660
FXUS62 KRAH 221808
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
210 PM EDT Mon Jul 22 2024

.SYNOPSIS...
The combination of a weak nearly stationary front sitting over the
Mid Atlantic region, a very moist air mass in place, and a series of
upper level disturbances tracking over the region will bring
continued unsettled weather through Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 210 PM Monday...

Forecast is largely on track, with a continued threat for localized
heavy rainfall as well as low-end severe storms, both primarily
across the east.

The surface frontal zone appears to have moved little today, still
extending SW-NE across TN, across far NW NC and NNE through central
VA to around NYC, and most of central NC remains in a warm and humid
air mass with rich moisture transport as noted on CIRA layer WV
transport imagery and 2.0-2.2" PW as seen on RAP-based mesoanalyses,
along with surface dewpoints in the 70s. CI has already begun in
earnest, focused along sea breeze and outflow boundaries in our SE
and along a differential heating boundary on the W edge of the
Triangle area, with activity also partially supported by weak mid
level perturbations tracking through the region. Poor lapse rates
aloft have kept convection from being overly robust thus far, but
this should change quickly with continued heating and growing
buoyance with the breakup of this morning`s low deck. SBCAPE is
already at 2500-3500 J/kg over all but the Triad, with increasingly
fat CAPE over the SE where normalized CAPE is 0.15 and rising. We`ll
continue to see showers and storms fill in across the area, and with
decent effective bulk shear of 30-35 kts, a few wet microbursts
can`t be ruled out, although DCAPE is rather modest. Gently curved
hodographs shown by the RAP along with low LCLs supports a possible
quick weak tornado spinup as well through the afternoon in the
Coastal Plain, but again the poor mid level lapse rates will temper
updrafts somewhat and should limit the threat of any deep
mesocyclones. Certainly isolated locations could easily get 2-3" of
rain within convection clusters today, and while these totals should
be isolated enough to preclude a flood watch at this time, will
continue to monitor. Will have pops peaking at likely to categorical
over much of the area, with good chances NW, through early evening,
with a slow downturn in coverage and intensity thereafter with
waning insolation, but at least isolated showers and a storm or two
are expected to linger over the S and E areas through much of the
night. After highs in the 80s to near 90, expect lows tonight to
once again be in the 70s. -GIH

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
As of 356 AM Monday...

It appears that the QPF will be on the uptick again on Tuesday
afternoon and evening. The forecast PW of 2.25-2.50" (120-140% of
normal) will support the development of scattered to numerous
showers and thunderstorms Tuesday afternoon and into the evening.
The threat for locally heavy rain and flooding will continue to be
the main weather hazard. Shear is expected to remain weak. However,
models do suggest that heating/lapse rates could be a little more
robust than previous days. Thus, the chance for a few strong to
locally severe storms may increase.

Highs in the mid 80s north to lower 90s south. Lows 70-75.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 358 AM Monday...

A mid/upper level trough will remain over the Upper Great Lakes down
into the MS Valley on Wednesday, shifting east into into New England
by Friday. Moisture transport from the southwest will continue
across Central NC through the weekend  with PW values of 2.25 to 2.5
inches (about 150% above value). At the surface a  series of lows
will move across the OH valley. This along with the unstable
atmosphere in place will result in widespread showers and storms
(likely to categorical POPs) each day from Wednesday through Friday,
maximized in the afternoon and evening hours. Weak shear will limit
the severe threat but increase the flooding rain threat as training
storms could develop across the area. WPC has all of central NC in
Marginal Risk (level 1 of 4) for excessive rainfall on Wednesday,
Slight Risk (level 2 of 4) for excessive rainfall on Thursday, and
most of Central NC in a Marginal Risk (level 1 of 4) on Friday as
the heaviest rainfall shifts to the southeast. High temperatures
Wednesday through Friday will range from upper 80s to low 90s
Wednesday, and cooling down Thursday and Friday with highs in the
upper 70s to mid 80s.

Reduced rain chances over the weekend as a cold front sags south
(slowly) across the region. Best chances for showers and storms will
generally be in the southeast. However, each afternoon kept chance
PoPs in the forecast everywhere. Highs will depend largely on the
timing of the front and will vary from the low 80s north, to upper
80s south.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of 1215 PM Monday...

IFR to MVFR cigs persist at this hour over much of central NC, a
result of light surface flow and a deeply moist air mass. Even
across our SE half, where the low cigs from earlier were first to
break up, have seen a redevelopment of MVFR cigs. Similar to the
last couple of day, cigs are expected to slowly improve at central
NC terminals, with a good chance that all sites will be VFR by 19z.
Just isolated showers are noted across the area currently, but
scattered to numerous showers and storms are expected to develop by
early afternoon and persist into the evening, before diminishing
slowly overnight. TSRA will be most likely at RDU/FAY/RWI with a
slightly lesser coverage near INT/GSO. The storm threat will also
end earlier at INT/GSO, by 00z, with RDU/RWI/FAY seeing a risk of
storms until 07z. Brief local sub-VFR conditions along with
gusty/erratic winds are possible in and near any storms. Later
tonight, cigs will drop to MVFR or high-end IFR after 07z, with MVFR
to IFR conditions prevailing areawide 10z-15z (shorter-lived MVFR is
more likely in the E, while longer-duration IFR is more likely in
the W). Patchy MVFR fog is also possible. Cigs will slowly lift Tue
15z-18z but should largely remain MVFR through the end of this TAF
period. Surface winds will stay light and variable, mostly under 10
kts and mostly from the SW or WSW.

Looking beyond 18z Tue, cigs are expected improved to VFR around or
shortly after 18z. Another round of scattered to numerous showers
and storms could impact terminals Tue afternoon/evening. Overall,
expect a high chance for showers and storms, primarily each
afternoon through the evening, along with a risk for late-
night/early-morning sub-VFR clouds/fog, each day through Fri. Rain
chance may be lessening across the NW by Sat. -GIH

&&

.CLIMATE...

Record High Minimum Temperatures:

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...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Badgett
LONG TERM...CA
AVIATION...Hartfield
Climate...RAH