ARB is in a clear and cold regime today behind the secondary trough
now starting to cut off in ERN AZ.
Wave of interest for the mid-week period initializes this morning at 150W.
GFS/UKMET/ECMWF models agree on placing a fairly strong cutoff low just W of
Santa Barbara by 00Z Thursday. GFS determinstic run keeps most of the precip
along the NRN CA coast, then progressing to be off the SRN CA coast as the
low drops south. The low eventually comes ashore in SRN CA on Saturday with
most of the precip still remaining S of the ARB.
The dprog/dt for the GFS shows the cutoff located various distances W of SFO
in the past several runs valid at 12Z Wednesday, we have to go back to the
run initialized 36 hours ago to find a solution with the cutoff over the
GFS ensemble members mainly support the above scenario with the earliest
member having the 500mb cutoff reaching LA by 00Z Friday 19 Jan and the
other members more to the WSW at that time.
In the longer term, the GFS has the next two upstream waves splitting off
more to the south to try and develop more of a southern branch of the jet.
The ridge that has been parked off the west coast may then get pinched a
bit and more inland over Idaho. This may open some potential for these
southern waves to come into SRN or possibly Central CA around 25 Jan.
So it looks quiet this week with little or no potential for IOP criteria
to be met.