Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
151 am EDT Wednesday Sep 24 2014
Canadian high pressure moves east of the area tonight. A warm
wave moves up the Middle Atlantic States Wednesday and Thursday.
High pressure returns for Friday and the weekend.
Near term /through today/...
145 am update...no major changes necessary.
basking in the sunshine amid cool afternoon temperatures. After a stellar
autumn day today...the overnight periods will feature a
continuation of the clear sky for most...save for some cirrus over
the mountains. The surface low and upper low over southeast states will be
responsible for the cirrus in the mountains along with developing
low level southeast flow. Tough to figure out fog tonight with most of
the guidance suggesting little in the way of dense fog for the
urban centers. They may be keying on bl winds and drying near the
surface with 3 to 4 degree dewpoint depression tonight.
However...main Stem river temperatures remain warm and model soundings
suggest very dense but shallow river fog. Regardless of extent of
River/Valley fog...tomorrow shaping up to be another fine weather day
with just some cirrus over the mountains.
For temperatures...incorporated the consensus MOS...tweaking toward local
MOS for coded cities forecast sites. This results in a warmer night than last with
no frost threat foreseen. Tomorrows highs looks to be an
improvement upon today by 3 to 5 degrees.
Short term /tonight through Friday/...
a low pressure system will move north along the Atlantic states and
could bring clouds and a low chance for rain showers along the
northeast mountains. Otherwise...a high pressure will remain in
control with dry weather...mild afternoons and cool nights across
the Ohio Valley and The Lowlands of WV through the period.
Some down sloping warming can be expected as well over The Lowlands.
Therefore...kept temperatures in the low to middle 50s during this time frame.
The flow weakens Thursday as the pressure gradient loosen up and a
new broad high pressure gradually builds from the Great Lakes
region...south across the Ohio Valley...WV and the Middle Atlantic States
through the weekend.
Left previous temperatures as they look good Thursday through
Long term /Friday night through Tuesday/...
large high pressure returns Friday into the weekend across the Great
Lakes region...the Ohio Valley and WV...to bring plenty of sunshine
and dry weather. The warmest day seems to be Sunday under near calm
flow with temperatures reaching 80 across The Lowlands.
Models showing inconsistencies from run to run in the extended
period. They are trying to bring a low pressure system and
associated precipitation in the beginning of next week...but have been flip
flopping in timing. The GFS is no longer bringing precipitation Monday and
Tuesday...and the European model (ecmwf) bring precipitation Tuesday night and Wednesday. Kept
low chance for Monday and Tuesday...but will have to wait as time
approaches to see better agreement among models.
Again...used HPC guidance for temperatures through the
period...except for Friday day 4 which used the bias corrected
Aviation /06z Wednesday through Sunday/...
IFR valley fog expected to develop...mainly after 07z...until
13-14z Wednesday. VFR conditions with light surface winds then expected
through at least 02z Thursday...although clouds will increase from the
east as a low pressure system moves north along the Atlantic
coast. This will create broken to overcast MVFR ceilings across the higher
terrain of WV and southwest Virginia...including at sites kbkw after
02z. In addition...rain showers will also be
possible...particularly across northern WV mountains...mainly
after 00z Thursday.
With the increase in cloud cover from the east Wednesday
night...development and extent of fog will be in question
Wednesday night/Thursday morning.
Forecast confidence and alternate scenarios through 06z
Forecast confidence: medium.
Alternate scenarios: timing and extent of fog overnight tonight
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 Wednesday 09/24/14
UTC 1hrly 06 07 08 09 10 11 12 13 14 15 16 17
EDT 1hrly 02 03 04 05 06 07 08 09 10 11 12 13
crw consistency M M M l l l l M M 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 h h
ekn consistency l l l l l l l l M h h h
pkb consistency h h h M M M M h h h h h
ckb consistency h h h h h h h h h h h h
After 06z Thursday...
IFR in valley fog possible Thursday and Friday morning.