nc discuss
Office: ILM
FXUS62 KILM 181330
AFDILM
Area Forecast Discussion
National Weather Service Wilmington NC
930 AM EDT Sat Aug 18 2018
.SYNOPSIS...
High pressure offshore will maintain warm and humid summertime
weather, with a chance of showers or a thunderstorm each day. A
cold front is expected to cross the coast late next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 915 AM Saturday...Morning visible satellite imagery shows
mid-level cloud cover advancing across the forecast area. There
are patches of low stratus across Darlington and Marlboro
counties that will mix out over the next couple of hours,
however general trends through this evening will be for cloud
cover to increase ahead of a shortwave making its way across
middle TN this morning. Latest hi-res guidance is indicating a
delayed arrival of associated convection. Although 12Z area
soundings are supportive of scattered non-severe thunderstorms,
the main forcing appears to arrive in the western CWA after 00Z
Sunday, so will reflect this in the upcoming forecast update.
Any shower and thunderstorm development today would initiate
first on the sea breeze front, followed by low chances far
inland by late afternoon.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 342 AM Saturday...'Unsettled" as elevated precipitable
water, strong August heating, and surface boundaries all come
into the mix, spurring smatterings of convection about the
region this period. GEFS surface to 500 mb 'shear magnitude'
values are low, and overall severe threat is low this period.
That said, Sunday a localized microburst is possible due to
layer of dry air above 20 KFT, boosting DCAPE. CB towers often
propel to drier upper reaches after boundary collisions or cell
mergers, so a non-zero downburst wind hazard, and localized,
looks favored moreso Sunday. A weak to moderate steering flow
and high column moisture may lead to brief minor flooding in
spots due to training or back-building torrential rainfall.
Max-T a few degrees above normal, and Min-T even more above
normal.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 300 PM Friday...An active period of weather looks likely
much of the extended as a series of fronts/troughs impacts the
Southeast. The net result will be an extended period during
which at least scattered convection is possible each day. Max
temperatures will be seasonable, reaching the upper 80s to lower
90s through Wednesday before a front in the area results in max
temperatures in the low to middle 80s for Thursday and Friday.
Mins should generally be in the low to mid 70s but a few upper
60s are possible well inland Thursday night.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
As of 11Z...Challenging aviation conditions arrive later this
afternoon in the form of thunderstorms. The activity should
begin inland mid to late afternoon and advect to the coast by
late afternoon into the evening. Some MVFR to even fleeting IFR
conditions are expected.
Extended Outlook...Precipitation chances will be fairly high
through Monday. Mainly diurnal thunderstorms will continue into
mid week.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 915 AM Saturday...Buoy obs this morning are showing some
gusts of 20 knots, with an occasional gust to 25 knots, however
sustained winds are clustered around 15 knots. Seas are running
around 3-4 feet. Trends will be for southwest winds to increase
during the afternoon and overnight as a mid-level shortwave
pushes into western NC, and shoves a surface trough towards the
coast. No significant changes will be made to the forecast with
this mornings update other than to add mention of some gusts in
excess of 20 knots.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 342 AM
Saturday...Not as easy marine period a SCEC or SCA cannot be
ruled out, mainly because of gusts near 25 kt. This will result
in a bumpy marine period both Sunday and Monday, as high
pressure offshore interacts with a surface trough inland,
bringing blustery SW winds. Scattered TSTMS will prevail this
period and radar updates are suggested. Cloud to sea lightning
may be active at times. The sea spectrum will just about all
wind waves with dominant wave periods around 5 seconds, and thus
steep wave faces.
LONG TERM MARINE /TUESDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...Overall, SW winds in the 10 to 15 KT
range can be expected through the long term period. Seas will
run 2 to 4 FT through much of the period, though 3 to 5 footers
are possible northern waters Tuesday into early Wednesday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Beach Hazards Statement until 8 PM EDT this evening for SCZ054.
NC...Beach Hazards Statement until 8 PM EDT this evening for NCZ106-
108.
MARINE...None.
&&
$$
SYNOPSIS...MJC
NEAR TERM...CRM/SHK
SHORT TERM...MJC
LONG TERM...RAN
AVIATION...SHK
Office: MHX
FXUS62 KMHX 181120
AFDMHX
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
720 AM EDT Sat Aug 18 2018
.SYNOPSIS...
High pressure will extend over the area from well offshore
through the weekend with a weak trough over the central
piedmont. A weak cold front will drop into the northern
forecast area Monday and Monday night, then lift back to the
north Tuesday. Another cold front will approach the area late
next week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 715 AM Saturday...Composite radar indicating showers and
thunderstorms well offshore in the Gulf stream, otherwise no
precipitation across our region with mostly fair skies with high
cloudiness. Deep moisture advection in eastern NC coupled with
an approaching mid-level trough will lead to increased chances
of showers and thunderstorms across our CWA, especially later in
the day. Precipitable water values will increase to more than
2.3 inches by late today and a marginal threat of heavy rainfall
exists for northern portions of the CWA. Per a consensus of the
high-resolution models, think convective activity will be
somewhat limited with the sea breeze during the afternoon with
more widespread storms to occur later in the afternoon into the
evening ahead of approaching trough. Will continue previous
forecast showing 20-30 pct PoPs with the seabreeze earlier in
the day, with likely PoPs over the western and northern CWA by
late afternoon. Before the more widespread precipitation
arrives, high temperature should be able to reach the upper 80s
to lower 90s inland.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
As of 340 AM Saturday...Higher resolution models such the NSSL
WRF, HRRR and WRF ARW show a line of showers and thunderstorms
entering the far northwestern CWA during the late afternoon and
crossing the CWA during the evening before moving offshore after
midnight. Will continue with previous forecast of likely PoPs
overnight. Clouds, precipitation and southwest breezes will hold
low temperatures in the mid 70s.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 3 AM Sat...A mean upper trough is forecast over the
Eastern US through the period while low level southerly flow
continues to circulate a very moist airmass across our region
with PW values AOA 2". The favorable combination of forcing
aloft and moisture/instability in the low levels will result in
unsettled conditions through next week with precipitation
chances at or above normal and temperatures at or slightly below
normal. Shower and thunderstorm chances increase above
climatological norms through most of the period as conditions
become favorable for scattered to numerous showers and thunderstorms.
Will continue chance to likely pops. Expect highs in the 80s
through the period.
WPC has the region outlooked in a Marginal Risk for excessive
rainfall Sunday. Expect best precip chances inland during the
afternoon, then likely shifting towards the coast overnight.
Locally heavy rainfall will be possible. A weak front is
forecast to drop southward into the northern forecast area
Monday and Monday night, then lift back north Tuesday. Another
cold front will approach the area late next week. The models are
now bringing the front into the area early Thursday, then
stalling it along or just off the coast into Saturday.
&&
.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
Short Term /through 12Z Sunday/...
As of 715 AM Saturday...No major changes this TAF cycle as VFR
conditions expected to prevail outside scattered to numerous
showers and thunderstorms later this afternoon and evening
before ending in the overnight hours. There should be a
sufficient breeze overnight to preclude fog formation.
Long Term /Sunday through Wednesday/...
As of 3 AM Sat...Scattered to numerous showers and storms will
produce sub- VFR conditions at times through the period. In
addition conditions will be favorable for periods of low clouds
and fog early each morning.
&&
.MARINE...
Short Term /through tonight/...
As of 715 AM Saturday...No changes needed with this update as SW
winds continue at 15-20 knots with a few gusts around 25 knots.
Seas have not yet responded and are generally running 2-4 feet.
Winds should increase hold at 15-25 knots today with seas
building to 4-6 feet by later in the afternoon today and
tonight. Current Small Craft Advisory have things well handled
and no changes are needed at this time.
Long Term /Sunday through Wednesday/...
As of 3 AM Sat...Little change to the surface pattern of a
trough of low pressure inland and high pressure offshore into
early next week. Gusty SW winds 15-20 kt expected Sunday with
seas 3-5 ft...6 ft seas could linger across the outer central
waters through the day. Ongoing SCA may need to be extended into
Sunday. A weak front is forecast to drop into the northern
waters Monday and Monday night before lifting back to the north
Tuesday. W/SW winds 5-15 kt early Monday with seas 2-5 ft,
becoming E/SE across the northern waters and remaining SW south
of Hatteras. S/SW winds return for all waters Tuesday 5-15 kt
early increasing to 10-20 kt in the afternoon. Seas 2-4 ft early
building to 3-5 ft. Gradient tightens Tue night and Wed, with
SW winds 10-20 kt, could see occasional gusts to 25 kt across
the outer central waters with seas briefly building to 6 ft.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for AMZ135.
Small Craft Advisory until 8 AM EDT Sunday for AMZ152-154-156.
Small Craft Advisory from noon today to 6 AM EDT Sunday for
AMZ150-158.
&&
$$
SYNOPSIS...CTC/SK
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...CQD
AVIATION...CTC/CQD
MARINE...CTC/CQD
Office: RAH
FXUS62 KRAH 181503
AFDRAH
Area Forecast Discussion
National Weather Service Raleigh NC
1105 AM EDT Sat Aug 18 2018
.SYNOPSIS...
A mid and upper-level trough and surface cold front will
approach the region from the west today. The front is expected
to drop into Virginia and the western North Carolina on Sunday
and drift into central North Carolina by Monday morning.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1105 AM Saturday...
Just minor tweaks required to the near term forecast. Scattered to
numerous showers and thunderstorms still appear likely later this
afternoon into the evening hours.
12Z upper air analysis depicts a weak low level trough bisecting
central NC SW-NE. A mid level vorticity maxima and attendant mid
level trough was positioned over SE KY-NE TN. This feature projected
to lift newd today, with the trail end of the trough brushing our
far northern counties. This feature, crossing during optimal
heating/instability, will trigger scattered convection in vicinity
of the VA border by early-mid afternoon. Outflow boundaries from
these convective clusters will likely initiate additional convective
clusters farther south across the bulk of the Piedmont and Coastal
Plain late this afternoon. Another minor mid level s/w, currently
lifting eastward across the TN Valley, will be in proximity of
central NC after 00Z Sunday to trigger/sustain additional scattered
convection well into the night. Thus, forecast of likely PoPs
warranted at this time. The main caveat to possible reduction in
convective coverage will be the deep wly flow over the region. The
slight downslope component of the low level flow may limit
convective coverage, primarily along and south of highway 64. This,
however, should be overcome by the slight-moderately unstable air
mass in place this afternoon. While much of the Piedmont covered in
a stratus deck, this deck only 500-1000ft thick per pilot reports.
With additional heating/mixing, expect this deck to lift into a
scattered-broken cu field by mid day.
Severe convection parameters not overly concerning at this time.
While the atmosphere projected to become slight-moderately unstable,
the shear is weak/marginal at best, primarily along and north of the
I-40/85 corridor. Currently believe that the bulk of the storms will
remain below severe criteria, with isolated strong/damaging wind
gusts possible. Precipitable water values 1.8-2 inches will lead to
efficient rain production, supporting heavy/torrential downpours.
Localized flooding may become a concern for any convection that
clusters over an urbanized area.
Highs today dependent upon when convection develops. With most
locations near 80-lower 80s at late morning, lower 90s should be
achievable across the far south-southeast, with upper 80s/near 90
probable across the far north-northwest.
Scattered convection will likely persist into the overnight hours
before diminishing toward daybreak. Expect the scattered convection
to be most probable east and south, and less so across the
northwest. Muggy overnight with min temps in the low-mid 70s.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 355 AM Saturday...
The mid and upper level trough axis reaches the coast on Sunday
morning briefly resulting in a more westerly flow across
central NC before an additional short wave trough approaches
from the northwest late Sunday. The westerly flow will result
in a modest decrease in the precipitable water values and
somewhat weaker forcing for ascent. A surface cold front
stretching the from the DelMarVa Peninsula southwest into
western NC will drift south into central NC by Monday morning.
The result should be a continuation of the unsettled weather
pattern on Sunday with a bit more limited convective coverage
than today. After a period of morning clouds, scattered showers
and thunderstorms will develop during the afternoon and continue
into the early evening hours with the greatest coverage across
the eastern Piedmont and Coastal Plain where moisture and
instability will be more plentiful. It will be cooler with highs
in the mid 80s to around and lows Sunday night in the 69 to 74
range. -Blaes
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 400 AM Saturday...
A compact tropopause perturbation evident in WV satellite imagery
this morning over nwrn MN/sern Manitoba will amplify sewd, and
become increasingly apparent at 500 mb, across the middle Atlantic
states through early Mon, then offshore by 00Z Tue. Shortwave
ridging aloft will follow briefly later Mon through Tue, downstream
of a series of shortwave troughs forecast to amplify from cntl
Canada sewd across the Great lakes and the Northeast/middle Atlantic
region mid-late week.
At the surface, a frontal zone related to the compact perturbation
now approaching nwrn MN is forecast to have settled into cntl NC by
early Mon; and this feature is forecast to remain quasi-stationary
overhead until retreating newd into VA by Tue evening. The models
then suggest a lead upstream cold front, associated with the initial
trough amplification across the Great Lakes ,will settle across cntl
NC on Wed, preceded by a sharpening Appalachian lee trough, then
drift to the vicinity of the NC coast and stall Thu-Fri. Following
high pressure will meanwhile build from the upr Midwest/mid MS
Valley ewd to the middle Atlantic coast, while extending swd into
cntl NC.
Despite the shortwave ridging aloft early in the week, bufr forecast
soundings over cntl NC reveal little signal of a capping inversion
aloft; and as such, low level convergence --amidst rich BL moisture
characterized by sfc dewpoints generally in the lwr 70s-- should
focus scattered to numerous showers and storms maximized with
diurnal heating and generally moderate destabilization both Mon and
Tue. The passage of the upstream front on Wed will likely do the
same, particularly over the ern half of cntl NC, where low level
moisture will be less prone to mixing out behind the pre-frontal/lee
trough. Perhaps the biggest change from earlier guidance and
forecasts is the presence of surface ridge over the middle Atlantic
states, and consequent drier forecast for Thu-Fri, with the brunt of
convection during that time focused over our srn/sern counties and
points sewd, in closer proximity to the stalled frontal zone and
moisture in return/ely flow peripheral to the ridge.
The presence of the front(s) and focus for convection/clouds should
yield near to slightly cooler than avg high temps Mon-Wed, ranging
to slightly below avg ones in post-frontal high pressure Thu-Fri.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
As of 650 AM Saturday...
Sky conditions across central NC feature a bank of MVFR to patchy
IFR stratus across the western Piedmont including the Triad
terminals KINT and KGSO while VFR conditions with scattered, mainly
high clouds is observed across the eastern Piedmont and Coastal
Plain. CIG restrictions across the western Piedmont should
gradually improve through late morning.
An approaching upper-level trough and associated cold front will
initiate showers and thunderstorms in the early afternoon hours
across western and northern NC with the convection expanding and
shifting southeast across central NC during the mid afternoon to mid
evening hours. The best chance of CIG and VSBY restrictions in
thunderstorms at the KINT/KGSO terminals will be between 18Z and 00Z
and across the KRDU/KRWI/KFAY terminals from around 20Z-02Z.
Convective coverage will diminish during the late evening hours.
Areas of low stratus look possibly toward daybreak on Sunday across
the northern terminals including KIT/KGSO/KRDU.
Looking beyond 06z Sunday, the approaching cold front will stall
across northern and western sections of NC on Sunday and linger
across the region into early Tuesday resulting in periods of adverse
aviation conditions. The front will dissipate and lift north on
Tuesday with another cold front moving across the region on
Wednesday bringing an increased chance of adverse aviation
conditions. -Blaes
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Blaes
NEAR TERM...WSS
SHORT TERM...Blaes
LONG TERM...MWS
AVIATION...Blaes
