Area Forecast Discussion
Issued by NWS Wilmington, NC

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578
FXUS62 KILM 301816
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
216 PM EDT SAT JUL 30 2016

.SYNOPSIS...
High pressure, both surface and aloft, will continue to bring
oppressive heat and humidity to the region today. The high will
break down late this weekend and early next week, allowing a cool
front to drop slowly across the area by Wednesday. This will
bring a high chance for thunderstorm activity during the mid-week
period of next week. In addition, daily temperatures will drop
back to near normal for the middle and end of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 12 PM Saturday...The heat advisory has been expanded to
include all of the forecast area until 8pm this evening. Dry air
has mixed down and dewpoint temps have lowered over much of the
area down closer to lower 70s. Although dewpoints have dropped,
temps have soared well into the 90s and the combination has
produced widespread heat indices above 105.

Moisture is abundant today with pcp water values up above 2 inches.
Although we are slowly losing our cap on convection as Atlantic
ridge slips away over the weekend, still holding on to the east and
southeast and expect convection to basically remain less widespread
today.

Cu development occurred by late morning and radar showed first
storms popping along sea breeze as winds backed toward the south
along the coast converging with more southwesterly winds inland.
This boundary should remain closer to the coast with the stronger
SW component to the flow and will be steered off to the NE
running mainly parallel to the coast.

Other storms were developing along trough inland and will reach
into inland areas from the W-SW later this afternoon through this
evening, dissipating by late evening. Temps will remain above 80
through much of the evening and overnight along the coast, but
will drop into the mid 70s well inland by daybreak.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 315 AM Saturday...The pattern still doesn`t change much with
the Piedmont trough in place and deep moisture will continue
overhead. A cold front will approach from the north late Monday
night. The models are indicating a chance of convection throughout
most of this period. With the high precipitable waters any
thunderstorm that forms is likely to produce heavy downpours and
frequent lightning. With the increase in cloud cover, ever so
slightly cooler 850 mb temperatures, and possible convection the
high temperatures will be 2 to 3 degrees cooler on Sunday (Max temps
92 to 96 degrees). This in turn will keep the heat indices just
below the heat advisory criteria.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 200 PM Saturday...Pattern changes occur Tuesday as a
trough digs along the east coast driving a cold front into the
Carolinas. This front will be accompanied by good chances for
showers and tstms Tue/Wed as it crawls southward before
dissipating on Thursday. This dissipating is cause by the parent
trough pushing off to the east, allowing for mid-level ridge to
re-blossom into the Mid-Atlantic. The ECM/CMC stall this front
longer with better convective chances as the trough is slower to
eject to the east, but the GFS has ensemble support and its
solution is more represented by WPC and the inherited grids, so
will continue to hedge towards a warmer/drier solution late in
the week and into the weekend. Convective chances will drop back
to seasonable or slightly below, with temps right around climo
Fri/Sat, after a period of around or slightly below normal temps
with higher POP the first half of the extended.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 18Z...All the near term guidance, RAP, WRF and HRRR
indicate scattered convection to occur along the sea breeze.
Elsewhere, tstorm coverage will be isolated. As a result, have
included tempo groupings for tstorms along the coastal terminals
thru early this evening. Inland terminals will remain VCTS unless
coverage increases. The sea breeze will be slow to progress inland
as evidenced at MYR and CRE with latest winds still w to nw and
temps in the upper 90s. In the wake of the sea breeze, the coastal
terminals will see winds back to ssw at 10 to 15 kt whereas
elsewhere, winds will run wsw to sw at 10 to 15 with g20 kt.
Convection will taper by mid-evening across all sites. A low level
jet will likely keep winds active all night at the sfc, ie. sw at
5 to 10 kt, in turn keeping fog development at bay. For Sunday,
convection will likely begin to re-fire by late morning.

EXTENDED OUTLOOK...Isolated to scattered afternoon and evening
convection each day may result in localized MVFR/IFR conditions.
Each morning may also observe brief MVFR/IFR from fog and/or low
ceilings. Otherwise, expect VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...

As of 12 PM Saturday...Much of the same with the Bermuda High and
Piedmont trough over central NC dominating the weather. This will
keep SW winds winds over the waters of 10 to 15 knots, with a
spike late aftn into early evening due to influence of sea breeze
and inland trough. Seas will basically remain in the 2 to 4 ft
range through tonight with a low-level jet keeping winds up to 15
knots.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 315 AM Saturday...Only change to the current pattern is a
front will shift into the northern waters just before daybreak on
Tuesday will cause the winds to increase to 15 to 20 knots on
Monday night. Seas will remain in the 2 to 4 ft range through
this forecast period. There will be a chance for thunderstorm over
the waters through this period.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
As of 200 PM Saturday...A cold front will cross the waters during
Tuesday turning winds slowly from SW at 10-15 kts, to NW at 5-10
kts Tuesday night. This front will dissipate on Wednesday leaving
a diffuse pressure gradient as high pressure re-expands slowly
from the Atlantic. This will bring mostly East to SE winds
Wed/Thu, at speeds around 10 kts. Seas will be highest on Tuesday,
3-4 ft, as the SW winds and residual SE swell drive an amplified
spectrum. Behind the cold front, as the winds ease and become
variable, the wind wave will shift to the E/NE on top of the
residual SE swell, but seas fall to around 2 ft the latter half of
the period.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory until 8 PM EDT this evening for SCZ017-023-024-
     032-033-039-053>056.
NC...Heat Advisory until 8 PM EDT this evening for NCZ087-096-099-
     105>110.
MARINE...None.

&&

$$
SYNOPSIS...RGZ
NEAR TERM...RGZ
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...DCH



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