Area Forecast Discussion Issued by NWS Raleigh/Durham, NC
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 170040
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
840 PM EDT Sat Mar 16 2024
.SYNOPSIS...
-- Changed Discussion --
A weak frontal boundary tied to a surface low will lift northeast
overnight tonight. A cold front will cross the region late Sunday,
bringing cooler air for the beginning of next week, including a
frost and freeze potential Monday night.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 840 PM Saturday...
The evening surface analysis shows a stalled and ill-defined surface
frontal boundary over central SC, stretching southwest into central
GA and portions of AL. A pair of surface lows were also evident,
though weak, over western NC and eastern SC. Model guidance suggests
the two surface lows tracking ENE overnight, with associated low-
level WAA and moisture transport mainly along/east of US-1 and the
Coastal Plain. Dewpoints upstream over eastern SC are in the upper
50s to low 60s and guidance supports these advecting into our
eastern zones overnight into early Sun. Satellite imagery reveals
low stratus in the 800 to 1500 ft range tied to the low-level WAA
and moist advection concentrated in the lowest few kft. While we
cannot rule out some drizzle/sprinkles or light spotty rain along
and east-northeast of the Triangle, most areas will be dry with
little moisture above 4 kft. The best chance looks to be over the
northern Coastal Plain where the GFS shows some weak low-level
frontogenesis with the low moving NE. Most of the guidance suggests
the low stratus, but cannot rule out some patchy fog, especially
over the Coastal Plain from Goldsboro to Rocky Mount given
increasing dewpoints. Lows tonight will be well above normal upper
40s to 50 NW to low/mid 50s in the east.-- End Changed Discussion --
&&
.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
As of 200 PM Saturday...
Aloft, a broad trough, encompassing much of the northeast quadrant
of the CONUS, will amplify southward through the MS Valley on Sun,
while a closed low over the Desert Southwest remains cutoff from it.
While central NC will initially be under westerly flow, on the
southern periphery of the trough, as the trough amplifies, the flow
will become more southwesterly, advecting warm, moist air into the
eastern half of NC from the Gulf of Mexico. A disturbance will track
eastward through the Southeast, then northeast through the Carolinas
Sun/Sun night. At the surface, the initial front and trough will
shift offshore as another trough develops over central NC on Sun
ahead of a reinforcing cold front, both of which should move through
the area Sun night. Expect rain along the initial front as the
disturbances tracks through the Southeast US. There is still some
uncertainty with exactly how far north precipitation will reach, but
for now best chances are expected over the Sandhills and Coastal
Plain. As the disturbance moves away from the area Sun eve/night,
the reinforcing cold front will finally surge through the area, with
cool, dry air advecting into the area in its wake. Temperatures
could be tricky, but for now expect upper 60s NW to possibly mid 70s
SE. Lows expected to bottom out in the low 40s NW to low 50s SE.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 250 PM Saturday...
Aloft, a closed, cutoff low will sit over the Desert Southwest
through at least Tue. To the east, the trough will continue to
amplify over the MS Valley and swing eastward and through the East
Coast Mon/Mon night, while the parent sits over Quebec, with several
s/w lows moving counterclockwise around it. As the initial trough
shifts offshore, a couple of the northern stream shortwaves within
the trough will move southeast through the Great Lakes and OH Valley
Tue/Tue night. Meanwhile to the west, the closed, cutoff low over
the Desert Southwest will finally open up and begin ejecting
eastward Tue night/Wed. While the upper trough will amplify some
through the Northeast US, it should remain fairly broad over NC
Wed/Wed night. As the low moves eastward through the Plains and into
the MS Valley Wed night/Thu, it should begin pushing the northward
and away from central NC. Advection of Gulf moisture into the s/w
low will increase Thu night as it moves through the MS Valley. It
will then continue eastward through the Deep South and Southeast
Fri/Fri night, settling just off the Southeast US coast on Sat.
At the surface, the Arctic high diving south out of Canada will
settle over the southern Plains/lower MS Valley Mon night/Tue, then
become elongated W-E through the Deep South and Southeast through
mid-week. While the coldest air associated with the high may remain
well to the north and to the west of the mtns, sufficient cold air
should filter into central NC behind the cold front for Mon/Mon
night. It remains a bit unclear how much the airmass may modify on
Tue/Tue night, and while the surface flow should gradually become
more southerly, the cold air should linger into Tue/Tue night. A low
should swing through the Great Lakes, OH Valley and northern mid-
Atlantic Tue/Wed, with a Piedmont trough developing and
strengthening over NC Wed, then progressing southeastward and
offshore as a cold front moves through Wed night. Yet another Arctic
high will move ESE through central Canada and into the upper MS
Valley/Great Lakes Wed/Thu, however the models cannot agree on how
far south the coldest air will progress as the high continues
eastward through southern Canada, but there is the potential for a
late-season CAD to set up on Fri. The medium-range models both
suggest a low could develop invof FL Fri/Fri night, but there is a
great deal of uncertainty beyond that.
The forecast should largely remain dry through most of the work-
week, with chances for precipitation increasing Fri/Sat depending on
what happens with the low off the Southeast US coast. Temperatures
should be below normal Mon/Tue, near to slightly above normal
Wed/Thu, then dropping back below normal again Fri/Sat.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 815 PM Saturday...
VFR conditions will continue across the region through this evening.
An area of low stratus will then develop and move into the
Sandhills, NE Piedmont, and Coastal Plain (including FAY, RDU and
RWI) beginning after midnight. Areas around FAY will likely be
affected by it first before it moves north and east into the rest of
that area overnight. Ceilings at least as low as MVFR are likely,
and even some periods of IFR and LIFR are possible, with the best
chance at RWI. Some patchy mist/fog with associated MVFR or IFR
visibilities also can`t be ruled out. Farther NW including at INT
and GSO, conditions will stay VFR. The low stratus and fog will end
at RWI by mid-morning, and likely earlier than that around RDU and
FAY. VFR conditions will prevail everywhere for the rest of the day
with mid and high clouds moving in from west to east. An isolated
light shower can`t be ruled out in the SE (including FAY) during the
afternoon. Winds will switch to a westerly direction tomorrow and
possibly gust to 15-20 kts, especially at INT and GSO.
Looking beyond 00Z Monday: A period of light rain is possible in the
SE on Sunday night, particularly at FAY, but conditions should stay
VFR. Breezy W to NW winds will develop late Monday into Tuesday, but
winds have been trending lower, with only 20-25 kt gusts expected.
VFR conditions are expected through the period.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Kren
NEAR TERM...Kren
SHORT TERM...KCP
LONG TERM...KCP
AVIATION...Danco/JJT