Area Forecast Discussion
Issued by NWS Wilmington, NC
FXUS62 KILM 221935
Area Forecast Discussion
National Weather Service Wilmington NC
335 PM EDT FRI JUL 22 2016
Seasonable temperatures today will yield to hotter weather over the
weekend. The heat wave will last into the early or middle part of
next week all while rain chances remain minimal.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 330 PM Friday...Warm and mostly sunny conditions persist
this aftn as ridging from the midwest slowly expands towards the
Carolinas. While the very hot temperatures across the midwest are
on the doorstep and will encroach upon this area during the
weekend, today has been actually a nice respite with highs around
90 and dew points which dropped below 70 at times.
This increasing ridge is also functioning as a convective lid to
most updrafts, which is clearly evident by the shallow cu on visible
imagery. A few showers have developed north of the area, likely
along a weak mid-level impulse aided by some differential heating,
and these will try to advect southward towards the far NW counties.
The HRRR wants to bring a few storms into the CWA, but it has been
running far too "hot" with its convective initiation today, and very
dry mid-level air should preclude much of this making the trip
south. However, have left an hour of two of SCHC for Darlington,
Marlboro, and Robeson counties this evening before convection wanes
with loss of heating. Additionally, an an isolated shower or tstm is
possible along the sea breeze through this evening, but coverage
will remain quite isolated. The soundings are very dry in the mid-
levels however, making even lightning difficult since the charge
separation zone is so far into the dry air, but have left TRW- as
the primary Wx type as there are a few lightning strikes upstream.
After nightfall, any diurnal cu will wane and a warm and mostly
clear night is forecast. Have forecast mins a degree above a MAV/MET
blend based off previous verification, and the presence of a 20-25
kts LLJ keeping mins elevated. Have lows forecast to be 72-75,
warmest at the coast.
.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 /19Z FRIDAY THROUGH WEDNESDAY/...
As of 18Z...High confidence in VFR through the Valid TAF period.
Bermuda High will bring warm temps aloft and subsidence which
will help to squash any significant cumulus buildups. Thus, have
left any mention of showers and thunderstorms out of the valid TAF
period. Few to sct cumulus will continue into the eve, 3-4 kft
with cirrus above that. Once the heating of the day is through, we
only expect some cirrus late eve and overnight as the cumulus
clouds slowly dissipate. Southerly winds will be 10 kt or less
through the early eve and then less than 5 kt overnight.
EXTENDED OUTLOOK...Brief periods of MVFR/IFR from isolated
afternoon convection Sunday through Wednesday. Otherwise expect
NEAR TERM /THROUGH TONIGHT/...
As of 330 PM Friday...Weak Bermuda high pressure will exert its
influence through tonight, but a weak gradient will persist. Winds
will gradually veer to the SW tonight, with speeds rising to
around 10 kts. Seas will be formed almost exclusively through a
3ft/9sec SE swell, producing wave heights of 2-3 ft.
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.