When I was a kid, growing up in San Diego and always looking for some sort of Wx, it seemed that the coming of a new month would bring the best chance for a change toward something more interesting. In that spirit, things are looking slightly more favorable for HMT. But, not till next week.
After many tries without success earlier this winter, a low-latitude connection underneath the persistent large-amplitude ridge has finally been established across the eastern Pacific between a mean-trough position north of Hawaii and the persistent large-amplitude trough over North America the past several days. (This can be seen most readily by viewing wind and PV on the 340K isentropic surface.) Southern California and northern Baja have so far been the only beneficiaries of this development. However, the models generally, and the GFS in particular, are indicating that the present low-latitude upper flow south of the ridge will eventually deepen in latitude, as the ridge itself becomes more entrenched at higer latitudes. This will allow the possibility of identifiable surface lows to make their way under the northward-displaced Pacific High to affect California, beginning middle or
late next week.
This morning's GFS ensembles would argue that the first system of substance to make it across the Eastern Pacific will most likely give rain to Southern CA, probably Th 8 Feb. However, last night's GFS and this morning's ECMWF suggest that northern and Central CA have a better chance, and as early as W 7 Feb. (Both models indicate this will be preceeded by a weak system now N of Hawaii that will approach the coast over the weekend, but turn north and weaken west of 130W, bringing no pcpn onshore.) The ECMWF, in my opinion, is the most optimistic for HMT, with the possiblity of 2-3 IOP potential systems over a week period beginning with the one on W 7th.
Ed Berry ventured that he thinks week 2 (i.e., 8-14 Feb) looks pretty good. He and Klaus W. will discuss these possibilities in more detail in tmrw's telcon.