Area NWS Forecast Discussion
000
FXUS62 KILM 252029
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
429 PM EDT Fri Sep 25 2020

.SYNOPSIS...
Moisture from the remnants of Tropical Storm Beta and a
disturbance aloft will combine to produce areas of showers and
thunderstorms through tonight. Weak high pressure will settle
into the area midday Sat through Sun with above normal temps and
mainly dry weather. Showers and thunderstorms will increase
Monday and especially Tuesday ahead of a strong cold front. Dry
weather and below normal temperatures will follow for mid to
late week period of next week.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
Warm front has lifted to a Greenville, NC to Columbia, SC line
and has pretty much stalled out. This places the majority of the
FA within the warm sector. As a result, instability having
increased by the time of this discussion, the mid-level s/w
dynamics and even synoptic UVVS resulting from the FA being
within the vcnty of the right rear quadrant of a 300mb jet max,
as mentioned in the MPD 0796. Nevertheless, with PWs around 2
inches within the warm sector and capitalizing on the precip
processes, will have a threat for heavy rain producing showers
along with isolated/widely scattered tstorms for the remainder
of this afternoon through late tonight. During the pre-dawn Sat
hrs, pcpn from off the Atlantic will become more dominant from
Cape Fear northward. And by Sat daytime morning, the majority of
the pcpn will have moved northeast of the FA. QPF across the FA
for this event, will run a widespread 1 to 1.5 inches. Some
spin-ups noted on KLTX 88D, primarily in the low levels, could
result in a few tornadoes and/or waterspouts over the adjacent
Atl waters. Have continued to highlight both the heavy rain and
localize flooding, and the severe potential in the Hazardous
Weather Outlook. The mid-level s/w trof axis will swing NE-E of
the FA early Sat, with some weak subsidence in it`s wake. This
will end the pcpn from this system. Enough instability develops
Sat aftn, mainly along a weak sea breeze boundary or what`s left
of a the warm front. Did include low chance for convection. Sat
night looks quiet with weak sfc high pressure across the FA. Min
temps tonight may stay around 70, Sat night may see 65-70 range.
Max temps Sat went at or a degree or 2 above guidance.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The period will begin with mid level ridging across
the area but a dampening shortwave moving across the Tennessee
Valley will make its presence short lived. At the surface weak high
pressure will give way to a broad south to southwest flow keeping
the area slightly unsettled through the period. The highest pops
(low chance range) occur Monday as whats left of the shortwave moves
across. Temperatures will be somewhat above climatology across the
board.


&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Still some uncertainty with regards to the extended
period. A potent shortwave will dive down into the upper Mississippi
Valley with a piece of this energy breaking off and cutting off to
the south. Both the GFS and ECMWF have this but the GFS is more
progressive with the system and the cold front associated with the
overall system moving across Tuesday night. The ECMWF is about a day
slower. Maintained the pops extending into Wednesday late due to the
uncertainty. Temperatures will be above normal ahead of the front
and drop down to near or just a little below normal in the wake of
the system whenever it occurs.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
The Cape Fear region is still lingering in overcast VFR, but
MVFR is starting to overtake the area. Showers are becoming more
widespread, as they enter stage left into the area. MVFR should
dominate over the next several hours, with occasional IFR in
heavier showers. Rain should taper off near the inland sites
after 02Z, while lingering around the coastal sites into 03-04Z.
Increasing confidence of seeing fog tonight, with restrictions
going toward IFR and even LIFR inland, while being more MVFR at
the coast. Guidance suggests fog lingering through the mid-
morning hours of Saturday.

Extended Outlook...VFR Saturday afternoon. MVFR to IFR
visibility in radiational fog could develop Sunday morning.
Otherwise, VFR conditions are expected going into early next
week.

&&

.MARINE...
Tonight through Saturday Night...
The tightened sfc pg between Atlantic sfc high centered well
offshore from the Carolinas and the remnants of Beta moving
across the Carolinas. This will result in SE-S winds around 15
kt across the local waters late this aftn thru early Sat
morning. Winds will veer to the SSW-SW during Sat at 10-15 kt,
dropping to 5 to 10 kt Sat night. Wind driven waves will become
the dominate production of significant seas with periods ranging
from 4 to 5 seconds. An underlying ENE swell at 9+ second
periods will continue to degrade during this period. An ESE-SE
swell at 7 to 9 second periods, associated/produced by an
inverted sfc trof moving along the periphery of the Atlantic
high, could mix in with wind waves come Sat or Sat night. Will
keep seas elevated 3 to 5 ft tonight through Sat night, with the
main effects from this swell felt from Cape Fear northward.

Sunday through Wednesday...
Conditions for the coastal waters look decent through the
period. Initially a southeast onshore flow will be in place for
a couple of days with wind speeds ten knots or less. A cold
front moving across mid week will shift the flow offshore but
not necessarily strong as the cold air advection isn`t too
impressive. Speeds will increase to a range of 10-15 knots
however. Significant seas will be 2-3 feet early increasing to
2-4 feet late.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...DCH
NEAR TERM...DCH
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...IGB
MARINE...DCH/SHK

NWS ILM Office Area Forecast Discussion