828
FXUS62 KRAH 211023
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
618 AM EDT Sun Jul 21 2024

.SYNOPSIS...
A series of convectively-amplified disturbances in moist,
southwesterly flow aloft will overspread and interact with a surface
front that will weaken over the Southeast and southern Middle
Atlantic through early this week.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 215 AM Sunday...

A MCV continues to spiral over the southern Piedmont this morning,
generating showers along an outflow/effective front currently draped
across the NC/SC border. There remains ~500 J/kg of MLCAPE in this
vicinity, and as such, expecting showers to continue as the mid-
level feature moves across the NC/SC border through sunrise. North
of the boundary, stable conditions will promote continued pockets of
stratiform rain and stratus.

In wake of the MCV`s exit to our east this morning, a period of
subsidence will keep much of the early part of today dry.  As we
pivot into the afternoon period, diurnal convection will likely
develop. Overall forcing aloft will be weaker today and thus
expecting less coverage compared to yesterday. However, given weaker
shear today, storm motion should be slower and therefore any
thunderstorms could be capable of locally heavy rainfall and
isolated flash flooding. It`s difficult to discern a specific
frontal zone in model sfc fields today, and thus pinpointing highest
POPs is a bit difficult. However, given we`ll have a gradient in
stratus coverage (thicker across the northern half of our CWA),
think some kind of differential heating boundary may develop over
the western/southern Piedmont through the Sandhills. Thus, perhaps
these areas may see a bit better coverage this afternoon.

Models suggest yet another MCV (perhaps currently over the Gulf of
Mexico) will approach our western areas this evening. Thus, we may
see additional showers and storms in these areas, some of which may
be capable of producing flash flooding. HREF QPF exceedance
probabilities peak along the foothills/mountains, but could easily
see higher QPF potential slip into our southern/western Piedmont
during this time. After collaborating with WPC, a slight ERO was
added across the western Piedmont to account for this possibility.

Showers/storms should diminish through sunrise Monday morning.
Overnight lows will remain in the lower 70s.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 215 AM Sunday...

The upper-level pattern will remain similar on Monday with a ridge
over the western US and troughing over the central/eastern US.
Embedded within the swly flow aloft, a short wave will eject across
the southern Appalachians through Monday night.  Associated mid-
level impulses will spread north over our area and trigger scattered
convection through Monday night.  While effective shear will
strengthen some across our area (highest east), it`s not quite clear
how much instability will develop Monday afternoon given lingering
showers and cloudiness from the overnight period. As such, storms
may lack explosiveness necessary to produce severe weather despite
better kinematics. Regardless, like recent days, any heavier
downpours would be capable of producing isolated flash flooding.
Latest guidance suggest coverage could be highest along an inland
penetrating sea breeze earlier Monday afternoon, and then pivoting
west later Monday evening/night. Showers/storms will linger into the
overnight period before dissipating near sunrise Tuesday morning.

Highs will remain in the upper 80s/lower 90s. Overnight lows in the
70s are again expected.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 215 AM Sunday...

An upper level trough will remain persistent over the Mississippi
River Valley through much of the week, continuing to bring likely to
categorical pops across the forecast area. Although it is a low
confidence solution, models are indicating that both Tuesday and
Wednesday evenings may have higher precipitation amounts than the
afternoon periods. While the new issuances for the WPC Excessive
Rainfall Outlook have not come out yet for this forecast cycle, the
entire forecast area remained under a marginal (level 1 of 4) risk
Tuesday and Wednesday, as far out as the ERO goes. There is some
broad agreement from the ECMWF and GFS that the upper trough will
finally begin to break down Friday into Saturday, and this could
bring a pattern change from the wet weather of late. Most locations
have measured rainfall the last 3 days, and it appears likely that
at least the next 6 days will also have rain. With minimal change to
the air mass, there will be minimal changes to the temperatures -
highs ranging from the mid 80s to the lower 90s, lows within a few
degree of 70 degrees.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
As of 618 AM Sunday...

KINT/KGSO/KRDU will likely stay socked in with IFR/LIFR ceilings
through early this morning before lifting to MVFR and eventually VFR
by late this morning.  Conversely, KFAY and KRWI have seen more
fleeting sub-VFR ceilings thus far.  These TAF sites should lift to
VFR by mid morning.

Additional showers and storms are possible late this
afternoon/evening, with best coverage likely near KFAY/KRDU early,
and shifting out towards KINT/KGSO later this evening. KRWI may stay
dry through the TAF period. Showers and storms should wane into the
overnight period, with additional MVFR/IFR stratus likely to blossom
across central NC late tonight.

Beyond 06Z Monday: Afternoon showers and storms will persist each
day through mid to late next week. Early morning fog and stratus
will be possible each day as well.

&&

.CLIMATE...

Record High Minimum Temperatures:

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

July 22:
KGSO: 77/2011
KRDU: 78/2011

July 23:
KRDU: 78/2011
KFAY: 79/2017

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