791
FXUS62 KRAH 070701
AFDRAH

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

.SYNOPSIS...
A weak frontal zone will remain stalled just east of the
Appalachians through early Monday. This front will weaken further
and dissipate Monday, as mid level high pressure builds over the
Southeast states and Carolinas Monday through Tuesday.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 255 AM Sunday...

Fairly high coverage of convection is expected once again today. A
very warm and deeply moist air mass remains over central NC, east of
a diffuse frontal zone stretching SW-NE over the E slopes of the
Appalachians, according to the latest surface analysis. The vast
majority of the area saw rainfall yesterday (much needed, given the
ongoing dry/drought conditions, although a bit too much/too fast in
some spots). This ground moistening has led to some light/isold
fog/stratus development early this morning, although this should be
limited by both considerable higher debris clouds (esp in the W) and
by relatively dry air just off the ground, noted on 925 mb progs.
Persistence will largely be the rule today: The weak surface front
should hold in place while slowly weakening, with weak low level
flow to its east over central NC and anomalously high PWs (150-175%
of normal) likely to linger across the area. Central NC will also
remain within weak mid-upper level flow, in a col area between SW
steering flow from the S Plains across the Ohio Valley and an upper
low spinning well off the Carolina coast, while through the lower
levels, the subtle trough noted on the 07/00z 925-850 mb UA analyses
across GA and the Carolinas will likely hold in place with no
mechanisms to dislodge it. All told, today`s convection pattern
should behave much like yesterday, except perhaps a bit earlier
initiation. Moderate SBCAPE is again expected, but with modest deep
layer shear, so we may again see a few strong cells with the
potential for downbursts, and the slow-moving water-laden cores will
present a threat of heavy downpours and localized flooding as well.
Recent CAM runs from various modeling systems have frankly been
rather poor, fairly to accurately depict current/00H precip over its
last several runs, going back to last evening, and they aren`t in
very good agreement with each other. As such, have gone with a
precip pattern not far off Saturday`s, most closely replicated by
the 00z HREF mean. Expect coverage to peak at numerous/likely pops
mid afternoon into early evening, with again a slow decline in
coverage through tonight as elevated CAPE very slowly wanes, similar
to last evening/early this morning.

Expect highs today in the upper 80s to mid 90s, with clouds
tempering heating a bit amidst thicknesses near to just slightly
above normal. This will also keep heat index values below heat
advisory criteria, although areas south and east of the Triangle may
still see a few hours of 100-104F. Lows in the low-mid 70s. -GIH

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 300 AM Sunday...

To be updated shortly.

&&

.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 /06Z SUNDAY THROUGH THURSDAY/...
As of 1230 AM Sunday...

Adverse aviation conditions are likely to dominate across the
Piedmont terminals (INT/GSO/RDU) through mid morning, with scattered
showers and isolated storms expected to persist here through around
09z, with just isold showers thereafter through the morning. These
sites will also see variable sct-bkn IFR/LIFR cloud bases topped by
bkn-ovc VFR decks through mid morning, although the highest chance
of IFR/LIFR cigs will be 09z-12z. There will be less of a chance of
IFR/LIFR cigs at FAY/RWI. Any fog this morning should be MVFR at
worst and focused in the SW Piedmont, S and W of INT/GSO/RDU. As
cloud bases rise slowly this morning, VFR conditions should return
by 15z areawide, but redevelopment of scattered to numerous showers
and storms is expected by 16z-18z 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. Outside of any storms, surface
winds will be light and variable, mainly from the SW at RDU/FAY/RWI.

Looking beyond 06z Mon, 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. VFR conditions should return 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...Hartfield
NEAR TERM...Hartfield
SHORT TERM...
LONG TERM...Swiggett
AVIATION...Hartfield
CLIMATE...RAH