Debate de meteorólogos científicos
Area forecast discussion
National Weather Service Raleigh NC
720 PM EST Thursday Dec 5 2013
Synopsis... a warm and moist southerly flow will persist through
Friday...resulting in above normal temperatures. A cold front will
move in from the north Friday night... bringing much colder
temperatures and occasional rain this weekend.
Near term /through tonight/...
as of 720 PM Thursday...
The problem of the night appears to be low stratus and possibly fog.
However... low stratus seems to be the main issue given the forecast
of increased mixing later tonight. A S-SW wind at 5-10 miles per hour is
expected to develop overnight. Even with the very moist boundary
layer... it appears this would be enough to keep dense fog from
developing. However... a low stratus deck is expected to overspread
the region overnight with ceilings at or below 500 feet above ground level
expected. This may create some issues at the local airports. See the
aviation discussion below. Otherwise... expect a very mild to warm
night for early December... with lows in the upper 50s to lower 60s
(which will be near the 30 year normal highs for this time of year).
There may also be scattered areas of light drizzle around... but
nothing more than a trace to possibly 0.01 expected.
Short term /Friday and Friday night/...
as of 258 PM Thursday...
As the upper level ridge shifts eastward offshore... the front
becomes increasingly aligned with the upper level flow.... slowing
its eastward progress and providing the area with another day in
southwesterly flow and above normal temperatures in the middle to upper
70s. The front progresses into the western part of the state around
06z Sat... bringing an increasing chance of rain overnight. Low
temperatures will be dependent on its progress... as strong cold advection
begins in its wake. Lows in the low 40s north to upper 50s south.
Long term /Saturday through Thursday/...
as of 230 PM Thursday...
Models remain in good consensus as to the timing of the frontal
passage late Friday night through Saturday morning. Will be a little
problematic for forecasting maximum temperatures as the high will occur
immediately prior to frontal passage...which could allow an hour or so for
temperatures to climb a little in the south and east Saturday morning.
Morning lows look to range from around 50 northwest to lower 60s
southeast and will show a falling trend throughout the day
northwest...with cold air advection delayed until perhaps late morning
in the far southeast. Will continue categorical pop trend from
Friday night to around middle day as strong low level lift will
accompany the front as it races across and south of the area by
Isentropic lift becomes the major player Saturday night into Sunday
as surface cold air advection undercuts moist southerly flow at h925
to 850 mb and establishes a precipitation-supported cold air damming regime in
the usual location. The moisture laden flow will strengthen later
Saturday night as a middle level wave lifts north of the area and
categorical probability of precipitation for light rain are warranted...especially
northwest...through most of the day Sunday.
Something to be watched...temperature profiles on forecast soundings
have trended towards a potential for light freezing rain in the
northwest Piedmont and along the northern tier counties after
midnight Saturday night into Sunday morning. At this point...with
temperatures bottoming out near freezing after a warm spell...would not be
a major concern as it would be primarily on elevated surfaces...
limbs...power lines...the like. Only takes a little...though...so it
will be monitored closely. Mins Saturday night will be in the lower
30s north to upper 30s south. With continued damming throughout the
day...sundays highs will show little inclination to rise...and highs
will range from middle 30s deep in the damming region to middle 40s in the
Cad erosion is underway late Sunday night into Monday as a surface
low associated the short wave mentioned above moves north into the
Great Lakes with an associated cold front becoming better organized
west of the mountains. Southerly flow ahead of this front will nudge
a warm front up the East Coast and will allow highs to warm into the
60s over much of the region except for some middle 50s in the northwest
where the cold air will linger through the morning. This cold front
will move east across the area Monday night or Tuesday morning...
prolonging the chance of rain through Tuesday with highs ranging
from the middle 40s northwest where the frontal passage will be
early...to middle 50s in the east. Unseasonably cool high pressure will
be building in by midweek with highs topping out in the 40s
Wednesday and Thursday.
Aviation /00z Friday through Monday/...
as of 720 PM Thursday...
Low ceilings with IFR to LIFR expected overnight. These ceilings will
gradually lift with the increasing SW flow on Friday into the MVFR
to VFR range by 18z. Ceilings will again lower to LIFR Friday night with
MVFR visibilities in fog and drizzle.
Sub-VFR conditions will again be likely as a cold front crosses the
area early Saturday... and unsettled weather with periods of rain
continues through Monday.
record high temperatures for December 6th:
Gso... 76 set in 1998
rdu... 80 set in 1998
Fay... 80 set in 1998