Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
643 am EDT Wednesday Jun 3 2015
unsettled conditions will persist through the end of the week
with the best chances of rain occurring today and Thursday.
Near term /through tonight/...
as of 615 am Wednesday...widespread shower activity continues over
nearly the entire County Warning Area. Tweaked forecast to make sure 100 probability of precipitation were
in place everywhere today...although as the forecast was already
for categorical probability of precipitation this does not make for much of a change.
Previous discussion follows:
Another day of convection is a certainty as an upper low drifts
east over the central Carolinas while a diffuse cold front at the
surface drifts southeast to the coast. Model soundings show a deep
southerly flow will keep the column nearly saturated through the
near term with p/west values in the 1.75 inch range today and closer
to 1.50 inches after midnight. Cool air aloft and daytime heating
will combine with the moist column for widespread convection well
into the evening hours. Multiple boundary interactions will
enhance coverage and intensity of convection and there is the
likelihood for training storms given anticipated storm motion...so
have retained heavy rain wording for today. Expecting quantitative precipitation forecast totals
over the near term in the one inch range...with locally higher
totals likely. Storm Prediction Center keeps US in a marginal risk area for severe
weather...with the primary threat being from locally-strong winds
and possibly hail.
Substantial cloud cover and precipitation will help keep a lid on daytime
temperatures. Forecast maximum temperatures today of right around 80
most places with overnight minimums in the middle 60s.
Short term /Thursday through Friday night/...
as of 315 am Wednesday...middle level low pressure will slowly meander
west to east across North Carolina through the period. As has
been the case recently...the deepest moisture resides on the east
side of the feature threrfore probability of precipitation will be highest Thursday in the
likely range. Scaled back to good chance along the coast Friday
with chance inland. I did adjust temperatures up slightly Friday
due to the expected decrease in convective coverage but overall
the forecast remains mostly unchanged.
Long term /Saturday through Tuesday/...
as of 315 am Wednesday...the middle level pattern will be weakly forced
as the main belt of westerlies is well to the north during most
of the period. A slightly deeper trough will briefly develop
across the eastern U.S early next week with a zonal pattern beyond
this. The weak trough over the Carolinas warrants a continuation
of probability of precipitation...primarily on a diurnal basis each day. Surface features
are weak as well with high pressure initially then a weak front
associated with the brief trough. Temperatures are mainly around
climatology warming a few degrees later in the period as a slight
westerly/downslope component is added to the winds.
Aviation /12z Wednesday through Sunday/...
as of 12z...a slow moving upper low will continue to sling moisture
into the region. In the very near term...a band of heavy precipitation will
move into ilm around 12-13z...and to a lesser extent The Myrtles.
Needless to say ceilings and visibilities are going to bound around
a lot. The predominate IFR conditions will stay inland...however
heavy precipitation at any time could drop visibilities to a couple of
miles. Surface high pressure will try to ridge into the region later
today...perhaps shifting the winds to the northeast. The gradient is
weak however and a better description of today's winds would be
variable. As the upper low approaches tonight...look for another
round of convection over the western half of the County Warning Area.
Extended outlook...a good chance for showers and thunderstorms
through Sunday...mainly in the afternoon. Brief periods of IFR
conditions possible in the showers/thunderstorms.
near term /through tonight/...
as of 615 am Wednesday...no changes to the forecast with the
latest update. Previous discussion follows:
Light winds of right around 10 kts or less will continue today
and tonight in advance of a very slow- moving cold front. The
front may move along the coast or offshore overnight. Seas will
stay in their current 2 feet range through the period. We will
continue to see extensive shower and thunderstorm activity over
the waters through the period.
Short term /Thursday through Friday night/...
as of 315 am Wednesday...light wind fields will continue to define the
coastal waters through the period. In fact the sea breeze and
convection will be the forcing mechanisms. Synoptically a weak wedge
pattern will warrant northeast winds outside of these features. Seas
remain capped at 1-3 feet.
Long term /Saturday through Sunday/...
as of 315 am Wednesday...synoptic forcing look a little stronger from the
northeast for the weekend which will serve to keep the direction
intact a little longer than previous days. Still the flow will
remain at the mercy of the seabreeze and at least the chance of
convection. Significant seas of 1-3 feet can be expected.