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Project Status: Monday 31 December (22:30 UTC)

IOP #4 is on its way...

A major system (or series of systems) is heading towards the west coast. The first wave should affect the PacNW Tuesday into Wednesday, but the 3 subsequent waves will begin to impact the HMT region beginning early Thursday. To recap the forecast: We expect the precip to begin at ~15Z or thereafter on Thursday (3 Jan); this will follow with a second surge on Friday with little in between to distinguish them -- heaviest precip should occur on Friday; then things get a little uncertain, but it appears that there will be a break on Saturday with another, colder wave on Sunday and into Monday.

Five day totals in the ARB are still expected to be in excess of 5", though perhaps not quite as wet as we were thinking yesterday (not so much discussion of 10"-15" today). But still an impressive event. Also note that this will be an excessively windy event (in fact a rare wind event according to the WFO in Sacramento - a "once in a decade" wind event). When coupled with snow levels that range between 4000 and 5500 feet Thurs-Friday then lower over the weekend, this will present very challenging conditions at Blue Canyon.


Supplemental soundings at Oakland, Reno and Sloughhouse will be required for this IOP (this will be refined on tomorrow call):
    • Begin: 12 UTC on Thursday Jan 3rd (i.e. the first "supplementals" at Oakland and Reno will be 16 UTC).
    • End: Undetermined at this time: we may get a break on Saturday and will need to consider whether to resume for the third wave on Sunday
    • Interval: every 4 hours

Radar Operations

Tentatively, the radar should be prepared to begin operations at 15 UTC on Thursday (3 Jan; 7 am local), Jan 3rd. The radar crew should be prepared to stay at the radar through Monday, 7 Jan. We may need to adjust the start time pending future forecasts.

Instrument Status

Canada Hill is back online after a temporary outage and the archive will be backfilled. Currently Chico and Lee Vining are not transmitting data to the web/data page.

Happy New Year everyone,


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