Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
913 am EST Sat Dec 7 2013
as cold front exits south...high pressure builds in to improve
weather conditions today. However...the front lifts north as a warm
front with widespread mixed precipitation tonight through Sunday night.
Near term /through tonight/...
910 am update... only minor tweaks made to todays forecast...based
on current observation and trends.
cold front moved south of the area overnight. Lingering
light snow showers or pockets of freezing rain will continue
through this morning. A high pressure will slide in providing
clear skies and drier conditions. However...the aforementioned
front will lift north as a warm front early Sunday with widespread
precipitation...some in the form of mix rain/snow and freezing rain.
Models are in agreement with the aforementioned solution. Went
with the wrfnmm for temperatures today...and closer to the NAM for
With the precipitation exiting the area...the threat for areal flooding has
diminished and flood is not longer expected today. Therefore...the
former Flood Watch was cancelled. The only headline stands for a
Winter Storm Watch that continues in effect until late tonight
for Pocahontas and Randolph counties.
Short term /Sunday through Tuesday/...
a very active pattern in the short term...and particularly Sunday
and Sunday night...as the next in a series of waves moves across the
forecast area. Primary forecast concerns revolve around impacts from
ice and rainfall.
Conditions still on track for an ice storm across the eastern
mountains Sunday afternoon into Sunday night. Sunday...the next surface
low pressure pushes northeastward along the quasi-stationary front
to the southeast with abundant deep layer moisture and overrunning
out ahead of it. Meanwhile...surface winds veer around to the
east/southeast with high pressure located to the
northeast...anchoring in cold air near surface. Precipitation will spread
north and east through the morning hours with categorical probability of precipitation
pretty much everywhere by 18z sun. At 12z sun precipitation will be snow
for most lowlands...with all rain for the Virginia counties and perhaps
McDowell County WV...and a wintry mix in between. The transition
zone will lift north through the morning hours...with rain expected
from the crw-heights corridor southward through the coalfields by around
18z. Northern zones will see snow a bit longer. Meanwhile...strong
warm advection at 850mb will transition what was initially snow
across the eastern mountains to freezing rain by 18z sun. With cold
air damming in place...expect the highest terrain and in particular
the eastern portions of Raleigh County WV northeastward through
Randolph counties to see the bulk of the ice potential. Upgraded
Pocahontas and Randolph counties from watch to warning for
significant ice accumulation potential of up to a half inch...again
especially across the eastern halves of these counties. Further
southwest with the remainder of the watch...question is whether to
upgrade to warning or advisory. Still not quite confident enough in
necessary ice accumulate for a warning here and will allow day shift to
take one more crack at it. Nevertheless...a good amount of ice
is possible from Raleigh County up towards Webster
County...especially the eastern parts of these counties where a
tenth to a quarter of an inch of ice appears possible. Elsewhere
across The Lowlands...expect a dusting to perhaps an inch or so of
snow prior to the changeover to rain. And finally...water will need
to be monitored once again with already swollen streams and rivers
from Thursday/Friday rains and upwards of 1.00-1.50in of quantitative precipitation forecast across the area
by Sunday night.
Temperatures continue to rise overnight with all locations seeing precipitation as
rain by 12z Monday. Precipitation will gradually end from northwest to
southeast as the surface low continues off to the northeast.
Inherited maximum temperatures Monday generally in the low/middle 40s still look
on track. Did warm min temperatures up on Monday night per latest guidance.
Much of Monday night continues dry...but yet another wave quickly
pushes northeast out of the Gulf by early Tuesday...which will bring
another increased chance of snow to the area by Tuesday.
Long term /Tuesday night through Friday/...
Canadian high pressure finally takes control Tuesday and lasts the
remainder of the work week...under dry west to northwest flow aloft.
This will bring lots of sunshine but cold temperatures through middle
week...then a slow warming trend into the 40s by Friday as the high
center slides east of the area. With dry air in place and lack of
clouds...expect large diurnal ranges in temperatures this
week...bringing quite cold nights.
Aviation /14z Saturday through Wednesday/...
areas of light snow or drizzle will diminish this morning to
improve LIFR conditions to IFR/MVFR during the morning hours...and
then to VFR by early afternoon.
The second batch of precipitation could provide areas 0f IFR
ceilings or visibilities as snow affects southeast Ohio and portions
of WV today.
Visibilities will be reduced to 1/4 of a mile or less. Sites
prone to snow effects are heights...pkb...and crw. Other sites such as
ekn and ckb could experience IFR conditions under snow later
High pressure briefly building into the area Sat will lead to
improving conditions...with MVFR stratocu in the morning giving
way to VFR by noon lowlands and during the afternoon mountains.
Surface flow will be north to northwest while moderate SW flow aloft shifts to
light northwest west of the Ohio River early on...this shift reaching the
mountains by 06z Sat...light northwest flow aloft then remaining throughout
the area through Sat.
Forecast confidence and alternate scenarios through 12z Sunday...
Forecast confidence: medium.
Alternate scenarios: timing of categorical and precipitation changes may vary.
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.
UTC 1hrly 14 15 16 17 18 19 20 21 22 23 00 01
EST 1hrly 09 10 11 12 13 14 15 16 17 18 19 20
crw consistency l M M 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 M h h M l l l h l l l l
ekn consistency M M M M M M M M M M M h
pkb consistency M M h h h h h h h h h h
ckb consistency l l M M h h M h h h h h
After 12z Sunday...
IFR possible Sunday and Monday in mixed wintry precipitation and then
runoff is beginning to slow across the County Warning Area...and most rivers have
or will soon crest. Flood warnings still in effect along the
Elk...Buckhannon...and Tygart Valley rivers.
In addition...more rainfall is expected Sunday into Sunday
night...which may cause additional rises on rivers. And may also cause
flooding along small creeks and streams.
additional parts for Parkersburg ASOS are expected Monday.
Automated observations will be unavailable at times until then.
WV...Winter Storm Warning from 4 am Sunday to 4 am EST Monday for
Winter Storm Watch from late tonight through late Sunday night