482
FXUS62 KRAH 131524
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1124 AM EDT Sat Jul 13 2024

.SYNOPSIS...
A front will weaken over the NC Coastal Plain through this evening.
A strong subtropical ridge will otherwise remain over the Southeast
through early to mid-week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1120 AM Saturday...

Hotter, with widely scattered convection possible in both the
Coastal Plain this afternoon and nw Piedmont this evening.

An anomalously strong subtropical ridge, one which this morning
broke daily 500 mb heights at JAX and MFL and will produce
standardized anomalies of 4-5 sigma from the Bahamas to the DR and
Cuba, will remain across the Southeast and swrn N. Atlantic.
Poleward of the ridge and trailing a prominent but compact MCV over
the Middle Peninsula, one related to convection that prompted the
issuance of a Flash Flood Warning over Franklin Co. overnight, a
weak mid-level shear axis will move east across the srn Middle
Atlantic coastal region through this evening.

At the surface, a front and prominent wind shift extended from near
the aforementioned MCV swwd across the NC Coastal Plain this
morning; and this boundary will move little while becoming
increasingly diffuse through this evening. Meanwhile, a weak lee low
may develop near ROA late this afternoon-evening, within a broader
trough forecast to develop just east of the Blue Ridge and which may
drift ewd into the nw Piedmont this evening-tonight.

As morning stratus/stratocumlus over ern and cntl NC lifts and
generally scatters from west to east through this afternoon, weak to
moderate destabilization and weakening convergence along the front
should support the developnent of scattered afternoon showers/storms
in the Coastal Plain. Additional, weaker cells may develop along and
east of the Blue Ridge and drift into the nw Piedmont before
dissipating this evening. High temperatures were raised slightly
mainly over the srn/wrn Piedmont and wrn Sandhills, where realtively
more-prolonged sunshine today should yield highs in the lwr-mid 90s,
with upr 80s to around 90 more likely across the nrn Coastal Plain
and ne Piedmont, where clouds will be slower to scatter. When
combined with mixed/afternoon dewpoints in the mid-upr 60s over the
nw Piedmont to lwr-mid 70s elsewhere, heat index values in the mid-
upr 90s, to around 100 over the srn half of cntl NC, will result.
After a lingering chance of a shower or storm over the nw Piedmont
this evening, temperatures will settle into the lwr-mid 70s for
most, with patches of altocumulus and fair skies likely.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 345 AM Saturday...

The stalled front over central NC will wash out on Sunday, as the
surface flow turns southwesterly across our whole area thanks to a
Bermuda High. Looking aloft, the 850 mb trough will move further
offshore and we will be under the influence of weak zonal mid-level
flow between broad troughing over the Northeast US and SE Canada and
broad ridging extending from Bermuda to the Gulf of Mexico. With a
lack of upper forcing, any showers and storms from daytime heating
should be isolated to widely scattered and quickly diminish after
sunset. The best chances will be in the Sandhills and Coastal Plain
where CAPE could reach 1000-2000+ J/kg. Not concerned about severe
weather given the lack of shear. The bigger change will be the
return of heat, as high temperatures will reach the mid-to-upper-90s
in many areas with increasing low-level thicknesses. Even with dew
points mixing out in the afternoon, heat indices of around 105 will
be possible from the Triangle south and east. Lows Sunday night will
also be warm, in the lower-to-mid-70s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY...
As of 410 AM Saturday...

Monday and Tuesday will turn drier with POPs only slight to low
chance at best both days, as the upper pattern stays fairly zonal
and PW values are near normal. Broad mid-level ridging will continue
to extend from the western Atlantic into the Southeast US. The best
chances for diurnal convection will be focused near the Piedmont
trough and sea breeze. While the ridging reduces the flooding
threat, it brings back the heat. Widespread highs in the upper-90s
are expected both days, with even some low-100s possible. Heat
indices are expected to reach 105-109 on Monday from the Triangle
south and east, and perhaps as high as around 110 on Tuesday when
the greatest combination of heat and humidity looks to be. Low
temperatures at night won`t provide a lot of relief, only dropping
to the mid-to-upper-70s.

Precipitation chances begin to increase again on Wednesday as mid-
level troughing moves into the Great Lakes associated with a closed
low over southern Canada. This will drag a strong cold front that
looks to reach the OH and TN Valleys on Wednesday/Wednesday night.
As the mid-level flow across central NC turns more southwesterly
again and brings in Gulf moisture, PW values will increase back
above normal. POPs increase to chance everywhere, highest NW.
Another hot day is expected, but temperatures may be kept down a bit
by the increase in clouds and precipitation. Still, forecast highs
are mostly mid-90s with heat indices around 105 possible in the
south and east.

Thursday and Friday will have the greatest rain chances in the
period as the cold front approaches central NC and slows down. Deep
southwesterly flow aloft ahead of broad mid-level troughing to our
west will bring in PW values of 2 to 2.5 inches. So there will be
plenty of moisture and instability for this front to tap. Capped
POPs at likely for now given this is Days 6-7, but they will need to
be increased further if trends continue. WPC QPF is around 1 to 2
inches each day on Thursday and Friday, so flooding could be a
concern once again. This will bring down high temperatures to upper-
80s/lower-90s on Thursday and only lower-to-mid-80s on Friday.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
As of 658 AM Saturday...

TAF period: Any VSBY restrictions from fog should improve rather
quickly after sunrise. However, the lifting of the widespread IFR to
LIFR ceilings will be more gradual as drier air spreads in from the
west. KINT and KGSO will be the first to lift to VFR between 14 to
16z, followed by KFAY between 16-18z, and last at KRDU and KRWI
between 18-20z.

Daytime heating within the lingering moist and humid air in place
across the eastern half of the forecast area will lead to the re-
development of scattered showers and storms. However, given limited
coverage will only include VCSH at this time.

Outlook: Morning low stratus and/or fog will be possible again Sun
morning mainly at RWI and FAY, followed by primarily hotter and
mainly dry, VFR conditions until the next front settles into the
region late Wed through Thu.

&&

.CLIMATE...
Record High Temperatures:

July 15:
KGSO: 97/1974
KRDU: 99/1997

July 16:
KGSO: 99/1915
KRDU: 101/1887
KFAY: 103/1937


Record High Minimum Temperatures:

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

July 13:
KGSO: 75/2017
KRDU: 78/2017
KFAY: 78/2017

July 14:
KGSO: 77/1981
KRDU: 77/2017
KFAY: 80/2017

July 15:
KGSO: 74/2019
KRDU: 76/1992
KFAY: 78/2015

July 16:
KGSO: 75/2010
KRDU: 77/2010
KFAY: 78/1992

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...Danco
LONG TERM...Danco
AVIATION...CBL/MWS
CLIMATE...RAH