Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
1030 am EDT Friday Oct 24 2014
high pressure at the surface dominates through tonight...even as
upper level disturbances cross. Mainly dry cold front crosses
Saturday evening. High pressure Sunday. Warmer early next week.
Near term /through today/...
current forecast on track. No changes anticipated this morning.
Short term /Saturday through Monday/...
for Saturday...a weakening cold front moves through and reaches the
eastern mountains overnight. The latest nam12...and to a lesser
extent the GFS...are spitting out the slightest amount of quantitative precipitation forecast for
the 06z sun timeframe. Left mention of light showers in for
mountains for the overnight hours...as this dying front makes its
Surface high pressure over Tennessee will gradually shift
eastward through the later part of weekend as a weak warm front
pushed north across the forecast area. Atmospheric column will
generally remain dry...with warm air advection taking place. This
will result in little chances for precipitation with an upswing in
daytime highs...especially by Monday after warmer airmass nudges
into the Ohio Valley.
Used inherited temperatures with a blend toward consensus British Columbia grids to cover
daytime highs which lead to minimal changes in values.
Long term /Monday night through Thursday/...
warming aloft...along with a pseudo dry warm front...should be
lifting north and northeast overnight Sunday night into Monday
morning. Will keep minimum temperatures just above frost advisory
criteria where the program still is ongoing.
Warming on Monday appears faster than we pictured 24 hours ago. 850
mb temperatures of 15 to 16c by 00z Tuesday are projected by 12z GFS
and European model (ecmwf). A marginal increase in moisture at 850 mbs on Tuesday
has GFS and European model (ecmwf) dropping 850 mb temperatures to around 12c Tuesday
afternoon. Will increase maximum temperatures Monday...but
boundary layer should keep maximum readings Tuesday nearing as
warm. Strongest wind gusts should be Tuesday afternoon. Have
surface dew points increasing from west to east in wake of the
pseudo warm front on Monday. Do not expect red flag criteria to be
meet. However...with the increase in wind and the warm afternoon
temperatures...will include an elevated/enhanced risk of the spread
of wild/brush fires Monday afternoon and again Tuesday.
Was also slower increasing cloud cover Monday into Tuesday...than
our medium range guidance from wpc.
Glad we delayed the probability of precipitation 24 hours ago...with the next front. The
front will have some right rear 250 mb jet support. So have
increased probability of precipitation...mostly in the 40 to 60 percent range for late
Tuesday night into Wednesday. Have probability of precipitation lowering Wednesday
afternoon in our Ohio Valley counties.
The front will likely slow down in our southeastern counties...with
another 500 mb trough still to our west Wednesday night. So will hold
probability of precipitation along our Virginia border counties into Thursday...but have the
western slopes dry on Thursday. Wave likely to enhance the rain
Thursday to our east and southeast. A deepening low pressure will
likely be well to our north...over Ontario late Thursday...which
will open the door to another downward swing on our autumn
temperature seesaw ride.
Aviation /10z Friday through Tuesday/...
MVFR stratocu dissipating in the mountains overnight may reform
briefly as morning cumulus after daybreak Friday. Otherwise vlifr dense fog
likely most sites...even bkw may get IFR fog.
The remainder of the period...the balance of the day Friday and Friday
nt...will bring mainly VFR conditions as an upper level trough
brings middle and high cloud. Valley fog may start to form by 06z
Sat. MVFR stratocu may also start to reform in the mountains by 06z
Calm air will give way to light west surface flow Friday and then become calm
again Friday nt. Light north flow aloft will become light northwest Friday.
Forecast confidence and alternate scenarios through 12z Saturday...
Forecast confidence: medium overnight into Friday morning...then high.
Alternate scenarios: fog timing...density...and locations overnight
could vary...as may MVFR ceilings at ekn into Friday morning and again Friday
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 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1hrly 07 08 09 10 11 12 13 14 15 16 17 18
crw consistency l l M h h h h h h h h h
heights consistency l l M 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 h h h h h h h h h h
pkb consistency l l h h h h h h h h h h
ckb consistency h l h h h h h h h h h h
After 12z Saturday...
no widespread IFR conditions expected.