091
FXUS62 KRAH 192336
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
735 PM EDT Thu Sep 19 2024

.SYNOPSIS...
An upper level low over the eastern Carolinas will lift northeast
along the Mid Atlantic coast through Friday and then persist as an
upper level trough just off the East Coast through the weekend. An
upper level ridge of high pressure will move into the northern Gulf
States late in the weekend and then extend into the Southeast states
through early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 235 PM Thursday...

The latest surface analysis continues to show surface high
pressure centered over Quebec that extends southwest across the
eastern Great Lakes and into the southern Appalachians. A
frontal zone with weak areas of low pressure extends northeast
to southwest just off the East Coast. A light north to
northeasterly low level flow persists across the region in
rather moist air mass with PW values of 1.6 to 1.8 inches or
about 125% of normal. The airmass across the region is weakly to
moderately unstable with MLCAPE values of 500-1000 J/Kg,
greatest in the southeast. Further aloft, a persistent upper-
level low was centered across southeastern VA and northeast NC
with 500 mb temps of -10C and a cyclonic flow from the northwest
across central NC.

The forecast through tonight remains a little uncertain as a
moist and weakly to moderately unstable airmass across central
NC is triggered by various mid and upper level disturbances in
the cyclonic flow aloft. An area of showers and a few embedded
thunderstorms continues to shift south across the southern
Piedmont, Sandhills and southern Coastal Plain. This area
appears triggered by a disturbance in the mid levels as noted on
the 1.5 PVU surface. Another cluster or two of showers and
possibly storm`s will drop out of VA into northern and
northwestern NC late this afternoon and evening. The convection
has not been terribly deep but precipitation rates seem to over
perform modest radar reflectivity signatures. With a moist
airmass, the rain may be heavy at times and with saturated
soils, some localized flooding can`t be ruled out. Despite the
instability, the low and mid level flow is rather weak and the
CAPE is skinny so not too concerned about any severe storms.
CAMs suggest that the convective coverage will relax decrease
quickly during the evening hours with dry conditions overnight.
Another round of stratus and fog is expected late tonight with
perhaps a bit more fog than last night. Lows tonight should
range in the lower to mid 60s. -Blaes

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 105 PM Thursday...

Aloft, the trough off the mid-Atlantic coast will continue to shift
ewd over the Atlantic, allowing high pressure to ridge enewd into
the area. A lobe of vorticity in the upper levels will swing sewd
through central NC Fri morn/aft, while a trailing mid-level
disturbance follows Fri aft/eve. At the surface, a low will continue
to meander off the northern mid-Atlantic/New England Coast Fri/Fri
night, while high pressure ridges swd through central NC. Some lower
dewpoint air should push into the far northeast portions of central
NC as the high ridges in. While widespread convection is not
anticipated, if showers do develop, the best chance would be over
the western Piedmont during the morn/aft with the passage of the
vort max aloft, and over the northeast Piedmont/northern Coastal
Plain during the aft/eve, generally along the dewpoint gradient as
the high ridges swd. The NAM does have some MUCAPE in the 500-1000
J/Kg range Fri morn through the eve, thus an isolated storm or two
is still possible if/where convection occurs. Highs should generally
range from around 80 degrees NE to mid 80s south, with lows in the
upper 50s to mid 60s expected.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 325 PM Thursday...

Saturday morning, surface high pressure will be centered over
eastern Canada with a pressure ridge extending all the way to the
Gulf Coast. A weak front will move across the area Saturday night.
Am not terribly impressed by the depth of the moisture with the
front, but there are too many models, deterministic and ensembles,
to keep a dry forecast in that time period. Rainfall does not appear
to be substantial, but have gone ahead and added slight chance pops
across the northern half of the area. Sunday and Monday continue to
have a dry forecast as high pressure reestablishes itself, with just
the Triad being clipped on Tuesday with a slight chance of showers
in advance of the next front. Low pressure will move across the
Great Lakes during the middle of the week, and it currently appears
that the most likely timing for any showers or thunderstorms with
the upcoming cold front will be Wednesday night. Highs will be
slightly above normal for the weekend, then drop a few degrees below
normal for the weekdays. Lows will be near normal through the
extended period.
&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 735 PM Thursday...

VFR conditions will persist for the next several hours as most of
today`s convection has diminished. There are a few isolated VA
mountain showers/storms that may approach KINT/KGSO the next few
hours, but this activity should also wane with time.  Otherwise,
there continue`s to be a good signal for widespread fog potential
early Friday morning. Will maintain low visibilities at all sites
between ~08 to 13Z via dense fog.

Any lingering fog/stratus should lift by mid to late Friday morning.
Otherwise, convection chances should be fairly limited Friday
compared to recent days.

Outlook: Areas of overnight and early morning fog and perhaps low
stratus are expected on Friday and Saturday morning. A transient
system may bring a few showers or storms to the area on Saturday
night otherwise a return to more tranquil weather is expected for
Sunday through Tuesday. -Blaes

&&

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

&&

$$

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