Scientific Forecaster Discussion
fxus62 kilm 161900
Area forecast discussion
National Weather Service Wilmington NC
300 PM EDT Wed Oct 16 2019
a cold front will cross the region this evening, bringing much
drier air to the region overnight. Unseasonably cool weather
will arrive Thursday as high pressure builds in through Friday.
Temperatures will warm through the weekend as the high shifts
offshore. Rainfall chances will increase early next week as Gulf
low pressure approaches.
Near term /through Thursday night/...
deepening low pressure moved across the area earlier today along a
warm front. Rainfall amounts averaged half an inch or better in most
locations, except for parts of Bladen and Columbus counties where
barely a tenth of an inch fell. Dual-pol radar estimates even in
areas not affected by beam blockage were a little on the low side.
The low is now in far-eastern North Carolina and will move out to
sea tonight. A cold front trailing behind the low is just about to
push from the Piedmont into the coastal plain and should be off the
coast this evening. West winds will shift northwesterly behind the
front with falling dewpoints heralding the arrival of the new
airmass. High-res models show limited potential for some shallow
forced showers along the front within a moist but only slightly
unstable airmass. I'm capping pops at 20 percent (slight chance)
during the frontal passage, with dry conditions and clearing skies
expected overnight. Crisp and typical Fall weather is expected
Thursday into Thursday night.
Enough boundary layer wind should exist near the coast tonight to
keep temperatures relatively warm (lower 50s). Normally cooler
outlying rural areas will probably run a good 5 degrees lower. Highs
should reach the upper 60s to around 70 on Thursday, but good
radiational cooling conditions on Thursday night should produce
widespread 40s and potentially a couple upper 30s in the coldest
locations. We're still a few weeks away from the climatological
first fall freeze for this part of the Carolinas.
Short term /Friday through Saturday night/...
exiting 5h trough and high pressure building in from the northwest
will keep the region dry Fri into Sat. West-northwest flow aloft Fri
and mid-level subsidence will minimize cloud cover. Despite lots of
sunshine highs will struggle to break 70 in most areas Fri
afternoon. Clear skies for much of Fri night and decoupled winds
will lead to lows dropping into the low to mid 40s with potential
for cold spots dipping into the upper 30s.
Moisture aloft starts spreading over the area Sat as shortwave 5h
ridge axis shifts offshore and southerly flow develops. Gulf Coast
system moving onshore along the Florida Panhandle Sat evening helps
spread deep moisture over the southeast. Still some uncertainty with
respect to how quickly the system will be moving, but there are
signals clouds and showers associated with this feature may reach
the forecast area before the end of the period. Will bump pop up a
bit across SC Sat night to account for potential for quicker
northeastward movement. Temperatures will be near climo Sat with
increasing cloud cover somewhat offsetting air mass modification.
Clouds and increasing boundary layer winds will keep lows above
climo Sat night.
Long term /Sunday through Wednesday/...
low pressure/trough moving into the southeast from the northeast
Gulf of Mexico Sun morning moves up the coast early next week. Still
a lot of uncertainty with respect to the nature of the low, but it
will bring an abundance of moisture with it. 12z GFS is noticeably
quicker with the low compared to its previous runs, wpc, and the
European model (ecmwf). So timing is somewhat questionable. This feature is then
followed by a cold front ahead of a deep 5h trough late Mon into
Tue. These 2 events will be the main chance for rainfall through
midweek with deep west-northwest flow developing Tue and continuing
Wed, drying the region out.
-Showers developing Sun morning as low/trough combo move into
the southeast from the Gulf of Mexico.
-Showers and isolated thunderstorms with a cold front crossing
the area Tue.
-Above to well above climo temps sun through Tue drop back to
climo midweek following the Tue cold front.
Aviation /19z Wednesday through Monday/...
conditions will begin to improve quickly over the next few hours,
with the warm front to our north and a cold front approaching from
the west. Currently widespread IFR ceilings across the area.
Expect widespread VFR by 21z, with any lingering IFR/MVFR at that
time, mainly near the coast, lifting quickly. Scattered clouds this
evening before skies clear around 0z with passage of cold front. May
see some scattered showers with cold front. Gusty southwest winds
this afternoon become westerly in the evening, sustained around 10
kts and gusts in the high teens, with higher values near the coast.
Northwest winds tonight through tomorrow between 5 and 10 kts.
Extended outlook...predominately VFR through extended. Sub-VFR
conditions possible Sunday with return of unsettled weather.
low pressure has shifted away from southeastern North Carolina and
is now crossing far-eastern NC. This has turned wind directions
southwesterly gusts of 25-30 knots are still being reported at some
coastal and offshore sites. A cold front moving quickly eastward
through the Piedmont region of the Carolinas should reach the coast
early this evening, possibly accompanied by isolated showers. Winds
behind this front should turn northwest with 15-20 kt winds
overnight occasionally gusting to 25 kt. Somewhat lighter northwest
winds are expected to continue through Thursday night as high
pressure over the Mississippi Valley moves east.
Seas built quickly in the south winds this morning, reaching 7 feet
at The Frying Pan Shoals buoy and 6 feet at the cormp Harbor buoy
near Southport. As winds turn offshore, sea heights should peak soon
across the coastal waters and then diminish overnight into Thursday.
For this reason i've trimmed back the ending time of the Small Craft
Advisory to 10 PM across the South Carolina coastal waters, and 6 am
Thursday for the North Carolina waters.
Northerly flow Fri into Sat afternoon will gradually become
southerly Sat night into sun as surface high slips off the coast.
Speeds will be around 10 kt Fri through Sat but gradient starts to
tighten up Sat night. Low moving from the northeast Gulf of Mexico
into the southeast helps increase southeast winds to a solid 15 kt
Sat night and sun before low exits northeast and southwest winds
drops closer to 10 kt. Seas will generally be 2 to 3 ft, mainly as a
northerly wind wave 4 to 5 seconds, through the end of the week. Sat
night into sun increasing wind speeds build seas near 6 ft on sun
with southerly wind wave around 5 seconds becoming dominant. Seas
diminish a bit Mon with southerly wind wave period running 5 to 6
Marine...Small Craft Advisory until 10 PM EDT this evening for amz254-
Small Craft Advisory until 7 am EDT Thursday for amz250-252.