NWS Newport/Morehead City, NC wrote its last area forecast discussion before the first event at Dec 24, 6:30 PM EST, 17 minutes earlier.
Area forecast discussion, Dec 24, 6:30 PM EST, 17 minutes before
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
630 PM EST Thu Dec 24 2020
.SYNOPSIS...
A strong cold front will provide a period of impactful weather
Christmas Eve into Christmas morning. Then, cold high pressure
will build back in late week and through the weekend. A mostly
dry cold front will cross the area late Monday, and then high
pressure will rebuild mid next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 630 PM Thu...No major changes with this update.
***The entire area is now under tornado WATCH 518 until 10 PM.
Note, the severe threat will likely extend past that***
Widespread showers and scattered thunderstorms are occurring
across Eastern NC early this evening. East of Highway 17, an
area of convection has moved onshore with periodic embedded
Supercell characteristics. This are extends south and offshore.
While the inland activity has become disorganized during the
past hour, new rotation has been noted in several cells
offshore. Over the coastal plain, a line of convection with
embedded meso-cyclones has also become disorganized in the past
hour as it moves slowly eastward. Thinking that storms should
begin to strengthen again as the atmosphere across Eastern NC is
favorable for organized convection. ML CAPES are close to 1000
J/kg, with the Super Cell Composite up to 12 and the STP 2 (both
from the SPC Meso-analysis page). A mid level warm layer
observed on the 18Z special sounding could be contributing to
the storms disorganization, but with increasing moisture
advection (increasing sfc dewpoints), think the Severe threat
will continue through the evening, especially with continued
strong kinematics supporting a tornado threat. Will continue to
leave mention of damaging winds in the forecast and highlight
tornado potential via social media. Please help us spread the
message of having multiple ways to receive warnings, as the
threat continues past when folks may be headed to bed.
As PWATS climb through evening, periods of heavy rain are also
possible. In addition, we will remain quite windy through 08Z,
with a strong low level jet. Mixing during the daylight hours
will allow for gusts 40+ mph, and any showers or storms tonight
will also be able to transport stronger winds down. Wind
advisory remains up for the entire area to account for this.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 1230 Thu...As mentioned above this will be short and
brief, to get ready for the impending weather.
Behind the line of storms tonight, wind shift quickly to the
WSW and usher in strong CAA. Expecting temps to drop sharply
behind the front by a magnitude of around 20-30 degrees, with
early morning lows in the mid 30s inland and low 40s along the
coast. A few lingering stratiform showers are possible as well
very early Friday. The HRRR, and to a somewhat lesser extent
some other hi resolution guidance, continues to show the
possibility of flurries over much of the area after 15Z. No
concerns with accums, with surface temps well above freezing and
boundary layer temps in the mid to upper 30s. Thought the trend
was worth a mention in the forecast, given the briefing from
the overnight crew. We did word it as slight chance scattered
flurries, with sprinkles or a mix there of along the coast with
warmer boundary layer temps. Increased clouds a tad, but we will
likely average out a mix of sun and clouds.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 340 AM Thurs...An exceptionally cold upper trough will
remain over the region Saturday with well below normal
temperatures expected. Then, moderating high pressure moves in
Sunday and Monday, with a mostly dry cold front expected to pass
through the area Tuesday morning. High pressure then builds
back in over the area Wednesday.
Friday night/Saturday...Low level heights will hit rock bottom
Christmas night, and with skies mostly clear this will bring the
coldest air of the season to Eastern NC. Expect lows reaching
the upper teens to low 20s inland, and the mid to upper 20s
along the coast. With a persistent breeze continuing, we could
see some single digit wind chills early Saturday morning.
Then on Saturday, much below average temps will continue, though the
upper level trough will depart and heights will build through the
day. Highs are only expected to reach the mid to upper 30s, with
wind chills remaining in the 20s all day.
Sunday and Monday...Moderating high pressure will move in from the
SW early Sunday, leading to continued dry weather Sunday and Monday,
with a rebound to near normal temperatures Sunday and highs into the
upper 50s to low 60s Monday. A mostly dry cold front is expected to
cross the area late Monday night or early Tuesday morning, bringing
with it breezy conditions and cooler temps.
Tuesday and Wednesday...Behind this front high pressure will build
in from the north with cooler temps in the 50s expected.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Short Term /through 18Z Fri/...
As of 630 PM Thu...Poor flying conditions thru about 06z with
bouts of shra/tsra and gusty winds. Strong cold front wl
approach thru this evening then move offshore overnight. Strong
S winds gusting aoa 30 kts expected thru the evening ahead of
front. Several rounds of shra and a few tsra expected that will
lead to frequent periods of sub VFR conditions. A strong storm
is poss with very gusty winds and even an isold tor threat. Best
low lvl jet crosses this evening and will show LLWS for this
period. After 06Z deeper moisture pushes E as front crosses with
westerly flow and precip ending resulting in cigs mainly in the
VFR range. SW to W winds will remain gusty thru Fri morn with
clouds sct out Fri later in morn.
Long Term /Friday afternoon through MONDAY/...
As of 400 AM Thurs...Mostly VFR conditions expected for this
period with high pressure over the area. Some gusty SW winds
will continue Friday which, could have some impacts at
terminals.
&&
.MARINE...
Short Term /through Friday/...
As of 630 PM Thu...No sig changes to previous forecast with
high impact period of weather causing dangerous marine
conditions Christmas Eve into Christmas Day across all our
waters.
Winds will steadily increase ahead of a strong cold front, with
winds now S 35-45 kts, with gusts peaking close to 55-60 kts
over the Gulf Stream. Storm Warnings remain in effect for all
coastal waters and the Pamlico Sound with Gales for all
remaining waters. Behind the cold front early Friday morning,
winds will turn to the WSW at 25-35.
Seas are already building to 8 to 10 feet, and then peak at
12-20 ft overnight. Seas then subside to 8-15 ft prior to
daybreak.
Storm force conditions will end early Christmas morning,
however Gale force winds are expected to continue through at
least early afternoon.
Long Term /Friday night through Sunday/...
As of 400 AM Thurs...After that winds become mostly west at
15-25 kts, and seas come down to 5-8 ft early Saturday morning
after starting out 8- 14 ft Christmas morning. Winds will be WNW
10-20 kts Saturday with seas 4-7 ft, and then winds really drop
out on Sunday becoming light and variable with seas dropping to
2-4 ft. Southerly winds will strengthen Monday to 10-15 kts,
and seas build slightly to 3-5 ft.
&&
.TIDES/COASTAL FLOODING...
As of 400 PM Thurs...Confidence continues to increase that
minor to moderate coastal flooding will occur across a large
portion of Eastern NC ahead of a very strong cold front. A
Coastal Flood Warning continues for the Outer Banks, and for
Beaufort and Hyde Counties. Coastal Flood Advisories also
continue for areas along the Crystal Coast, and adjacent to the
NNE Pamlico Sound, and eastern Albemarle Sound. Strong southerly
winds will reach Gale to Storm Force late today and tonight,
then shift to the WSW Friday. Water level rises will be highest
across areas adjacent to the northern (and eastern) Pamlico
Sound, and up the Pamlico and Pungo Rivers initially. There is
potential for 2-4 ft AGL inundation, mainly along the Outer
Banks, and also locations adjacent to the Pamlico and Pungo
Rivers as water funnels up into these areas. Elsewhere, minor
coastal flooding is likely for the Crystal Coast (Bogue Sound
and lower White Oak River), the Bay River, and western Pamlico
Sound. Behind the front, winds will turn to the southwest which
will focus the highest water over the Outer Banks north of Cape
Hatteras.
There is also the potential for moderate to significant ocean
overwash and beach erosion, mainly between Oregon Inlet and Ocracoke
Island through Friday afternoon. Highway 12 will likely be
impacted and portions could be impassable at times, especially
during high tide. Wave guidance shows seas just off the coast
building to 10-15+ ft with periods of 9-11 seconds which would
result in wave runup resulting in the potential for moderate to
sig ocean overwash.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...High Surf Advisory until 11 AM EST Friday for NCZ195-196-199.
Coastal Flood Advisory until 11 AM EST Friday for NCZ047-094-
195-196-199.
Wind Advisory until 4 AM EST Friday for NCZ029-044>047-079>081-
090>092-094-193>196-198-199-203.
Coastal Flood Warning until 4 PM EST Friday for NCZ203>205.
High Surf Advisory until 4 PM EST Friday for NCZ203>205.
Coastal Flood Warning until 11 AM EST Friday for NCZ080-081.
High Wind Warning until 4 AM EST Friday for NCZ204-205.
MARINE...Gale Warning until 4 AM EST Friday for AMZ131-136-137-230-231.
Storm Warning until 4 AM EST Friday for AMZ135-150-152-154-156-
158.
&&
SYNOPSIS...MHX
NEAR TERM...EH/JME
SHORT TERM...EH
LONG TERM...SGK
AVIATION...RF/JME/SGK
MARINE...EH/JME/SGK
TIDES/COASTAL FLOODING...MHX