070
FXUS62 KRAH 191556
AFDRAH

Area Forecast Discussion
National Weather Service Raleigh NC
1056 AM EST Sun Jan 19 2025

.SYNOPSIS...
An area of low pressure and complex frontal zone will move northeast
across the area through the afternoon. Arctic high pressure will
build in this evening and tonight and bring bitter cold temperatures
into the region through the middle of next week.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 1010 AM Sunday...

This mornings update included extending the Dense Fog Advisory
through at least 11 am. A few areas are still seeing poor
visibilities and low stratus, and the DFA will most likely end at
11am. The rain is generally across the southeast, east of the US1
corridor for now and continuing to spread slowly north, a few light
areas of rain are developing across the NW Piedmont and expected to
increase in coverage through the day, but the rain will be light.
Forecast is generally on track for the rain to begin clearing out SW
to NE this afternoon and everyone should be dry by the evening
hours. Cold dry airmass will move in behind the rain bringing NW
winds of 10-15 mph with gusts 25 to 30  mph at times this afternoon
and evening. Lows tonight in the teens NW to mid/upper 20s SE.

As of 505 AM Sunday...
....Periods of rain showers through the afternoon...
...Arctic Air Arrives Tonight...

Embedded and rounding the base of the deep long wave trough that
encompasses the entire CONUS, a shortwave trough is forecast to
traverse the southern/central Appalachians today and then accelerate
across the northern Mid Atlantic this evening and tonight. As the
subtropical and polar jet streams converge and strengthen over the
region, a developing wave of low pressure over the Carolinas will
ride NE along a complex frontal zone that will move NE across the
eastern half of NC through the morning and early afternoon, just
ahead of the slow moving Arctic cold front that will pass through
the area during the late afternoon and evening.

A mixture of stratus and fog has developed across central NC, with
some areas of dense fog being observed. These lower visibility
restrictions(0.25-0.5 mile) over the Sandhills and coastal plain
should start improve as warm frontal rain showers, most extensive
along and east of US 1, spread NE through the area during the
morning and early afternoon hours.  This area of shallow convection
should move north into Va ~ 18z, followed by isolated to widely
scattered showers through 00z as the Arctic cold front moves east
through the area. The highest rainfall amounts are expected to range
from up to a quarter to half inch inch or more is over the eastern
Sandhills and southern Coastal Plain. Further north and west, a
tenth of an inch or less is expected.

The surface low and complex frontal zone will result in a sharp NW
to SE temp gradient across the area. Highs in the mid/upper 50s and
even some lower 60s in the warm sector, to lower/mid 40s on the cool
side of the lead frontal zone. Winds will increase and gusts will
develop behind the exiting lead sfc wave. Expect gusts of 20 to 30
mph at times , strongest across the south.

Strong cold air advection tonight should allow some gustiness of 15
to 20 mph to linger well into the overnight hours. Lows Monday
morning in upper teens NW to mid/upper 20s SE, with some wind chills
in the high single digits to teens(just above criteria for Cold
Weather Advisory).


&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 300 AM Sunday...

...First Day of Bitterly Cold Temperatures...

Under the influence of an expansive Arctic high pressure system that
covers much of the CONUS, highs will average 20 degrees below normal
with much of the Piedmont, and northern coastal plain counties
expected to stay just at or below freezing. Highs ranging from
mid/upper 20s NW to mid 30s SE with intermittent gustiness of 15 to
20 mph resulting in expected wind chills in the upper teens to 20s.

Pressure gradient relaxes enough that winds become light Monday
night. Skies will start out mostly clear, but models do show an
increase in jet cirrus clouds after midnight, especially over the
southern half of the forecast area. Lows in the lower to middle
teens, with some upper single digits possible in the colder outlying
areas.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 335 AM Sunday...

First, the high confidence portion of the extended forecast - the
cold temperatures. Highs on Tuesday will range from the mid 20s to
the mid 30s, lows Tuesday night will be in the teens, highs on
Wednesday will be in the 20s and low 30s, and lows will range from 6
to 16 Wednesday night. For many locations, Wednesday night will be
the coldest night since December 24, 2022. Luckily, winds will be
relatively light during this time period, so there will be little
additional contribution to wind chills. At some point an Extreme
Cold Advisory will be likely, a product which has officially
replaced Wind Chill Advisories.

Now, the lower confidence portion of the extended forecast - snow
Tuesday into Wednesday. The massive high pressure system that will
cover most of the United States will be hard to dislodge as low
pressure develops over the Gulf of Mexico, crosses Florida, and
emerges over the Atlantic Ocean. By Wednesday morning, all models
are showing a lobe of the high pressure at nearly 1040 mb over West
Virginia, and with such cold/dry air, it will be hard for
precipitation to make much inward progress from the coastline. This
will be an unusual storm in that models have consistently shown that
higher snowfall totals will occur along the coastline, where warmer
air would normally allow for a changeover to rain. However, the 00Z
models have suppressed higher liquid totals closer to the coast,
reducing precipitation amounts inland. There is still high
confidence that all precipitation locally will fall as snow, and did
not make much chance to the chances of precipitation with this
forecast - snow is still likely generally along and east of the US-1
corridor. The window for snow to fall has shrunk slightly, with the
chance of snow moving in from the south late Tuesday, peaking in the
late evening, and departing to the east by late Wednesday morning.

Similar to yesterday, model disagreements continue for the late week
storm between the GFS and the ECMWF. The GFS remains an earlier
solution that is quicker moving, while the ECMWF remains a later
solution that will linger across the region longer. The Euro has
trended closer to the GFS in keeping precipitation a bit closer to
the coast and not bringing precipitation quite as far inland.
Precipitation types are quite varied with this system, and rain,
snow, and freezing rain all remain possibilities with this system,
although the chance of precipitation remains relatively low. Models
are in agreement that after the low pressure moves off the coast,
high pressure will move over the Carolinas from the Plains on
Saturday. Temperatures should moderate somewhat during this period,
but still remain below normal.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
As of 600 AM Sunday...

A developing wave of low pressure over the Carolinas will ride NE
along a complex frontal zone that will move through the area through
the afternoon. A mixture of stratus and dense fog is producing IFR
to LIFR restrictions at all TAF sites. Rain/showers will begin to
overspread central and eastern NC as a warm front lifts north into
the area. This area of rain should move north into Va ~ 18z,
followed by isolated to widely scattered showers through 00z as the
Arctic cold front moves east through the area. The resultant strong
cold dry air advection will scatter out the sub-VFR restrictions
from SW to NE between 18Z-02z. Additionally, westerly and NWLY
gustiness of 20-25kts will develop. The gustiness could linger into
the overnight hours.

Outlook: VFR conditions are expected Monday and Tuesday. Forecast
uncertainty is high, however a potential winter storm system could
bring sub-VFR restrictions in the form of snow Tuesday afternoon
through early Wednesday.


&&

.CLIMATE...

Record Low Maximum Temperatures:

January 20:
KGSO: 29/1983
KRDU: 28/1970

January 21:
KFAY: 31/1983

January 22:
KGSO: 29/2014
KRDU: 27/1970

January 23:
KFAY: 30/1970


Record Low Minimum Temperatures:

January 23:
KRDU: 8/1977
KFAY: 9/1970

&&

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

&&

$$
SYNOPSIS...Swiggett/CBL
NEAR TERM...CBL/CA
SHORT TERM...CBL
LONG TERM...Green
AVIATION...CBL
CLIMATE...RAH