Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 262235
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
636 PM EDT Thu Apr 26 2018

.SYNOPSIS...
Low pressure will pass across northern North Carolina late
tonight bringing a good chance of showers. A pair of cold fronts
will push offshore late Friday and Saturday night, bringing
unseasonably cool temperatures for Sunday and Monday. Canadian
high pressure will push offshore late Monday, and temperatures
should warm rapidly Tuesday and Wednesday, with dry weather
continuing.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 300 PM Thursday...Combination water vapor imagery and regional
radar mosaic show a large spin across northern AL into GA
representative of both a closed upper low and surface reflection.
These will slowly eject to the NE tonight to become over VA on
Friday. As this occurs, 500mb diffluence increases as the flow
spreads out ahead of the mid-level low, in conjunction with 300mb
divergence in the RRQ of an exiting upper jet. At the same time,
moist advection peaks in the warm sector ahead of the associated
weak cold front, and this combination of moisture and lift suggest
precip chances will increase from west to east and this is echoed by
all available high res guidance. However, despite mins expected to
remain around 60 tonight, diurnal instability will wane
significantly and this will limit both coverage and intensity of
showers overnight. Have maintained high CHC showers with SCHC tstms
since elevated instability is progged to remain 300-500 J/kg which
could support a few lightning strikes in any stronger updrafts,
aided additionally by a robust 30-40 kt LLJ. Most of this activity
will occur after midnight, moving from SW to NE and leaving the area
by daybreak on Friday.

Another very nice day forecast Friday with a ridge of high pressure
building in from the west while yet another weak cold front pushes
down from the NW. This front is driven by another spoke of vorticity
moving through the longwave eastern CONUS trough, and will exit
offshore just beyond this period. Despite temps climbing into the
mid 70s once again, do not anticipate convection Friday even with
the added lift of the FROPA thanks to very dry air aloft keeping
PWATs around 0.75 inches. There should be rather extensive diurnal
Cu Friday however as soundings saturate at the LCL beneath a
pronounced subsidence inversion.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Quiet, rain-free, and seasonable weather
expected through the short term period. The area will find itself
between two cold fronts and under a broad mid level trough. The
second cold front will come through Saturday night with far too dry
an antecedent airmass to bring any weather. It will mark the turn to
slightly cooler weather.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...Model differences are very small through
the extended portion of the forecast and have only minor impacts
on sensible weather. Confidence is rather high.

The tail-end of an upper trough will pass over the Carolinas
Sunday as high pressure, centered over the Midwest, builds
southeastward toward the area. Chilly air beneath the upper
trough (850 mb temps only +2C to +3C Sunday) should give us
another unseasonably cool day despite nearly full sunshine:
highs only 69-72. The upper trough pushes offshore Monday, but a
lobe of that chilly low-level air remains behind with highs not
expected to be warm much from Sunday.

Nighttime lows early in the week should be quite chilly for this
late in the year. Diminishing winds and clear skies Sunday night
should allow lows to fall into the low-mid 40s, and it wouldn`t
surprise me if a few of the typical cold spots get into the
upper 30s. We`re not expecting a freeze, but it`s interesting
that the latest freeze on record in Elizabethtown, NC was May 2,
1963, and for Lumberton was May 10, 1980.

By Tuesday, the surface high should push offshore with upper
level ridging building across the Carolinas. Our high and low
temperatures should quickly warm as 850 mb temps rise to +12C
Tuesday and +14C Wednesday and Thursday. The orientation of the
mid and upper level ridge should prevent any inflow of moisture,
and skies should remain very clear through the extended
forecast period. Dewpoints dipping into the 30s Sunday and
perhaps Monday should moderate through the week, finally
reaching 55-60 by Thursday which may develop the first flat
cumulus we will have seen all week!

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 23Z...An upper level disturbance will push into the western
portion of the CWA just before midnight, with scattered convection
expected. The upper low will weaken as it turns the base of the
longwave trough, and this should weaken the showers as they approach
the coast. Have not introduced IFR at this time, but it is a
possibility, particularly along the coast around 10-12Z. Friday,
becoming scattered with a moderate southwest wind.

Extended outlook...VFR.

&&

.MARINE...
NEAR TERM /THROUGH FRIDAY/...
As of 300 PM Thursday...Light S/SE winds this eve will veer
gradually to the SW as a weak cold front moves across the waters.
Wind speeds will generally increase to 10-15 kts tonight, and then
slightly higher towards 15-20 kts Friday as the gradient becomes more
pinched ahead of another weak cold front which will approach late on
Friday. Seas this even will remain 2-3 ft, but a gradual
amplification to 3-5 ft is expected as the winds increase to drive a
growing 6 sec wind wave, which will combine with the 8-9 sec SE
swell.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...West to southwest flow to dominate through
the period as the area spends most of the time in between two cold
fronts. The second boundary is slated for passage near the end of
the period, and it may bring a sharp turn to the north towards
daybreak. Swell energy will be quite minimal, seas will be comprised
of a series of fairly diminutive wind waves.

LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 300 PM Thursday...High pressure will build southeastward
behind Saturday night`s cold front, finally reaching the
eastern Carolinas Monday afternoon or evening. Northerly winds
as strong as 15-20 kt at daybreak Sunday should subside to
around 10 kt Sunday afternoon. An upper level disturbance
passing just to our north late Sunday night should bump winds
back up toward 15 knots, but winds should diminish again as the
high pressure area approaches later Monday. Westerly winds
behind the high Monday night will turn more southerly along the
beaches Tuesday afternoon with the daily seabreeze circulation.

&&

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

&&

$$

SYNOPSIS...TRA
NEAR TERM...JDW
SHORT TERM...MBB
LONG TERM...TRA
AVIATION...43


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