033
FXUS62 KRAH 171855
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
255 PM EDT Fri May 17 2024

.SYNOPSIS...
An unsettled pattern is expected through the weekend before high
pressure builds in for the start of the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1100 AM Friday...

A shortwave over OK/TX will move east to the lower MS Valley through
tonight, as mid/upper ridging remains just off the southern Mid-
Atlantic coast, with central NC under the influence of WSW flow
aloft in between these two features. The latest surface analysis
shows a weak boundary/convergence axis stretching from the NW
Piedmont into the southern Coastal Plain, accompanied by a wind
shift from E/NE to W/SW. Meanwhile a quasi-stationary frontal zone
extends across the northern Gulf Coast, which is being overtaken by
an MCS across southern MS/AL/GA. This MCS will continue to move east
and off the coast by this evening, weakening as it does so. Weak
perturbations in the WSW flow aloft will help generate scattered
showers and maybe a few storms this afternoon and evening. Today`s
mid-level lapse rates look very unimpressive, which will limit
instability, as guidance shows MLCAPE in the 500-1000 J/kg range.
Furthermore, the MCS to our south may end up choking off our
moisture feed, and it is bringing widespread mid and high clouds
across the area which will continue through the day. Thus not
expecting any storms today to be widespread, and not concerned about
anything severe. POPs are slight to chance today, highest across the
north and west. As another perturbation aloft approaches and the MCS
to our south moves away, shower coverage may actually increase in
the evening and overnight hours, still highest in the north and west
where POPs are likely. However, with the nocturnal timing any
instability looks limited and elevated, and only carry a slight
chance of thunder overnight. Today`s forecast highs look on track,
still in the upper-70s to mid-80s. Lows tonight will be mild (in the
60s) with the overcast skies and precipitation.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 240 PM Friday...

Overall showers and thunderstorms are expected in all locations
tomorrow, although confidence is low in overall potential for severe
weather. Showers/storms should be ongoing across the northeast
around sunrise, then there should be a relative lull across the area
during the morning hours. By the afternoon, coverage of storms
should increase from north to south, with greatest coverage likely
to occur during the late afternoon. Showers will continue through
the evening, with rain possibilities dropping to chance after
midnight.

Confidence is low in where severe weather could occur because of the
uncertainty of today`s upstream MCSs moving into the region and how
those boundaries will affect development of storms tomorrow along
with moisture transport from the south. However, instability has the
potential to range between 1000 and 2000 J/kg along with 30-40 kt
effective bulk shear. The afternoon Day 2 update from SPC had
minimal changes in the convective risk from the overnight issuance,
with half a dozen southern counties still under a slight (level 2 of
5) risk and the rest of the forecast area under a marginal (level 1
of 5) risk. Damaging winds will be the primary threat for severe
weather, with large hail the secondary threat. In addition, the
entire forecast area is under a marginal (level 1 of 4) risk for
excessive rainfall.

Temperatures appear to be cool near the VA/NC border with highs in
the lower 70s with the rest of the area in the upper 70s and lower
80s. Overnight lows should range from the mid 50s to the lower 60s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 255 PM Friday...

Sunday and Monday: Aloft, the mid/upper s/w will be over the mid-
Atlantic and Carolinas early Sun, drifting slowly sewd through the
area through Sun night. By Mon morning, the trough should be
offshore, with the sub-tropical ridge building from the southern
plains to the Northeast US. Both the trough and the ridge will shift
slightly ewd through Mon night, with the ridge over the Appalachians
by 12Z Tue. At the surface, the surface low will be off the Carolina
coast, with a backdoor cold front through the area and cool high
pressure ridging into the area by early Sun. The ridge will
strengthen over the area Sun and generally remain in place through
Mon night, while the low sits/drifts slowly eastward offshore. There
is some continued forecast uncertainty, especially wrt temperatures
Sun and Mon. The model solutions have trended drier for Sun and Mon,
with Sun still potentially wet. However, chances for storms will be
limited to the far south or southeast. While Mon should be largely
dry, there is still the possibility for a brief period of lingering
light early.

Temperatures: Tricky, especially Sun as there is some bust potential
with the wedge airmass and possible light rain, but for now expect
highs ranging from mid/upper 60s NE to low/mid 70s SW. Lows Sun
night generally in the low to mid 50s. For Mon, some continued
uncertainty in highs, but for now expect low/mid 70s east to
mid/upper 70s west. Lows again in the low to mid 50s.

Tuesday onward: The ridge axis will generally remain over the area
through at least Wed night. The ridge will be suppressed sewd
Thu/Fri as a s/w tracks from the mid-MS Valley, enewd into the
northern mid-Atlantic/Northeast US. This wave may amplify the larger
scale trough over the Northeast and mid-Atlantic Thu night/Fri. The
next potential for showers/storms across the area will be with this
disturbance Thu/Thu night. Expect temperatures to moderate through
mid-week.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 155 PM Thursday...

VFR conditions will prevail across central NC through this
afternoon, with mid and high clouds overspreading the area. The one
exception is potential brief sub-VFR conditions with any scattered
showers and storms that develop. Scattered showers and maybe
isolated storms will persist in the evening and overnight hours,
especially across the northern and western Piedmont. Ceilings will
also begin lowering to MVFR after about 03z and IFR shortly after
that. A period of LIFR ceilings can`t be ruled out in the late
overnight and early morning hours, especially across the Piedmont.
Ceilings will slowly lift tomorrow morning, becoming MVFR from SW to
NE in the late morning and early afternoon hours.

Looking beyond 18Z Saturday: An unsettled weather pattern is
expected with period of showers and some thunderstorms over the
weekend. Coverage will likely be the greatest tonight into early
Saturday and again late Saturday afternoon and evening with a
lingering risk on Sunday. Areas of sub VFR conditions are likely
during this period. Mainly dry weather and mainly VFR conditions
are expected Monday into Wednesday.

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Danco
SHORT TERM...Green
LONG TERM...KC
AVIATION...Danco/Blaes