874
FXUS62 KRAH 121524
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1025 AM EST Wed Feb 12 2025

.SYNOPSIS...
A series of upper level disturbances will cross the region through
Thursday, as chilly surface high pressure noses into the area from
the northeast, bringing periods of rain. A surface cold front will
cross the region Thursday afternoon, bringing dry weather Thursday
night through Friday as high pressure builds in from the Midwest.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1025 AM Wednesday...

Just minor adjustments this morning. The latest surface analysis
shows the wedging high nosing into central NC from the N and the
wedge front off the S NC coast and wrapping back through extreme S
SC, central GA, NE AL, into E TN. A weak wave evident on UA analyses
passing over the region at 700-500 mb is bringing an area of more
steady, widespread precip now over the central and E portions of the
CWA. While the surface WBZ is hovering near 0C over our NW border,
observations support this falling as all rain in our area. This area
of steady rain will exit to the NE in the next few hours, leaving
behind just patchy light rain and drizzle into early afternoon, but
this relative lull will be short-lived, as an approaching area of
strong upper divergence over the lower Miss Valley into MS draws
more steady rain across mainly the NW third of the CWA starting mid
afternoon. Thick cloud cover within the CAD wedge along with weak
but steady CAA will allow for very little heating today, and still
expect temps through this afternoon to peak in the mid 30s N to low-
mid 40s SE. -GIH

Earlier discussion from 327 AM: A handful of locations across the
northern Piedmont are holding steady 31-32 F. This could allow for
some light icing on elevated surfaces in the advisory area. However,
most if not all roads should remain ice free. Once the sun rises,
even the light coating on elevated surfaces should end. Thus, plan
to let the Winter Weather advisory at 7 am.

Perturbed deep SW flow aloft will continue to funnel anomalous moist
PWATS of 1.4-1.7" (200-300% percent of normal)across the region.
While temporary buckling of the expansive SW to NE oriented precip
shield rain will occur at time, a broad regime of WAA and associated
isentropic lift atop a wedge of cool high pressure will support a
continuation of wet and cold conditions through the afternoon.
Expect a slow rise in temperatures throughout the day. Afternoon
highs ranging from mid 30s north to lower/mid 40s SE.

By late afternoon and into the evening and overnight hours, a
coastal warm front will start to retreat inland, into the coastal
plain counties/I-95 corridor. As it does so, models are in good
agreement in a short-lived northwestward shift of the precip shield,
generally west of US 1. As the precipitation briefly comes to and
end, dense fog will be apt to develop over the NC coastal plain,
Sandhills, and possibly eastern portions of the Piedmont counties.

Then between 06 to 12z, near-frontal convergence and lift spreading
into the area from the west will bring renewed rain/showers into the
area through daybreak. Models hint at some weak elevated instability
making into the SW Piedmont and western Sandhills around daybreak,
so some isolated thunder is possible.

Temperatures will rise area-wide overnight, with the greatest
warming occurring with the intruding warm sector over eastern NC.
Temperatures warming from mid 30s to near 40 NW Piedmont, while the
eastern Sandhills and southern coastal plain will warm from lower/mid
40s to mid/upper 50s and even lower 60s across the far SE zones.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 320 AM Wednesday...

* A band of showers and isolated thunder will bring the last of the
  rainfall for the work week.

* Periodic strong wind gusts possible initially ahead of the band of
  showers and then later behind a cold front Thursday night.

Thurs will be a transition day away from the persistent CAD and cold
rain over the previous couple days. The day will however begin still
locked in the CAD regime with the wedge boundary lifting into our
area. The 00z HREF suggests its 12z position edging into the eastern
Sandhills and central Coastal Plain. This boundary will separate two
very different airmasses with temperatures in the 30s to around 40
to its northwest to 50s to near 60s to its south and east Thurs
morning. Continued strong low-level WAA will likely overwhelm the
very shallow cold nose and lift the boundary northward as a warm
front through the morning hours. At the same time, a band of steady
rain and embedded showers, driven by strong low-level convergence
band and moisture transport ahead of a cold front, will already be
ongoing over the NC Piedmont and continue to shift eastward through
the early afternoon.

Ahead of this band of precipitation and south of the warm front,
diurnal heating may begin to mix down stronger winds just above the
surface and result in wind gusts of 25 to 35 kts before the passage
of the rain and pre-frontal trough. This will greatly depend on the
timing of the rain band as a slower passage would allow for the
boundary layer to deepen and these gusts to materialize, while a
quicker solution would keep the mixed layer very shallow and likely
not mix these winds to the surface. Additional gusts will be
possible in the CAA behind the cold frontal passage late Thurs into
early Fri with periodic gusts 15 to 25 kts.

Timing temperatures will likely be the most difficult part of the
forecast with the very tight temperatures gradient along the wedge
boundary in the east and the erosion of the CAD airmass in the west.
Between these various frontal passages through the afternoon
temperatures should reach into the mid/upper 50s (NW) to low/mid 70s
(SE). Continued CAA overnight will drive low temperatures into the
low 30s with some mid/upper 20s possible in the typical cool spots
of the Piedmont and northern Coastal Plains where briefly calm
conditions and radiational cooling may occur.

&&.

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 320 AM Wednesday...

* A brief period of dry weather and sunshine Friday ahead of our
  next system Saturday into Sunday.

A progressive but strong 1040mb Arctic high over the Ohio Valley Fri
morning will shift eastward over the Mid-Atlantic Fri evening and
slide off the NJ coast by Sat morning. A dynamic system diving into
the southern Plains Sat morning will combine with the surface high
slipping into the western Atlantic to strengthen low/mid-level WAA
and deep moisture return atop a hybrid CAD over the southern Mid-
Atlantic through the day Sat. Central NC appears to only be glanced
by the deeper synoptic forcing and results in mainly very light
accumulation during the day on Sat. Continued isentropic ascent atop
the CAD boundary will still produce very light rain and drizzle
through the early overnight hours. This regime is forecast to lift
into VA behind the warm frontal passage Sat night into early Sun.
Some light rain may continue to be possible across the Carolina
coast into the I-95 corridor overnight.

A surface low over the lower OH Valley early Sun morning will
continue to deepen as it shifts into the northern Mid-Atlantic and
Northeast Sun afternoon. Mid-level RH fields depict a fast moving
but narrow band of showers and perhaps some thunder traversing the
area on Sun. Predictability is low on any severe chances at this
time range given the uncertainties on the preceding environment
ahead of the frontal passage. Storm total rainfall ranges from
around 1" in the northwest Piedmont to around 0.5" in the southern
Coastal Plain. ECMWF EFI and EPS planer plots are highlighting a
potential for strong wind gusts with this system Sun into Sun night.
Reliable diagnostic tools for wind gusts are limited at this time
range, but a period of strong pre-frontal wind gusts and post cold
fropa appear possible with this dynamic system.

Drastic roller coaster temperatures continue for the weekend into
early next week as this system progresses across the eastern CONUS.
Below normal temps on Fri will transition to well above normal for
Sat and Sun behind the warm frontal passage. Cooler high pressure is
expected to build into the area late Sun into early Mon behind the
cold frontal passage with a return to below normal conditions into
early next week.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
As of 600 AM Wednesday...

TAF period:
Perturbed deep SW flow aloft will continue to funnel
anomalous moisture across the region. A broad regime of WAA and
associated isentropic lift atop a wedge of cool high pressure will
support a continuation of widespread IFR to LIFR restrictions in an
expansive SW to NE precip shield rain. The primary threat for
freezing rain has ended at KINT and KGSO, with all liquid rain
hereafter.

During the evening and overnight hours, a coastal warm front will
start to retreat inland into interior NC. As it does so, models are
in good agreement in shifting the precip shield northwestward,
generally west of US 1. As the precipitation comes to an end at
KFAY, KRWI, and possibly KRDU, dense fog will be apt to develop
within the developing warm sector. Additionally, a strong 50-60 kt
LLJ will overspread the area this evening and tonight, resulting
in LLWS at all TAF sites.

Outlook: A period of pre(SWLY) and post(NWLY) wind gusts are
possible ahead and behind a cold frontal passage and associated band
of showers advances east through the area between 12-18z Thursday.
Some isolated thunder is also possible Thursday, mainly at KFAY and
KRWI. After a brief period of dry, VFR conditions Friday, sub-VFR
restrictions and showers are expected to redevelop Saturday into
Sunday ahead of a stronger cold frontal passage.

&&

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

&&

$$

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