Area Forecast Discussion
Issued by NWS Wilmington, NC-- Remove Highlighting --
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FXUS62 KILM 201947
Area Forecast Discussion...COR
National Weather Service Wilmington NC
333 PM EDT FRI MAY 20 2016
A weak storm system will bring showers and isolated thunderstorms
tonight. More thunderstorms are possible ahead of a cold front
Saturday afternoon and evening. An upper low will keep conditions
cool with a slight chance for showers through Monday. More summer
like weather develops by the middle of next week with above
normal temperatures and drier conditions.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --As of 300 PM Friday...Penny and nickel rain amounts will
transition to dimes and quarters overnight...as a stationary
frontal boundary straddled east to west across southern SC and
central GA lifts north as a warm front overnight and early SAT.
Satellite derived precipitable water sensors reveal 1.7 - 1.9"
along and in proximity of the boundary presently. The bulk of
rainfall associated with the offshore coastal trough will fall
into the ocean but coastal zones should receive some contribution
bleeding off this feature given the stout low-LVL easterly flow
per recent KLTX VWP scans and time height plot forecasts into this
evening...and weak upglide. Overall it appears 0.50 - 0.75" of
rainfall on average will descend on NE SC and SE NC now through
Saturday morning...equally distributed for the most part as 2
features (upper disturbance to the W and coastal trough E) impact
our eastern and western halves...and a broader encompassing warm
frontal passage as the 3rd trigger. While a rumble of thunder may
grumble overnight no severe threats are expected since column
winds and shear parameters are weak through the near term period.
Surface dewpoints are on their way up and this will maintain
elevated minimum temperatures overnight...63-69 mildest near the
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.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Primary headline here is a marginal risk of
severe TSTMS Saturday afternoon ahead of the cold front. Fruition
hinges on the degree of low-level heating/destablization from late
morning through afternoon...which is contingent upon getting cloud
breaks and warming up the ground. Plenty low-level moisture will
still be in place so this may not be an easy task and much if not
all of the morning should feature considerable cloudiness. Because
of the timing of the frontal passage Saturday night...the zone of
frontal convergence may not be a player except possibly west of I-
95. If the warm sector can reload however then the coupling of
DCAPE and modest Bulk Shear values could lead to a few severes.
The continued drying trend will take its toll on convective
coverage and strength into Saturday night and dwindling POP values
played. Sunday a cold pool aloft will slip off the mid- atlantic
coast. Lapse rates are highest north of us but enough instability
should trip off showers in scattered to isolated fashion Sunday
under a partly sunny dome. The coolest portion of the period is
Monday morning in the 50s...the mildest Saturday afternoon
reaching around 80.
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...Yet another closed upper low will plague the
east coast early next week...but fortunately will get kicked out to
the northeast by Tuesday. Residual lowered heights will exist
Tuesday...but late Tuesday and Wednesday ridging blossoms across the
southeast bringing a return to more typical summertime weather
through mid-week. After a chance for showers and storms beneath the
upper low Monday...Tue/Wed should be dry with more seasonable
temperatures. A brief return to increased POP is forecast
Thursday as a shortwave races across the mid-atlantic bringing
some mid-level forcing and slightly lower heights in an otherwise
warm and increasingly humid airmass. Thunderstorms will be
possible Thursday before ridging increases even more significantly
late in the period. This will bring a return to drier and
potentially above normal temps leading into the Memorial Day
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
As of 18Z...High pressure extends down through the Carolinas from
the north as coastal trough remains off the coast. Coastal
trough/warm front will lift north through tonight as low pressure
moves north. This will produce a shift in winds from E-NE to E-SE
through this evening and eventually more SW behind warm front
through early tomorrow morning. Overrunning type precip is
expected through much of the day as warm air out of the south
overruns the cooler NE-E flow. Periods of heavier rain and some
fog overnight will will reduce visibilities and lower ceilings to
IFR levels. As low pressure lifts off to the northeast Sat
morning, IFR will transition to MVFR conditions. Expect MVFR/VFR
by Sat aftn.
Extended Outlook...Expect MVFR/VFR Sat aftn with periods of IFR
in any isolated thunderstorms. Shwrs/tstms on Sat decrease with
improvement to VFR on Sunday through the end of the extended
NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Friday...An exercise caution headline will need to
remain posted for 15-20 kt winds and 4-5 foot seas. This headline
will likely be removed tonight sometime as winds ease...either
prior to warm frontal passage or into daybreak...because even the
S-SSW windspeeds behind the warm front could remain frisky and
extend the SCEC. Spectrum analysis shows the dominant energy will
be SE waves 3 to 5 feet every 7 seconds co-mingled with a NE wave
1-2 feet every 5 to 6 seconds. Showers and isolated TSTMS will
reduce VSBYs at times tonight below 2 NM.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Although no advisories are expected sea
heights will run 3-4 feet Saturday with visibility restricting
rain in the morning. Dominant wave periods will run between 7-9
seconds so the wave faces will not be extraordinarily steep.
During the afternoon a few TSTMS could move off land over the 0-20
NM waters...and some could be strong to severe. A wind shift to W
and NW will occur late Saturday night as cold front crosses the
waters. An improved marine environment Sunday as winds become
offshore W-NW and knock down near shore chop. Gusts to 20 KT from
the NW can be expected Sunday...and sea heights will be 3-4 feet
offshore and 1-2 feet inshore. Isolated showers or a TSTM will be
in the mix but they will remain widely separated and favored
mostly over the NC waters.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 300 PM Friday...High pressure expanding towards the waters
will create W/NW winds Monday...of 10-15 kts early and just 5-10
kts late thanks to the diffuse pressure gradient. On
Tuesday...this high will move offshore and then expand off the
coast creating persistent SW winds around 10 kts Tuesday...and
10-15 kts Wednesday. Seas will be 1-3 ft Monday...with the
offshore flow producing 0-1 ft near shore. Sea heights will become
more uniform Tue/Wed as a SE swell and southerly wind wave drive
the spectrum. Wave heights will be around 2 ft Tuesday...and 2-3
ft on Wednesday.