Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 242215
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
618 PM EDT SUN JUL 24 2016

.SYNOPSIS...
A ridge of high pressure will expand across the Carolinas bringing
uncomfortable levels of heat and humidity this week. Isolated to
scattered showers and thunderstorms are possible each afternoon
and evening.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 320 PM Sunday...Another day, another widespread set of 90+
temperatures as this hot July continues. Massive ridge continues to
evolve and expand across the southern tier, and heights/mid-level
temps have warmed today. The combination of these temps plus
dewpoints in the low to mid 70s has pushed heat index values to
around 105 degrees, and while many places are falling just short
will leave the HT.Y unchanged for now as slightly higher dewpoints
during recovery may push HI`s to 105 for a bit this evening.

This airmass is also very unstable, as evidenced by recent
mesoanalysis showing 1500-2000 J/kg MLCAPE. This is truly the only
forcing to drive convection today however, as the aforementioned mid-
level warming and drying is keeping mid-level lapse rates very weak,
and thus only the sea breeze boundary is strong enough to push
updrafts up into showers/tstms today. A few storms have fired along
this boundary, and the current POP grids reflect slow westward
advancement of SCHC. This activity will wane quickly after dark
though since no other forcing exists to tap elevated residual
instability. Mins tonight will remain quite warm as return flow
persists, dropping only into the mid 70s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
As of 320 PM Sunday...A subtle cooldown Monday will be followed by
even hotter temperatures beginning Tuesday as the expansive upper
ridge dominates the southern tier of the CONUS. Weak height falls
occur Monday, likely in response to a mid-level impulse moving
across Florida. While the mid-level flow becomes more SE than E, this
remains a drying direction, and PWATS are forecast to drop to around
1.25 inches. 850mb temps still up around 18C will support slightly
above climo temps, around 90 at the coast and low to mid 90s well
inland, but with slightly lower dewpoints as well, heat index values
will likely remain just below advisory criteria on Monday. While it
is rare to have a day in July around here without at least a few
diurnal tstms, the soundings suggest no activity on Monday, and will
keep POP silent. Return flow around Bermuda high will only allow
temps to fall Monday night into the mid 70s.

A hotter day forecast on Tuesday, and heat index values are again
expected to necessitate a heat advisory. The mid-level ridge builds
overhead once again and 850mb temps climb towards 20C. Persistent
moist return flow will allow dewpoint recovery even during the aftn,
so highs in the mid 90s combined with dewpoints in the low to mid
70s will cause heat index values to rise above 105 degrees. This
slightly more moist column will allow for at least a SCHC of tstms
along the piedmont trough and sea breeze boundary, before convection
wanes nocturnally and temps fall back in the mid and upper 70s by
Wed morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 320 PM Sunday...Little change required in the extended period
as the mid level pattern will feature slowly falling heights
across the east with a corresponding ridge out west. The relevant
surface features for the eastern Carolinas are the Piedmont trough
and Bermuda high pressure. The front associated with the trough
remains well to the north. The highest pops reside over the
weekend based on increasing PWs and the subtle trough. There is at
least a slight chance all days however and basically all periods.
No significant changes to the temperature forecast with basically
above normal readings across the board.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 00Z...High confidence in predominately VFR through the valid
TAF period. Some patchy ground fog is possible overnight, but not likely.
Little to no convection is expected tomorrow due to an increasing
subsidence inversion. South southwest flow is forecast, mainly
below 10 kts.

EXTENDED OUTLOOK...Isolated to scattered afternoon convection
Tuesday through Friday may create periods of MVFR/IFR. Otherwise
expect VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 320 PM Sunday...Other than the near shore southerly sea
breeze, which will weaken this evening, winds will be consistently
SW at 10-15 kts across the waters through tonight. This will allow
the sea state to remain unchanged from this aftn, and 2-3 ft seas
are forecast to persist thanks to an 8 sec SE wave and 4 sec SW wave.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 320 PM Sunday...Bermuda high remains into mid-week, driving
consistent SW winds across the waters. As temperatures warm however
and the ridging strengthens, wind speeds will increase from 10-15
kts Monday, up to 15-20 kts late Tuesday. The near shore waters will
be influenced by a strong sea breeze each aftn as well, producing a
slight backing in wind direction to the south along with a subtle
increase in speed. Wave heights will remain consistently around 2-3
ft, with an 8 sec SE swell and a 4-5 sec SW wind wave comprising the
spectrum.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 320 PM Sunday...Bermuda high pressure and the piedmont trough
inland will maintain the south to southwest flow through the period.
Speeds will be of the standard summertime variety with 10-15 knots.
Not a real clear signal of much enhancement via nocturnal low level
jetting at least to this point. Significant seas remain typical of
the season and modest wind fields with 1-3 feet.

&&

.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...SHK
NEAR TERM...JDW
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...43



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