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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 161751
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
150 PM EDT Tue Apr 16 2024

.SYNOPSIS...
-- Changed Discussion --
A weak backdoor cold front stretching across the region today will
lift north as a warm front tonight through early Wednesday. A
weakening cold front will move across the region early Thursday,
follwed by a stronger front that will cross the area over the
weekend.
-- End Changed Discussion --

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1000 AM Tuesday...

No major changes to the forecast with this morning update. As of the
12Z surface analysis, the backdoor cold front has settled W-E
through central NC, with high pressure over the mid-Atlantic and
nely winds advecting slightly cooler, drier, more stable air into
the northern half of central NC. The 12Z upper air analyses show a
weak jetlet over the area, with 90 kts at H25 over GSO. H5 heights
have risen another 20m since 00Z. There was still a good bit of dry
air at H7, with a bit more moisture pooling ahead of the front at
H85, maximized along the NC/SC border.


Previous discussion (as of 325 AM Tuesday):

* A good deal of uncertainty with the coverage and location of
  showers and possible storms late this afternoon and evening.
* SPC has removed the marginal risk of severe storms.

The front across VA is expected to linger through the day, bisecting
the area from west to east. North of the front, a northeasterly flow
will transport cooler and more stable air into the area while south
of the front, it will be warmer and a bit more unstable. The upper
flow will become a bit more westerly today with a series of
disturbances forecast to move across the area late this afternoon
and evening. The combination of the upper air disturbances and the
front should result in a few showers and storms. NWP guidance has
struggled a bit with this pattern but the best signal is for some
showers and a few storms to develop across the western/southern
Piedmont late this afternoon and then push east across the southern
Piedmont during the evening and perhaps into the Sandhills before
dissipating. The HRRR/Nam Nest and other guidance are centering in
on the southern tier from east of KCLT to near KFAY as the region
with the best instability. The greatest convective coverage is
expected from about 22Z to 02Z but with the uncertainty have opted
to keep PoPs in the chance range. SPC has backed off the marginal
risk that was in place for today likely resulted from the limited
convective coverage and instability although fairly steep lapse
rates could still support a stronger wind gust or two.

With the cold front extending across the area from west to east,
expect a good spread in max temperatures today with cooler upper 70s
expected across the northern Coastal Plain, the lower 80s in the
Triad and Triangle to the upper 80s near the SC border. Lows tonight
should be moderated by a good deal of cloud cover and a light
southeast wind with lows mainly in the upper 50s to lower 60s. -Blaes

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 340 AM Tuesday...

A short wave ridge axis will move across the Carolinas and VA
early Wednesday morning with a west to southwest flow aloft
expected later Wednesday and Wednesday night. A weak short wave
trough will move east across central NC on Wednesday. At the
surface, the combination of surface high pressure across the
southwestern Atlantic and a decaying cold front moving across
the southern Appalachians will result in a southwesterly low
level flow across the area. Increasing moisture at various
levels will result in an good deal of cloud cover for much of
the period. While forcing for ascent is weak, NWP guidance
suggests there may be a few sprinkles on Wednesday morning with
perhaps a shower or storm possible across the eastern areas
during the afternoon or evening. Highs on Wednesday should range
mainly in the upper 70s to lower 80s although if the cloud
cover is a bit thicker or a little bit more precipitation
develops, high temperatures may not get out of the 70s. Lows on
Wednesday night will mainly range in the lower 60s. -Blaes

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 310 AM Tuesday...

Upper pattern through the extended: Weak mid-level ridging will move
over the southeast Thursday into Friday promoting nwly flow aloft
over central NC.  A series of short-wave perturbations will
periodically pass over central NC Friday through Sunday, followed by
a potentially more vigorous short-wave Monday into Tuesday.

Thursday:  A brief period of drying is expected as flow turns nwly
aloft on Thursday.  Downslope warming will promote another day of
above normal highs in the mid to upper 80s. Decent mixing will
promote wly gusts of up to 20 mph at times Thursday afternoon.

Friday through Sunday: Flow aloft will generally remain wly Friday
through Sunday. However, ensembles are hinting at a few passing
short-waves potentially moving over our area in this time period.
These features could trigger scattered showers and thunderstorms
Friday and Saturday afternoon/evening. Forcing for ascent does like
pretty muted as guidance maximizes mid-level height falls well to
our north. This may limit coverage both afternoons, but scattered
showers and storms appear plausible.

Flow aloft turns a bit more swly Sunday and Monday increasing low-
level moisture advection into the southeast. However, guidance is in
a bit of disagreement wrt to rain and thunderstorm chances in this
period. The GEFS/GFS shunt instability and heavier rain to our
south. Conversely, the Euro/EPS/GEPS are more convectively active
over central NC. For now, maintained high chance to low likely POPs
favoring our southern zones Sunday through Monday.

Temperatures Saturday through Monday will largely depend whether CAD
will set up or not (the raw 18Z GFS has highs in the upper 40s in
the Triad Monday afternoon). For now will favor a blend of cooler
and warmer solutions Sunday and Monday with highs in the mid 60s.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 150 PM Tuesday...

VFR conditions will generally prevail across central NC for the next
24 hours, with a couple of potential exceptions. A weak frontal
boundary currently stretches NW to SE across central NC, separating
ridges of high pressure to our northeast and centered off the
Southeast coast extending westward. This is resulting in a light
surface wind from the NE or ENE over northern terminals
(INT/GSO/RDU/RWI) and from the ESE across the south (FAY). Passage
of weak disturbances aloft from WNW to ESE is associated with patchy
mid clouds topped with a veil of high clouds, and this will continue
through Wed morning. We`ll also have sct clouds based at 3500-6000
ft AGL from time to time late this afternoon through tonight, and an
isolated shower or storm can`t be ruled out, mainly at INT/GSO/RDU
this evening, but these should be very brief and circumnavigable.
Late tonight, from 09z-13z, areas of MVFR stratus expected to form
in coastal sections tonight may drift westward to RWI/FAY with a
lower risk of reaching RDU, but confidence in this being a
prevailing conditions for more than an hour or two at these
locations is low. Surface winds will be mostly light through
tonight, then shift to be from the SSW and SW near 10 kts after 14z
Wed as the weak frontal boundary lifts back northward as a warm
front and fizzles out.

Looking beyond 18z Wed, VFR conditions are expected to dominate
through much of Fri, although isolated showers and storms are
possible very late Wed afternoon through Wed evening. We`ll have
another chance of showers/storms late Fri, then a risk of sub-VFR
cigs/vsbys in fog Fri night ahead of a cold front. Uncertainty grows
over the weekend with respect to timing of this cold front passage,
but an uptick in shower/storm chances and accompanying sub-VFR
conditions is expected over the weekend just ahead of and with the
front. -GIH
-- End Changed Discussion --

&&

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

&&

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

&&

$$

SYNOPSIS...Blaes/Hartfield
NEAR TERM...KC/Blaes
SHORT TERM...Blaes
LONG TERM...Luchetti
AVIATION...Hartfield