IASC Presentation A Discussion of CANSAC Weather Products John Snook, USFS Reg. 5 Northern Ops Predictive Services Mgr. Thurs. May 3, 2012

6 km resolution 2 km resolution Notice the increased WRF Mixing height detail in the finer resolution (2 km) view on right, compared to the coarser 6 km view

2-km resolution, but State-wise view 2-km resolution, but NW Quadrant view Effects of improved resolution on depiction of Surface 10-m Wind

This is what a strong convective downdraft pattern looks like on the 2 –km WRF model

Comparison of the 18-hour prediction of expected 3-hour rainfall from pm PDT Wednesday May 2, between the 6-km resolution model on the left, and the 2-km resolution WRF on the right. model

This field, High Level Total Totals, was added in 2009 upon CANSAC OAG request. It has been a valuable item in our thunderstorm-forecast toolkit, particularly for high based convection In this product, the yellow color starts at about HLTT mark of 26, and red at 30. We have found the following threshholds, for getting at least one lightning strike in a several-county area around these sites: Reno 26+ = 89% Medford 31+ = 87% Oakland 31+ = 100%

This is a Sounding taken off CANSAC WRF model, from the Wed. a.m. model run, valid at 2am last night. Notice the winds changing from SSE at the surface to WSW as they climb to the 750 mb level. This is a relatively stable sounding, common near the coast. In a northern CA thunderstorm situation, K is usually above 28 and LI below zero.

72-hour summation of WRF model expected precip from 5pm yesterday afternoon through 5 pm this coming Saturday

Lowering of the predicted 2pm Relative Humidity from today in frontal system (on left) to 48 hours later, this Saturday afternoon, also 2pm

Preliminary 2012 Fire Season Assessment for California and Hawaii