Valid 311200Z – 011200Z
…NO SEVERE THUNDERSTORM AREAS FORECAST…
Severe thunderstorms are not expected on Tuesday.
An occluded mid-latitude cyclone will be located over the northern
Great Lakes today with a secondary weak surface low off the
Northeast coast. A cold front will extend southeastward from this
surface low and remain mostly offshore until reaching the far
southern tip of Florida. Thunderstorm development is not expected
due to inhibition (caused by warm temperatures between 850 and 700
mb) and weak forcing along the front.
Farther west, a closed low will be located near the Baja with a
strong upper jet approaching the Pacific Northwest. Precipitation
will be mostly stratiform across western Washington and northwest
Oregon today, but weak elevated instability (100 to 250 J/kg MUCAPE)
and enhanced lift due to orographic effects may lead to some
lightning during the day and evening hours, mostly in Washington.
The better chance for thunderstorms will be early Wednesday morning
(06Z to 12Z), when colder air moves in aloft and lapse rates
steepen. Surface based convection may develop during this period
with MLCAPE around 250 to 500 J/kg. Isolated strong wind gusts may
be possible with any stronger updrafts due to the strong wind field
(40 kts below 925 mb), but overall, the limited instability and
coverage should preclude any substantial severe weather threat.