Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
722 PM EDT Monday Jul 6 2015
upper trough will open and move away tonight as ridge develops
overhead. This ridge will combine with a Bermuda high pressure to
create typical summertime heat and humidity along with diurnal
thunderstorm chances through mid-week. Increasing heat and
humidity will build late week with temperatures rising to well
above normal along with continued typical thunderstorm chances.
Near term /until 6 am Tuesday morning/...
as of 300 PM Monday... deep convection has thus far failed to
develop today. Shallower extremely isolated showers have popped up
briefly along the NC seabreeze and at this time over SC sea
breeze. Piedmont trough also seeing similarly scant activity.
Given that the normal diurnal peak is upon US and in the absence
of any real forcing later on this is probably it. The hrrr has
been insisting that the seabreeze continues to be productive but
is now falling a bit behind the 8ball in being overdone west its
initialization. Even so...it is July in the coastal Carolinas and
we need a stronger cap than the paltry one in the chs referenced
this morning to bring a completely dry day so the small probability of precipitation along
the coast have been maintained albeit lower than previous
forecasts. The overnight period will be dry though we could see a
repeat of last night where Gulf Stream convection affected the
very immediate coast.
Short term /6 am Tuesday morning through Wednesday night/...
as of 300 PM Monday...slow moving middle-level low will open and push
off to the northeast leaving building upper heights through
Wednesday. This will drive increasing temperatures thanks to the
higher thicknesses...but will help to somewhat suppress
convection...especially on Wednesday. Although heights begin to
build Tuesday...a shortwave is prognosticated to move overhead...likely
remnant energy from the more significant upper low from Monday...and
this will help to support and drive afternoon convection along the
typical summertime boundaries. Wednesday will also have at least
isolated storms on the sea breeze and Piedmont trough...but more
subsidence and drier middle-levels will limit total coverage.
Convection will wane diurnally each day...but continued SW winds
will keep mins a degree or two either side of 75 each
night...falling from highs in the low to middle 90s during the aftns.
Long term /Thursday through Monday/...
as of 300 PM Monday...hot and dry conditions will continue into
the latter part of the week and into the weekend as we close out
on the first full week of July. Latest guidance continues to
illustrate a middle to upper ridge building across the southeast and
extending back as far west as Texas. With increasing
heights...fairly dry middle levels...and subsidence aloft...am not
expecting much in the way of convection on Thursday and Friday.
However...with that said...will not entirely rule out isolated
development in the afternoon hours with diurnal heating and along
the sea breeze. Into the weekend...the ridge gradually begins to
move westward...allowing for a weak front to drop south close to
the area. Thus have kept with increased probability of precipitation for isolated to
scattered showers this weekend through into Monday.
As for temperatures through the period...expect highs in the middle 90s
with overnight lows in the low to middle 70s. Heat indices will likely
break the 100 degree mark with a few locations potentially reaching
heat advisory criteria of 105 degrees as in addition to high
temperatures...dewpoints remain in the lower 70s.
Aviation /00z Tuesday through Saturday/...
as of 00z...tropical like atmosphere will persist throughout the taf
period. The only impediments to aviation concerns will be a little
MVFR fog inland late tonight and Tuesday morning. Some scattered
showers and thunderstorms are possible once again Tuesday late
morning and afternoon but limited coverage doesn't warrant inclusion
in the forecast at this point.
Extended outlook...chance of showers and thunderstorms each
day...with brief periods of MVFR/IFR possible. Otherwise VFR.
near term /through tonight/...
as of 300 PM Monday... southerly winds will pick up overnight by
about 5 kts as a very weak low level jet develops. Expecting no worse than
about the 15 to 20kt range thus precluding any advisories or
headlines. Seas will also remain below any thresholds though The
Bump in speed could change a few zones' forecast from 3 to 4 feet to
just a mainly 4 feet forecast as the nearshore/offshore wave height
gradient diminishes ever so slightly.
Short term /Tuesday through Wednesday night/...
as of 300 PM Monday...Bermuda high and SW winds to persist in
typical summertime fashion this period. Speeds will be predominantly
10-15 kts...but slight increases to 15-20 kts are possible each
afternoon/evening due to the sharpening of the Piedmont trough. Seas of 3-4
feet are expected...with a SW wind wave the most significant in the
Long term /Thursday through Saturday/
as of 300 PM Monday...as the waters remain under the influence of
the Bermuda high...will see continue west-southwest flow 10 to 15
kts Thursday and Friday...decreasing to around 10 kts on Saturday.
Not much in the way of change of wave heights...as we will
continue to see a 2 to 4 feet range with a blend of wind waves and a
long period swell around 9 to 10 seconds coming into play.