-- Discussion containing changed information from previous version are highlighted. --
531
FXUS62 KRAH 011035
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
635 AM EDT Wed May 1 2024

.SYNOPSIS...
An upper level trough will shift slowly eastward across the central
and eastern Carolinas through this afternoon. Deep high pressure
will build over the Carolinas and Southeast this evening through
Friday, resulting in very warm temperatures. A series of weak upper
level disturbances will move through the region Friday evening
through Sunday, bringing periods of unsettled weather.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
-- Changed Discussion --
As of 230 AM Wednesday...

Update at 530 AM: Forecast updated to account for cluster of
convection with lightning over our SE, within an area of steeper mid
level lapse rates and SBCAPE near 1000 J/kg with minimal CINH,
beneath the slowly departing mid level low. These should continue a
slow NE motion, exiting the forecast area in the next couple of
hours. -GIH

A bit of a forecast challenge early this morning, as most recent
model runs including CAMs did not capture the clusters of showers
which have moved over our central and E sections in the last several
hours, dropping nearly a tenth of an inch in Raleigh and trace to a
few hundredths of an inch in isolated spots in the Sandhills through
the Coastal Plain. The development and sustainment of these showers
has been due in part to a band of 1.25+" PW aligned with a max in
low level moisture transport and a SBCAPE gradient (albeit with
decent CINH) with over 500 J/kg from the Triangle to the S and E,
all just east of a distinct mid-upper low seen spinning in WV
imagery over north central SC. This low is within a weak shear
regime, such that DPVA is minimal, with no other noteworthy dynamic
forcing for ascent, so I would expect these showers to very slowly
dwindle as they push NE over the next several hours as residual
CAPE slowly declines.

Otherwise, as the mid-upper low (and its weak surface counterpart
trough) shifts slowly eastward, so too will the sufficient moisture
through the column to support convection with heating. Until this
time, though, as our eastern sections heat up with surface dewpoints
still in the 60s and PWs still over 1", we should see enough CAPE
develop for scattered showers and a few storms pop up this
afternoon, mainly E of I-95. Some sea breeze interaction is possible
as well. HREF mean soundings in the E Coastal Plain show 500-1000
J/kg SBCAPE this afternoon, although shear is rather poor, so expect
little more than the typical gusty winds in/near any showers or
storms. Locations along and W of Hwy 1 should stay mostly dry as the
mid-upper levels dry and stabilize. Lingering mid clouds in the E
through midday may temper heating and CAPE a bit, while west
sections should see quite a bit of sunshine today as heights rise
aloft. Expect highs of 80-86, 5-10 deg above normal, hottest in the
SW.

Skies should trend mostly clear tonight, although patchy fog is
possible across the E, given the light winds, low dewpoint
depression, and good radiational cooling. Lows in the upper 50s to
lower 60s. -GIH
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 300 AM Wednesday...

Dry and warmer weather is likely Thu with rising heights aloft as
mid level ridging builds strongly over the Carolinas from the SW and
PWs fall to generally under 1". Light onshore (SE) low level flow
develops over the E Carolinas, which should facilitate an inland sea
breeze push into our area, and this may result in some convective cu
in the afternoon from the Triangle to the S and E. Otherwise, skies
should be mostly sunny through sunset, with a trend to clear skies
Thu night. As thicknesses rise to 25-30 m above normal, expect highs
of 85-90, around 10 deg above normal. Lows in the upper 50s to lower
60s, perhaps mid 60s far SE. -GIH

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
As of 350 AM Wednesday...

Unsettled weather expected over the weekend into early next week,
but confidence in the timing of possible showers and storms, as well
as total rainfall amounts remains relatively low .

A strong ridge over the southeast US will slowly shift east and
offshore by Saturday, allowing weak height falls aloft and the
passage of a series of weak shortwaves in more moisture-favorable
west-southwest flow aloft.

At the surface high pressure over eastern Canada will extend through
New England and nudge a backdoor cold into northeastern North
Carolina by Saturday morning, while a surface low migrates through
the Ohio Valley and its trailing weak cold front advances east into
the Appalachians by Sunday.  The weak front may not actually make it
into NC, but the presence of disturbances aloft along with
precipitable water increasing to over 1.5 inches should result in
scattered to numerous showers and a moist and less capped warm
sector, augmented by diurnal heating and instability, and the timing
of the disturbances.  A limiting factor in the coverage of precip
may be the absence of greater larger scale forcing and increased
cover/reduced instability as highs are expected to drop back into
the upper 70s and lower 80s.

The best time for precip appears to be late Saturday through Sunday,
though the models appear to be trending at least slightly wetter for
Monday and Tuesday as well.  All-in-all, near normal rainfall of up
to one inch is possible across the area, but the pattern doesn`t
appear to favor much more than that on the whole.  After the brief
relative cool down, upper 80s look to return by midweek next week
-- End Changed Discussion --

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 635 AM Wednesday...

A few spots have seen IFR conditions this morning, mainly aross the
SW, but otherwise our primary terminals have largely avoided fog and
low stratus development so far this morning, despite high surface RH
and earlier showers that wetted the ground esp at RDU/RWI. We still
may see a little fog and low clouds for the next couple of hours
(and in fact GSO is reporting shallow fog in the vicinity). The
showers and a few embedded storms have pushed E of FAY, and only
very isolated light showers are expected at most through mid
morning, as the slow-moving mid level trough shifts gradually E of
the area. Overall, VFR conditions will be dominant from mid morning
on in the W, with clearing skies in the W terminals late in the day.
Mid clouds will linger for a longer time in the E terminals, and
scattered showers and storms will be possible this afternoon at
RWI/FAY, which could produce local brief sub-VFR conditions and wind
gusts. There is a chance for patchy to scattered sub-VFR clouds and
fog early Thu morning esp across the NE areas.

Looking beyond 12z Thu, apart from the possible daybreak
fog/stratus, VFR conditions will prevail through Fri. The chance for
sub-VFR conditions within scattered to numerous showers and storms
will increase starting Fri night, lasting through Sun, as a series
of disturbances passes over the region. Areas of early-morning fog
are also expected. -GIH
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Hartfield
NEAR TERM...Hartfield
SHORT TERM...Hartfield
LONG TERM...BLS
AVIATION...Hartfield