Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
701 PM EST sun Dec 8 2013
warm front lifts north into tonight. A low pressure wave crosses
later tonight into Monday. A weak system crosses late Monday night
into Tuesday. Chilly dry high pressure for Wednesday into Friday.
Near term /through Monday/...
secondary wave and associated precipitation starting to push into
the County Warning Area this evening. For now...taking a watchful approach
concerning expanding a Flood Watch across southern Coal fields and
southwest Virginia. So far...generally 0.1 to 0.15 inches of
precipitation observed from band in an hour. Ffg in these areas is
averaging about 1.15 inches in 3 hours. In addition...this is an
area that received less rainfall than the remainder of the County Warning Area a
few days ago. If higher rainfall rates are observed...will issue a
watch. Most of the precipitation from this wave is expected
remain generally along and east of the i79 corridor.
Temperatures are struggling to warm along the mountains...where
cold air continues to remain trapped along eastern slopes. Did
elect to extend the advisory for Nicholas and Webster until
05z...and extend the warning for Raleigh and Fayette counties
until 05z. Also decided to extend the warning for Randolph and
Pocahontas counties until 12z based on latest model runs which
suggest freezing rain could occur well into Monday morning. Did cancel the
advisory across Ohio and adjacent WV counties this evening.
Previous discussion follows...
jet streak induced heavy snow band decreasing in intensity as the
jet starts pulling out. Also have warmer 850 temperatures gradually inching
northward across County Warning Area resulting in precipitation changing from snow to sleet
to rain from south to North. Western County Warning Area will hang onto cooler temperatures
a bit longer and snow will linger longer. Bulk of the snow/sleet
accumulations are done across the County Warning Area...with best chance of
additional snow accumulation across the northwest County Warning Area and northern
mountainous counties. Attention then turns to ongoing freezing rain
event. Across the WV lowlands and middle Ohio River
valley...temperatures will slowly climb above freezing...but even
with the current temperatures of 30-32f...ice accumulations on roads will
be very minimal. Cancelled southeast tier of Winter Weather Advisory and
warning from this morning and will linger the north and west
portion as temperatures still below freezing with snow/sleet/rain.
Farther east...in southeast flow expect eastern slopes to remain below
freezing for much of the day. Special 18z rnk sounding shows warm
nose of +7c aloft. Another enhanced area of precipitation on radar
moving up The Spine of WV mountains with freezing rain likely.
Have surface temperatures warming above freezing in the bkw area around
00z and switching to a cold rain. Cooler temperatures remain in place
across the eastern slopes/valleys of the northern mountains
through much of the night.
Models show another slug of moisture tonight. NAM shows highest quantitative precipitation forecast
amounts across SW Virginia and southern WV...while GFS is a bit farther
north ohrfc has roughly three quarters of an inch across southern
zones and will go with that. Precipitation will gradually clear out from
west to east through the day tomorrow.
Warm advection should continue through the night...so have
non-diurnal temperatures...based heavily on the raw NAM. This has
much of the WV lowlands and west staying in the middle to upper 30s
overnight...with near steady temperatures tomorrow.
Short term /Monday night through Wednesday/...
upper level SW flow finally flattens...becoming more zonal...in the
wake of a short wave trough that crosses Tuesday. System in the near term is
about exodus by 00z Tuesday...the start of the short term...with perhaps
light upslope precipitation winding down. While not as moisture
rich as previous systems...jet dynamics and short wave forcing in the
baroclinic zone should generate a quick hitting band of
precipitation through the middle Ohio Valley early Tuesday morning.
Another band brushes the central Appalachians as a surface wave moves NE
along the front which will be over the Carolinas at that time.
Colder air moving in Monday nt will drive 850 mb temperatures to -6c to
-10c north by Tuesday afternoon...so the precipitation will take the form of
snow...save for mixed precipitation early on over the central
Any upslope precipitation in the wake of this event Tuesday afternoon is
brief...and high pressure builds in for a dry and cold Tuesday nt...and
then hangs on for a dry Wednesday.
Used adjmet and NAM for temperatures in cold advection Monday
nt...blended in adjmet for highs Tuesday and bias corrected adjmet for
lows Tuesday nt. Blended in bias corrected adjmex for highs Wednesday.
Overall no major changes.
Long term /Wednesday night through Sunday/...
still just what the doctor ordered. A mostly dry pattern
Wednesday night into Saturday. Have a slight chance of some
light snow showers Wednesday night across the northern WV
Dry air and the long December nights yields cold dawn temperatures.
Down the Road...moisture increases Saturday...have some chance probability of precipitation
by Saturday for rain and snow. Still appears not a heavy event.
Aviation /00z Monday through Friday/...
00z Monday through 00z Tuesday...
Widespread MVFR/IFR ceilings in mainly rain...except along
mountains...where freezing rain is expected across the central
mountains including through 05z...and northern mountains through 12z
Monday. Gusty southeasterly winds...mainly along the higher
terrain...with gusts in the middle to upper 20 kts through at least
Areas of LIFR ceilings developing mainly 03z through 14z
Monday...lifting to IFR/MVFR for remainder of taf period.
Forecast confidence and alternate scenarios through 00z Tuesday...
Forecast confidence: medium.
Alternate scenarios: timing of IFR/LIFR ceilings may vary from current forecast.
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 00 01 02 03 04 05 06 07 08 09 10 11
EST 1hrly 19 20 21 22 23 00 01 02 03 04 05 06
crw consistency h M M M M M M M M h h M
heights consistency l M M M M M M M h h h h
bkw consistency M M h M M M h h h h h M
ekn consistency h h h M M M M M M h M h
pkb consistency h h M M M h M M M M M M
ckb consistency h h h M M M M M M M h M
After 00z Tuesday...
IFR possible in snow Monday night into Tuesday.
the last of the river flood warnings at Belington associated with
the rainfall last Thursday and Friday...is gone.
Have Flood Watch for much of the WV lowlands and into NE Kentucky as more
rainfall is expected tonight into Monday...which may cause
additional rises on rivers. This additional rain may also cause
flooding along small creeks and streams. Will need to monitor trends
tonight for where the band of heaviest precipitation sets up...and
thus where the area of highest concern is.
additional parts for Parkersburg ASOS are expected to arrive Monday.
Automated observations will be unavailable at times until then.
WV...Flood Watch through Monday afternoon for wvz005-006-013>016-
Winter Weather Advisory until midnight EST tonight for wvz037-
Winter Storm Warning until midnight EST tonight for wvz035-036.
Winter Storm Warning until 7 am EST Monday for wvz046-047.
Kentucky...Flood Watch through Monday afternoon for kyz105.