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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 150842
AFDRAH

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
341 AM EST Sun Dec 15 2019

.SYNOPSIS...
Broad high pressure will extend across North Carolina today into
Monday, with deepening low pressure expected to move north of the
area on Tuesday and bring a cold front across the region.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 240 AM Sunday...

Quiet weather is expected to finish the weekend and start the work
week. Broad high pressure extends from Minnesota south into Missouri
and southeast into Florida. The high will slide east today, but be
somewhat eroded by developing low pressure across the Southern
Plains. A warm front that will develop off the surface low will
extend to the northeast, but stay north of North Carolina overnight.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 240 AM Sunday...

The low will take its time moving east, not making its way much
farther east than Mississippi by Monday afternoon. Over the last
several days, models have continued to show the warm front remaining
north of North Carolina on Monday as well, except for a few GFS
ensemble members showing rain falling just south of the Virginia-
North Carolina border. Have bumped up cloud cover a bit across the
region, but still think that this entire period will be dry. Brought
highs on Monday down a degree or two considering the increased cloud
cover, but with the area still in the warm sector, nearly all
locations should rise into the 60s.

Monday night will see high pressure retreat off the coast ahead of a
developing mid tropospheric trough over the Ohio Valley. Increasing
clouds and strong surface WAA will play havoc with temperatures and
some spots could end up flirting with record warm min temperatures
early Tuesday morning. Steady or slowly rising temperatures area-
wide were already drawn into the digital forecast in this scenario
and I see no reason to change that thinking.

The main story with this approaching trough is precip chances, this
time around p-type will not be an issue. Taking a look at this
morning`s 00Z deterministic and probabilistic guidance, timing
remains relatively on track showing precip moving into the Triad
between 06Z-12Z Tuesday and into the Triangle closer to 12Z. PoPs
were adjusted accordingly to match these timing trends.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 341 AM Sunday...

Precip should be ongoing at nearly all sites by Tuesday morning,
rapidly ending from west to east around 00Z Tuesday. Not going to
introduce thunder at this point but most models agree that there
should be about 100-300 J/KG SBCAPE in the warm sector just prior to
FROPA. This also lines up well with SPC general thunder mention for
Day 3. More concerning is the nearly 40kts of 0-1km shear and 90kts
of 0-6km shear, suggesting the potential for weakly rotating
showers/storms. Most of the shear is fairly unidirectional in nature
but certainly something worth monitoring as we get closer. Precip
tapers off as mentioned Tuesday night into Wednesday, with surface
high pressure/dry weather building in Wednesday through Friday.

The forecast for next weekend remains uncertain as there have been
inconsistencies from run to run of the ECMWF and GFS as well as
their respective ensemble counterparts. GFS and GEFS solutions have
been depicting a very deep upper trough and associated surface low
moving through the Southeast. EC and ECENS have maintained a similar
idea but much less intense. Today`s 00Z ECMWF is depicting and even
weaker upper trough than before, but does continue the idea of weak
coastal cyclogenesis off the South Carolina coast. This solution
would bring some rain to the area Saturday and Sunday but nothing
significant. NBM PoPs during this period are near climo and until a
more clear consensus can be reached, sticking with its low impact
forecast for next weekend with slight chances of rain and above
freezing temperatures seems like the best approach.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
As of 1210 AM Sunday...

24 hour TAF period: Although some patchy high clouds are possible
during the daytime hours, it should be a very quiet period with
little cloud cover and light southwest winds.

Looking ahead: Some MVFR cigs assoc with cloud may develop across
the western Piedmont Monday morning. Flight conditions will then
enter of period of reduction late Monday through Tuesday assoc with
low clouds and rain chances with the next front. Look for improving
flight conditions by Tuesday night in the wake of that front. -NP

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Green
NEAR TERM...Green
SHORT TERM...Green/Leins
LONG TERM...Leins
AVIATION...Green/np