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HMT Forecast Mon 1/21/2008 2015UTC

For this week we will have a couple of cutoff lows to watch producing light
to moderate intensity precip that is fairly persistant and adds up over time.

For today and the next couple of days we have the E/W oriented trough becoming
a bit more cutoff just offshore from CA. Light precip over the ARB should
continue with LAPS analysis showing 1-3" of snow over the past 6 hours.
The peak precip in the GFS over CA is just under 1"/6h near Santa Barbara
Wednesday afternoon. As the low is kicked out to the east we do get some
moderate precip (GFS has .28"/6h) over the ARB Wednesday evening. This is
unsupported in the ESRL WRF-NMM with the higher totals staying mostly near
the coast.

Next shortwave of interest currently near 165E longitude again rides to the
north by the Alaska and BC coasts before approaching the ARB Thursday evening.
Even though its a fairly strong system, there is little in the way of a
trajectory that feeds into any atmospheric rivers. Thus we would be marginal
for an IOP, particularly as the GFS is keeping the main precip to the
west of the ARB closer to the CA coast. Amounts reach .45"/6h west of the ARB
on Friday morning. The ECMWF is a bit more cutoff and this would also keep the
precip to the west.

Later in the weekend and early next week the long wave ridge off the west
coast gradually breaks down with each passing shortwave. The PacJet that
develops may initially aim towards WA. The wave passage on Sunday may be worth
watching for an IOP within this context. The ECMWF is about 12 hours slower
than the GFS timing. The GFS is currently generating .6"/6h near the ARB, with
about 2" accumulating over a 42 hour period.

Longer range GFS IWV plots show continuing atmospheric river potential in the
Jan 30 to Feb 6 time frame.

Steve Albers