HMT Forecast

A weak wave is moving over the forecast area today with precip amounts
up to about .10".

A moderately strong short wave is on track to come in over the weekend
and still looks a bit under IOP criteria. The GFS has the timing
of the event from about 08Z Saturday until 10Z Sunday with about 3/4
inch of liquid precip progged. The GFS ensemble mean is closer to 1/2 inch.
The AWIPS derived snow product yields about 10" of snow in the highest
elevations from this model run. Thicknesses are running about 546dm during
the event. This is therefore a relatively warm event with the main thrust of
the wave passing to the north. Best dynamics are near Seattle with
a 500mb low sitting just offshore NW British Columbia. For comparison,
the NAM80 run has the timing from 15Z Saturday with lingering precip until
mid-day Sunday with only about 1/3 inch of precip..

Longer range 12Z GFS90 forecast run suggests a split wave whose southern
branch comes on in early Tuesday with light-moderate precip.
The second mid-week wave sets up more as a plume of moisture in a flat
wave for a more prolonged period of moderate precipitation from Wednesday
through Thursday night. The PW field shows a long narrow plume of PW over 30mm
reaching the San Francisco coast during this event.

Steve Albers