Valid 020100Z – 021200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER CENTRAL AND
Scattered severe wind gusts are likely across parts of central and
southern Arizona this evening. A few strong to severe storms remain
possible over western Pennsylvania through mid evening and over the
central and northern Plains later tonight.
…Central and southern Arizona…
Easterly deep-layer winds along southern periphery of an upper ridge
have promoted storms that developed over the mountains of southeast
AZ moving westward into the desert valleys. Tendency has been for
storms to evolve into multicell clusters. Deep, inverted-V
well-mixed boundary layers as indicated by the 00Z RAOB data will
continue to promote scattered damaging wind gusts as storms continue
westward this evening.
A cluster of storms continues through western PA in association with
a low-amplitude shortwave trough. The 00Z Pittsburgh RAOB indicates
around 1500 J/kg MLCAPE and 160 m2/s2 0-1 km storm-relative
helicity, but modest effective bulk shear. This environment may
continue to support a marginal risk for locally strong wind gusts
and perhaps a brief tornado with transient supercell structures
before weakening toward mid evening.
…Central through northern Plains…
Isolated storms remain possible later tonight within zone of
increasing warm advection and isentropic ascent as the low-level jet
strengthens and interacts with baroclinic zone across the central
and northern Plains. These storms will be elevated, but moderate
MUCAPE and 35-40 kt effective bulk shear will support mid-level
updraft rotation along with a risk for a few instances of hail and
locally strong wind gusts.