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HMT Forecast Discussion: 7 March 2008 at 1945 UTC

Mostly clear skies graced the Sierras this morning under transient ridge conditions. Meanwhile, the next progressive shortwave trough is clearly evident in the IR imagery making landfall in the PacNW and N CA. High and middle clouds will increase this afternoon and tonight across the ARB, as the tail end of the shortwave skirts the region and flattens the ridge aloft. However, no significant precip is expected locally.

Midtrop heights will promptly rebound tomorrow and Sunday in response to ridge building along the West Coast and weak Great Basin cyclogenesis downstream. Consequently, the dry wx will persist through the weekend across the ARB, although light warm-advection precip may fall across the PacNW and over extreme N CA later Sunday and Sunday night.

The progressive storm system slated to make landfall along the West Coast for Monday evening into Tuesday is still progged to remain mostly N of the ARB. Current model solutions are consistent with their predecessors in depicting the large-scale dynamics and orographics primarily impacting the PacNW, although the trailing cold front may generate some light precip along the N half of the Sierras Monday night into Tuesday.

The West Coast ridge amplifies yet again for the middle of next week. Unsettled wx may be in the offing toward week’s end.

Paul Neiman
NOAA/PSD