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2011-06-01 FCST: CA

R R Smith

EF0
Joined
Oct 24, 2008
Messages
49
Location
Yreka, California
Some severe potential exists this afternoon for the Sacramento Valley. An upper level low centered just off the northern California coast is forecast to move inland later today. With it will come very cold (-27) 500 temps and steep 1000 to 700 lapse rates (-8). More than adequate CAPE (for California) should be present...the 15Z RUC has 500 + this afternoon over much of the northern Sacramento Valley. This is similar to the setup that spawned several tornadoes last week. The question will be whether or not there's adequate shear. Some surface convergence and good backing flows are currently present in the northern Sac Valley as Chico is reporting SSE at 16 knots. While decent 700 winds (SW at 30 knots) are forecast for late afternoon, the 500 flows look whimpy over the area of greatest instability as the front shifts to the east.

While my buddy Bill and the Tempest folks play with the real severe stuff in the Plains... I'll have to settle for maybe drifting towards the Corning area this afternoon just to see what pops.
 
How does the non-supercell tornado parameter compare with other CA events? Value of 2. And apparently better than 1 is "enhanced"

(Non-Supercell Tornado parameter (NST)

The non-supercell tornado parameter (NST) is the normalized product of the following terms:

(0-1 km lapse rate/9 C/km) * (0-3 km MLCAPE/100 J/kg) * ((225 - MLCIN/200) * ((18 - 0-6 km bulk wind difference)/5 m/s) * (surface relative vorticity/8**10-5/s)

This normalized parameter is meant to highlight areas where steep low-level lapse rates correspond with low-level instability, little convective inhibition, weak deep-layer vertical shear, and large cyclonic surface vorticity. Values > 1 suggest an enhanced potential for non-mesocyclone tornadoes.


http://www.spc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=11#

*NST is now up to 3 (make that 4) in a little section of NW CA valley. Little cells starting to pop to the N. of Sacramento, mainly Woodland. Finally some tops over 10,000. Bit of lightning showing on http://www.uspln.com/
 
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