Valid 022000Z – 031200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
Isolated lightning flashes may occur near the central California
Coast today. Severe thunderstorms are not expected.
…20Z Outlook Update…
Within elongated mid-level troughing across the far eastern mid and
subtropical eastern Pacific, a couple of cyclonic circulations are
present. This includes at least one of mid-latitude origin, which
may be accompanied by a 500 mb cold pool with temperatures of -22 to
-24 C. However, this feature is currently 300-400 miles west of
Eureka CA, and forecast to continue to dig southward, well offshore,
through the remainder of the period.
Within southwesterly flow to the east of the mid/upper trough axis,
a weak perturbation is currently approaching coastal areas south of
San Francisco Bay, and is forecast to progress inland and across the
southern Sierra Nevada by late this evening. This is being
accompanied by considerable convection, the leading edge (rooted in
the lower/mid troposphere) of which is already spreading inland
across coastal areas. However, likely due to the lack of
colder/drier air at mid-levels, there has been no evidence of
lightning near or inland of coastal areas, and it seems increasingly
probable that this will remain unchanged through 12Z Tuesday.
While, an isolated lightning flash or two might still not be
completely out of the question, probabilities for thunderstorms
generally appear less than 10 percent.
.PREV DISCUSSION… /ISSUED 0955 AM CST Mon Dec 02 2019/
The combination of cold, dry continental air across much of the
country will limit buoyancy for deep convection. Severe
thunderstorms are not expected. A few thunderstorms are expected
across central California coastal areas and adjacent Pacific waters
today as lift associated with a mid/upper low and the exit region of
a mid/upper jet remain favorably located across that area.