339
FXUS62 KRAH 040611
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
211 AM EDT Thu Jul 4 2024

.SYNOPSIS...
A subtropical ridge will remain anomalously-strong over the Deep
South today, then gradually weaken ahead of a cold front that will
move into and stall over the southern Middle Atlantic and Carolinas
this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 836 PM Wednesday...

Little change to the going forecast through tonight. Surface high
pressure offshore of the Mid-Atlantic will continue to progress
eastward, resulting in a return southerly flow taking shape
overnight and become SSW toward sunrise. Satellite imagery reveals
some mid and high clouds streaming in from the NNW. Model guidance
shows these high clouds will continue to be a player through the
overnight hours, especially west of the Coastal Plain. Hard to tell
how opaque these clouds are, but they are likely to prevent some
radiational cooling in an otherwise light southerly flow. We raised
highs a tad over the Piedmont as a result, with urban areas in the
71 to 74 degree range. In the outlying areas and over the Coastal
Plain, lows will be in the mid to upper 60s.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 230 PM Wednesday..

A 595dm upper level ridge will extend from the Gulf Coast states NE
toward the Mid-Atlantic on Thursday while surface high pressure
continues to slip further offshore and allows moist southerly return
flow to engulf the Carolinas.  With southwesterly flow and deep
mixing, dry adiabatic mixing technique yields mid to upper 90s for
highs, which is on the higher side of guidance (equivalent to the
75th to 90th percentile range of the NBM) but not out of the realm
of possibility. Thus will lean towards the higher side of guidance
for highs. Deep mixing also suggests dewpoints will be able to mix
out a little into the mid to upper 60s in a lot of areas, helping to
keep heat indices in the low 100s for the most part.  Will note that
HeatRisk suggests moderate impacts, with much greater impacts Friday
into Saturday.

Regarding any convection, the stout mid-level cap that has been
present this week will still be around early Thursday, weakening
somewhat across the north as a trough moving into the Great Lakes
tampers down the northern edge of the upper ridge.  CAPE looks
pretty limited due to the cap and mixing of dewpoints, but hires
guidance suggests some isolated development on the mtn ridges and
lee trough, perhaps migrating from SW VA toward the northern
Piedmont along loosely-consolidated outflow.  PW will also still be
less than 1.5 inches, so the number of storms should also be
limited. Thus the best chance of isolated storms should be from the
Triad to Person County later in the afternoon and evening.  Where
storms do occur, the deep mixing and dry air will favor damaging
winds as the greatest threat.

Without better moisture available, convection is expected to wane
quickly Thursday evening.  Dewpoints will continue their background
rise with the return flow, creeping into the lower 70s and keeping
overnight lows in the low to mid 70s as well.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 321 PM Wednesday...

The pattern aloft from Friday into the weekend will feature
troughing across the Great Lakes and increasing southwesterly flow
aloft across the Southeastern US. Strong 591dm H5 ridging will
gradually slide offshore as the longwave trough and attendant
surface cold front make their way across the mountains and into the
Piedmont. This front will struggle to make it through the area,
stalling out somewhere across central NC and serving as a focal
point for afternoon showers and storms pretty much each afternoon
through early next week. A series of reinforcing shortwave troughs
will move through the Great Lakes early next week, but nothing
significant enough to push the front through the area. If anything,
the front will likely wash out at some point early next week with
scattered diurnally driven showers and storms becoming the theme
through the middle of next week. PoPs will be at their highest (50-
70 percent) Friday and Saturday, then retreat a bit into the 40-50
percent range Sunday through Wednesday. Favored areas will be the
western Piedmont and Sandhills, with slightly lower chances
elsewhere in line with climo.

Temperatures will be on the rise as well, with highs reaching the
mid to upper 90s Friday and Saturday, retreating into the low/mid
90s from Sunday onward. Heat Indices will approach 105 degrees along
and primarily east of US-1 Friday and Saturday, with slightly lower
values Sunday into next week. Overnight lows will range from the low
to mid 70s.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 200 AM Thursday...

VFR conditions, influenced by high pressure extending from just
offshore the Middle Atlantic coast southwestward into the Carolinas,
will continue through at least mid-afternoon. An Appalachian-lee
surface trough and/or outflow from upstream convection will provide
foci for shower/storm development that will probably affect INT/GSO
and surrounding vicinity across the nw NC Piedmont this afternoon-
evening. Some of that gusty outflow, and focus for additional,
isolated to widely scattered showers/storms, may drift to near RDU
and RWI through 00-03Z, before dissipating.

Outlook: A chance of showers/storms will exist Fri and especially
Sat through Mon, as a pre-frontal trough and surface front move into
and stall over cntl NC. Late night-early morning stratus and fog
will also be possible this weekend.

&&

.CLIMATE...
Record High Temperatures:

July 4:
KGSO: 98/1970
KRDU: 101/2012
KFAY: 98/2019

July 5:
KGSO: 98/2012
KRDU: 102/1999
KFAY: 101/2002

July 6:
KRDU: 102/2022
KFAY: 99/1990


Record High Minimum Temperatures:

July 4:
KGSO: 73/2018

July 5:
KGSO: 74/1999
KRDU: 78/1902
KFAY: 77/2005

July 6:
KGSO: 76/1999
KRDU: 79/1900
KFAY: 76/2017

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

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...Kren
SHORT TERM...bls
LONG TERM...Leins
AVIATION...MWS
CLIMATE...RAH