Area Forecast Discussion
Issued by NWS Newport/Morehead, NC

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FXUS62 KMHX 221127
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
727 AM EDT Fri Mar 22 2024

.SYNOPSIS...
A coastal low and cold front will impact the area this weekend.
High pressure builds in early next week. Another coastal low is
possible mid to late next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 725 AM Fri...No changes to the previous forecast.

Prev disc...Early this morning, radar and satellite imagery
reveal a warm front offshore to the south of Eastern NC. Over
the past several hours, convection has been gradually increasing
along this boundary. The warm front will steadily lift north
through the day today, reaching the Crystal Coast by late this
afternoon. We`re dry this morning, but low-level moisture will
steadily increase as the flow becomes southeasterly off the
Atlantic, allowing dewpoints to rise through the 50s. A weak
area of low pressure will develop along the advancing warm
front, which will help to enhance low-level convergence as it
reaches the coast. The combination of increasing low-level
moisture, weak instability, and increasing low-level forcing
will support an increasing chance of showers and isolated
thunderstorms from south to north this afternoon. The previous
forecast handled this expectation nicely, and no significant
changes were needed. The one change, while minor, was to
increase winds from mid- morning into the afternoon as the
pressure gradient tightens between the approaching warm front
and a departing area of high pressure to the north. During peak
heating/mixing, gusts of 20-30 mph will be possible for much of
the area per BUFKIT momentum transfer guidance, and the winds
were nudged up to reflect this expectation.

While low, short-term guidance has trended up some with
instability this afternoon, especially near the Crystal Coast,
and I added a mention of thunder for that area. However, due to
a lack of appreciable instability, the risk of severe weather is
low (<10% chance).

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
As of 330 AM Thursday...

**Low pressure system to impact ENC with multiple hazards
 tonight through Sunday**

An upper level shortwave will move across the Southeast US
through Saturday, then shift offshore Saturday night. At the
surface, low pressure will track northeast from the northern
Gulf Coast through the eastern Carolinas. Guidance is now
solidly focused on a surface low track along the coast of
Eastern NC, although there will be a secondary low that will
track inland, which complicates the forecast some.

The greatest low-level convergence will be focused along the
low that tracks along the coast, and this is still where we
expect the heaviest rainfall to be with this event. Essentially,
this puts most of Eastern NC along and east of HWY 17 in a
solid 2-3" of rain, with 1-2" to the west. Where convection
occurs, max rainfall guidance suggests amounts as high as 4-6"+.
Coming on the heels of a period of very dry conditions, the
area should be able to handle 1-3" of rain. However, where/if
those higher amounts occur, there will be an increased risk of
hydro concerns (small creek, urban, poor drainage, and flash
flooding). Confidence in those higher amounts is low enough to
preclude a Flood Watch, but this potential will be re-evaluated
in later shifts.

Regarding the convective potential, confidence is about the
same as before. As deeper moisture moves in tonight, there will
be a gradual increase in instability, but poor mid-level lapse
rates and only modest boundary layer moisture quality will tend
to keep instability on the low side (<500j/kg) tonight, and
convection will probably tend to be more elevated in nature. For
these reasons, I expect the risk of severe weather to be low
tonight. On Saturday, the coastal low will shift away from the
coast as a cold front approaches from the west. Widespread rain
along the track of the low will limit daytime heating, and the
better quality moisture will held to our east, along and east of
the departing SFC low. The question, then, is how much
destabilization can occur ahead of the advancing cold front
during the day Saturday. HREF probabilistic guidance gives a
60-80% chance of MLCAPE exceeding 500 j/kg, while the SREF only
gives about a 30-50% chance. For any severe weather risk to
materialize, we will need some heating to help offset the lack
of better quality moisture. If sufficient
heating/destabilization can occur, there would be an increased
risk of deep convection with gusty/damaging winds the primary
risk. A tornado cannot be ruled out, but the flow will be
trending more unidirectional, limiting this risk. SPC has
continued with a "Marginal" risk for our area on Saturday, and
this seems perfectly reasonable given the potential outlined
above. The key message here is that it is not a high- confidence
risk.

Behind the front, a strong northerly surge of wind will develop
by late afternoon into the evening hours Saturday. The strong
northerly winds will last well into Saturday, with widespread
gusts of 30-45 mph expected. Along the Outer Banks, gusts as
high as 45-50 mph are possible. The complicated aspect of this
system is that there will be impacts both in the southerly flow
regime tonight into Saturday, and then with the northerly flow
regime Saturday night into Sunday. For now, a Wind Advisory has
been issued for a portion of the Outer Banks to highlight the
impacts with the strong southerly winds tonight into Saturday
morning. Additional wind headlines will likely be needed later
to cover the strong northerly winds. With the strong winds comes
an increased risk of coastal impacts. Please see the "Coastal
Flood" section of the AFD for additional details.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 420 AM Fri...

High pressure builds south into the Carolinas early next week
as the weekend low departs. However, coastal impacts will likely
continue especially across the northern Outer Banks with
persistent northerly flow as low pressure lingers offshore.
Attention turns to yet another cold front and attendant coastal
low late next week, although as expected nearly a week out
details on the system`s evolution are murky. Still, if realized
another round of heavy rainfall, strong winds and coastal
impacts are possible.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHORT TERM /through 12Z Sat/...
As of 730 AM Fri...VFR conditions will start the period this
morning as high clouds gradually increase through the day ahead
of ongoing convective activity across the Gulf of Mexico. Light
easterly flow this morning will increase with gusts up to 20-25
kt in the afternoon as frontal boundary remains stalled to our
south. Shower activity ahead of the boundary will gradually
encroach from south to north starting at around 18z, which may
result in some isolated periods of MVFR flight conditions, but
otherwise VFR conditions are likely to hold until after 06z when
deepest moisture and heaviest rainfall shift across the area.
MVFR conditions are expected to prevail with periodic drops to
IFR in heaviest precip, but more predominant IFR conditions are
likely for the coastal plain terminals west of Highway 17.

LONG TERM /Friday night through Monday/...
As of 425 AM Fri...A coastal low will impact Eastern NC Friday
through Sunday with an increased risk of sub-VFR conditions,
possible TSRA, and strong winds. Wind gusts of 25-40kt are
likely during this time, especially across the Outer Banks.
Widespread +RA and reduced VIS can be expected as well.
Conditions will improve Sunday into Monday, but strong northerly
winds will persist particularly for coastal locales.

&&

.MARINE...
SHORT TERM /through Fri night/...
As of 430 AM Fri...Marine conditions continue to gradually
improve early this morning with easterly winds of 10-15 kt and
seas now 3-4 feet, but these benign conditions will be short-
lived as a coastal low moves northeast through area waters late
tonight into tomorrow, with lingering impacts lasting well into
next week. After sunset tonight, southeasterly winds of 25-35 kt
with frequent higher gusts are expected to overspread all
coastal waters and sounds. Seas will be extremely quick to
respond, with the highest waters across Raleigh Bay with wave
heights reaching 10-15 feet by Sat morning.

All existing Gale Watches have been upgraded to Gale Warnings
this morning, with the exception of the Pamlico/Pungo river
where a SCA is in effect.


LONG TERM /Sat through Monday/...
As of 440 AM Fri...Dangerous marine conditions carry through
the weekend and into Monday. As low lifts across the region on
Saturday, winds will weaken slightly as winds veer northerly. By
Sun morning, strong winds will return but this time due north
at around 30-35 kt with higher gusts and a few Storm force gusts
possible over the far outer central waters. These winds will
this time focus highest waves north of Cape Hatteras with seas
of 12-15 feet, although widespread 6+ foot seas will still be
ongoing across all waters through Monday.

&&

.TIDES/COASTAL FLOODING...
As of 445 AM Fri...

A strong, complex low pressure system will impact the area this
weekend into early next week. Still some uncertainty with
respect to the track, and strength, of the low, but based on the
latest guidance, we expect minor to moderate coastal flooding,
both soundside and oceanside, with ocean overwash, rough surf
and beach erosion also expected. Impacts could begin as early
as tonight, then peak Saturday and Sunday. Impacts are expected
to linger into Monday.

Areas vulnerable to 20-25 kt sustained SE winds (locations up
the Neuse, Bay, Pamlico, Pungo Rivers, Bogue Sound and oceanside
areas from N Topsail Beach up towards Oregon Inlet) will likely
see minor coastal flooding Friday night into Saturday morning.
Then winds will shift to the N Saturday night through Sunday
into the 25-35 kt range with higher gusts, with the coastal
flood threat shifting to soundside areas adjacent to the S/E
Pamlico Sound and oceanside areas from Duck to Cape Lookout.
Troublesome area on the northern end of Ocracoke Island may be
impacted with ocean overwash on Hwy 12...along with other
oceanside areas with vulnerable dune structure. Stay tuned for
updates on this potential.

A High Surf Advisory is in effect for all coastal zones south of
Oregon Inlet for much of Saturday. Resultant ocean overwash
across Ocracoke Island will likely cause flooding across Highway
12 as early as tonight.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...High Surf Advisory from 8 AM to 5 PM EDT Saturday for NCZ195-
     199.
     Wind Advisory from 2 AM to 2 PM EDT Saturday for NCZ196-204-
     205.
     High Surf Advisory from 5 AM to 11 PM EDT Saturday for NCZ196-
     204.
     High Surf Advisory from 8 AM to 8 PM EDT Saturday for NCZ205.
MARINE...Gale Warning from 11 PM Saturday to 5 PM EDT Sunday for AMZ131-
     230.
     Gale Warning from 5 AM Saturday to 2 AM EDT Monday for AMZ135.
     Small Craft Advisory from 5 AM Saturday to 11 PM EDT Sunday
     for AMZ136.
     Gale Warning from 5 AM to 2 PM EDT Sunday for AMZ137.
     Gale Warning from 8 AM Saturday to 2 AM EDT Monday for AMZ150.
     Gale Warning from 2 AM Saturday to 5 AM EDT Monday for AMZ152-
     154-156.
     Gale Warning from 2 AM Saturday to 2 AM EDT Monday for AMZ158.
     Gale Warning from 5 AM Saturday to 11 PM EDT Sunday for AMZ231.

&&

$$
SYNOPSIS...MHX
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...MS
AVIATION...RM/MS
MARINE...MS
TIDES/COASTAL FLOODING...MHX


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