Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
637 am EDT Monday Apr 27 2015
chilly north flow today with a middle/upper level disturbance passing
late today. Dry Tuesday. Moisture creeps north Wednesday from
weakening southern system. Northern trough sweeps through Thursday.
Near term /through tonight/...
have a couple 500mb ripples and vorticity maxes to focus on for this near
term period. The first is evident by clouds in Ohio and eastern
Kentucky. Do not expect much more than some clouds with this one as
it passes this morning due to dry air in place. The second feature
has some associated showers over Lake Huron and eastern Michigan.
Expect this feature to rotate across County Warning Area this afternoon and evening.
Have showers with this...with the best chance across the northeast
quadrant of the forecast area from 18z to 00z. 850mb temperatures across
the northeast will be near zero...and even dropping below zero late
this evening. Because of this...have snow showers above 3500
feet...with even a dusting to half inch of accumulation at the highest
Today will be another cool day. Minimal changes made to the forecast
highs. Also expect a decent northerly breeze today...with gusts of
10-20 kts across lower elevations and 20-30 kts in the mountains.
Somewhat uncertain how quickly clouds will scatter out
tonight...which makes the low temperature difficult. Only made
insignificant changes to previous numbers using a consensus blend.
This still keeps up on the upper end of the frost range...so have
some patchy frost in the forecast. Not confident enough in
widespread damaging frost to issue an advisory but will continue
mention in the severe weather potential statement.
Short term /Tuesday through Thursday night/...
a strange middle/upper level pattern as middle/upper low lingers off
northeast coast. Overall...a rather weak low level flow in our
Another southern middle level disturbance weakens as it lifts toward
southern counties on Wednesday. Will not be too eager moving chance
probability of precipitation into our northern counties...but did increase probability of precipitation toward likely
in the bkw vicinity on south into SW Virginia Wednesday afternoon. The
only solution I saw that kept it totally Bone dry was the
Meanwhile...the notable change from yesterday is the northern
stream disturbance dropping south from western Ontario on Wednesday.
00z model consensus is to drop this disturbance a bit further west
into the middle/upper Ohio Valley on Thursday. As a result...had to
increase probability of precipitation on Thursday and linger the higher probability of precipitation longer into
Thursday evening. Seems to be the appropriate way to end the wet
month of April. Though with precipitable water below an inch...no
water concerns with these systems. Even lingered chance probability of precipitation until
Friday morning over the mountain counties.
No mention of thunder through this time frame.
Lowered maximum temperature a bit in our south on Wednesday...but
not a strong upslope flow this time around. Thinking maximum
temperature on Wednesday may actually be warmer north of crw than
south of crw...based on less clouds and drier.
Also started to lower maximum temperature on Thursday based on
increase chances of showers.
Long term /Friday through Sunday/...
yet another battle between the northern and southern streams early
in this period...before the northern stream takes over. There are
model differences in how far north a southern stream upper low from
the Southern Plains states gets ingested into the amplifying
northern stream upper trough...which drops down through the Great
Lakes Wednesday night and Thursday. The trend is for a more
northward track of the southern system in the GFS and Euro models
before getting kicked out off the Carolinas. This scenario will
bring rain with likely probability of precipitation to the southern and central mountains
Wednesday night and Thursday...with probability of precipitation tapering off slight chance
over parts of southeast Ohio and northwestern West Virginia...along
with cooler than normal temperatures. By Thursday night...with the
southern system having moved east of the area...will leave just a
low chance for a bit of upslope rain showers in the northern
mountains as Canadian high pressure builds in from the northwest.
Will not put any snow in at this point...but this cannot be ruled
out for the highest elevations. Thereafter...dry northwest flow
aloft and surface Canadian high pressure will bring cooler than
normal temperatures Friday into the weekend...but no extremes.
Aviation /10z Monday through Friday/...
VFR is expected through this morning. An upper level wave will
pass through this afternoon...with some rain showers possible. Mainly
across the northeast. Also have some MVFR ceilings at ekn and bkw
tonight in the north to northwest flow behind this feature.
North winds will become gusty this afternoon...with gusts of
15-25 kts...before decreasing again tonight. Think enough flow and
some clouds will keep fog at Bay tonight...although some guidance
does suggest river fog formation. Will have to keep track of how
quickly clouds scatter out overnight.
Forecast confidence and alternate scenarios through 12z Tuesday...
Forecast confidence: high.
Alternate scenarios: may get brief MVFR ceilings at ekn early this
morning. May get River Valley fog tonight if skies clear.
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 h h h 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 h h h h h h h h h h h h
ekn consistency M h h h h h h h h h h h
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h h h h h
After 12z Tuesday...
no widespread IFR conditions expected.