Area Forecast Discussion
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FXUS62 KRAH 270752
Area Forecast Discussion
National Weather Service Raleigh NC
352 AM EDT SAT AUG 27 2016
An upper level ridge will persist over the region through the
weekend. An upper level disturbance over the Atlantic will then
drift west and linger over the Southeast states early next week.
.NEAR TERM /THROUGH TONIGHT/...
As of 350 AM Saturday...
The 595dm ridge at 500mb is centered eastern KY last evening has
shifted over VA, per latest RAP analysis. Meanwhile, a weak low-
level trough, evident at 925mb in regional VAD wind profiles, is
slipping into the northern coastal plain and will washout today as
east-northeasterly flow sets in over the CWA. There is little
other evidence of the trough, and the few showers the HRRR was
showing popping around Halifax/Edgecombe/Nash counties have yet
to materialize, and probably won`t. Diurnal convection should fire
by early afternoon, however, as moist easterly flow and a slight
reduction in 850mb temps help weaken the CAP over NV, resulting in
1000-1500 j/kg MLCAPE. Forcing is otherwise very weak, and the
CAMs favor development in the southern Piedmont/coastal plain,
drifting southwest with time. With the core of the 850mb thermal
ridge still northwest of the Piedmont and mixing fairly similar to
yesterday, temps should be within a 2 or 3 degrees of yesterdays
highs in many spots tempered slightly by the easterly flow; 92-96.
This will keep conditions rather humid, but heat indices should
stay below 105.
Diurnally driven convection will die off this evening, yielding
to mostly clear conditions for the first half of the night and
increasing probability of stratus in easterly flow over the
coastal plain. lows 70-74.
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 350 AM Saturday...
The upper level ridge will continue a northward drift on Sunday,
while an upper disturbance over the Atlantic slowly drifts west
and undercuts the ridge, essentially settling over the Southeast
US through early next week. This disturbance along with increasing
moisture flux off of the Atlantic - PW increasing to around 2
inches - and weak to moderate instability will likely result in
enhanced convective coverage along the coast, drifting inland
through the day. Coverage will be best over the coastal plain,
diminishing with westward extent into the Piedmont where deeper
mixing and drier air will limit coverage. Some of the showers may
continue into the evening and overnight hours, mainly across the
southern coastal plain. Highs 89-92, warmest west. Lows 69-74.
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 310 PM Friday...
Medium range models appear to be coming into a bit better agreement
on showing the weak tropical low located between the northeastern
coast of Cuba and the central Bahamas shifting west-northwestward
across FL and into the far eastern Gulf of Mexico/near the western
FL coast this weekend into early next week before slowly lifting
north and eventually northeastward. However, there is still a lot of
uncertainty with regard to the timing of this system and timing of a
s/w trough approaching/amplifying in the northern stream mid to late
week (which will play a key role in our precip chances mid to late
Further northward across our latitude, a weak mid/upper level low is
forecast to move westward late Sunday into Monday and into eastern
portions of the Carolinas. This will provide eastern/southeastern
portions of the area with a chance of mostly diurnal showers and
storms on at least Monday. The mid level low is forecast to linger
across eastern portions of the area on Tuesday, before being
suppressed by a approaching northern stream s/w trough.
However, with still a significant spread in some of the models and
ensembles with regard to the track and timing of the possible
tropical system and potential moisture possibly pulled northward and
across eastern portions of our area we will keep a chance of showers
and storms across eastern portions of the area through midweek. As
the northern trough further amplifies and shifts eastward across our
area an associated cold front will move through the area on Thursday
into Friday (with a possibly some showers and storms areawide
accompanying the front). High temps are expected to generally be in
the upper 80s to lower 90s, with mid to upper 80s on Friday. Lows
are expected to be near 70 to the mid 70s. However, if the track
and/or intensity were to change with the aforementioned tropical
system, then High temps may be lower midweek.
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
As of 205 AM Saturday...
VFR conditions will generally rule through the current TAFS period
with high pressure aloft over the region. There is a weak and
shallow trough that will slip into the area tonight, with
northeasterly winds to follow on Saturday. Some hi-res model
guidance indicates a few showers could pop up in the coastal
plain early this morning, near RWI if they did, but confidence is
rather low given no ongoing showers. Otherwise, just some pockets
of MVFR vsbys will be possible prior to sunrise.
Widely scattered showers and storms are possible this afternoon,
though most should develop to the south and west of the TAF
sites, and then drift further southwest, limiting the impacts at
Long Term: Low rain and thunder chances will
prevail for the next several days keeping conditions mostly dry
with some isolated to scattered convection during the afternoon
hours, particularly across the east. Otherwise mostly VFR
conditions are expected.