Day 1 convective outlook
nws storm prediction center norman ok
1156 pm cdt wed mar 18 2015

valid 191200z - 201200z

...there is a mrgl risk of svr tstms across portions of southern
oklahoma and northern texas...

...summary...
A few storms with a threat for marginally severe hail and gusty
winds may occur across parts of the southern plains this afternoon
and evening.

...synopsis...

A weak upper low in southern stream flow over baja/northern mexico
will shift slowly eastward today. This will result in a band of
enhanced southwesterly mid to upper level flow across the southern
plains. At the surface...a relatively moist and warm airmass will
exist as far north as the red river in north tx/southern ok. A weak
surface trough will extend south/southwest from a low over western
north tx into southwest tx. At the same time...a cold front will
track southeastward across the southern plains and a few strong to
perhaps severe thunderstorms will be possible during the afternoon
and evening near the intersection of the sfc low and cold front.

...portions of southern ok and northern tx...

Surface dewpoints in the low 60s should extend as far north as
southwest and south-central ok this afternoon...while temperatures
warm into the upper 60s to mid 70s. While cloud cover may inhibit
greater heating...this should be sufficient to achieve mlcape values
approaching 750 j/kg. Isolated convection is expected to develop
near the triple point in the vicinity of cds to sps by 21-00z. While
instability will be marginal...effective shear near 35-45 kt and
modest lapse rates could be enough for some short-lived supercell
structures...capable mainly of marginally severe hail. These storms
should quickly become undercut by the southeastward advancing cold
front with only a brief window for surface based convection...but a
few stronger wind gusts may be possible as well.

...southwest tx...

A storm or two may also develop in the vicinity of the surface
trough...where stronger insolation is expected. If storms
develop...they will be diurnal in nature as convergence along the
trough will be much weaker than that near the cold front further to
the north. Still...should a storm develop...marginally severe hail
may be possible. Low confidence in coverage and conditional nature
of the threat will preclude severe probabilities at this time.

..leitman/dean.. 03/19/2015