Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
404 am EDT Friday Mar 27 2015
much colder air into the weekend...with lingering mountain snow
showers today and tonight. Strong upper level disturbance passes
Friday night. Cold high pressure crosses Saturday night.
Near term /through tonight/...
cold front has exited east of the mountains early this morning. Last
wave of low pressure riding up along the front will linger light
Post frontal precipitation mainly in the mountains through early this morning.
Much colder air...especially aloft...will change the rain to snow
with some minor accumulations in the higher elevations before the
precipitation tapers off early this morning. Models have a relative
dry slot through middle day before somewhat deeper moisture returns under
the cold upper trough moving across late this afternoon and tonight.
Thus...expect mainly lots of lower type stratocu clouds through middle day
with just lingering scattered light rain and snow showers in the
mountains with little accumulation. Even with colder air moving
in...the boundary layer will actually recover under thinning cloud
cover into the lower 40s in the low lands...but cold enough to
maintain a snow/or snow rain mixture in the higher elevations.
From late afternoon into tonight...with the arrival of the deeper
moisture and cold upper trough...models redevelop mainly upslope
snow showers in the mountains...while the low lands will likely see
scattered very light rain and snow showers. Will confine probability of precipitation to
east of the Ohio River...increasing as we go into the mountains.
Temperatures will drop to well below freezing tonight as the lower levels
really cool off with loss of daytime solar radiation. Thus...the
northern and central mountains will likely see a light accumulation
of snow...ranging from just a coating at lower elevations to an inch
or two at the highest elevations. Generally no accumulations in the
low lands. Precipitation should taper off later tonight as high pressure
builds in and moisture becomes more shallow. Look for lows well down
in the 20s.
Short term /Saturday through Sunday night/...
surface high builds in Saturday as 500 mb trough axis shifts to the
east. Models generally in agreement through the weekend. Main
story will be cold air in place into Sunday morning which could be
the last dying gasps of winter 2015. Will keep just a slight
chance of snow for the eastern mountains Saturday as 500 mb trough
axis... associated moisture...and 850 mb thermal trough tranistions
east out of the area. Deep moisture will remain limited though.
For temperatures...used British Columbia grids with some adjustments...especially for
Saturday night as we will be in a light flow clear sky regime.
Sunday will see a return to warm advection with gradaul warming
Long term /Monday through Thursday/...
roller coaster ride in the temperature department to continue through the
extended period. A cold front will slide through Sunday night into
early Monday with a chance for showers. A wave may develop in the Tennessee
Valley on Monday which would keep the rain threat going across SW
Virginia and southeast WV. Temperatures will come back down behind the front as northwest
flow aloft becomes established behind a clipper system early
Tuesday...with a small chance for a shower and snow shower for the
north mountains. Upper heights will quickly rebound midweek with
decent warm air advection cranking once again...ahead of the next front. As a
result...temperatures should spike into the 70s once again long about
Wednesday. This front looks to cross Wednesday night or early Thursday.
Aviation /08z Friday through Tuesday/...
06z Friday through 06z Saturday...
cold front has exited east of the mountains. Lingering light
rain/snow in the east associated with the last wave of low pressure
along the front will mostly end by 12z. Much of the day will be
precipitation free with a relative dry slot...only scattered light
rain/snow showers mainly in the northern mountains. Cold upper
trough and deeper moisture will redevelop some light rain/snow
showers for early tonight in the low lands east of the Ohio
River...and more numerous snow showers in the mountains. Most of the
snow showers will be in the northern mountains tonight.
Given all this...expect IFR in the mountains to improve to MVFR by
15z and VFR ceilings by 18z...while low land MVFR/low end VFR
ceilings will be VFR by 15z. Despite the increase in moisture late
today into tonight...guidance keeps most of the low lands low end
VFR in widely scattered light rain/snow showers...while general MVFR
conditions in snow showers for especially the northern mountains are
Forecast confidence and alternate scenarios through 06z Saturday...
Forecast confidence: medium.
Alternate scenarios: flying categories may be lower than
forecast...especially in the mountains early this morning...and
tonight area wide.
Experimental table of flight category objectively shows consistency
of weather forecast office forecast to available model information:
h = high: taf consistent with all models or all but one model.
M = medium: taf has varying level of consistency with models.
L = low: taf inconsistent with all models or all but one model.
Date Friday 03/27/15
UTC 1hrly 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1hrly 04 05 06 07 08 09 10 11 12 13 14 15
crw consistency h h h h h h h h h h h h
heights consistency h h h h h h h h h h h h
bkw consistency h h h h h h h h h h M h
ekn consistency h h h h h h h h h h M M
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h M h h h
After 06z Saturday...
no widespread IFR conditions expected at this time.