zczc spcswod48 all
acus48 kwns 210844
spc ac 210844
day 4-8 convective outlook
nws storm prediction center norman ok
0344 am cdt sun apr 21 2019
valid 241200z - 291200z
...wednesday/day 4 and thursday/day 5...
on wednesday, the medium-range models move an upper-level low
east-northeastward into west texas as a mid-level jet rounds the
base of the trough. at the surface, a moist airmass is forecast
across the texas coastal plains where moderate instability should be
in place by afternoon. this combined with moderate to strong
deep-layer shear, associated with the mid-level jet, will make
severe thunderstorm development possible in south-central and
southeast texas. for this outlook, the 15 percent contour in this
area has been maintained for wednesday.
on thursday, the models including the ecmwf, gfs, ukmet and canadian
are in reasonable agreement, moving the upper-level low eastward
into the arklatex. ahead of the system, a moist airmass is forecast
across the lower mississippi valley where a potential for severe
storms will exist. however, deep-layer shear is forecast to be on
the weak side which introduces too much uncertainty to introduce a
slight risk at this time.
...friday/day 6 to sunday/day 8...
the models move the upper-level system eastward into the eastern
gulf coast states on friday but deamplify the wave some. a moist and
unstable airmass may be in place ahead of the system but the models
differ on the timing of the upper-level trough and magnitude of
instability. for this reason, predictability is too low on friday
for a severe threat area.
for saturday and sunday, the models diverge sharply in their
solutions. there appears to be potential for moisture return into
the great plains but again, the models show large differences. for
this reason, will maintain predictability too low for late in the
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