NWS Newport/Morehead City, NC wrote its last area forecast discussion before the first event at Jan 9, 1:16 PM EST, 3 hours 9 minutes earlier.
Area forecast discussion, Jan 9, 1:16 PM EST, 3 hours 9 minutes before
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
116 PM EST Tue Jan 9 2024
.SYNOPSIS...
A powerful low pressure system will move up the Eastern
Seaboard today and bring a very strong cold front through
Eastern NC as well as a bevy of impacts. Behind this system high
pressure will build back into the area through Thursday.
Another strong low pressure system will then affect the region
Friday and into this weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 1245 PM Tuesday...
A 996mb surface low was analyzed over the upstate of SC, with a
synoptic warm front extending northeast into central NC, then on
east along the VA/NC state line. An effective warm front (separating
mid to upper 60s dewpoints from 50s dewpoints) stretches from
central GA northeast to near Columbia, SC, and then on east into
coastal SC. A QLCS stretches from Charlotte, NC south through
southern GA. Reports of wind damage have come in all along the line
from SC to Florida thus far today, including some measured 70-90 mph
wind gusts. Over ENC, increasing WAA has led to the development of
widespread showers and isolated thunderstorms, especially along/west
of HWY 17. Some of these showers are mixing down some higher gusts.
To the south of ENC, recent regional radar imagery shows scattered
showers/shallow convection attempting to develop off the coast of
SC. No lightning has been noted with these yet, but they are
developing well within the effective warm sector, and the evolution
of these will be closely monitored through the afternoon as they
work up the coast.
In the near-term, then, ENC still looks to stay stable, with the
main focus being the increasing gradient winds and occasionally
stronger gusts associated with the heavier showers. With time,
though, the effective warm front is forecast to continue to lift
north, reaching SW ENC by late this afternoon. Some thinning of the
clouds noted on satellite beneath the widespread cirrus, plus
dewpoints rising into the low-mid 60s should support an area of
MLCAPE as high as 500j/kg developing along and south of the
advancing warm front. I still expect the greatest tornado threat to
be focused along/south of that boundary, as that is where the
greatest risk of SFC-based convection will reside. The low-level
shear/helicity with this system cannot be stressed enough, as on the
worst-case scenario, it opens the door to a risk of more significant
severe weather (70+ mph wind gusts and possibly even a strong
tornado). However, it also cannot be stressed enough how important
the mesoscale features mentioned above are to the severe weather
risk. Stay tuned for updates on this potential. Otherwise, given
such strong winds aloft, even shallow convection should be able to
mix down some 50-70 mph gusts at times, and this risk generally
applies to much of ENC, but especially the western 2/3rds of our
area.
Regarding gradient winds, we continue to slowly warm, with deepening
mixing supporting 30-50 mph, non-convective gusts. These gusts will
continue to increase, as will the risk of wind damage.
SPECIFIC HAZARD INFORMATION
1) Winds
- Peak Impact Period: this afternoon to around midnight
High winds will be the most significant hazard to the area, due
to the strength of the deepening surface low and its associated
low level jet (LLJ). The winds within the LLJ are forecast to
be unusually strong for this time of year, and possibly exceed
the observational records for winter in this part of the
country. Surface winds will steadily ramp up through the day,
and occasionally tap into the strong winds just above the
surface when mixing is enhanced by showers, thunderstorms, or
any breaks of sun. The areas most likely to see the strongest
winds are along and just inland of the coast (generally east of
HWY 17) and High Wind Warnings have been issued here. In these
areas, wind gusts could reach 60-70 mph. Of greatest concern are
areas across the Outer Banks and Downeast Carteret, where near
Hurricane Force wind gusts of 70-80 mph are possible this
evening as the LLJ reaches maximum strength. Further inland,
frequent gusts of 45-55 mph are expected, and a Wind Advisory is
in effect there. These winds will lead to an increased risk of
coastal flooding and ocean overwash concerns, see the
TIDES/COASTAL FLOOD section for details.
2) Severe Thunderstorms
- Peak Impact Period: this afternoon to around midnight
Steady low-level moistening will occur across the area as the warm
front lifts north through the area this morning, with dewpoints
rising through the 50s and eventually low 60s by this afternoon.
Guidance continues to indicate a plume of modest instability
(250-750 J/kg MLCAPE) will nose into ENC late this afternoon.
This will support a narrow, but strongly-forced QLCS or squall
line that will race east across the Carolinas late this
afternoon through the evening hours with an enhanced risk of
transporting those strong LLJ winds to the surface. One
potential limiting factor is that there will be a narrow warm
nose aloft above a coolish boundary layer. While not overly
strong, this will setup an inversion that may prevent those
strongest LLJ winds from mixing down. It should be noted that
where the warm nose can be overcome, the potential exists for
peak convective gusts to exceed 70 and potentially 80 mph.
The damaging wind potential is by far the greatest risk with
this event. However, it should be noted that there is also a
conditional tornado risk given the exceptionally strong
kinematic fields. 0-3km shear vectors oriented with some angle
to the advancing QLCS will be supportive of QLCS-type tornado
spinups/embedded vortices. This is especially true where
sufficient low-level instability can be realized. Additionally,
there is a risk for some pre-QLCS discrete storms to develop
within the strong WAA regime. Any discrete storm that develops
would be capable of a more substantial tornado risk, given the
anomalously strong shear and helicity in place. This risk
continues to be highly conditional on sufficient instability
being realized.
3) Heavy Rainfall
- Impact Period: this afternoon to around midnight
Latest forecast trends show little to no rainfall for the region
until this afternoon, and as a result rainfall totals have
decreased to 1" to 1.5" with only isolated totals above 2".
That being said the rain that does fall will do so very quickly
and heavy rain rates may briefly overwhelm local drainage and
lead to some minor flooding of low lying areas.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
As of 7 AM Tues...Extreme winds and a heavy convective line
will be over the Outer Banks this evening, and exit around
midnight. Behind this line winds will remain strong (35-40 mph)
as lapse rates become steep behind the cold front. There may be
enough mixing for winds to gust to wind advisory criteria, but
there is not enough confidence at this time to extend any
headlines, mostly due to the peak nocturnal timing. Temperatures
will drop dramatically behind the front, and likely reach the
low 40s to upper 30s by sunrise.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 420 AM Tue...
Dry high pressure builds in from the south Wednesday and Thursday
with near normal conditions expected, although breezy southwesterly
winds will hold on into Wednesday behind the departing low.
Attention then turns to yet another strong low pressure system,
expected develop across the Deep South Friday and lift northward
bringing a strong cold front through Eastern NC early Saturday
morning - almost a carbon copy track of today's system. Guidance
points to this system being relatively weaker, although it will
still bring a renewed risk of strong winds and minor to moderate
coastal flooding, heavy rain, and a low-end risk of severe
thunderstorms. Given increased confidence with better agreement
amongst ensemble members, raised PoPs to categorical for the
period.
Behind this system colder but drier conditions will move in for the
rest of the weekend and into early next week. Spread among guidance
is considerable, but there is at least some potential for a return
of unsettled conditions at the beginning of the work week followed
by the intrusion of an Arctic airmass.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
SHORT TERM /Through Wednesday Morning/...
As of 1 PM Tues...Sites have been bouncing between VFR and MVFR
over the past couple of hours as clouds continue to lower and
showers increase in coverage.
Scattered showers will continue for the next few hours, which
will allow sites to continue their current pattern of bouncing
between VFR and MVFR. As we get into the late afternoon, rain
will become more widespread and the severe threat will increase.
Then, a strong convective line will push from west to east
across ENC after dark. Storms are expected to be strong to
severe and a few tornadoes cannot be ruled out.
Strong winds will continue through the period with gusts of
40-50 kts possible over the coastal plain and 50-60 kts across
the coast by late this afternoon. In addition to this, 60-80 kts
of LLWS is possible (strongest near the coast), which will
create dangerous runway conditions.
Conditions will quickly improve behind the front late
tonight/early tomorrow morning.
LONG TERM /Wednesday through Saturday/...
As of 430 AM Tue...Strong cold front will push offshore after
midnight Wed with VFR conditions returning, however SW to W winds
will continue to gust around 25-30 kt through Wed morning, then
gradually diminish during the afternoon. High pressure builds in
Thursday with pred VFR conditions expected. Another strong low
pressure system will impact the region Friday into Saturday with a
return of strong gusty winds, although likely not as strong as
today.
&&
.MARINE...
SHORT TERM /Through tonight/...
As of 1100 AM Tuesday...
The forecast is on track for the most part across area waters,
but there are a couple of important observations as the event is
now underway.
1) Over the warmer waters south of Cape Hatteras, wind gusts
are already exceeding our forecast, but only by about 5kt or so.
Given this trend, I increased winds a couple of knots through
this evening. This increase now gives a few hours of occasional
gusts to hurricane force. For now, we'll keep the Storm Warning
headlines as is, and continue to message a few gusts to 64kt+.
We'll closely monitor trends in case this changes.
2) With the higher winds mentioned above, seas are building
faster than forecast, and adjustments have been made to match
the recent buoy trends. At the peak, this still gives the
potential for 20-25ft seas from Cape Hatteras south.
PREVIOUS DISCUSSION...Extremely dangerous and perilous marine
conditions will develop later today ahead of a powerful low
pressure system. Storm Warning conditions (48+ kts) are expected
across all coastal waters and inland sounds/rivers for a period
of time this afternoon through early tonight. Additionally,
brief Hurricane Force wind gusts (65+ kts) are likely across the
coastal waters and Pamlico Sound this evening ahead of a strong
convective line which could have additional extreme wind gusts
and/or waterspouts. Seas will build through the day, and peak at
15-25 ft.
Behind the front early tonight, conditions will being to
improve, but increased mixing will lead to Storm conditions
continuing south of Cape Hatteras to around daybreak, while
conditions improve to Gale Force elsewhere.
LONG TERM /Wednesday through Saturday/...
As of 430 AM Tue...Storm force winds will quickly give way to Gales
Wednesday morning as the front departs, then falling off quickly Wed
afternoon and evening while seas greater than 6 ft linger into Thu
morning. High pressure brings better boating conditions Thu
afternoon into Fri morning but conditions will quickly deteriorate
Friday afternoon into early Saturday as another strong frontal
system impacts the waters. Although this storm system will not be as
strong as today's, Gales appear highly probable especially over
coastal waters and adjacent sounds.
&&
.HYDROLOGY...
As of 500 AM Tues...Forecast rainfall amounts have continued to
trend down with only 1-1.5" expected, though some isolated
higher amounts of around 2" are possible. While widespread
flooding is not expected at this time, the potential exists for
a few instances of flash flooding, given the expected high rain
rates and anomalous moisture. Rivers will eventually respond to
the rain as well, but ensemble guidance suggests these rises
may hold off until later this week as water upstream works
towards the coast.
&&
.TIDES/COASTAL FLOODING...
As of 435 AM Tue...Very strong southerly winds will develop ahead of
a powerful cold front today into tomorrow. Large southerly swell and
storm force winds are currently forecast, with the potential for
minor to locally significant coastal impacts, both oceanside and
soundside.
No changes were made to headlines this morning. Coastal Flood
Warning (inundation 2-4 ft AGL) remains for Beaufort, Mainland Hyde
and Dare counties, along with the Outer Banks given the potential
for sound/tidal river and oceanside flooding.
-Oceanside impacts include the potential for moderate to locally
significant ocean overwash (where dune structures are vulnerable),
along the entire coast given the wave runup setup.
Areas of highest concern - beaches from Oregon Inlet down to
Ocracoke, as well as North Topsail Beach. This could impact portions
of Highway 12, especially during times of high tide, rendering it
impassable at times.
-Moderate coastal flooding is expected across soundside Outer Banks,
as well as areas adjacent to the northwestern Pamlico Sound
including the Pamlico and Pungo Rivers. Though winds will be quite
intense Tuesday, a continuous slight veering of the winds through
the day will keep any one area from seeing significantly high water
levels. As winds veer southwest and then west tonight into tomorrow
morning, rapid water rises are likely for soundside locales north of
Buxton.
Elsewhere, minor coastal flooding is expected along the Crystal
Coast as well as up the Neuse/Bay Rivers, with 1 to 2 feet of
inundation possible.
Beyond today, another strong storm system on Friday and Saturday
will bring a renewed coastal flooding threat for many of the same
areas. Winds are forecast to be weaker than today's system, but at
least minor to moderate impacts are possible.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Wind Advisory until 1 AM EST Wednesday for NCZ029-044-079-090-
091-193.
High Wind Warning until 11 PM EST this evening for NCZ045-046-
080-092-094-194-198.
Coastal Flood Warning until 4 AM EST Wednesday for NCZ047-080-
081.
High Wind Warning until 1 AM EST Wednesday for NCZ047-081-195-
196-199-203>205.
Coastal Flood Advisory until midnight EST tonight for NCZ094-
194>196-199.
High Surf Advisory until 7 PM EST Wednesday for NCZ195-199.
High Surf Advisory until midnight EST Wednesday night for
NCZ196-204-205.
Coastal Flood Warning until 3 PM EST Wednesday for NCZ203>205.
High Surf Advisory until 11 AM EST Wednesday for NCZ203.
MARINE...Storm Warning until 1 AM EST Wednesday for AMZ131-230.
Storm Warning until 1 AM EST Wednesday for AMZ135-231.
Storm Warning until 11 PM EST this evening for AMZ136-137.
Storm Warning until 3 AM EST Wednesday for AMZ150-152.
Storm Warning until 8 AM EST Wednesday for AMZ154-156-158.
&&
SYNOPSIS...MHX
NEAR TERM...RM/SGK
SHORT TERM...SGK
LONG TERM...MS
AVIATION...MS/OJC
MARINE...RM/SGK/MS
HYDROLOGY...MHX
TIDES/COASTAL FLOODING...MHX