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HMT wx forecast discussion: 11 February 2008 at 1945 UTC

And the beat goes on… high and dry for the foreseeable future.

Deep tropospheric ridging today and tomorrow across the ARB will provide mostly clear and mild conditions. Meanwhile, a prominent midlevel S/W trough is evident in the satellite loops, presently crossing the 150W meridian at ~44N latitude. This wave is moving ENE and will flatten the EPAC ridge on Tuesday and make landfall in the PacNW Tuesday evening.

Once E of the ridge axis, the S/W will vigorously dig SSEward into the Great Basin on Wednesday, as strong cold advection and a developing 300-mb jet become established on the back side of the wave. The newest model solutions continue the decreasing trend for QPF in the ARB during this event. Specifically, the strong large-scale dynamics and enhanced moisture remain N-E of our area. Also, as was the case in previous model solutions, the low- to mid-level flow remains NWerly prior to, during, and after the wave passage, which is quite unfavorable for orographic forcing. Hence, expect little or no precip across the ARB with the wave passage.

The EPAC ridge amplifies yet again Thursday and beyond, so the dry wx shall continue. Subsequent S/W troughs propagate into the diffluent upper-level flow across the EPAC, weaken, and make landfall in the PacNW and/or BC through the middle of next week (~20 Feb). Thereafter, perhaps some zonal wave energy will finally reach CA… maybe.

Paul Neiman
NOAA/PSD