626
FXUS62 KRAH 240707
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
305 AM EDT Fri May 24 2024

.SYNOPSIS...
A warm and humid air mass over our region, combined with the passage
of a series of upper level disturbances over the area, will produce
unsettled weather through Monday, with daily chances of showers and
storms. A drier air mass will arrive by the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 810 PM Thursday...

A series of convectively enhanced disturbances will traverse the
region tonight and again on Friday.

The first disturbance and associated convection tracked mainly
across northern portions of the Piedmont earlier this evening and in
the process of exiting the northern coastal plain counties. Areas
along and north of the 64 corridor have either been rain or out-flow
cooled from the earlier convection. Thus, the threat for severe
storms across the northern half of the forecast area looks to be
greatly diminished.

Trailing this lead vort, a secondary impulse is supporting an area
of showers and storms across the western Piedmont. The southern
portions of the Piedmont/south of 64, has yet to be worked over. So
could still a severe or two over the next hour or two before the BL
starts to cool from loss of heating.

Finally, a tertiary disturbance, the strongest of the bunch, is
starting to move into the southern Appalachians. The vort
disturbance is progged to cross the area between 06 to 15z Friday.
Further nocturnal stabilization should preclude any severe storms,
but will continue to support scattered to numerous showers, with
some embedded thunder overnight.

Lows tonight generally 65-70.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 305 AM Friday...

A shortwave trough, likely a remnant MCV from the current convective
complexes over SE OK into the Arklatex region, is expected to be
over NC early Sat (although it is worth noting that the
predictability of individual perturbations and convective initiation
within such a wavy flow that is so heavily influenced by
convectively-induced PV maxima and near-surface outflows is rather
low). Weak surface troughing will hold across our Piedmont. Low
level lapse rates should be fairly high with good mixing and warm
surface temps, and the HREF members show SBCAPE peaking Sat
afternoon at 1000-2000 J/kg with PW around 1.5", near the 90th
percentile. But the GFS/ECMWF have somewhat low mid level lapse
rates, and mid level flow is likely to be very weak, so the risk of
severe storms appears to be lower than previous forecasts suggested.
With high moisture through the column and high dewpoints in the
upper 60s to around 70, scattered to numerous storms are possible
with heating, with highest coverage across the Coastal Plain and E
Sandhills, E of the surface trough. The anticipated slow storm
motion could lead to some heavy rain rates and isolated minor
flooding threats. Expect dwindling pops overnight as the shortwave
trough shifts off the coast and our heights aloft begin to rebound.
Highs 84-90 and lows 64-70. -GIH

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 155 AM Friday...

Best rain chance in this stretch will be Memorial Day into the
night. A pattern change should bring a dry period for mid to late
week.

Starting Sun, with the shortwave trough expected to be shifting well
off the Mid Atlantic coast early, we`ll be under the influence of
mid level shortwave ridging building in from the W, ahead of a
potent northern stream low/trough over MT into the Midwest. While
the weak surface trough will hold in place through the NC Piedmont,
there will be little opportunity for low level moisture influx until
late in the day into Sun night, and even this is more focused to our
W. The warm and relatively stable mid levels and lull in mid level
flow along with the limited moisture transport into the area should
greatly limit rain chances, and will keep late day and evening pops
mainly in the far NW to account for any mountain convection spilling
toward our area. It`ll remain warm and humid for this time of year,
highs in the upper 80s-lower 90s and lows in the upper 60s/lower 70s.

Rain chances may increase late Sun night with an upturn in low level
moisture and greater PW spreading in ahead of a pronounced low to
mid level trough that will move in from the W, attending an
approaching surface cold front. Winds at all levels will strengthen,
including a low level pump from the Gulf that starts ramping up Sun
night. The improving kinematics and vorticity maxima moving through
the mean trough base across our area in tandem with this
increasingly deep moisture should prompt high rain chances. The
severe threat with any storms is tough to pin down, as an early
arrival of frontal showers and clouds will hold down SBCAPE,
although the incoming cooling aloft and rising low and mid level
lapse rates should still allow for a risk of a few strong storms.
Still warm and muggy with highs in the upper 80s-lower 90s. Lower
dewpoints should start to filter into the NW Mon night, so expect
slightly lower lows there, mid 60s with upper 60s to around 70
across the S and E.

Behind this front, as mid-upper level longwave troughing sets up
over E NOAM with low level CAA and drying through the column, we
should see largely dry weather Tue through Thu. Some deterministic
models do slow down the cold front such that a passing wave produces
convection chances across the S and E Tue, so will leave in a low
chance there. Otherwise, will have dry conditions through Thu with
temps running close to normal. -GIH

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 200 AM Friday...

A loosely organized band of showers and isolated storms stretching
from RWI to FAY will continue to shift east and out of the vicinity
of the eastern TAF sites over the next hour. Another round of
showers will be possible as they blossom over western NC and
transition eastward across central NC tonight towards daybreak.
Current timing in the 06z TAFs is based on the time-of-arrival tool
and tracking the leading edge of developing showers over western NC.
Coverage and timing of restrictions reaching terminals remains
fairly uncertain. Towards daybreak, IFR to MVFR cigs should develop
and be slow to lift through the morning hours at RDU and RWI and to
a lesser extent GSO, INT, and FAY.

Model guidance has considerably backed off on areas of fog over the
area, likely due to multi-layered cloudiness preventing much fog
formation; although patchy fog may still be possible where several
hours of clearing can occur. Showers and storms will be possible
near all terminals Fri afternoon/evening, but confidence in timing
is low at this time. Surface winds will remain less than 10 kts and
generally from a W to NW direction through the evening hours.

Looking ahead: Primarily diurnally driven showers/storms will be
possible at all terminals through Tue, with the best chances Fri,
Sat, and Mon.

&&

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

&&

$$
SYNOPSIS...Hartfield
NEAR TERM...CBL
SHORT TERM...Hartfield
LONG TERM...Hartfield
AVIATION...Swiggett/KC