114
FXUS62 KRAH 200706
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
305 AM EDT Sat Jul 20 2024

.SYNOPSIS...
A series of convectively-amplified disturbances in moist,
southwesterly flow aloft will overspread and interact with a surface
front that will remain nearly stationary over central NC through the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1015 PM Friday...

Amid swly flow downstream of a shortwave perturbation that will
pivot from sern MO/nrn AR newd and across the mid-South, a series of
convectively-amplified disturbances will be directed from the lwr MS
and TN Valleys to the srn Middle Atlantic. The most notable and
probably influential of these features for the sensible weather in
cntl NC was well-defined in regional radar data over n-cntl SC this
evening, including in KCAE velocity data that depict a deep
circulation from around 3 to 25 thousand ft ARL in wrn Chester and
Fairfield Co. SC. This feature will continue to move generally newd
and across cntl NC overnight. As it does so, it will encounter an
environment characterized by only weak instability from widespread
outflow and surface cooling from prior convection and otherwise
weak, 5-5.5 C/km lapse rates upward through 500 mb. As such, it
seems most likely that a mix of stratiform rain immediately
surrounding the approaching MCV, and occasional weak cellular
development preceding it, will spread newd into/across cntl NC
overnight. Hourly rainfall amounts in the stratiform rain have
generally been light, from several hundredths to a quarter inch over
nrn SC in the past couple of hours. Given that the stratiform rain
shield will likely continue to diminish in the absence of
additional, concentrated deep convection, beyond the sporadic/
isolated cellular development like that which has recently developed
from near FAY to CTZ to GSB, the risk of flooding overnight appears
low.


.PREV DISCUSSION... /ISSUED 318 PM EDT Fri Jul 19 2024/

The cold front is now a stationary front as it has moved little
since this morning. The best estimate position of the front, mindful
of an outflow boundary sagging south from the boundary, stretches
from Davidson/Randolph east into southern Wake and into Wilson
County. An outflow boundary exists south of this tied to convection
from Wayne to Lee counties. The front arcs to the southwest to near
CLT and into northern SC/GA/AL.

Since the front has not made any southward progress the main showers
and storms have occurred along and south of the boundary, along US-
64. Storm chances are thus highest over the next few hours in this
area. With time, southward movement of the outflow from convection
should aid increased coverage of storms in the southern Piedmont,
Sandhills, and southern Coastal Plain by early evening.

While convection along and north of the boundary should weaken near
sunset with loss of heating, additional convection is forecast to
move into the southern and western Piedmont later tonight and
overnight into early Sat. This would be tied to mid-level energy
from MS/AL and upstream convection that may congeal over GA/SC and
track ENE. Isentropic ascent could also favor showers over the Triad
and western Piedmont overnight. Guidance also suggests perhaps an
MCV may track into the Triad early Sat, which could also touch off a
few isolated showers/storms along and north of the boundary in the
Triangle and northeast Piedmont early Sat morning. How much of this
convection survives with nocturnal stabilization is unclear, but
have 30-60 percent PoPs mainly US-1 westward.

Outside of convection, low stratus is forecast to envelope the area
overnight, especially along and north to northwest of the boundary.
Overnight lows are expected to be in the upper 60s to low 70s,
coolest across the north.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 305 AM Saturday...

The front that is lingering over the region appears as if it should
spend most of the day south of the forecast area. While all
locations still have likely pops in the forecast, did bump up
southern counties to categorical being closer to the focus area of
the front. Highs should again be close to normal, ranging from 85 to
90. Conditions will remain muggy, although even with high humidity
values, temperatures in the 80s should minimize the amount of triple
digit heat index coverage.

&&

.LONG TERM /MONDAY THROUGH FRIDAY...
As of 305 AM Friday...

There is minimal change to the long term forecast. A longwave trough
will extend from Quebec south into the Gulf of Mexico, and warm,
moist advection will persist across much of the eastern United
States. Will continue with likely pops during this time period. In
addition, heavy rainfall rates means that isolated flash flooding
will continue to be a threat across the entire area despite the area
being in a drought. Highs should remain near climatology in the
upper 80s and lower 90s.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
As of 201 AM Saturday...

MVFR to IFR ceilings will continue to fill across central NC this
morning, persisting through mid to late morning.  Additional showers
and a few storms will be possible later this afternoon which could
produce brief sub-VFR conditions at all terminals. A few stronger
thunderstorm gusts could also be possible especially at KRDU and
KRWI.  Otherwise, expect MVFR to IFR stratus to sock back in later
tonight.

Beyond 06Z Sunday: Showers and storms will continue Sunday into
early next week.  Early morning fog and stratus will be possible
each day as well. The wet pattern will continue into middle of next
week.

&&

.CLIMATE...
Record High Minimum Temperatures:

July 20: KGSO: 75/2019 KRDU: 76/2020

July 21: KGSO: 76/2011 KRDU: 78/1932 KFAY: 80/2017

July 22: KRDU: 78/2011

July 23: KRDU: 78/2011

July 24: KRDU: 79/2011 KFAY: 79/1945

July 25: KFAY: 78/2016

July 26: KGSO: 76/2016 KRDU: 77/2010

&&

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

&&

$$

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