Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
631 am EDT Tuesday Mar 31 2015
high pressure into tonight. Low passes north with cold front Tuesday
afternoon. Gusty winds. High pressure middle week. Warmer Thursday.
Stronger cold front Friday.
Near term /through tonight/...
no changes to the forecast this morning.
have downplayed the probability of precipitation from the previous forecast with a swift
moving cold front today...but keep the likely probability of precipitation in the northeast
mountains where the moisture depth should be sufficient for some
showers developing with the cold front. This will be a low quantitative precipitation forecast event.
Winds will gust significantly today in the strong low level flow
ahead of the front transferred down to the surface with the help of
mixing. But...925mb winds are only showing 20-30kts and will be
upgliding in warm advection ahead of the front. Colder air descends
behind the front...so could some good gusts with the actual
frontal passage...but should lose those pretty quick into the tonight period.
Have upped the temperatures across The Lowlands today and think some
70s here and there are not out of the question in the tri
state/Kanawha valley/Coal fields area.
See fire weather section below.
Short term /Wednesday through Friday/...
after a brief appearance by dry high pressure on Wednesday...models
continue to advertise a very unsettled weather pattern Thursday and
Friday...within a multiple stream zonal flow aloft coming off the
Pacific Ocean. A frontal system will approach Thursday...then slow
as it crosses the area Thursday night and Friday as waves of low
pressure ride along the front...thanks to a series of short waves
crossing the area. While details on each wave that rides along the
front are somewhat different among the models...the agreed slow
frontal progression itself across the area spells a general
widespread regime for showers and a chance for thunderstorms...
especially Thursday night and Friday. This is supported by a well
defined influx of moisture and some instability as southerly winds
around the western side of high pressure off the Atlantic coast
feeds the frontal system. So...nice and dry and warm Wednesday under
sunshine and light southerly flow...then a wet and cooling trend
Thursday due mainly to the clouds and rain ahead of the front. This
will be followed by the front progressing slowly southeast across
the area Friday and Friday night...with cooler air on cold
advection. However...air not cold enough for any snow at this time.
Models do push front east of the area by Saturday...with any
lingering rain showers ending early...as dry and cooler high
pressure builds in.
Long term /Friday night through Monday/...
a rather unsettled end to the work week with the potential for the
front to be slowed by a surface wave. Will be watching the trends to
see if any water issues arise. The Easter weekend...though...is
shaping up to be mainly dry with seasonal temperatures.
Aviation /12z Tuesday through Saturday/...
expecting gusts in the 25-35kt range today ahead of the cold
front...with the cold front passage...and then easing overnight
after 00z Wednesday. Cold front will be dry for the most
part...but some brief MVFR ceilings and 6sm -shra in ekn is
possible around the 21z time frame today. Otherwise...VFR ceilings
expected...with clearing overnight.
Forecast confidence and alternate scenarios through 12z Wednesday...
Forecast confidence: high.
Alternate scenarios: gusts may need to be upped slightly.
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 h 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 Wednesday...
IFR possible in showers and/or storms Thursday night through
there are a few Keys to the fire weather forecast today. First of
all...looking at forecast soundings...should only have a couple
hours during mixing where the dewpoints in the 900-880mb layer will
drop below -10c...so think the guidance dewpoints should be fairly
representative. Across the north...clouds and probability of precipitation should keep the
relative humidity values from plummeting too far by adding minimal precipitation over the
northeast mountains and keeping the maximum temperatures in check. Wind
velocities are the strongest proponent for fire weather
conditions...with gusts in the 20-30kt range...and 30-40kts over the
ridges. Fuel stick moisture is forecast to be borderline on the 8