Severe Thunderstorm Warning 174, NWS Raleigh, NC

Area Forecast Discussion
National Weather Service Raleigh NC
955 AM EST Sun Dec 29 2024

.SYNOPSIS...
Low pressure will deepen as it moves northeast through the Ohio
Valley and Great Lakes through tonight. A trailing cold front will
move east across our region tonight. Mild high pressure will move
over the Carolinas then push offshore Monday through Monday night.
Another low pressure area will track northeastward over the Great
Lakes Tuesday and Tuesday night, dragging another cold front through
our area. Colder and drier air will spread into the area Wednesday
through next weekend.

&&

.NEAR TERM /TODAY AND TONIGHT/...
As of 955 AM SUNDAY...

* Slight Risk for severe storms for most of central NC today *

Forecast is still pretty much on track, as we're expecting a strong
system to cross the region, manifesting in a QLCS with embedded
bowing segments producing strong straight line winds. Confidence is
high in strong kinematics through the troposphere over our area and
points south today, including both vigorous upper divergence and a
40-50 kt low level jet, both between 15z and 00z. The wind profile
will result in looping and fairly long hodographs generating SRH of
250-300 m2/s2, so isolated tornadoes embedded within the bowing line
segments remains possible. As the low levels begin to mix in earnest
with the steady WAA and modest heating (curbed by cloud cover),
these winds just aloft will mix to the surface, even outside of
convection, and we're already seeing this in the W Piedmont with 15-
28 kt gusts. The biggest question mark and possible impediment to
severe weather is the cloudiness and how much CAPE we'll be able to
achieve. At least some daytime heating combined with the influx of
higher dewpoints should help push SBCAPE to 250-500 J/kg this
afternoon, however this is based on recent CAM runs which are a bit
slower with the convective line as compared to reality. With the
strengthening winds just off the ground, we may be able to reach the
lower reaches of damaging wind threshold irrespective of CAPE,
though, so the severe risk persists, and we've just issued a SVR
watch for all but our NE to account for this. Still expect highs in
the 60s W and low-mid 70s E. -GIH

Earlier discussion from 405 AM: Aloft, a potent s/w over the mid-MS
Valley will lift nnewd through the OH Valley today, with its trough
becoming negatively tilted over the Carolinas and mid-Atlantic this
aft/eve. The trough should continue newd and out of the area tonight
as the s/w low moves into the Great Lakes. At the surface, the warm
front has progressed westward through the Triad as of 08Z, while the
primary low was located near the Bootheel of MO. The low should
deepen as it lifts nnewd through the OH Valley today and with high
pressure situated between the NC coast and Bermuda, the pressure
gradient will increase significantly over central NC. The cold front
should move into the area from the west after 00Z Mon, and should
largely be through the area by 12Z Mon.

Temperatures: With all of central NC now in the warm sector, but
with extensive cloud cover expected to persist, highs should top out
in the mid 60s NW to low/mid 70s SE. Lows Sun night will depend on
fropa timing, but for now expect mid 40s west to low/mid 50s east.

Convection: The 925mb LLJ will peak around 50 kts, while the 850mb
jet should peak around 65 kts. PWATs are expected to be in the 1.3
to 1.5 inch range. The trough and front should provide forcing for
ascent, and the vertical shear is strong. The big question remains,
how much, if any, instability will be realized. The model guidance
varies wrt available instability, ranging from 100 J/kg to around
800 J/Kg of SBCAPE, with 1-Km bulk shear values of 30-40 kts. Expect
the greatest instability over the south and east. Models continue to
show a line of showers/storms progressing through central NC between
10A and 8 PM, however there may be a secondary line of showers and
possible storms with the cold front as it moves through between 6 PM
and midnight. Greatest severe threats still appears to be with the
initial line, with the primary threat expected to be damaging winds.
However, an isolated tornado or two will also be possible. With the
potent LLJ, any downward momentum transfer along and ahead of the
convection could produce wind gusts of 30 to 40 mph. Latest rainfall
forecast from the WPC ranges from roughly half an inch to an inch.

&&

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

With the cold front moving off shore by Monday morning, high
pressure will build into the region with fair weather. A few clouds
in the morning will give way to sunshine in the afternoon.
Temperatures will be above average with highs in the low 60s north
to mid 60s south. Light to calm winds overnight with temperatures in
the low to mid 40s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 300 AM Sunday...

As the next low pressure system moves across the Ohio Valley and
into the northern Mid-Atlantic, isolated to scattered showers will
be possible New Year’s Eve Day. The models have been trending the
center of the low a little more north with each run, and with that,
our southern counties have been trending drier. No need to cancel
plans quiet yet, as much of the precipitation is expected to move
out of the area and to the north around midnight. However, there
could be a few lingering light isolated showers across the northern
Piedmont until just after midnight. Stay tuned for when more Hi-Res
models come into the time frame for greater PoP confidence. For now,
have the best chance Triangle north, in the afternoon and early
evening hours. Overall, temperatures will be above average with
highs in the upper 50s/low 60s north to mid 60s/low 70s south.
Temperatures at midnight on NYE will range from upper 40s NW to low
50s SE.

After the front passes the region, expect winds to pick up Wednesday
afternoon with NW flow bringing in cooler and drier air. Gusts up to
25 mph are possible in the afternoon especially across the northern
Piedmont and Coastal Plain. As high pressure builds in from the
west, NW flow continues through the weekend with below average
temperatures Thursday through Sunday. Highs will be generally in the
40s, with a few areas in the south around 50 degrees. Overnight lows
will be chilly with temps each night in the mid/upper 20s and maybe
a few warmer spots in the low 30s.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
As of 655 AM Sunday...

24 hour TAF period: A line of showers and storms will move through
central NC late this morning/aft, with another area of showers along
the front late aft/eve. Additionally. strong southerly winds, with
gusts of 25-35 kts, are expected today. Cannot rule out some gusts
around 40 kts with storms. Winds should increase after sunrise this
morning, persist through the aft/eve, and decrease behind the front
late this eve/tonight. Aviation conditions should improve to VFR in
the wake of the front tonight, with winds becoming more swly and
decreasing to around 6-10 kts.

At KINT/KGSO, IFR/LIFR cigs should prevail through the day, with
vsbys possibly dropping to MVFR/IFR with the showers/storms. There
could also be lingering LLWS this morning.

At KRDU and KFAY, with VFR conditions should prevail until the
showers/storms move in late morn/early aft, when MVFR/IFR conditions
are expected. Cigs may stay sub-VFR until the front moves through
this eve. There could be a period of LLWS at KRDU this morning.

At KRWI, VFR conditions are expected until the showers and storms
this aft/eve, at which point they should drop to at least MVFR, if
not IFR, and remain there until the front moves through tonight.

Outlook: A weak, fast moving frontal system will favor a chance of a
few showers/storms and brief restrictions again Tue/Tue night.
Otherwise, VFR conditions should prevail.

&&

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

&&

SYNOPSIS...Hartfield
NEAR TERM...Hartfield/KC
SHORT TERM...CA
LONG TERM...CA
AVIATION...KC

Hazardous Weather Outlook...UPDATED
National Weather Service Raleigh NC
949 AM EST Sun Dec 29 2024

NCZ021>025-038>042-073>078-083>086-088-089-301130-
Forsyth-Guilford-Alamance-Orange-Durham-Davidson-Randolph-Chatham-
Wake-Johnston-Stanly-Montgomery-Moore-Lee-Harnett-Wayne-Anson-
Richmond-Scotland-Hoke-Cumberland-Sampson-
949 AM EST Sun Dec 29 2024

...SEVERE THUNDERSTORM WATCH 726 IN EFFECT UNTIL 5 PM EST THIS
AFTERNOON...

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Today and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

Even outside of any storms, wind gusts between 30 and 45 mph will be
possible through this afternoon.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.

NCZ007>011-026>028-043-301130-
Person-Granville-Vance-Warren-Halifax-Franklin-Nash-Edgecombe-Wilson-
949 AM EST Sun Dec 29 2024

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Today and tonight.

Wind gusts between 30 and 45 mph will be possible through this
afternoon.

Additionally, a band of showers and isolated storms, with strong to
locally damaging wind gusts and a risk of an isolated tornado, will
move east across central NC between 10 AM and 8 PM.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.