Area Forecast Discussion
Issued by NWS Wilmington, NC-- Highlight Changed Discussion --
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FXUS62 KILM 230609
Area Forecast Discussion
National Weather Service Wilmington NC
1041 PM EDT FRI JUL 22 2016
-- Changed Discussion --Increasingly warm temperatures and high humidity will produce
dangerous heat in places across the area over the weekend. This heat
wave will last into the early or middle part of next week all while
rain chances remain minimal.
-- End Changed Discussion --
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 1030 PM Friday...500 mb high pressure centered over the
Texas Panhandle will build eastward across West Virginia over the
next 12-18 hours. The rising heights to our north will turn our upper
level steering flow from northerly to northeasterly. This
readjustment due to rising heights is already apparent in the
gradual curving motion of the persistent cluster of thunderstorms
currently moving south through the Lumberton area. Despite what
should be a fairly capped surface layer by this point, wind gusts
in these storms were still able to exceed 25 mph about an hour
ago. The 00z/01z HRRR runs were much better initialized than the
earlier 21z run and are most likely correct in their idea of the
storms weakening due to stabilizing low-level parcels. Debris
cloudiness and some lighter showers will veer more southwesterly
and move across Florence for the next several hours, otherwise
mainly clear skies are anticipated overnight.
Bermuda High pressure dominates the surface weather map. A modest
low level jet is already in place over the Coastal Plain but will
only be able to keep light southwesterly winds in place at the
surface. Given the airmass, this should yield lows in the lower
to middle 70s for most locations.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
As of 330 PM Friday...Hot with increasing humidity forecast for
the weekend as this hot July continues. Massive ridge across the
central part of the country will expand to become a broad feature
across nearly the entire southern tier of the CONUS. As this
occurs, a weak closed mid-level low off the SC coast will be
suppressed to the SW, driven by increasing heights to its north.
This keeps this feature weak and away from the Carolinas, moving
across Florida Sunday night. No surface reflection is progged with
this impulse, but as it moves overhead Florida late, it will cause
a better SE moisture tap and increasing clouds are forecast Sunday
The big story this wknd is a return to uncomfortable and dangerous
heat as the mid-level dome of high pressure expands overhead. This
occurs in conjunction with persistent Bermuda ridging, and 1000-
500mb thicknesses approach 580dm by Sunday. Developing SW flow this
wknd will pump in additional moisture, and this means humidity will
be on the rise at the same time temperatures climb back well into
the 90s. While isolated convection is possible each aftn during peak
heating, widespread tstms are not forecast thanks to warm and
relative dry air aloft, and will carry only SCHC along the sea
breeze and piedmont troughs, highest Sunday. Very little airmass
change is forecast Sat to Sun, so highs both days will be in the mid
90s, slightly warmer Sunday, and a bit cooler at the coast each day,
with lows in the mid to upr 70s. The combination of these hot temps
and high dew points will create heat index values just below 105
(heat advisory criteria) on Saturday, but a heat advisory will
likely be needed on Sunday and will mention in the HWO.
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 330 PM Friday...The extended period as would be expected,
offers little change in the summertime pattern. The eastern
Carolinas will be in between a subtle northwest flow aloft and at
times ridging building in from the central Atlantic. Any synoptic
forcing mechanisms are relegated to the Piedmont trough with the
more local feature being the seabreeze. Precipitable water values
remain somewhat unimpressive with perhaps an increase later next
week. This warrants no more than either slight or low chance pops
for any period. 850mb temperatures remain pegged right around 20
degrees C so surface readings should be a few degrees above
normals for both daytime highs and overnight lows.
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --As of 06Z...VFR at TAF issuance time at all terminals. Lingering
high clouds streaming in from the north across mainly inland areas.
Confidence is high for VFR through sunrise, although where rainfall
occurred last evening at KLBT there is a chance of MVFR vsbys
despite 20kt boundary layer winds. Models continue to show another
impulse moving down in the deep northerly flow aloft tomorrow.
Timing should be aftn into eve with Shwrs/Tstsms possible at
terminals. Confidence is low when it comes to timing and strength of
this disturbance and therefore potential for convection. Winds will
be WSW, but will back to the SSW-SW by mid-late morning.
EXTENDED OUTLOOK...Brief periods of MVFR/IFR from isolated
afternoon convection Sunday through Wednesday. Otherwise expect
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NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Friday...Bermuda High pressure offshore is in
control of our weather, and that means a completely normal pattern
for mid-summer. Southwest winds 10-15 kt and seas 2-3 feet in an
east-southeast swell will continue overnight. Radar shows shower
activity well inland with only a small potential that showers
could develop later tonight.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 330 PM Friday...Bermuda high pressure will be the dominant
feature this weekend as it expands again into the Carolinas. This
produces SW winds around 10 kts Saturday, increasing to up to 15
kts Sunday thanks to a sharper piedmont trough. Seas will be
formed through an amplifying SW wind wave and a persistent SE
swell, producing wave heights of of 2-3 ft Saturday, and more
widespread 3 ft on Sunday.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 330 PM Friday...South to southwest winds of 10-15 knots
will continue across all waters through the period. There is a
little hint of higher winds overnight Tuesday into Wednesday
morning with the low level jet and this is reflected in the
forecast. Significant seas will be mostly in a range of 2-3 feet.