761
FXUS62 KMHX 120120
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
920 PM EDT Thu Jul 11 2024

.SYNOPSIS...
A cold front will remain stalled across the region through
Saturday with moist southerly flow bringing periods of heavy
rain. The front will dissipate early next week with hot temps
and the potential to heat indices in excess of 105 degrees
returning.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 920 PM Thursday...

- Flood/flash flood risk continues through tonight

The organized convection from earlier today which produced
Flash Flooding over the coastal plain has dissipated with the
character of the precipitation becoming more disorganized and
showery early this evening. Expect this showery type regime to
persist for most of the night while becoming better organized
then possibly becoming more widespread toward daybreak.

This evening, a frontal boundary stretches SW to NE across the
coastal plain of ENC. Showers and thunderstorms continue to
redevelop along and east of this boundary thanks to a continued
influx of a extremely moist, and very unstable, airmass into
the area. Where showers and thunderstorms develop, the
combination of 2000J/kg+ MUCAPE, 2-2.5" PWATs, and training of
showers and storms will favor intense rainfall rates and an
increased risk of flash and river flooding. While it has been
dry of late, the rainfall rates will be high enough to overcome
the dry soils, supporting the flood risk. In general, urban
areas will be the most susceptible to flooding, but the risk
won`t be limited to those areas only.

Through this evening, then, the greatest risk of flooding will
be over the coastal plain where earlier heavy rains occurred and
any additional heavy rains will more effectively run off to
produce flooding. Expect the flood threat to then spread east late
tonight and especially Friday as an additional influx of
moisture off the Atlantic will combine with an area of low
pressure approaching the Carolina coast from the south, with a
renewed round of showers and thunderstorms appearing likely per
recent short-term guidance. There is still some uncertainty
regarding where the strongest forcing will be focused, as this
is where the heaviest rainfall rates, and highest risk of
flooding, will be. Earlier, the Flood Watch was extended east to
include most of ENC. For now, we left Ocracoke and Hatteras
Islands out of the watch as confidence in rainfall amounts is
lower there comparatively. We`ll re-assess those areas later as
additional guidance comes in.

Rain aside, winds are forecast to increase along the coast as
southeasterly winds increase ahead of the approaching coastal
low. For now, it appears winds will top out in the 20-35 mph
range along the coast tonight. Lows will be very sultry in the
mid to upper 70s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 230 PM Thursday...

 - Renewed flood/flash flood threat Friday

A coastal low will approach ENC from the south and will
interact with a stalled frontal boundary, a very moist airmass
(2-2.5" PWATs), and moderate instability, leading to additional
rounds of showers and thunderstorms capable of intense rainfall
rates. Instability Friday looks lower than today, but increased
forcing is expected along/near the track of the coastal low,
which should still be supportive of heavy rainfall
rates/amounts. Ensemble guidance suggests 3-6" of rain for much
of the area, with higher end amounts up to 7-10" where
thunderstorms are the most intense/persistent. We`ll continue to
refine the risk areas through Friday, but confidence is high
enough to warrant a continuation of the Flood Watch into Friday
evening.

Breezy onshore winds will continue along the coast as well, as
the coastal low approaches from the south. Southeasterly winds
of 20-35 mph will be common. If the low were to deepen more than
currently forecast, those winds would top out a bit higher.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 330 AM Thursday...
Key Messages:

-Very wet period expected into Saturday, with heavy rain
 chances likely (70-80%) at times with localized flooding
 possible. Severe threat remains relatively low at this time.
 4-6 inches of rain possible west of highway 17.

-Warm and humid conditions continue. Sunday through Wednesday
 heat indices of 105-110 degrees are possible each day.

Not many changes to the forecast over the last 24 hours. Wet
and warm will be the story for the long term forecast as a
frontal system extending southward into the Carolinas remains
nearly stationary through Saturday. This feature will remain
between high pressure offshore and lower pressure to the north
and west. This pattern will facilitate extremely efficient
moisture transport off of the Atlantic over the Carolinas. This
is highlighted by the ECMWF extreme forecast index which is
showing anomalously high precipitation values over the
Carolinas. In addition model soundings show PW values
approaching 2.5 inches at times.

While there will also be a chance for thunderstorms each day,
the chances for severe weather remain underwhelming. While there
will certainly be enough moisture and instability to initiate
convection, shear values are lacking. Thus the heavy rain is the
primary threat during this time period.

Not to be overlooked in the long term is the threat for extreme
heat, particularly beginning on Sunday through Wednesday.
Expect high temperatures in the low to mid 90s inland with upper
80s to low 90s along the coast. Heat index values will push or
exceed 105 degrees each day in most locations except the extreme
coastal areas.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
SHORT TERM /Through Friday/...
As of 635 PM Thursday...

 - TSRA and sub-VFR conditions to impact ENC through Friday

The combination of a stalled front, a coastal low approaching
from the south, and a very deep moist airmass will support an
increased risk of SHRA and TSRA through Friday for much of
Eastern NC. Timing out the greatest chance of SHRA and TSRA at
any one TAF site will be complicated, but occasional to frequent
showers should be a threat for the next 36-48 hours. Where TSRA
occur, periods of LIFR/IFR conditions can be expected due to
very heavy rainfall rates. Gusty winds will be possible as well,
especially along the coast as the low approaches. The aviation
ceiling guidance is indicting varying ceilings through the
period with MVFR being the prevailing category through Fri.

LONG TERM /Friday night through Tuesday/...
As of 330 AM Thursday... For Saturday expect periods of sub VFR
conditions as heavy rain is expected across eastern NC.
Precipitation will affect ceilings and visibilities during the
heaviest rainfall and overnight periods. Rain is expected to
continue through Saturday and possibly into Sunday before
tapering off early next week. Thunderstorms are also possible
during this time, particularly in the afternoons but severe
weather is unlikely. Winds will keep a southerly component at
5-10 knots gusting to 15 kts.

&&

.MARINE...
SHORT TERM /Through Friday/...
As of 920 PM Thursday...

 - Deteriorating boating conditions through Friday

A coastal low approaching from the south will lead to building
winds and seas tonight into Friday, with 15-30kt southeasterly
winds, and seas peaking as high as 5-8 ft. Of note, the
potential exists for stronger winds and higher seas depending on
the strength of the low as it approaches the southeast coast.
SCA headlines continue to cover these hazards, with adjustments
made to account for recent trends in model guidance (ie. mainly
to increase winds).

LONG TERM /Friday night through Tuesday/...
As of 330 AM Thursday...Small craft conditions will likely
continue across the central and southern waters through Saturday
afternoon with wind gusts approaching 25 kts and seas near 6
ft. For Pamlico Sound, expect SCA conditions to relent Saturday
morning. Waves and winds will relax for Sunday and into the
middle part of next week.

&&

.HYDROLOGY...
As of 230 PM Thursday...

Despite high flash flood guidance values (3-5") across much of
ENC, intense rainfall rates of 2-3"/hr have been overcoming the
dry soils of late, leading to increased runoff and flood/flash
flooding impacts. This has especially been the case in urban
areas where dry soils have less of an impact. A Flood Watch has
been issued for much of ENC, and is in effect through late
Friday evening. This may need to be adjusted in time and area
depending on how conditions evolve over the next 24-36 hours.
Ensemble guidance shows rainfall amounts of 3-6" through Friday
night, with amounts as high as 7-10" where rainfall is the most
persistent and where thunderstorms materialize.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Flood Watch through Friday evening for NCZ029-044>047-079>081-
     090>092-094-193>196-198-199-203.
     Beach Hazards Statement from 8 AM EDT Friday through Friday
     evening for NCZ195-196-199-204-205.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for AMZ135-152-
     154-156-158.
     Small Craft Advisory until 6 PM EDT Friday for AMZ136-137.
     Small Craft Advisory until 6 PM EDT Saturday for AMZ150.
     Small Craft Advisory until 8 PM EDT Friday for AMZ231.

&&

$$
SYNOPSIS...MHX
NEAR TERM...RM/JME
SHORT TERM...RM
LONG TERM...RTE
AVIATION...RTE/RM/JME
MARINE...RTE/RM/JME/RCF
HYDROLOGY...MHX