Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Norman OK
707 am CDT Monday may 25 2015
aviation discussion for the 12z tafs is below.
have moderate confidence in the tafs.
IFR/MVFR conditions will slowly improve west to east at all sites
through 21z. A few sites may go to LIFR through 15z.
Thunderstorms and rain will affect all taf sites except perhaps kwwr and kgag
18-24z. Brief very strong winds and MVFR and lower conditions will
occur with thunderstorms and rain.
After 00z...uncertainty increases. Went with VFR conditions for
now though there is a chance widespread MVFR or lower conditions
form...especially after 06z.
Previous discussion... /issued 416 am CDT Monday may 25 2015/
additional flooding...heavy rainfall...and severe
thunderstorms...especially today...remain the main concerns.
An active weather pattern will continue this week.
The Flash Flood Watch is in great shape today and did not alter.
This morning...warm and muggy conditions will occur. Think capping
will not allow for storm formation.
This afternoon into early evening...storm chances will increase
across much of the area from a potent fast moving middle level
disturbance/short wave that will move east northeast today and
become negatively tilted. Latest short term models...particularly
the hrrr and WRF models...suggest that a fast moving line
band...Bow...or line of storms will move northeast and affect
much of the area. Increased rain chances to account for this with
the highest chances near a Wichita Falls to Durant line. This
complex of storms may affect far western North Texas near Knox
City and Crowell as early as 11 am then exit the Ponca City and
Durant areas towards 9 PM. The Oklahoma City metropolitan area will most
likely be affected in the 3 to 6 PM time frame.
In regards to heavy rainfall and flash flooding potential this
afternoon and evening...concerned with brief heavy rainfall rates
of 1 inch or more for an hour or two along the leading edge of
the line of storms. This will cause very rapid runoff and
possible flash flooding. Do not think total rainfall amounts will
be excessive...generally 1 to 2 inches as the storms should move
quickly to the northeast. Thus...kept the Flash Flood Watch in
In regards to severe thunderstorm potential this afternoon and
evening...there is a chance for a fairly widespread damaging wind
event near and southeast of I-44 with some gusts over 70 miles per hour. The
air will be moist with precipitable water values in the 1.3 to 1.8
inch range and very unstable...MLCAPE 2000-4000 j/kg...along with
strong 0-6 km 30-50 knots shear. There is a low potential for
tornadoes due to increasing 0-1 km shear in the 20-30 knots range
southeast of I-44. Some severe hail may occur as well...but sizes
may be limited due to the widespread coverage of the large line or
Bow of storms. Cannot rule out the potential for a few supercells
ahead of the main Bow or line...but this potential seems to be
Storms should mainly diminish during the evening hours. Kept
slight chances for storms overnight...though subsidence behind the
departing short wave/disturbance should limit storm formation.
Some patchy fog could form late tonight into Tuesday morning...but
did not mention due to low confidence of occurrence.
Tuesday and Wednesday...chances for storms will continue...though
should be lower than today due to slightly warmer middle level
temperatures and slightly stronger capping. The air will be very
moist and unstable with marginal shear so a few severe storms
with locally heavy rainfall and flash flooding remain possible.
Storm coverage and motion should be lower compared to today. Will
not extend the Flash Flood Watch at this time due to the lower
coverage of storms. Temperatures will get closer to average for
this time of year.
Thursday through Sunday...storm chances continue nearly each day.
More heavy rainfall...flash flooding...and severe storms could
occur nearly each day as the air will remain moist and unstable.
Preliminary point temps/pops...
Oklahoma City OK 79 63 81 64 / 70 20 20 50
Hobart OK 77 59 82 61 / 50 20 20 40
Wichita Falls Texas 78 63 85 65 / 90 20 20 20
gage OK 79 56 80 57 / 20 20 30 20
Ponca City OK 80 61 80 62 / 30 20 20 50
Durant OK 79 65 83 67 / 90 40 20 30
OK...Flash Flood Watch until 7 PM CDT this evening for okz008-012-013-
Texas...Flash Flood Watch until 7 PM CDT this evening for txz085-086-