Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Norman OK
639 am CDT Wednesday may 27 2015
the 12z aviation discussion follows....
a small area of dense fog has formed once again along the west edge of
departing middle-level clouds. This fog appears to be very
shallow...so should be gone within an hour or two. A few rain showers and
thunderstorms and rain have developed in parts of west OK...and a few may affect taf
sites. In particular...a rather strong thunderstorms and rain will probably pass
over or near klaw around 12z. These elevated storms should
dissipate around middle- to late-morning. New thunderstorms and rain development is
expected to begin around 19z in SW OK. These thunderstorms and rain will likely
spread out and advance NE during the afternoon and
evening...affecting mainly west and north OK and the ksps area...but a
few may reach kokc/koun this evening or overnight. Br/fog may form
again tomorrow morning...but until we have a better idea of where
Post-thunderstorm clouds will be...any forecast of br/fog would be
little more than a guess.
Previous discussion... /issued 419 am CDT Wednesday may 27 2015/
departing convective systems have left a situation similar to this
time yesterday...with clearing skies over very high relative
humidities at the surface. This resulted in an area of dense fog
yesterday morning. So far today...however...there are no
significant visibility restrictions...and with low confidence that
any fog will develop...have opted not to include it in the
forecast for this morning.
The 00z and 06z NAM generates a convective system over eastern
Oklahoma this morning...then drives it west-southwest across our
forecast area during the day today. There appears to be no real
justification for this scenario...so have ignored the NAM for the
first 12 to 24 hours of the forecast.
The next couple of days will feature weak flow aloft and near the
surface...moderate to strong instability...and little in the way
of focusing mechanisms. So...expect showers/thunderstorms with
relatively little geographic or timing coherence. This changes
Thursday night into Saturday...as an upper-level system...followed
by a surface cold front...move into Oklahoma and North Texas. Rain
will be more likely...and rainfall amounts will increase overall.
Beginning Sunday or Monday...upper-level ridging starts to take
hold...which should provide Summer-like weather across Oklahoma
and North Texas. Assuming this happens...it will finally shut
down the almost daily barrages of storms and flooding
rain...leaving only isolated showers and storms in the afternoons.
With the very wet ground...these afternoon showers/storms will be
more common than in a normal Summer pattern. Similarly...afternoon
temperatures will remain somewhat cooler than what would otherwise
be expected...as the heat is used to evaporate water rather than
heat the ground and adjacent air.
Preliminary point temps/pops...
Oklahoma City OK 80 65 80 66 / 40 40 50 60
Hobart OK 82 64 78 63 / 40 50 50 60
Wichita Falls Texas 85 65 82 66 / 50 40 40 70
gage OK 82 62 80 61 / 40 50 50 50
Ponca City OK 80 65 80 66 / 30 40 40 50
Durant OK 81 66 82 67 / 60 40 40 60