Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
252 PM EDT Tuesday Jun 2 2015
heavy rainfall will remain a concern into Wednesday. A cold front
will approach the area tonight and Wednesday and then stall as it
slowly becomes diffuse by the weekend. Another front may approach
the area early next week. Although there will be dry periods...
unsettled weather is expected and showers and thunderstorms will
remain in the forecast each day.
Near term /through tonight/...
as of 150 PM Tuesday...storms congregating SW to NE along the
inland-bound and decelerating sea breeze. Sat imagery also shows
minimal cumulus development west of this line as previous convection
has stabilized these areas. Will delay the onset of precipitation return
since there is still plenty of daylight left for destabilization.
The hrrr however which is initializing fairly well as of late is
not overly enamored with the idea of storms redeveloping. Just
west of our County Warning Area the sky does have a more convective/cumulus
appearance. Should storms develop there they may clip part of the
area with a general storm motion from 210 degrees. Should these
trends continue however probability of precipitation will be lowered a bit west of the
current line. Similarly the marine layer has largely stabilized
areas east of the line and probability of precipitation generally slight chance to low
chance there. Rain chances will increase towards the end of the
period and it is tough to say which areas will be favored. The
coast will benefit from some channeled vorticity while height
falls and cooling aloft impinge from the west.
Short term /Wednesday through Thursday night/...
as of 200 PM Tuesday...low pressure aloft across the southern
Appalachians at the start of the period will remain cutoff from
the progressive flow to the north through Thursday. The low is expected
to drift across the Carolinas and southeast states Wednesday and Thursday and
then finally open up...eventually getting absorbed into the large
cyclonic circulation across eastern Canada and the northeast
states late week and during the weekend.
Colder air aloft will make its way into the eastern Carolinas
later Wednesday and Wednesday night and this will help to steepen lapse rates
and elevate instability levels into Thursday. At the same time...
shortwave troughs rotating around the upper low will Foster
organized convection. Thunderstorms should be slow movers given
the light winds throughout the column. This activity is expected
to train...which over time...could lead to excessive rainfall in
some communities. Thus...in addition to high probability of precipitation...will highlight
heavy rain risk as precipitable water values will remain near or
above 1.5 inches on Wednesday. These values will begin to come down
slightly by Thursday. The strongest storms may produce some hail...
especially late in the day Wednesday and Wednesday night and into Thursday as well
given the core of coldest air at 500 mb will move across the area.
Developing inverted v soundings and dry air in the middle levels may
lead to strong or damaging wind gusts in the strongest thunderstorms.
Model soundings show the middle levels will be drier Thursday and this is
when the inverted v soundings will also be most pronounced.
Long term /Friday through Tuesday/...
as of 200 PM Tuesday...unsettled conditions will prevail through the
period with subtle middle level troughing and deep moisture over the
southeast into next week. Remains of dissipating front will sag
south across the area this weekend but by the time it reaches the
area there will be little of it left. Afternoon showers and
thunderstorms are pretty much a given with lingering surface
boundaries and middle level shortwaves working to enhance activity at
times. Locating/timing these feature at long ranges is quite
difficult at best so plan to continue carrying high chance pop through
the period. Activity may not just be diurnal in nature given
potential shortwave enhancement. A second front will try to drop in
from the northwest late in the period but it too is likely to stall
before reaching the area. Cloud cover and precipitation will tend to keep
highs a little below climatology but hold lows a bit above climatology.
Aviation /18z Tuesday through Sunday/...
as of 18z...an upper low centered to our west will send US a series
of short waves over the next 24 hours. This combined with high
precipitable water...old outflow boundaries...and the sea breeze
boundary will all contribute to multiple rounds of convection
through the forecast period. It will be difficult to time the
convection...but it is safe to say the showers and possible storms
will be most numerous in the afternoon and early evening...however
overnight convection is also expected. Mainly southerly flow is
forecast. Look for ceilings to lower overnight with possible IFR by
Extended outlook...a good chance for showers and thunderstorms
Wednesday through Sunday...mainly in the afternoon. Brief periods of
IFR conditions possible in the showers/thunderstorms.
near term /through tonight/...
as of 150 PM Tuesday...cold front to our west may still make
enough southward progress to get into at least the northern part
of the area tonight especially if 'pushed' a bit by rain cooling.
Otherwise most of the area will stay in a very light prefrontal
flow regime with a predominantly southerly component. The sea
breeze and rain cooled outflow may lead to short-lived deviations
from this trend.
Short term /Wednesday through Thursday night/...
as of 200 PM Tuesday...there is a high risk for numerous to
widespread showers and thunderstorms for much of the period.
A weak cold front will limp into the area from the north and northwest before
stalling and then wavering across the area during this forecast
period. The front should become ill-defined Friday and Sat. Light
and variable winds Wednesday morning will settle on southeast during the day
Wednesday. Southeast to S winds Wednesday evening will again become light and variable
Thursday morning with light winds likely through the remainder of the
period. Wind speeds will be 10 knots or less for much of the period...
but up to 10 to 15 knots later Wednesday and Wednesday evening. Seas will be 2 to 3
feet throughout. Mariners should expect higher winds and seas in
Long term /Friday through Sunday/...
as of 200 PM Tuesday...winds through the period will generally be
light with a northerly component. Direction is likely to be
influenced by smaller scale features at times...with convection and
sea breeze being the most likely. Wind speeds generally 10 knots or
less through sun will keep seas 2 to 3 feet.