focus for showers/storms.
This should favor rain/storm chances continuing through Wed night
and above normal precipitation chances heading into late week. There
remains some important along-track inconsistencies on how quickly
this area of low pressure shifts northeast, so confidence on timing
and eastward extent of the pressure trough and/or effective cold
front is lower than normal during this time. Mostly cloudy
conditions and above normal chances for rain will temper highs
towards below normal by late week, but overnight lows will likely
remain around 5 degrees above normal (low/mid 70s).

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
As of 620 AM Sunday...

The abundant low clouds that were previously expected to develop
early this morning have not panned out, in large part due to the
lingering considerable mid and high level cloudiness leftover from
last night`s storms, and the persistent isolated showers that have
come and gone across the area overnight. Nevertheless, a few low
clouds are noted around the area, and there remains a risk of an
hour or two of MVFR vsbys in fog along with mostly scattered IFR-
level clouds through mid morning, along with an isolated shower or
two. As cloud bases rise slowly this morning, VFR conditions should
return by 14z areawide, but redevelopment of scattered to numerous
showers and storms is expected by 16z-19z starting first in the W
Piedmont before quickly expanding across all of central NC, lasting
through the afternoon and evening, and aviation interests can expect
a risk of storms, with periods of sub-VFR cigs/vsbys and
gusty/erratic winds, across all terminals during this time, although
coverage should begin to decrease toward 04z. There is a high chance
of IFR cigs and MVFR vsbys in fog developing areawide shortly after
06z, forming first at INT/GSO then expanding E. Outside of any
storms today/tonight, surface winds will be light and variable,
mainly from the SW at RDU/FAY/RWI.

Looking beyond 12z Mon, the daybreak sub-VFR conditions should
improve to VFR by 15z. Another round of scattered showers and storms
is expected Mon, with coverage slightly lower than today. The
general pattern of scattered to numerous showers and storms each
afternoon through evening will continue through Thu, with 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...Blaes
NEAR TERM...Blaes
SHORT TERM...Hartfield
LONG TERM...Swiggett
AVIATION...Hartfield
CLIMATE...RAH