Scientific Forecaster Discussion
fxus62 kilm 120529
Area forecast discussion
National Weather Service Wilmington NC
1229 am EST Thu Dec 12 2019
high pressure will bring a chilly period through Thursday. A
coastal trough and wave of low pressure will bring rain late
Friday through Saturday morning. High pressure will then give
way to a cold front on Tuesday.
high clouds are now clearing out of Bennettsville, Darlington,
and Florence and are still expected to be off the coast before
midnight. Tweaks to wind direction, dewpoints, and sky cover
have been made to the forecast based on current obs. No changes
to low temp forecasts.
Near term /through Friday/...
the weather for the next 36 hours will be dominated by high pressure
behind a cold frontal passage that brought a big temperature change
and gusty winds to the Cape Fear region. Highs this afternoon under
cold air advection will range from the upper 40s to the lower 50s,
which is between 5 and 10 degrees below normal and between 20 and 30
degrees below yesterdays maximum afternoon temperatures. As strong
high pressure to the north moves eastward, the surface pressure
gradient will allow for gusty winds up to 30 mph at times today and
tonight. The wind direction will shift from the northwest to the
northeast as the high pressure moves eastward Thursday and winds
should relax a bit, although gusts could still reach into the 20 mph
range at times Friday afternoon and evening.
Short term /Friday night/...
a good dose of warm advection-induced rain to spread across the area
late Friday. The better dynamics come Friday night but it appears
they will lag the deep moisture. With this lack of phasing and poor
deep layer lapse rates convection may be hard to come by, even the
elevated variety. Near seasonable highs on Friday will not fall much
Friday night in the ongoing warm advection.
Long term /Saturday through Wednesday/...
rain may linger a bit into Saturday even though the deep moisture
will be moving off the coast-the main vort Max will still be
crossing the area. Dry air moves in Saturday night. By Sunday any
weak cool advection will be offset by the return of sunshine and a
fairly seasonable weekend is expected. Warm and moist advection
spread west-to-east on Monday first only leading to increasing
clouds but then rain chances. Tough to say when the latter
materializes as it may be quite gradual and usually a bit slower
than progged by models. Also, most of the warm air advection rain may stay north of
the County Warning Area and the best rain chances may come on Tuesday with cold
Aviation /06z Thursday through Monday/...
VFR through the 06z taf period as a few high clouds transition
to sct-bkn late in the taf period. North winds of 5 to 10 knots early
this morning will become NE 10-15 kts after daybreak with gusts
near 20 kts.
Extended outlook...another round of MVFR/IFR is possible Friday
into Saturday as an area of low pressure moves by the coastal
Carolinas. VFR expected Sunday and Monday.
high pressure will keep things dry offshore, but a building pressure
gradient offshore is expected to kick up north to northeast winds
over the next 36 hours between 20 and 25 kts with gusts up to 30 kts
at times. Significant wave heights between 5 and 7 feet are
possible, especially beyond 10 nm. Wave trains from the southeast
between 8 and 10 seconds and the north between 6 and 8 seconds. A
Small Craft Advisory remains in effect.
Winds and seas may dip below advisory thresholds on Friday as a
coastal trough weakens the gradient. Surface low pressure moves up
the coast Friday night and cold frontal passage expected to lead to
a sharp turn to offshore flow soon thereafter on Saturday. The
following cold air push may allow some 6 ft seas to once again
necessitate an advisory, though it may be short-lived. Weakening
winds and diminishing seas Sunday into early Monday as weak high
moves off the coast. A return flow/southerly winds establishes
itself by Monday.
Marine...Small Craft Advisory until 6 am EST Saturday for amz250-252-