Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Norman OK
1046 am CDT Wednesday may 6 2015
some light showers continue to develop this morning in parts of SW and
central OK. Looks like there may be a weak disturbance in the flow
that is helping to generate this activity. The showers will likely
shift out of the area or end early this afternoon as this disturbance
moves out of the area. Gusty winds today... especially in northwest OK.
Some locations are currently gusting above 40 miles per hour. Wind speeds are
expected to decrease slightly late morning/early afternoon so will hold
off on a Wind Advisory but if the strong winds persist may need
one for a few counties in northwest OK. Will continue to monitor.
Some severe storms are still possible later this afternoon and
this evening across parts of the forecast area... with large hail... damaging
wind gusts... and a few tornadoes possible.
Previous discussion... /issued 630 am CDT Wednesday may 6 2015/
Aviation...06/12z taf issuance...
active aviation period... ceilings will vary this morning between
IFR and MVFR at all sites... with widely scattered showers and
thunder across central Oklahoma. Storms will continue to move
slowly eastward through middle to late morning... with ceilings
expected to improve to MVFR to VFR through 06/18z. Thunderstorm
chances will increase late this afternoon and evening across far
western OK/western North Texas... felt confident to mention in
kcsm/khbr/klaw/ksps tafs with tempo group. South winds will remain
gusty today... increasing to 20 to 30kts through the late morning
and through the afternoon.
Previous discussion... /issued 548 am CDT Wednesday may 6 2015/
precipitation/weather through this morning...
isolated storms have continued to develop south of the okc metropolitan
near the Canadian River Valley... lifting north/NE this morning. This
activity appears to be tied to a weak 850mb dpt axis that nudges
into central OK... with storms developing on the axis of 12 to 14c
dewpoints. Elsewhere... storms continue to develop near the
terminus of the low level jet over north central OK... near Ponca City.
Expect this activity to persist through sunrise... with the bulk
of the precipitation continuing to exit across eastern OK.
Previous discussion... /issued 348 am CDT Wednesday may 6 2015/
a lot to cover... tried to hit the highlights today through
This morning... thunderstorms will continue to move eastward
across central OK. Aloft... the h500 negatively tilted trough
continues to churn north/NE into eastern Colorado/western Kansas... resulting in a
region of strong ascent across much of OK. This combined with
decent ll shear... gusts of 35 to 45 miles per hour and sporadic gusts of 55
to 65 miles per hour will continue to be possible with the strongest
thunderstorms through 4 to 5 am. Heavy rainfall across the region
has also resulted in several reports of flash flooding...
including significant flooding of roadways in Norman and in Cyril.
Through sunrise... expect skies to continue to clear across western OK.
Through 08z... WV imagery paints the picture fairly clear... with
drier air helping thin cloud cover within the middle-levels across
portions of the Texas ph. It appears... at the moment... that we will
recover fairly well today ahead of the next h500 impulse that is
currently traversing through northestern nm. Ll moisture will steadily
increase through the day across central into western OK... especially
across southwestern OK into northern Texas where middle 60s dewpoints are expected by early
afternoon. With surface warming through the afternoon... instability will
increase... with MLCAPE values anywhere from 1200 to 2500 j/kg
pooling ahead of the dry line. Speaking of the dryline...
traditional guidance (nam/GFS/ecmwf) develop a modest dpt
gradient... advancing just to the western OK/Texas border. Mesoscale
guidance from the nmm and arw flavors of the WRF are a tad more
aggressive... advancing it a touch further into western OK/western North Texas.
Expect modest deep layer shear... 30-40kts and oriented
perpendicular to the boundary... suggesting supercell development.
Bufr profiles of cape within the hail growth zone would easily
suggest Golf balls... to near baseballs with the strongest storms.
As for tornadoes... better chance will likely be in southern Kansas where ll
wind fields will have more influence from the resident surface low.
However... there remains a low chance of tornado development with
the strongest storms across portions of western OK/western North Texas... as ll
shear increases within a narrow window late this aftn/evening... and
could be enhanced if the dryline makes it a tad farther east and
storms can maintain residence on the boundary or if additional
storms go up on any outflow from earlier updrafts. Overall...
damaging hail and winds remain the primary concerns.
Overnight and Thursday... scattered storms will likely linger across
portions of the region... primarily from western North Texas and southern OK through
northestern OK as broad isentropic ascent remains across the region...
while to the north in Kansas... a cold front will stall... lingering
from the northern panhandles into northestern Kansas with a surface low developing over
the panhandles through Thursday afternoon. Once again... the dryline will make
another push into the eastern panhandles near the OK/Texas border. Storm
development will rely heavily on how the atmosphere responds to the
prior morning activity. At the moment... expect enough recovery to
get MLCAPE values in the 1200 to 2500 j/kg range again... with
initiation somewhere near the triple point in southwestern Kansas... where the
dryline and cold front intersect... with deep layer shear supportive
of supercell development along the dryline across the panhandles
through the late aftn/evening. Large hail and damaging wind gusts
will be the primary hazards... with a window for tornado development
with initial development across southwestern Kansas and the panhandles... with a
low chances across northwestern OK/western OK. Overnight... agree with Storm Prediction Center
analysis... storms will likely merge into an mesoscale convective system overnight into
Friday morning aided by the increasing low level jet and moving eastward
across southern Kansas/northern OK through Friday morning.
For Friday... severe weather chances will develop once again as
another h500 impulse traverses the western trough and lifts east/NE into
the Southern Plains. Similar to today and Thursday... instability development
will be conducive to recovery... but a quick glance this morning
suggest large scale lift and focusing from the cold front in southern Kansas
and the dryline will combine with increasing instability once again
for storms. Large hail and damaging winds will be the threats...
with a possible tornado hazard in the early evening as bufr
soundings suggest low LCLs and ll shear will increase as surface winds
back across southwestern Kansas/northern panhandles/northwestern OK. Overnight... storms will
once again likely develop into an mesoscale convective system... moving across southern Kansas/northern OK.
Pressing for time... storm chances will exist on Saturday as well...
with severe storms possible once again in the afternoon and evening as
the dryline makes another surge east... with guidance suggesting a
farther push into western OK. Middle-Range guidance suggests a similar
setup to Thursday and Friday... with a surface low lifting northward and storms
developing on the dryline late in the afternoon with decent shear and
For Sunday... the cold front will finally push S/southeast across the Southern
Plains as the western trough finally advances across The Rockies. Precipitation
chances will continue through the day... ending northwest/southeast overnight into
Preliminary point temps/pops...
Oklahoma City OK 76 64 77 64 / 60 50 40 60
Hobart OK 78 62 77 64 / 30 60 50 70
Wichita Falls Texas 80 64 79 66 / 30 60 50 50
gage OK 81 62 80 59 / 10 20 50 60
Ponca City OK 76 66 79 63 / 70 50 40 70
Durant OK 77 65 79 67 / 60 40 50 50