Valid 071200Z – 081200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
A few thunderstorms may occur along the coast of the Pacific
Northwest and northern California through Tuesday evening. Severe
thunderstorms are not expected.
As an eastern upper trough — reinforced with time by a second
trough shifting southeastward out of Canada and across the Great
Lakes — continues steady eastward progression, a second trough is
forecast to move inland from the eastern Pacific and across the West
Coast states through the period.
Cold surface high pressure will prevail across much of the U.S., in
the wake of the departing eastern upper trough and the approaching
western one. As such, deep moist convective potential will remain
quite low across much of the country. One exception will be across
the Pacific Northwest coastal ranges, as the aforementioned upper
trough moves onshore. With cold air aloft yielding steep lapse
rates, a few lightning strikes may accompany a band of convection as
it moves onshore during the afternoon, in conjunction with the
surface trough, and then in the showery upslope precipitation
expected once the trough passes.