712
FXUS62 KRAH 270850
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
449 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 /THROUGH TONIGHT/...
As of 445 AM Thursday...

A Heat Advisory remains in effect from 11 AM to 5 PM for the eastern
Sandhills, srn-cntl Coastal Plain, and Wake Co.

A positive tilt, convectively-amplified mid-level trough, one which
includes a prominent MCV now over nern TN, will move east and across
the srn Middle Atlantic and Carolinas today, then offshore tonight.

At the surface, 08Z data depict a lee trough from cntl NC swwd
through a ~1007 mb lee low over the Upstate of SC and nrn GA. An
outflow boundary, and focus for isolated to widely scattered
shower/storm development, has intersected the trough and extended
from near ASJ to TTA to VUJ in cntl NC. These two features will
merge and become an effective cold front, and nwrn bound of severe
storm potential, that will move sewd and across cntl and ern NC
today. Meanwhile, a couple of synoptic cold fronts stretched from 1)
the lwr Great Lakes wswwd across the OH and mid MS Valleys, and 2)
the nrn Middle Atlantic coast swwd through a ~1007 mb low over cntl
MS, to the lwr MS Valley, respectively. The two will merge in the
post-effective frontal regime over the Middle Atlantic and move swd
in backdoor fashion across VA and nrn NC tonight.

A combination of morning stratus over cntl NC, now developing in
both the rain-cooled, post-outflow regime over the nrn NC Piedmont
and in the maritime tropical (70s dewpoints) ahead of it, and also a
multi-layered mid/high-level cloud band accompanying the approaching
mid-level trough, will result in cloudy or mostly so conditions to
start the day. A differential heating zone will probably develop
along the sern edge of these clouds from cntl SC to sern NC and
contribute to additional frontogenesis along the aforementioned
effective frontal zone (merged lee trough/outflow), with the hottest
(mid 90s) , most humid, and unstable conditions preceding it through
early this afternoon. Scattered, deeper convection will likely
develop along and ahead of this boundary and congeal into line
segments or a broken line with strong to locally damaging wind gusts
as it moves through the Coastal Plain/ern Sandhills and to the coast
through early-mid afternoon, augmented by lift ahead of the
approaching MCV and mid-level trough.

As that activity moves toward the coast, partial clearing will
probably result wwd across cntl and wrn NC later this afternoon; and
this will allow for stronger diurnal heating into the upr 80s to lwr
90s and weak late day destabiliation there. Isolated to widely
scattered showers and storms will probably result in that regime and
continue through early tonight.

Overall, the combination of clouds and convection/outflow will favor
less hot than previously forecast temperatures; and when factoring
in mixed dewpoints that will again decrease into the mid 60s to
around 70 F this afternoon, also lower than previously forecast, the
risk of reaching or exceeding Heat Index values of 105 F appears low
except for perhaps in Cumberland, Sampson, and Wayne Co. It will
nonetheless be hot, with Heat Index values around 100; and given the
consecutive days of heat with Heat ndex values having been
consistently 102-110 F, and still with moderate to major HeatRisk,
the Advisory will remain in place. A slightly cooler and less humid
airmass behind both the efftvive front of today and synoptic front
tonight will favor low temperatures in the upr 60s to lwr 70s for
most.

&&

.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...MWS
SHORT TERM...Green
LONG TERM...Green
AVIATION...MWS
CLIMATE...RAH