Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
759 PM EDT Wednesday Mar 12 2014
gusty winds and turning much colder. Cold Thursday...but warming
Friday. Weak cold front late Friday night to the north...chance
of rain in southern Coal fields late Saturday.
Near term /through Thursday/...
730 PM update...
updated recent observation and re-ran hourly temperatures as those have been a
bit slower to fall early this evening. And although winds continue
to gust around the 25-30mph range this evening...per collaboration
with surrounding offices...cancelled the Wind Advisory as wind
gusts are remaining well below the 46mph advisory criteria and are
expected to remain at sub-advisory speeds. Still do expect gusts
upwards of 30 to perhaps 35 miles per hour over the course of the next few
hours before gradually beginning to subside somewhat late evening
and overnight. Will take a better look at snow amounts this
evening and make decisions on our current Winter Weather Advisory
by the next update.
prefrontal convection band exiting mountain counties 19z to 20z.
Strong cold air advection with strong pressure rises through 00z.
Pressure rises on the order of about 8 to 10 mb/3 hours. Continuing
the Wind Advisory that we posted yesterday...for the period noon
today to midnight tonight.
An example of the cold air advection...the 850 mb temperature on the
12z NAM was plus 7 c at 18z then minus 10c by 00z for crw. That is
17 degrees celsius in 6 hours. Surface temperature at heights went from 59
to 42 in one hour between 17z and 18z.
The transition from rain showers...to drizzle...to snow showers
beginning in southeast Ohio currently...have reaching our far SW
Thinking the NAM a bit overdone on the snow accumulations overnight
in our mountains...still thinking mostly 2 to 4 inches our central
mountains...with mostly an inch or less through The Lowlands...with
an 1 or 2 possible in north central WV and far northern southeast
Will hold onto the Winter Weather Advisory in the middle Ohio Valley
where our criteria is lower than north central WV. But see no big
reason to expand the Winter Weather Advisory.
No major changes to temperature. Did take the minimum temperature
for elevations at or above 4 thousand feet to at or below zero for 12z/13z Thursday.
Short term /Thursday night through Saturday night/...
cold air exits Thursday night and warm advection out of the
southwest brings Friday highs back into the upper 50s with some
locations in The Lowlands touching 60. A fast moving clipper system
across southern Canada brings a weak cold front across the area late
Friday night/early Saturday with clouds building in Friday afternoon
ahead of the front...have chance probability of precipitation mainly across northern zones
drying out early Saturday morning.
A second system moves across the Tennesee valley late Saturday
night with precipitation confined mostly across the southern coalfields
beginning after 00z Sunday...with chance probability of precipitation extending into the
long term period.
Long term /Sunday through Wednesday/...
both the GFS and European model (ecmwf) models bring a cold front sinking south
across northern WV by 12z Sunday. At the same time...an upper
level trough in the northern stream...with embedded shortwaves
passing mainly south of the area...suggest a developing of a surface
low pressure system nearby the front the Middle Atlantic States by
The GFS looks faster than the European model (ecmwf) bringing precipitation across southern
WV...northeast Ohio...and southwest Virginia by 06-12z Sunday.
Temperatures aloft look warm with the GFS suggesting the onset of
precipitation being mostly liquid...until 00z Monday when colder air rushes
in from the north. This colder air is evident in 850 mb temperatures in the
minus 5c to minus 7c by 18 Monday. Any lingering moisture will
transition quickly to a brief period of mixed precipitation then to all
snow during the day Monday with a possible non-diurnal temperatures
The European model (ecmwf) looks similar but about 12 hours slower than the GFS.
Therefore...populated probability of precipitation and weather with a compromise between
both models at this time. Confidence runs high on probability of precipitation...the tricky part
of the forecast recedes on the timing of the precipitation.
For temperatures...started with HPC guidance incorporating trends
from a blend of the GFS and European model (ecmwf) through the period.
Another low pressure system an associated fronts could affect the
area by middle week.
Aviation /00z thurdsay through Monday/...
00z Thursday through 00z Friday...
cold front is now well east of the area...and although the
strongest gusts from earlier this afternoon have also pushed
eastward...still seeing gusts around 30-35mph across mainly the
eastern half of the area.
Widespread MVFR ceilings overnight...but did not go quite as
pessimistic with IFR ceilings as previous taf per latest guidance. Kept
most of The Lowlands at low MVFR ceilings overnight...while kept IFR
ceilings at the mountains sites. Still...snow showers continue across
the area this evening...with the most general coverage of snow
showers roughly between 00z-04z and across the southern parts of the
area. Visible may ceratainly be reduced to IFR limits in these snow
Flight conditions are expected to improve from west to east between
09z west...and between 12z-15z east. VFR conditions will prevail for
the remainder of the period...with a breezy west/northwest wind
continuing through the day.
Forecast confidence and alternate scenarios through 00z Friday...
Forecast confidence: medium.
Alternate scenarios: timing of improving conditions from west to
east 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.
Date Thursday 03/13/14
UTC 1hrly 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1hrly 20 21 22 23 00 01 02 03 04 05 06 07
crw consistency l l l l l l l l h h h h
heights consistency l l l h M l h h h h h h
bkw consistency l M M M M l l l l M M M
ekn consistency M M M M M l l l l l l l
pkb consistency l l l M M M l l h h h h
ckb consistency M M l l l l l l l l l h
After 00z Friday...
IFR possible Sunday in rain or snow mainly southern West Virginia...
mountain counties...and southwest Virginia
WV...Winter Weather Advisory until 2 am EDT Thursday for wvz009-010-
Ohio...Winter Weather Advisory until 2 am EDT Thursday for ohz066-067-