Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
832 PM EDT Sat Jul 12 2014
fair high pressure will remain over the area through Sunday.
Hot temperatures are expected Monday and Tuesday ahead of a
cold front. The front is expected to stall along the Carolina
coast from middle week into next weekend...bringing a good chance
of showers and thunderstorms...and slightly cooler than normal
Near term /until 6 am Sunday morning/...
as of 830 PM Saturday...pleasant conditions were settling over the
eastern Carolinas this middle evening under clearing skies and a
relatively dry air mass. A few showers have popped up just east of
the sea breeze boundary now well inland...but longevity has been
lacking due to unable-supportive dry middle-level air and waning solar
energy. This sets up up for nearly a typical Summer overnight
period except perhaps drier and a few degrees cooler than normal.
We have yet to log any complaints about this expected weather so
far tonight at the National Weather Service office.
Isolated showers over land will further dissipate and the focus
may shift to the coastal waters and South Coast but isolated
activity at best expected. Minimums early Sunday upper 60s inland
and lower 70s near the coast.
Short term /6 am Sunday morning through Monday night/...
as of 330 PM Saturday...only tweaks needed to the previously
issued short term from last night. Models continue with major
longwave trough amplification aloft across the eastern 1/3rd of the
U.S. During this time period...with a reflection of these changes
beginning across the forecast period on Monday. This upper trough
axis to remain west of the ilm County Warning Area and positively tilted during
For Sunday...after residual morning patchy/areas of fog...model
time height displays indicate subsidence and dry air above 850 mb
reaching all the way to the immediate coasts of the bi-state
forecast area. Other than isolated sea breeze induced
convection...have pretty much kept a null pop day across the ilm
County Warning Area...somewhat unusual for middle July. Have stayed close to a model
MOS guidance consensus for temperatures Sunday into Sunday night.
For Monday...changes to begin. A rather robust central Carolinas
surface trough ie. Piedmont trough...is prognosticated to develop. Between this
trough and the well amplified Bermuda high ridging/extending
westward across the forecast area...the surface pg will tighten resulting in
SW-west-southwest winds increasing across the forecast area during Monday and continuing
through Monday night. The afternoon/evening sea breeze will provide
some convection as moisture increases through the atmosphere column through
Monday night. The Piedmont trough west of the ilm County Warning Area should fire
some convection that may drift/move into the western portions of
the ilm County Warning Area before the days insolation ceases. Overall...probability of precipitation will
only peak in the chance criteria. For temperatures leaned on the higher
side of model MOS guidance for both Monday maxes and mins. The SW
flow Monday night will remain active across the entire ilm County Warning Area
which will negate any radiational cooling possibility. Look for
mins especially closer to the coast to hover around 80 all night.
Long term /Tuesday through Saturday/...
as of 3 PM Saturday...rather impressive upper trough over the Great
Lakes on Sunday. Although centered over the lakes it will be deep
enough to veer local flow to southwesterly and moisture should be pretty
deep. Pair this with a healthy Piedmont trough and the stage appears
to be set for a healthy distribution of thunderstorms. Wednesday
could offer similar or even high rainfall distribution as the upper
wave spreads even more cyclonic curvature. Meanwhile at the surface
the trough will be overtaken by a cold front. The boundary may stall
right along the coast on Thursday shifting the best chances for rain
along with it...but the GFS now implies that trailing upper energy
draws it inland roughly the length of our entire County Warning Area. European model (ecmwf) does the
same but is slower. In the end probability of precipitation will still likely remain a bit
elevated with respect to climatology but not as high as early in the
period during the pre-frontal regime.
Aviation /00z Sunday through Thursday/...
as of 00z...conditions are favorable for another round of MVFR/IFR
visibilities early Sunday morning due to fog. Clear skies...calm winds and
dewpoints around 70 should promote fog development after 06z...with
the lowest visibilities expected inland at kflo/klbt. IFR appears most
likely at these terms between 09-12z based on guidance and forecast
soundings. Tempo IFR visibilities are possible along the coast as well...
most likely at kcre...though MVFR visibilities should prevail. Once the fog
dissipates...Sunday will be VFR with south winds increasing to
around 10 kts in the afternoon. Although a stray sea breeze thunderstorm
cannot be ruled out after midday...our taf sites will likely remain
dry through the period.
Extended outlook...increasing chances for showers/thunderstorms and MVFR
conditions Tuesday through Thursday as a cold front stalls over the
near term /through tonight/...
as of 830 PM Saturday...high pressure offshore will result in a
southeasterly flow through the early evening...becoming south-
southwest after midnight. The pressure gradient will remain
relatively weak and winds are expected to remain 10 knots or less.
Can not rule out a few showers or thunderstorms advecting into the waters
in southerly slow late tonight. Seas around 2 feet in a mix of southeast
waves 1-2 feet every 8-9 seconds...and south-southeast waves 1 foot every 4-5
seconds. Isolated thunderstorms possible on the waters...but mainly late
tonight into daybreak Sunday...remaining widely separated.
Short term /Sunday through Monday night/...
as of 345 PM Saturday...scec conditions from both winds and seas
may be realized Monday through Monday night.
Dissipating old frontal boundary just east and south of the ilm
coastal waters will start out the short term. It will give way to
ridging from the strong Bermuda high centered well offshore/high
seas. The surface ridge axis prognosticated to remain south of the ilm
coastal waters as it extends westward. This will result with a
south-southwest-SW wind direction with benign wind speeds. Winds may possibly
initially begin variable 10 knots or less early Sunday.
The Piedmont surface trough across the central Carolinas is prognosticated to
develop later Sunday...becoming more of a player to the winds on
Monday as the surface pg between the trough and Bermuda ridging
tightens. Look for wind speeds to increase to a solid 15 to 20 knots
during Monday through Monday night. Significant seas will remain
docile on Sunday...except 3 foot sea breeze induced wind-chop near
shore. For Monday...wavewatch3 and Swan models both increase the
significant seas across the local waters...due to building wind
driven waves and the Bermuda high induced ground swell...albeit
small. The both will combine to build seas to 5 feet...possibly up
to 6+ feet especially off Cape Fear...later Monday through Monday
Long term /Tuesday through Thursday/...
as of 3 PM Saturday...a rather tight gradient on Tuesday.
Southwesterly flow the result of a pinch between large area of
Atlantic high pressure and a well defined Piedmont trough. Should
5 feet seas become prevalent enough then scec could be needed
especially for northern zones. As the trough drifts to the east on
Wednesday this gradient may be nudged just out to sea enough for
about a category decrease in wind...allowing seas to fall perhaps
a foot in height. Cold front stalls right along the coast on
Thursday keeping winds west to SW and more seasonably light. Another
approximate 1 feet decrease in the larger waves expected.