347
FXUS62 KRAH 270717
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
315 AM EDT Thu Jun 27 2024

.SYNOPSIS...
A mid-level disturbance and surface cold front will move across NC
today. The front will linger across the southern and eastern
Carolinas through early Friday, before lifting back north as a warm
front. A stronger cold front will approach the area on Sunday.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 315 PM Wednesday...

A Heat Advisory has been issued for portions of central NC Thu, with
heat indices between 102 and 108 over portions of the Triangle,
Sandhills, and Coastal Plain.

A frontal boundary will likely be draped northeast to southwest from
the Mid-Atlantic into eastern TN to far western NC early Thu. The
front will try to move south and east through the day and evening as
high pressure settles into the northern Mid-Atlantic in western NY.
However, the front will most likely get hung up along the NC/VA
border sometime early Fri.

Some of the high-res models are indicating a secondary boundary
draping southward with convection from Wed night to early Thu
morning along US-64. Perhaps this is related to the lingering
discontinuity currently over southern VA. However, other guidance
indicates less of a defined wind shift. How this evolves may
ultimately depend on what happens with convection tonight across
northern NC and southern VA. With the uncertainty, we believe that
with warm overnight lows tonight in the mid 70s, high dewpoints in
the 70s again Thu, and max temperatures over the Triangle,
Sandhills, and Coastal Plain in the mid to upper 90s, will lead to
another heat risk across the region. Heat indices could be as high
as 108 over the far eastern Sandhills and southern Coastal Plain.
The only fly in the ointment is whether convection/clouds start
earlier in the day to limit daytime heating. For now, though, we
hedged toward enough solar heating for the higher heat risk. Highs
will be lower in the northwest Piedmont with upper 80s to near 90.

As for convection, some CAMs are showing the greatest coverage south
and east of the Triangle along their effective boundary, while
others extend convection further west to mainly along/east of US-1.
We hedged with this further west solution, thinking that any
boundary would be draped along US-64. Machine-learning models and
guidance suggest the prime storm risk would be between 1 pm and 8
pm, with greatest coverage along/east of US-1, with storms waning by
late evening and overnight as a mid-level trough axis slides south
of the region. SPC has continued a marginal risk of severe storms
mainly over the Sandhills to Coastal Plain. However, we would not be
surprised if that expands north and west to include the Triangle in
later updates. Point forecast soundings indicate high instability
upwards of 2000 J/kg, DCAPE around 1000 J/kg, and decent shear of 20-
30 kts from the WSW supportive of a damaging wind threat with any
stronger organized cells. Hail can also not be ruled out. As
convection wanes overnight, low stratus or fog may develop by early
Fri with lows in the upper 60s to mid 70s.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 315 AM Thursday...

Cannot rule out a stray thunderstorm Friday morning across southern
counties, but the chance for a thunderstorm should spread across the
entire region Friday afternoon as today`s cold front lifts back to
the north. In addition, an upper level shortwave still appears
poised to bring a chance of thunderstorms across western counties
overnight. In the northwest, highs should be similar to today`s
values, in the upper 80s to lower 90s. In the southeast, highs
should be about 5 degrees cooler than today, reaching the lower to
mid 90s. Heat index values should peak near 100.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 315 AM Thursday...

Sat/Sun: Increased pops Saturday afternoon as ensembles have become
a bit more generous with coverage of precipitation, although
deterministic models are a little more reluctant to do so. Pops
settle down Saturday night before increasing again as a cold front
moves from the Ohio River Valley southeast across the state. Have
continued with likely pops, and this front appears as if it may be
the best chance for rain in the next seven days. Highs will be well
into the 90s each day along with heat index values over 100 degrees.
The values should be highest on Sunday, although the arrival of
showers/thunderstorms could temper these readings.

Mon/Wed: The front will be reluctant to move through, and have
maintained chance pops across generally the southern half of the
forecast area Monday afternoon and just slight chances across
southern tier counties Tuesday afternoon. As the front slides south,
a surface high will build in from the north, allowing for flow out
of the north and a brief relief from the heat. The predicted high at
RDU on Monday, July 1 is 87 degrees, which would break a forecast 18
day string of 90+ highs. By Wednesday, the high moves offshore,
allowing a southerly wind to develop again and raise highs back into
the 90s everywhere.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 215 AM Thursday...

An outflow boundary from previous and ongoing convection over VA
will continue to trigger additional showers/storms, and also cause
initially swly surface winds to become calm/variable or light nwly,
as it moves sewd at 10-15 kts across the nrn Piedmont and nrn
Coastal Plain of NC this morning. While patches of IFR-MVFR stratus
may develop in the rain-cooled air behind the boundary over the nrn
Piedmont, a higher probability of IFR-MVFR ceilings will exist at
FAY, as a separate area of 800-1900 ft AGL ceilings now developing
across nrn SC and srn NC --in a similar manner as Wed morning--
spread nwd to FAY and possibly at RDU/RWI through 12Z. Associated
ceilings, should they indeed develop as described, should then lift
and scatter to VFR through ~14Z.

A mid-level trough, embedded disturbances, and multi-layered
mid/high-level ceilings will then move east and across cntl-ern NC
today. The airmass ahead of the trough and clouds may destabilize
sufficiently for the redevelopment of scattered early-mid
afternoon storms particularly from FAY ewd to the coastal Carolinas.

Outlook: IFR-MVFR stratus will again be possible especially at FAY
Fri morning and area-wide Sat-Sun mornings, followed by a good
chance of mainly afternoon-evening showers/storms Sunday.

&&

.CLIMATE...
Record High Temperatures:

June 27:
KFAY: 102/1998

June 30:
KFAY: 102/2012

Record High Minimum Temperatures:

June 27:
KGSO: 76/1969
KRDU: 76/1952
KFAY: 77/1998

June 28:
KGSO: 76/1969
KRDU: 76/1952
KFAY: 78/1914

June 29:
KGSO: 74/2010
KRDU: 78/1914
KFAY: 76/1969

June 30:
KGSO: 74/1936
KRDU: 80/1936
KFAY: 79/1936

July 1:
KGSO: 77/1970
KRDU: 75/2012
KFAY: 76/1990

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 5 PM EDT Thursday for NCZ041-042-
077-078-085-086-088-089.

&&

$$
SYNOPSIS...MWS/Blaes
NEAR TERM...Kren
SHORT TERM...Green
LONG TERM...Green
AVIATION...MWS
CLIMATE...RAH