383
FXUS62 KRAH 082018
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
418 PM EDT Mon Jul 8 2024

.SYNOPSIS...
Mid and upper level high pressure will build over 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 /THROUGH TONIGHT/...
As of 338 PM Monday...

A weak mid-level MCV continues to slowly spiral across our Southern
Piedmont and Sandhills region this afternoon promoting some isolated
convection in this vicinity. Further east, isolated convection along
the sea breeze continues to migrate northward, but the better
coverage will likely stay to our east. Overall, coverage has been
fairly limited and weak so far today across central NC. Given little
sfc forcing, this limited coverage trend should continue into the
overnight period. Expect isolated showers and perhaps a storm or two
generally across the Piedmont/Sandhills and southern Coastal Plain
through this evening. Otherwise, drier conditions can be expected
overnight.

Overnight lows will remain warm in the mid 70s, with some patchy fog
possible especially across southern areas.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 352 PM Monday...

...Heat Advisory in effect for portions of the eastern Piedmont,
Sandhills, and Coastal Plain from 11 AM to 8 PM Tuesday...

Aloft, central NC will be under relatively high pressure, situated
between a trough containing the remnants of hurricane Beryl to the
west and a low off the Southeast US coast to the east. Deep
southwesterly flow will persist. The remnants of Beryl should move
nnewd through the MS Valley and into the OH Valley Tue/Tue night.
The low off the Southeast US coast should drift slowly westward
through Tue night. At the surface, generally sly to sely flow will
prevail over central NC as the remnants of Beryl lift nnewd through
the MS Valley and into the OH Valley Tue/Tue night. Low level
thicknesses are expected to rise into the 1425 to 1435 meter range
Tue aft/eve. Highs should top out in the low to mid 90s across
central NC, while lows Tue night will only dip into the mid 70s.
Expect heat index values ranging from 101 to 106 degrees Tue
aft/eve, highest over the Triangle and along the I-95 corridor.
Convective coverage on Tue should be similar, albeit a little less
than, today. Generally isolated to widely scattered showers and
storms possible. While forcing may be hard to come by and the wind
profiles should be weak, instability should be in the 1000-1500 J/Kg
range and PWATs are forecast to top out in the 2.3 to 2.5 inch range
Tue aft/eve. All that in mind, where showers/storms do develop,
locally heavy rain will be the primary concern.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 415 PM Monday...

A wet pattern is expected across central NC for the first part of
the extended period, as the remnants of what is currently Tropical
Storm Beryl move NNE and interact with a positively-tilted mid-level
trough over the Upper Great Lakes region. The shortwave and
associated surface low from Beryl`s remnants will move NE from the
Great Lakes into southern Ontario/Quebec from Wednesday through
Friday. This will drag a cold front that will reach the Appalachians
on Wednesday night before stalling over central NC from Thursday
through Saturday. Meanwhile the broad trough axis will remain over
the Upper Great Lakes from Wednesday through Friday, and central NC
will be in the right entrance region of a southwesterly upper jet on
the eastern side of the trough, providing us with plenty of lift for
precipitation. PW values will also be in the 2-2.5 inch range over
much of our area from Wednesday through Friday, which is 125-150% of
normal.

This continued deep moisture in place combined with increased lift
and the approaching front will support increased shower and storm
chances on Wednesday, particularly in the west where POPs are
likely. But precipitation chances really ramp up to likely and
categorical on Thursday and Friday as the front stalls over our
region and interacts with the very moist airmass in place. If I had
to pick the wettest day it looks to be Friday, as this is when
models depict potential for a weak area of low pressure (potentially
an MCV) over GA/SC interacting with and getting pulled north by a
shortwave trough over the western Atlantic (just east of the
Carolinas), with plenty of vorticity streaming over our area. While
WPC forecasts average rainfall of about a quarter to three quarters
of an inch on Wednesday night/Thursday, this increases to one to one
and a half inches on Thursday night/Friday. Of course, locally
higher amounts will be possible given relatively slow storm motion
and potential training that occurs. While we have been dry lately
and the rain should provide some welcome drought relief, this much
rain could still result in localized flooding issues. So WPC has us
in a marginal (level 1 of 4) risk for excessive rainfall on
Thursday, increasing to slight (level 2 of 4) on Friday given the
multiple days in a row of potentially heavy rain. Not expecting much
of any severe threat given the lack of shear. Heat will still be a
concern on Wednesday with highs in the lower-to-mid-90s and heat
indices in the 105-110 degree range from the Triangle south and
east. But temperatures will be knocked down on Thursday (highs in
the upper-80s to lower-90s) and especially Friday (highs in the 80s)
with all the clouds and precipitation. Lows will largely be in the
lower-to-mid-70s.

Precipitation coverage will begin to decrease on Saturday and
especially Sunday/Monday as the upper pattern gets less active and
PW values drop back to near normal. The Great Lakes trough will
finally move into northern New England and the Canadian Maritimes,
and central NC will just be under the influence of weak zonal flow
aloft. At the surface, the stalled front will gradually wash out.
The best shower and storm chances look to be in the east on
Saturday, and by Sunday and Monday they should be back to near climo
(25-40%). While this reduces the flooding threat, it brings back the
heat. Highs should be close to normal on Saturday, but by Sunday and
Monday they will be back in the lower-to-mid-90s with heat indices
in the upper-90s to low-100s.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
As of 228 PM Monday...

VFR conditions will largely prevail at all TAF sites over the next
several hours. However, brief periods of sub-VFR conditions will be
possible from isolated showers/storms through this evening. Coverage
overall, however, should be less compared to recent days. Fog and
stratus appear possible tonight, primarily over the southern/western
Piedmont (i.e. best chances for sub-VFR conditions at
KFAY/KINT/KGSO). Any fog/stratus should lift by late Tuesday
morning. Shower and storm chances on Tuesday should be fairly
limited to the coast and mountain areas.

Outlook: Coverage in showers/storms should be fairly limited again
on Tuesday into early Wednesday. A boundary will stall over the area
Thursday into the weekend inducing increasingly wet weather and
potential for adverse aviation conditions.

&&

.CLIMATE...

Record High Temperatures:

July 10:
KRDU: 99/1993

Record High Minimum Temperatures:

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

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

July 10:
KGSO: 77/1981
KRDU: 77/1981
KFAY: 77/1998

July 11:
KGSO: 75/1992
KRDU: 77/1981
KFAY: 76/2019

July 12:
KGSO: 76/2011
KRDU: 78/2011
KFAY: 80/1935

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 8 PM EDT Tuesday for NCZ007>011-023>028-
040>043-076>078-088-089.

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Luchetti
SHORT TERM...KC
LONG TERM...Danco
AVIATION...Luchetti
CLIMATE...RAH