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314
FXUS62 KRAH 221118
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
620 AM EST Wed Jan 22 2020

.SYNOPSIS...
High pressure will extend through central North Carolina from the
north and northeast through Thursday. A strong, slow moving storm
system will approach from the west late Thursday, then cross the
region Thursday night through Saturday morning. High pressure will
build in from the southwest late Saturday through Sunday.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 220 AM Wednesday...

Another quiet and cool day is likely, although it won`t be as chilly
as yesterday given the modification of the surface ridge extending
in from the N. The strong mid level low which dove over the
Southeast states yesterday now sits over the NE FL coast and is
projected to steadily fill as it tracks SE then E out over the
Atlantic. Amplified shortwave ridging rearward of this low will
build overhead from the W today, ensuring a continued dry and
subsiding column within below normal PW. Thicknesses will have
rebounded today from yesterday`s readings with the air mass
modification and reduced CAA, and while they`re still projected to
be 20-25 m below normal, the plentiful sunshine should help offset
these readings, supporting highs in the mid 40s to around 50, 5-8
degrees F below normal. The column will remain dry and stable
tonight, but high clouds will spread in from the west overnight
ahead of the incoming amplifying/phasing mid level shortwave trough
moving through the Great Plains. There are also signs that we could
see some low cloudiness working into the eastern Coastal Plain and
eastern Sandhills late tonight, as the low level flow at 1000-2500
AGL / 280-285K takes on an easterly component and draws low level
Atlantic moisture into the area within the stable surface-based
depth. Confidence in this is not high, though, as not all models
agree on this occurrence, so will keep just partly cloudy skies at
most in the extreme E and SE CWA late tonight. Expect temps to be a
few degrees higher than this morning`s temps, especially in the E
where dewpoints will be fastest to recover. Lows in the mid-upper
20s with some lower 20s in some rural Piedmont locations. -GIH

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 245 AM Wednesday...

The mid level trough will continue to amplify as it heads E and
closes off a low over the Mid Miss Valley by daybreak Fri. Preceding
high clouds spreading into NC will thicken and lower into the mid
levels, while in the lower levels, as the ridge heads further out
over the N Atlantic and weakens, the increasing and deepening E and
SE flow will draw greater moisture and clouds into central NC,
especially Thu evening/night. The deepest forcing for ascent with
the approaching trough will hold to our W through Thu night, with
the greatest mid level height falls and upper divergence holding
back over the Mid South, but the increasing PW to above normal
values and a shot of weak DPVA swinging out of the mean trough
supports bringing in slight chance pops in the far W CWA overnight.
Expect highs from the upper 40s to lower 50s Thu, with the
rebounding thicknesses balancing the increased cloud cover. Lows in
the 30s. -GIH

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 330 AM Wednesday...

An upper level low located over the Mid MS valley Friday morning is
forecast to track east, along the Mason-Dixon Line, and is progged
to reach the Mid-Atlantic Coast by Saturday night. As the associated
sfc low follows a similar track, models are in good agreement that
a secondary, triple point low will develop INVOF of the western
Carolinas Friday afternoon and will move north through the area
Friday evening, before reaching the DELMARVA coast by daybreak
Saturday.

Strengthening isentropic lift and overrunning will lead to
increasing rain chances across the western Piedmont Friday morning
and then into the central Piedmont and the Sandhills by the
afternoon, with the early onset of precip across NC Piedmont helping
to set the stage for a strong CAD event on Friday. The strongest
forcing and heaviest rain arrives during the late afternoon and
evening as the occluded front and triple point low move north
through the area. Models indicate that the true mT air will remain
off the SE Coast( dewpoint recovery limited to the 50s across
interior NC). This will set up a classic high shear/low CAPE
environment, with very weak surface based instability of only MLCAPE
of 100 to 200 J/KG expected to preclude a threat of severe storms
across the area at this time.  The front and forcing looks to exit
north and east of the area between 06 to 09z Saturday, ending rain
chances SW to NE across the area. Rainfall amounts are expected to
range from 0.25 to 0.50" across the eastern half of the forecast
area, to 0.50 to 1.0" across western portions.

As previously mentioned, a strong CAD across the NC Piedmont on
Friday will result in a sharp NW to SE temperature gradient across
the area; highs ranging from lower 40s NW Piedmont to lower 60s
across the coastal plain zones. Partial clearing and CAA in the wake
of the cold front late Friday night will drive overnight lows; lows
ranging from mid 30s NW to mid 40s east.

Upper troughiness will persist across the area Saturday through
early next week, resulting in some periodic cloudiness, but
generally dry conditions. A modified cP parent high will build
slowly east, resulting in seasonable temps through the period.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
As of 620 AM Wednesday...

High confidence in continued VFR conditions well into tonight. High
pressure continues to extend over central NC from the NNE today into
tonight, with dry air at multiple levels and ridging aloft keeping
clouds at bay, although we may start to see high clouds moving in
from the west after midnight tonight, thickening as they spread E
and lowering into the mid levels toward morning. In addition, patchy
low level moisture streaming inland from low pressure off the
Southeast coast may bring a few MVFR clouds into the SE Coastal
Plain including FAY toward daybreak, but confidence in this is not
high. Winds will hold mostly under 10 kts from the NNE or NE.

Looking beyond 12z Thu, the storm system moving in from the W/SW
will bring increasing chances for sub-VFR conditions starting Thu
night, with rain chances peaking Fri afternoon/Fri night, highest at
Triad terminals. Low cigs may linger into Sat morning, but otherwise
fair skies and VFR conditions are expected Sat/Sun. -GIH

&&

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

&&

$$

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