215
FXUS62 KRAH 031932
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
329 PM EDT Fri May 3 2024

.SYNOPSIS...
Sub-tropical high pressure will extend across the South Atlantic
states today, while a backdoor cold front will move through eastern
VA and northeastern NC. The front will settle southwestward and into
north-central NC tonight, where it will stall through Saturday
night, then weaken and move northward into VA on Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1145 AM Friday...

A mid/upr-level ridge centered near the srn Middle Atlantic coast
will remain so through tonight, while a mid-level trough and
embedded, weak MCVs now over the ern OH and TN Valleys will be
directed around the ridge and into the cntl Appalachians.

At the surface, a 1019-1020 mb sub-tropical high will remain
situated off the coast of the Carolinas. Meanwhile, a backdoor cold
front, now stretching from the mouth of the Chesapeake Bay nwwd to a
1014 mb frontal low over OH, will merge with a developing bay breeze
and move swwd to the vicinity of the Roanoke River between 22Z-00Z. A
separate, srn stream front extending from cntl TX enewd and across
the lwr MS and TN Valleys, to a 1013 mb frontal low over Middle/wrn
TN, then ewd across nrn GA and the Piedmont of the Carolinas, will
move little through the period.

With no airmass change from Thu and continued influence of ridging
aloft, today will be persistently, unseasonably warm, with
temperatures continuing at 10-15F above average - mid 80s to around
90. Showers and isolated storm will focus today along both fronts
noted above, including into the NC nrn Coastal Plain and far ne
Piedmont early this evening and also with diurnal heating along a
differential heating zone evident in late morning visible satellite
and surface observational data along the srn stream front from AGS
to HKY. The latter activity, should it indeed develop, would then be
steered in weak wswly steering flow and into the srn and wrn NC
Piedmont late this afternoon-evening.

Areas of persistence fog and low stratus will likely redevelop into
the srn-cntl Coastal Plain and ern Sandhills tonight, while a
separate area of post-frontal, very low stratus will develop behind
the backdoor front across the ne Piedmont and nrn Coastal Plain.
Temperatures tonight will remain unseasonably mild and mostly
persistent in the upr 50s to mid 60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 230 PM Friday...

Aloft, the sub-tropical ridge will stall along the eastern seaboard
through Sat night. A southern stream disturbance will move into the
Southeast US on Sat, then lift newd through the area as a sheared
out northern stream s/w moves through the OH Valley/Great Lakes Sat
night. The sub-tropical ridge will shift offshore and breakdown
Sun/Sun night as the disturbances move through the mid-Atlantic and
Northeast US. Another southern stream s/w will develop over the
southern Plains on Sun, then move eastward into the lower/mid-MS
Valley Sun night. At the surface, as high pressure sits over the New
England coast, the backdoor cold front is expected to stall over
nrn/nern NC through Sat and into Sat night then lift northward late
Sat night/Sun. The high should move eastward over the Atlantic as a
low moves through the Great Lakes and into the Northeast Sun/Sun
night.

Precipitation/Convection: Still fairly high confidence/chances for
showers and possible storms Sat and Sun. Best threat for storms will
be across the Piedmont, mainly along and south of the surface
boundary, where surface-based CAPE will be maximized. Bulk shear
still appears weak, and PWATs are expected to range from 1.4 to 1.8
inches. Do not expect the entire day to be a wash-out by any means,
and Sat could start dry for most, but there will be a chance for
showers across all of central NC, with greatest coverage from Sat
eve through Sun aft. Highest chances NW, lowest SE. Given the high
PWATs and scattered, somewhat disorganized mode of convection,
isolated locations could receive locally heavy rainfall, with any
potential for minor flooding issues largely limited to urban areas.

Temperatures: A bit tricky on Sat, as there is some bust potential
north of the front. Widespread overcast skies should somewhat limit
heating as well. For now expect highs to range from the mid 70s
along the NC/VA border to mid 80s SE. Sat night temps should be
continued mild, mainly in the low to mid 60s. On Sun, with the
retreat of the front northward, areas across the north may be a few
degrees higher than Sat, but given the expected showers/storms
through the day, temps may otherwise be limited. Highs in the upper
70s north to low 80s south.

&&

.LONG TERM /MONDAY THROUGH THURSDAY...
As of 329 PM Friday...

The extended forecast upper pattern will largely include mid-level
ridging over the eastern US. A stronger short-wave will move over
the area Monday into Tuesday increasing rain chances. After
relatively zonal flow Tuesday, mid-level ridging will then re-
amplify over central NC through the end of the extended. Another
potentially stronger trough may approach late in the period.

Monday/Tuesday: A potent mid-level short-wave and associated
vorticity max is forecast to move across the southern Appalachians
Monday afternoon. Mid-level height falls will maximize over us later
Monday afternoon/early evening coinciding with peak
heating/instability. At the sfc, a piedmont trough will develop
Monday afternoon which, in combination with forcing aloft, should
help to focus showers and storms across our area.  Bulk layer shear
will be much too weak to support severe storms, but given the
presence of anomalous PWAT (150 to 200 % of normal) any storm that
develops could produce brief heavy downpours and gusty winds. POPs
should decrease late Monday night/early Tuesday morning as flow
aloft turns a bit more nwly and the atmosphere stabilizes.  In
absence of upper forcing aloft, rain chances Tuesday afternoon will
largely rely on diurnal shower/storm development which should remain
mostly scattered.

Temperatures Monday will peak in the mid to upper 80s, increasing
into the upper 80s by Tuesday afternoon.

Wednesday/Thursday: The mid-level ridge will re-establish itself
Wednesday and Thursday as temperatures soar into the lower to mid
90s. The NBM is particularly stoked about 90 temps for highs these
days with >80% of it`s members reaching this threshold for much of
this area. The LREF (GEFS, GEPS, EPS) is a little less enthused on
Wednesday, but does suggest decently high probabilities on Thursday
(generally 40 to 60 % across the area).

Otherwise, anomalous moisture will remain in place
Wednesday/Thursday which should promote a continuation of low-chance
POPs each afternoon.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 235 PM Friday...

Isolated to widely scattered showers and storms will focus this
afternoon-evening along a differential heating zone and surface
trough over the Foothills and wrn Piedmont of NC (including at
INT/GSO) and also along a backdoor cold front that will reach the
Roanoke River vicinity (including near and just north of RWI) around
sunset. Areas of very low overcast and fog will likely redevelop
through sern NC, including to around FAY between 10-12Z, in a
persistence regime of humid, sly flow there. Meanwhile, a separate
area of post-frontal, low stratus in enely flow, will develop behind
the backdoor front and reach RWI and all Piedmont sites around the
same time (between 10-12Z). Ceilings in both regimes should then
lift through MVFR through midday Sat, during which time showers/
storms are apt to redevelop with diurnal heating. The greatest
concentration of that convection should be along the front, which
will likely become quasi-stationary between I-85 and US-64 on Sat.

Outlook: IFR-MVFR ceilings are likely to redevelop each night-
morning through Monday, as are scattered to locally numerous
showers/storms each afternoon-evening.

&&

.CLIMATE...

Record High Temperatures:

May 3:
KGSO: 92/1959
KRDU: 93/1959
KFAY: 95/1913

Record High Minimum Temperatures:

May 4:
KGSO: 65/2022
KRDU: 68/1938
KFAY: 68/1942

&&

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

&&

$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...KC
LONG TERM...Luchetti
AVIATION...MWS