Area Forecast Discussion
Issued by NWS Charleston, WV-- Remove Highlighting --
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FXUS61 KRLX 211753
Area Forecast Discussion
National Weather Service Charleston WV
1253 PM EST Sat Jan 21 2017
Unseasonably warm through the weekend. Upper trough Sunday.
Stronger upper low Sunday night and Monday, exiting Tuesday.
.NEAR TERM /THROUGH TONIGHT/...
As of 950 AM Saturday...
Prolonged the areas of dense fog across the Western Appalachian
Valleys for a few more hours this morning. Visible imagery
clearly shows fog entrenched in the mountain valleys this
morning and the edges have not dissipated much as of 1430Z, so
current thinking is that we will not see it lift in these areas
until about noon. Also went ahead and updated sky cover based on
latest METSAT and trends as mid and upper level clouds continue
to push northward with overrunning ahead of our next system.
As of 540 AM Saturday...
Although the last hourly updated hi res models of the HRRR and
RAP have suddenly shifted the precip shield of the upper
disturbance northward over our area later today, will not jump
on raising pops at this time. Issues are that the NAM is still
confined to the mountains, it is only one model run so far of
the HRRR and RAP, and the strong MCS along the Gulf coast with
the disturbance should help to suppress the rain shield
somewhat. Thus, little change to the current forecast.
As of 305 AM Saturday...
This period will be dominated by a warm and deep moist southwesterly
flow, well ahead of a strong upper low emerging into the Plains
states later today and tonight. One leading upper disturbance
will pass mostly south and east of the area this afternoon and
evening. Models place the northern edge of the precip shield
just touching our central and southern mountains this afternoon
and evening. Will place chance pops there for showers, while
cannot rule out a sprinkle elsewhere. In any case, any precip
will be light. A second stronger upper trough ahead of the upper
low will lift northeast toward our area later tonight, bringing
a better chance of showers into southern areas later tonight.
Even with considerable clouds today, temperatures will be quite
warm again with highs well into the 60s. Look for a very mild
night with lows dipping to just below 50 degrees.
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
As of 235 AM Saturday...
Looking at a significant, long duration rain maker through the
short term with a deepening upper level low rotating
northeastward from the deep south. Two distinct waves of energy
will bring the rain. The first is an upper level trough oriented
west to east, moving northward, and the second is the parent
low. NAM showing strong low level frontogenesis Sunday night,
and good upper level support in the form of Q vector convergence
over the northeastern CWA. Right now, will handle the potential
for flooding in the HWO, but high QPF amounts over the short
term with good basin coverage could be problematic.
All of this will occur in the warm sector of the surface frontal
system associated with the upper low, so there is need to
determine the efficacy of the dynamic cooling in terms of snow
potential. Core of the upper low will need to be in close
proximity to the CWA for snow to occur, which will primarily be
in the highest elevations. Rain otherwise.
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
As of 235 AM Saturday...
System exits, pulling a colder airmass into the area, but only
chances for snow will remain in the mountains. A brief recovery
to the temperatures back above normal comes Wednesday, with the
next cold front not far behind, and a wholesale airmass change
heading for the end of the week and the weekend.
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 1245 PM Saturday...
Upper level disturbance pushing into the region this afternoon
and evening, but mostly spreading overcast mid and upper level
clouds overhead. There is a low chance for a shower across the
West Virginia Mountains this afternoon and evening as this
system heads NE, but not enough confidence to put into BKW or
EKN TAFs at this time.
Most sites will remain VFR throughout the period, but
thinking with the abundant low level moisture still in place that
mountain valleys may see IFR fog develop again late tonight.
Finally, at BKW ceilings may lower to IFR overnight with
persistent moist southeasterly upslope flow.
Ceilings will start to lower tomorrow morning everywhere with
warm advection ahead of our next system. This system will bring
scattered showers to the region but timing will be towards the
end of the TAF period.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY...
FORECAST CONFIDENCE: Medium.
ALTERNATE SCENARIOS: Fog may not develop tonight at EKN due to
increased mid and upper level cloud cover. Showers this
evening could bring lower ceilings to BKW than currently
highlighted in the TAF. Timing of onset of precip and lower
ceilings tomorrow may bring MVFR ceilings before 18Z Sunday for
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO 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.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY H H H H H H H H H H H M
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY H H H H H H H H H H M L
EKN CONSISTENCY M M M M M M M M M M M L
PKB CONSISTENCY H H H H H H H H H H H L
CKB CONSISTENCY H H H H H H H H H H H M
AFTER 18Z SUNDAY...
IFR will be possible again Sunday through Monday with another