Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
625 am EDT sun may 24 2015
high pressure with a dry and warm Memorial Day weekend. Convection
becomes more common during the short work week in an increasingly
warm and humid air mass...under weak upper level disturbances.
Near term /through tonight/...
no significant changes were needed to the previous forecast.
Surface high to the east...along with building upper heights will
result in increasing temperatures and humidity during the near
term and into early next week. Outside of some afternoon
cumulus...expecting another mostly sunny day...although clouds will
increase late tonight from the west out ahead of an approaching
Short term /Monday through Wednesday/...
very warm and humid pattern setting up in deep layer S to SW
flow...with precipitable water values of 1.50 to 1.75 in and surface dew points in the
middle 60s becoming common. Upper level short wave troughs coming out of a
general area of troughiness over the western Continental U.S....lift and
minor out as they approach the forecast area from the west...on account
of a very tenacious Atlantic ridge.
The initial short wave trough minors out quite a bit as it approaches on
Memorial Day...as the ridge flexes its muscle. It looks like
there is a better chance outdoor Holiday activities will be able
to Dodge a pop up afternoon or evening shower or thunderstorm. The
next short wave trough is prognosticated to make better in roads Tuesday nt and Wednesday
although it too will minor out. Thus have a better chance for
showers and thunderstorms these periods including overnight Tuesday nt
and Wednesday morning.
While the forcing may prove to be weak...it will not take much to
get convection going given the amount of moisture available...and
it will be tough to get rid of any convection overnight once it
forms in the and evening. Prognosticated bouyancy of at least a grand
j/kg of cape and 30 kts mean low to middle level flow is consistent
with Storm Prediction Center marginal risk for day 3 so will include a low probabilitysevere
threat in the severe weather potential statement..and add the possibility for localized dumpers
Not much changes need to temperatures...near high end of guidance
for highs and close to a guidance blend for lows.
Long term /Wednesday night through Saturday/...
dirty ridge becomes more of a factor in determining our sensible
weather. Kept chance or better probability of precipitation through the period as impulses
will be riding north in SW flow this period. Diurnal trends become
less of a factor as impulses could help drive convection into the
overnight hours. Thus carried some probability of precipitation during the overnights as
well. Mainly used wpc guidance for temperatures.
Aviation /12z Sunday through Thursday/...
any patchy low VFR valley fog will dissipate after 13z. Otherwise...VFR
conditions with light surface winds expected. Scattered-broken middle and high
clouds increase from the west after 06z.
Forecast confidence and alternate scenarios through 00z Monday...
Forecast confidence: high.
Alternate scenarios: none.
After 06z Monday...
widespread IFR not expected.