989
FXUS62 KRAH 061135
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
635 AM EST Fri Dec 6 2024

.SYNOPSIS...
Cold Arctic high pressure will build into the region today and
persist through Saturday before moving offshore on Sunday.  A
frontal system will approach the area from the west late Sunday and
move across the region on Tuesday and Wednesday.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 300 AM Friday...

* Unseasonably cold across central NC with wind chills in the teens
  to low 20s this morning and early Saturday morning.

Water vapor satellite imagery shows an expansive longwave trough
positioned over the eastern CONUS and extending back into the Mid-MS
Valley. A compact shortwave rotating through NW flow over IA and IL
this morning will pivot across central NC through the late morning
into the early afternoon. The preceding thermo-profile will be
considerably dry and outside of some orographic cirrus into VA, the
shortwave is expected to pass by without much affect on the sensible
weather.

The newly deposited Arctic airmass will lead to an unseasonably cold
day with temperatures around sunrise in the upper teens to low 20s.
Light northerly winds and a brief period of increased gusts 15 to 20
mph after sunrise will result in apparent temperature values (AKA
wind chills) in the teens in most locations. Through the afternoon,
highs are only expected to reach into the upper 30s to low 40s. Some
mid 40s will be possible closer to the NC/SC border, but even these
temperatures are 15 to 20 degrees below normal for early December.

A relaxing pressure gradient overnight, clear skies, and dew points
in the single digits, will result in a favorable pattern for
radiational cooling. This will support temperatures dropping into
the mid teens to low 20s by early Sat morning (10 to 20 degrees
below normal).

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 310 AM Friday...

* The airmass moderates over the weekend with highs 5 to 10 degrees
  below average on Saturday warming to 2 to 8 degrees above average
  on Sunday.

Arctic high pressure centered across AL/GA/SC on Saturday morning
shifts southeast and moves off the GA/FL coast early Sunday morning.
Further aloft, the northwest flow becomes more zonal as a closed low
in the Four Corners region lifts into the central Plains on Sunday
and heights rise across the Carolinas with flat ridging developing
across the Deep South. After a chilly morning Saturday, sunshine
will mix with a few high clouds and highs will range in the mid 40s
near the VA border counties and northeastern areas to around 50 in
the Sandhills and near the SC border. Another night of good
radiational conditions will result in a strong surface inversion and
lows in the 20s on Sunday morning. High clouds will increase on
Sunday as cirrus clouds spill across the mid/upper level ridge to
our south. Highs on Sunday will warm into the upper 50s to lower
60s. -Blaes

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 335 AM Friday...

* An active weather pattern sets up for the upcoming work week with
  temperatures warming to well above normal through Wednesday.
* A weakening system will bring a chance of mainly light rain on
  Sunday night into Monday with a bit of a lull late Monday into
  Tuesday.
* A stronger system arrives for late Tuesday and Wednesday with more
  widespread and significant rain expected.

A closed low across the Desert Southwest region on Saturday will
open up across the MO and western TN Valley on Sunday night and lift
into the mid Atlantic on Monday night. This system will bring an
increase in moisture and scattered showers to central NC beginning
after midnight Monday morning through Monday afternoon. The best
rain chances will be across western and northwestern location with
rainfall amounts ranging from around 0.25 inches in the Triad/Yadkin
Valley to less than a tenth of an inch across the Coastal Plain.
Highs on Monday will range in the upper 50s to lower 60s.

A pair of northern stream short wave troughs will dive into the
Plains states on Tuesday and carve out a high amplitude trough that
moves into the western Great Lakes and western TN Valley early
Wednesday before shifting east across the OH Valley across across
the mid-Atlantic by Thursday morning. The upper trough may become
negatively tilted across the TN valley late Wednesday with a very
strong southwesterly flow spreading across the Carolinas. Deep layer
moisture also increases with precipitable water values increasing to
more than 1.5 inches late Tuesday into Wednesday which is 250-275%
of normal. With the strong forcing for ascent and plentiful
moisture, PoPs have been raised into the categorical range for
Tuesday night into Wednesday. Have also introduced a slight chance
of thunderstorms across the Coastal Plain and increased wind gusts
ahead of the eastward advancing front. Highs on Wednesday will range
from the upper 50s in the Triad to the mid 60s across the Coastal
Plain which is about 5 to 10 degrees above average. The rain should
diminish from west to east on Wednesday night as colder air advances
east and chases the departing precipitation. Rain totals for Tuesday
and Wednesday should range between 1 and 2 inches.

Behind the front a much colder airmass spreads into the region for
Thursday. Highs should range in the mid 40s to around 50 with
mainly clear skies. -Blaes

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 620 AM Friday...

Cold high pressure shifting into the area will keep conditions VFR
with clear skies through the TAF period. Brief gusty winds out of
the NW this morning of 15 to 20 kts will be possible at all TAF
sites for a few hours as 20 to 30 kts winds just off the surface
translate to the surface. Gusts will relax through early afternoon
with mostly calm surface winds overnight.

Outlook: VFR conditions should prevail through Sun. Multiple waves
of rain, sub-VFR conditions, and LLWS are possible Mon morning into
early Tues. A stronger system is likely late Tues into Wed becoming
more convective in nature; bringing a threat for sub-VFR conditions
and adverse aviation conditions such as LLWS, wind shift in the form
of a cold frontal passage, and slight chance for thunder (15 to 20%
chance).

&&

.CLIMATE...
Record Low Maximum Temperatures:

December 6:
KGSO: 34/1904
KRDU: 38/2010
KFAY: 39/2010


Record Low Temperatures:

December 6:
KGSO: 16/1992
KRDU: 19/1992
KFAY: 17/1945

December 7:
KFAY: 17/1954

&&

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

&&

$$

SYNOPSIS...Blaes
NEAR TERM...Swiggett
SHORT TERM...Blaes
LONG TERM...Blaes
AVIATION...Swiggett
CLIMATE...RAH