Valid 292000Z – 301200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH TEXAS…EASTERN OK…FAR SOUTHEAST KS…SOUTHWEST MO AND
Isolated severe storms are possible late tonight across parts of
east/central Oklahoma and North Texas to western Arkansas, southwest
Missouri and far southeast Kansas.
…20z Update – North Texas and eastern OK into southwest MO…
Overall, forecast reasoning remains similar to the previous outlook
issuance. Confidence has increased sufficiently to expand the
Marginal outlook northeastward into parts of southeast KS, southwest
MO and northwest AR. Latest forecast soundings from the NAM and RAP
marginally severe hail will be possible in stronger storms. A deep
layer of elevated instability resulting in MUCAPE as high as
1000-1500 J/kg will exist in combination with long, modestly curved
hodographs. Lapse rates will remain modest, around 6.5-7.0 C/km.
These weak lapse rates, along with some midlevel dryness above 700
mb, should act to limit larger hail potential. If any cell this
evening into tonight can become sustained long enough to take
advantage of the strong shear and adequate elevated instability,
hail generally approaching .75 inches to less than one inch is
Otherwise, no other changes have been made to the outlook. See the
previous discussion for further details.
.PREV DISCUSSION… /ISSUED 1030 AM CST Fri Nov 29 2019/
…Central/eastern Oklahoma and North Texas to western Arkansas…
Overall forecast details/reasoning are unchanged from prior
outlooks. Satellite/radar imagery at late morning continue to
reflect prevalent multi-layer cloud cover and light rain from the
Edwards Plateau/west-central Texas into north-central Texas and the
eastern half of Oklahoma. Thick stratus is also prevalent along the
Texas coastal plain where a maritime air mass with lower 70s F
surface dewpoints is currently located.
This richer moisture will steadily develop northward today and
tonight within an evolving warm sector in advance of a cold front
that will reach central portions of Kansas/Oklahoma and North Texas
late tonight (06-12Z). A number of factors including persistent
cloud cover and the late-period arrival of richer moisture and more
appreciable mass response continue to suggest that any severe threat
will be confined to overnight/early Saturday, and probably just the
last few hours of the period (09Z-12Z; after 3AM CST).
Near/just ahead of the front, surface dew points should reach the
mid 60s across southeast Oklahoma overnight, resulting in corridor
of MLCAPE of 500 J/kg, with up to 1500 J/kg MLCAPE across
north-central Texas. Convection should gradually increase/deepen in
a northeast/southwest-oriented corridor near the front late tonight.
Much of this convection will be at least slightly elevated. A couple
of instances of hail to near severe levels is a possibility,
although modest overall lapse rates and a tendency for updraft
interference will be limiting factors. A few near-surface-based
storms could occur mainly across far southeast Oklahoma/North Texas,
but near-neutral 0-1 km lapse rates and progged veer-back signatures
in the hodograph between 850-700 mb will probably curtail sustenance
of more robust low-level updraft rotation through 12Z/6AM CST.
…Southeast Kansas and southwest/south-central Missouri…
A few stronger storms could occur this evening, with some hail a
possibility owing to sufficient elevated buoyancy. However,
organized/sustained severe storms are not currently expected.