Morning AFD from LWX
.LONG TERM /FRIDAY THROUGH MONDAY/...
To conclude the work week, the longwave pattern will feature an
upper ridge across the eastern Pacific with a myriad of shortwaves
tracking between the Intermountain West and Mississippi Valley.
Resolving the complexity of these impulses will be the key to
determining the level of threat a winter storm poses to the region
late Friday into Saturday.
On Friday morning, conditions should be quite chilly in the wake of
the cold frontal passage 24 hours prior. A seasonably cold surface
ridge sets up from the Great Lakes up into Quebec with pressures
around 1041-1043 mb. Starting off, temperatures are forecast to be
in the teens east of the Blue Ridge/Catoctins, with single digits
off to the west. If any residual wind persists, there may be a
threat for wind chill headlines over the Alleghenies where forecasts
call for -5 to -15 degree readings. Clouds will be on the increase
as southwesterly flow aloft steers a shield of mid/high level
moisture toward the Eastern Seaboard. Expect plenty of clouds with
highs struggling to escape the low/mid 20s in many spots.
The looming question heading into the weekend is whether it will
snow, and exactly how much will fall. The 00Z deterministic model
suite all show a surface low forming in the vicinity of the
southeastern U.S. coast by Friday evening. Surveying the ensemble
low plots from the 00Z GEFS/EPS/CMC means yields plenty of menacing
low tracks for a Mid-Atlantic snowstorm. Most notably, the EPS
members are more numerous and deeper than the other solutions. This
will continue to be monitored in the days ahead as the parent
shortwave currently appears as an innocuous wave over far northern
Alberta. Until it moves into a denser observation network,
uncertainty will continue to plague the forecast. One thing that is
a sure bet is it will be cold heading into Saturday morning with
temperatures in the teens to low 20s.
For Saturday, the high temperature forecast will highly dependent on
the storm track with any resultant snowpack. It does seem certain to
be chilly with temperatures around 8 to 13 degrees below average.
Conditions remain on the colder side through the remainder of the
weekend and into early next week. The upper pattern changes very
little with the stagnant ridge over the eastern Pacific and broad
cyclonic flow over northeastern North America. Reinforcing shots of
cold air will arrive with each passing disturbance. This keeps
forecast highs in the 30s on Sunday into Monday with the mountains
confined to the 20s. Overnight lows stay well below average as well
with temperatures in the 10s to low 20s. For the Saturday and Sunday
period, the winds will be dependent on the coastal low track. So the
forecast has been kept more conservative given the degree of
uncertainty.
