Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 300750
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
350 AM EDT Sun Apr 30 2017

.SYNOPSIS...
High pressure will extend across the area from offshore through
early Monday with warm and humid conditions continuing. A cold
front will bring a likelihood of showers and thunderstorms late
Monday into early Tuesday. High pressure will follow for the
mid-week period. A Low pressure system will impact the region
Thursday into Friday amd may bring widespread showers and
thunderstorms and heavy rain.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Sunday...Light southerly flow continues with very
humid air mass over the area this morning. Winds slightly lower
than last night has allowed for some patchy fog. Moisture
profiles show a shallow saturated level once again below 1k ft.
Looking around at obs, many sites to the south and west of local
area were reporting decks of stratus right around 800 to 900
ft. Have included several hours of these low clouds into the
morning before they lift leaving some strato cu and cirrus
around this afternoon. Overall expect a fair amount of sunshine
this afternoon. Temps early morning will remain right around 70
degrees which will jump start the temps to continue well above
normal temps for today. Should see max temps in the mid 80s most
places. Although the temps will be running several degrees
above normal today, records will be tough to beat most places
except perhaps for North Myrtle Beach.

Record max temps around the area for today
Wilmington 92 set in 1974
North Myrtle Beach 83 set in 2007
Florence 94 set in 1981

Have included a brief period of very slight chc pops west of
I-95 this afternoon as the upper ridge begins to slip east
losing the strong cap aloft. A deep trough will drive a cold
front toward the Carolinas by Monday morning. Although the front
remains well west at the end of the this period, the gradient
will tighten and expect increasing winds through tonight. All
pcp associated with the cold front will hold off until Monday.
Soundings continue to show very shallow moisture in place once
again tonight but dewpoint temps seem a bit lower so not as
confident. Overnight temps will once again remain a good 10
degrees above normal in a unseasonably warm and humid air mass.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Chances for convection increase on Monday
as a cold front moves east across the coastal Carolinas as an
upper trough transits across eastern CONUS. High pressure over
the western Atlantic will retreat east as the cold front
approaches, with spotty late afternoon convection increasing
into the likely category from west to east Monday evening as the
front moves across the forecast area. A consensus of guidance
has the precip well offshore by daybreak on Tuesday. Post-
frontal airmass is very dry and a bit cooler. Steady SW flow in
advance of the front will maintain above-normal temperatures on
Monday, with highs in the lower to mid 80s and lows in the lower
to 60s. Tuesday will be a bit cooler although still above
normal, with highs of around 80 and lows in the upper 50s and
lower 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 315 PM Saturday...High pressure will remain in place
Wednesday with slightly warmer temperatures but continued dry
weather before it shifts offshore Thursday. This occurs in
response to a deep mid-level trough digging into the middle of
the country and then evolving across the eastern CONUS into the
weekend.

There exists two distinct camps in the guidance: the GFS has
this low cutting off and dropping southeast through the end of
the period. The CMC/ECM have a similar pattern initially to the
GFS, but the upper low drifts north before cutting off over the
Northeast. The biggest difference between the guidance appears
to be the evolution of the ridge across the middle of the
country. The CMC/ECM keep the ridge axis aligned N/S, while the
GFS produces a more tilted NE/SW ridge which suppresses the
upper low. The agreement between the ECM/CMC tends to favor that
solution a bit more, despite the fact that the GFS has been
consistent and we had a similar setup just last week so there is
precedent. The evolution of this upper pattern is critical
because, while all scenarios support showers and thunderstorms
late Thursday and Friday, the CMC/ECM would dry things out for
the weekend, while the GFS would maintain unsettled and possibly
very wet weather for several days. Without a clear solution at
this time range, will hedge with a WPC favored blend of guidance
but with a bit more weight on the drier ECM by the weekend.
This would also bring much cooler temperatures to the region
Fri/Sat with highs and lows falling below climo.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
As of 06z...Although there is a decent low status deck across
many TAF sites south and west of local area, confidence is lower
tonight for prevailing IFR/LIFR ceilings. Soundings and moisture
profile continue to lock in moisture right below 1000 ft in this
unseasonably humid air mass over the area. Have included a tempo
group between 06z and 10z at all TAF sites for LIFR stratus deck
lifting after sunrise, through the morning and maintaining some
MVFR stratocu and also some cirrus through the aftn. Southerly
winds are slightly lower overnight into early this morning and
therefore may see some MVFR fog but have not included in TAFs
for now as winds were remaining up near 4 to 5 kts. Ridge slips
east through this aftn and allows for convection to develop a
bit closer to inland TAF sites but have held it to the west and
therefore did not include any shwrs. Soundings and guidance hint
at another night of low clouds for Sunday night and therefore
put some SCT lower ceilings at the end of TAF period.

Extended outlook...Periods of IFR/MVFR conditions are possible
in showers and thunderstorms late Monday into early Tuesday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Sunday...Southerly return flow will continue around
high pressure well offshore. Expect winds 10 to 15 kts today
with an uptick due to sea breeze in the aftn where gusts could
reach over 20 kts. By tonight the gradient will tighten as a
cold front nears the Carolinas from the west. Expect winds to
increase up to 15 to 20 kts with higher gusts after midnight.
This will drive seas up from 2 to 3 ft today to 3 to 5 ft after
midnight and could possibly see a few 6 fters by Mon morning.
Precautionary conditions will exist after midnight tonight with
a small craft advisory launched for after this period.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 AM Sunday...Increasing SW flow in advance of the next
cold front has prompted the issuance of a Small Craft Advisory
for Monday afternoon and night. By Monday night seas will have
built to 4 to 7 ft, although winds may slacken in the pre-dawn
hours of Tuesday as the front makes its close approach to the
waters. Expect SCA to be short- lived as post frontal surge will
be modest and offshore, with seas decaying back before 6 ft by
Tuesday afternoon.

LONG TERM /WEDNESDAY THROUGH THURSDAY/...
As of 315 PM Saturday...A secondary surge flips winds around to
the NW by Wednesday at less than 10 kts. As the high shifts
offshore into Thursday, southerly winds will ramp up quickly
becoming 15-25 kts, driving seas back to 4-7 ft after being just
2-3 ft much of Wednesday. An SCA will likely be needed
beginning late in the extended.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from noon Monday to 8 AM EDT Tuesday
         for AMZ250-252-254-256.

&&

$$

NEAR TERM...RGZ
SHORT TERM...REK
LONG TERM...JDW
AVIATION...RGZ



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