Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
1001 PM EST Thursday Feb 26 2015
high pressure will build across the area through Saturday and
begin to take on a wedge signature...locking the cold air across
the Carolinas. This high will move offshore Saturday. The next
chance of precipitation will come early next week in association
with a cold front. No risk of wintry precipitation expected next
week...as much warmer temperatures arrive through early March.
Near term /through Friday/...
as of 10 PM Thursday...just recently a nearly static T/dew point regime
across the area is seeing lowering surface dewpoints and temperatures
upstream in central North Carolina. This is lending to partially
clear skies in spots and cooler temperatures which is bringing
lowering dewpoint depressions. Visibilities were lowering below
10nm miles in a few locals and will retain the mention of fog/fzfg
already in the grids...especially since boundary layer north winds do
not increase until about daybreak. No significant changes to the
forecast at this time as inherited grids are in good shape.
Short term /Friday night through Saturday night/...
as of 245 PM Thursday...a broad zonal flow will be in place through
the period. At the surface...moderating Arctic high pressure will
be in place through early Saturday. After this some developing
confluence in the middle level pattern allows a wedge to build down
into the area. Very shallow Arctic air will once again surge into
the area. With the airmass continuing to be very dry...probability of precipitation should
not be an issue although the temperature forecast is challenging.
Friday and even Saturday are fairly straightforward. Guidance has
trended up slightly for Friday with the outside possibility of 50
degrees in Wilmington. Both the met and mav have 49. With the
possibility of at least some partial clearing middle 20s seem OK for
Saturday morning. Saturday will be much cooler vs Friday as the
reinforcing shot of dry Arctic air pushes in. It may be a struggle
to reach 40 in northern areas. Finally Sunday morning guidance is in
two distinct camps with the met some five to ten degrees warmer vs
the mav. I leaned slightly toward the more modified met citing
overcast skies...which are depicted by the guidance usually warrants
guidance being on the cool side.
Long term /Sunday through Thursday/...
as of 245 PM Thursday...Sunday looks cloudy and cool but largely
rain-free as wedge of high pressure struggles to hold on across the
Carolinas, its main center drifting off the Delaware-Maryland-Virginia coast. The
Wedge lifts out Sunday night as the high more or less bifurcates.
By 12z Monday only the eastern/offshore center remains and a cold
front will be bearing down on the area from the northwest. Rain chances
will slowly rise Sunday night and non-diurnal temperature trends may
be possible. As seen yesterday with respect to sunday's highs mex
guidance is now 10 degrees cooler for Monday as there is little
opportunity for solar insolation to aid in thermal advection. Even
so Monday will end up being closer to climatology highs than the area has
seen in some time making upper 50s feel welcome. Will trim slightly
towards those values. Tuesday on the other hand now doesn't look
quite as cold and wedge-like behind the Monday cold front. Although
another cloudy day with rain chances Tuesday highs may be close to
those of Monday. This weak wedge washes out on Wednesday with yet
another boundary en Route from points north and west. A deep and
moderately strong southwesterly flow develops and we shall finally
see an unseasonably warm afternoon despite what may be a rather
cloudy day. In fact because of the clouds i'd Love to believe the
mex numbers that show all areas away from the immediate coast
hitting a high of 80 or better-but I don't. With 850mb temperatures around
12c and lapse rates a bit steeper than moist adiabatic low 70s seem
much more probable.
Aviation /03z Friday through Tuesday/...
as of 00z...expect MVFR/possible IFR due to low ceilings and possible areas
of fog tonight into the overnight hours...with conditions gradually
improving to VFR as high pressure continues to slowly build in.
With northerly winds at or below 10 kts...widespread low ceilings as seen from
latest 11u-3.9u satellite are creating mainly MVFR at the terminals
this evening...with the exception of kcre and klbt where there are
some breaks in the clouds. Expect the trend of MVFR with
intermittent periods of VFR possible through the early overnight
hours...with even lower ceilings and/or patches of fog to create IFR.
Confidence remains low...thus have kept tempo groups in going
Expect a gradual improvement to VFR across
the area late overnight well into Friday as high pressure continues
to build into the area. Northeast winds around 10 to 12 kts will
prevail on Friday.
Extended outlook...MVFR/IFR possible late Sunday into Monday.
Otherwise expect VFR.
near term /through tonight/...
as of 10 PM Thursday...all advisories expires as of 10 PM as seas
dampen to less than 6 feet. Frying Pan 6.9 feet at 10 seconds but
the longer period energy will decay onto the shelf. Will need to
replace NC waters with an exercise caution statement however since
winds will remain fair frisky from the north overnight in conjunction
with the elevated seas.
Short term /Friday through Saturday night/...
as of 245 PM Thursday...a northerly component to the winds will be the
common factor across the coastal waters for the short term period.
For Friday winds will maintain a mostly north direction with speeds
of 15-20 knots. Some veering to to northeast can be expected
overnight Friday and into Saturday as more of a wedge configuration
develops. With a secondary surge of shallow cold air winds will
increase in magnitude to around 20 knots. Seas will rise from 2-4
feet Friday to 3-6 feet early Saturday and maintain these heights
through late in the period. An extended Small Craft Advisory will
probably be in order.
Long term /Sunday through Tuesday/...
as of 245 PM Thursday...a wedge of high pressure over the Carolinas
will bring a northeasterly flow over the waters on Sunday. The
gradient will only be moderate at best so despite some swell energy
mixing in with the wind waves overall seas will be fairly typical
for the time of year with no headlines or flags in effect.
Troughiness will develop between this wedge and the west Atlantic
high Sunday night and the former airmass should be gone by Monday.
This will bring light winds that will turn to the SW early Monday
followed by a veer to the northwest midday Monday or Monday afternoon as a
weak cold front pushes through the region. Significant wave height
may not change much and dominant period may shorten some as swell
energy abates. Northeasterly flow returns Tuesday as another weak
high wedges up against the East Face of the Appalachians and an axis
of high pressure develops into the Carolinas. Slight increase in
swell and wind wave could bump seas up but still no