Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 250054
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
853 PM EDT Tue May 24 2022

.SYNOPSIS...
Cold front will move offshore this evening and will stall off the NC
coast through Wednesday before returning inland Thursday. A slow
moving upper level low pressure system will approach from the west
late in the week, bringing a round of wet weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 850 PM Tuesday...

Surface cold front has exited the area and will move offshore during
the late evening, where it where it temporarily stall through
Wednesday night. This will allow the cool surface high and
associated NELY low-level that has been well established across
western NC to expand into all of central NC overnight. Along with
the advection of cooler and drier air into the area, the NELY low-
level flow will result in the lowering and re-development of stratus
across all of central NC. Lows in the mid 50s north to lower 60s SE.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 1141 AM Tuesday...

CAD regime will be in place to start the day Wednesday with cool
northeasterly winds at all sites, not to mention widespread stratus.
The lingering cold front that has been the focus for showers and
storms the past few days should clear (most of) the area by
Wednesday morning, although some guidance keeps it right along the
NC/SC border through the day. Regardless of that fact, northeast
winds and cloud cover will keep temperatures well below normal with
highs in the low 60s to the north. Across the Sandhills/southern
Coastal Plain the presence of the nearby front may allow
temperatures to warm into the upper 70s very late in the day as the
front start retreating northward but even these values would be
below normal for late May. The day should be mostly dry outside of
some light rain or drizzle in the northeast. However by Wednesday
night we should see the beginnings of WAA aloft with a few isolated
showers moving into the Western Piedmont after midnight.
Temperatures Wednesday night should bottom out in the upper 50s to
lower 60s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 156 PM Tuesday...

An anomalous mid-level ridge across the east coast will start to
shift offshore late Thursday as a strong upper-low over the deep
south drifts east towards the area. Mid-level height falls and
associated vorticity perturbations will couple with a surface cold
front to produce increasing precipitation chances late Thursday
through early Saturday morning.

On Thursday, residual CAD early will give way to east/southeasterly
turning surface flow in the afternoon. While the response may be
slow to develop, increasing southerly flow should increase moisture
transport across western portions of central NC late Thursday.
Aloft, weak mid-level height falls and a few vorticity lobes ahead
of the main upper low are forecast to traverse central NC late
Thursday into early Friday. These features may act to spin up
showers and perhaps a few thunderstorms with highest POPs and
coverage likely across the western Piedmont Thursday
afternoon/evening. Coverage and POPs then increase from west to east
overnight Thursday through Friday as heights aloft continue to fall
with the nearing upper low to the west. Given the turn to more
southerly flow, high temps Thursday will return to the upper
70s/lower 80s across the north, to mid to upper 80s across the
south.

Deterministic and ensemble guidance have consistently pointed to
Friday for the surface cold front to drift into central NC. However,
the timing of the front, and consequently the potential impacts,
remain somewhat uncertain at this forecast update. There has been a
general trend amongst the models to slow down the arrival of the
front to more-so the Friday afternoon/evening time frame, which will
inherently enhance the potential hazards with this system. If this
solution pans out, heavy rain rates and perhaps some flooding may be
possible Friday afternoon/evening given forecasted PWAT >1.75 in,
warm cloud depths >12,000 ft, 30-45 kts of front-parallel flow at
850 mb, and forecast sounding profiles featuring tall, skinny, CAPE
profiles ahead of the advancing front. Furthermore, both the
deterministic GFS and ECMWF produce decently healthy 0-6 km shear
(35-45 kts) and low-level SRH (100-150 units) Friday evening,
perhaps hinting at the potential for severe weather. Future forecast
shifts will have to monitor model trends as we approach later this
week, but the general consensus suggests a wet and unsettled Friday.
Strong CAA is not expected with this front, and thus highs on Friday
will climb into the upper 70s (NW) to mid 80s (SE).

There is a little bit of uncertainty in the upper-level pattern
Saturday through early next week, but the general trend suggests the
upper low will slowly move through the mid-Atlantic Saturday/Sunday
and pull off into the Atlantic by early next week. Ensembles then
quickly re-build a mid-level ridge across the deep south extending
north through the Midwest. The main upper-level forcing appears to
stay north of the area this weekend, however, ensemble guidance
still shows enough precipitation to warrant at least slight chance
POPs area-wide Saturday, tapering to just slight chance POPs across
the far east Sunday afternoon. Precipitation chances then diminish
Monday and Tuesday with increasing subsidence and dry air intrusion.
Daytime highs are expected to rebound into the lower to mid 80s (N)
to upper 80s (S) Sunday, with ensemble guidance hinting at a
possible return to the lower 90s by next Tuesday.

&&

.AVIATION /00Z THURSDAY THROUGH SUNDAY/...
As of 715 PM Tuesday...

Poor aviation conditions will dominate through at least Wed morning,
particularly at the northern terminals (INT/GSO/RDU/RWI). A front
pushed slowly south and east through central NC earlier today and
now extends across northern SC and eastern NC. As this front stalls
out to the south and southeast of central NC, low clouds and a cool
surface flow from the NE will continue to spread over most of
central NC, with only the far southeast sections perhaps escaping
the lowest clouds. IFR/LIFR cigs with mostly MVFR vsbys are expected
through tonight and much of Wed morning, before a slow rise to MVFR
(NW and far N) and low-end VFR (SE) from late morning through the
rest of the day. A little patchy drizzle is possible tonight until
around daybreak Wed, otherwise dry weather is expected over the next
24 hours, with a steady NE wind.

Looking beyond 00z Thu, a trend back to thick IFR clouds is expected
at INT/GSO starting mid evening Wed, with IFR/LIFR cigs and patchy
drizzle at those sites through Wed night. RDU should also trend to
IFR after midnight, with a lesser chance of drizzle, while RWI/FAY
are likely to drop to MVFR cigs overnight. All central NC sites
should trend to VFR by noon Thu as a southeast and south flow
overtakes the area ahead of an approaching storm system. This will
bring high rain/storm chances Thu evening through Fri evening. Drier
and mostly VFR conditions will follow for Sat/Sun. -GIH

&&

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

&&

$$
SYNOPSIS...CBL/Leins
NEAR TERM...CBL
SHORT TERM...Leins
LONG TERM...Luchetti
AVIATION...Hartfield


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