Severe Weather Threat Day 2 Tue Dec 18

Posted: Mon 5:43 PM, Dec 17, 2012

Synopsis...

An Initial Shortwave Trough Over The Lower And Middle Ms Valley Will
Move Off The Middle And Se Atlantic Coasts Early Tuesday...As An
Upstream Trough Progresses Inland From The Pac Coast To The Great Basin And Four Corners By 12z Wednesday.

Any Risk For Isolated Thunderstorms In The 12-18z Time Frame Will Be Limited By Early Passage Of The Midlevel Wave/Dry Slot...Prior To Surface Cold Frontal Passage. Farther N...A Zone Of Ascent Will Persist Over Se New England Through The First Part Of The Day...Where Forecast Soundings Reveal Weak Elevated Instability. A Few Lightning Strikes Will Be Possible Across Se New England Through About 18z.

Otherwise...Isolated Lightning Strikes Will Be Possible Along The
Pac Coast From Nrn Ca Nwd As The Midlevel Thermal Trough And
Associated Steep Lapse Rates Contribute To Weak Surface-Based
Buoyancy W Of The Coast Ranges. Weak Instability Is Also Expected
Farther Inland Across The Great Basin...Though Limited Moisture And
Cloud Profiles Almost Entirely Below -10 C Will Tend To Limit Mixed
Phase And Lightning Production.