Just to be brief….Although areas of Heavy Rain are expected to develop in the southern portions of the Owens Valley late today and this evening, Expectations is that this continues to be a light snowfall producing system for the Mono County High Country, with 1 to 4 inches expected above 7000 to 8000 feet.

Of more interest, is a pattern change now developing over the Gulf of AK (-EPO) with a strengthening positive upper height anomaly (High Pressure aloft at 18000 ft) providing high latitude blocking in that area. There does not appear to be any undercutting forecasted by the models. However, the screaming message this morning is that all 5 global models that I have seen, including the outlier GFS from yesterday, now have the upper center forming off, or just off the coast of Northern CA over the weekend as it tracks SSE.. The system may slow down as well. At the same time, the upper flow becomes natural to the Sierra, thus there should be good orographical enhancement with this weather system. Considering the storm motion….Potentially moderate to even heavy snowfall, of the likes we have not seen since last December may develop, beginning Saturday then into Tuesday. So far the Northern Sierra is targeted for the Bulls-Eye with greatest snowfall potential in their high country.


Dr Howard and the Dweebs……………………………:-)


12:25 PM 3/9 Update:


Latest model runs show the Ecmwf  having a good snow producer for the Central Sierra Later Saturday into early the following week.   However the GFS has more of an inland track which severely limits the snowfall. This model solution give us all the cold and wind, but not much more than light amounts.  The Canadian Model is more like the ECMWF but quicker getting into Mammoth on Saturday and slower to leave on Monday. Looking at the 12z UK, its trof axis is on the coast and the JAMSTICK has over water trajectory as well. So the message this afternoon is that the vast majority of the models give us a good snow storm later Saturday into Monday AM.   The GFS is currently the outlier, but its Ensembles are more optimistic….



Our forecast models continue their trend of over forecasting snowfall amounts at distance, then back peddling within 3 days before an event.  For our particular area, as evidenced by the 2 inches received yesterday.  What appeared potentially to be more of a moderate snowfall producer for Mammoth Mt for the first half of this new week, now has been down graded to one of light exceptions…..1 to 6 inches.  So far, nothing appears in our two week outlook that resembles anything like a Miracle March. However, looking down the road, there are still some interesting possibilities worth considering beginning next weekend and the following week.


The Low pressure system that was due west of the Bay Area area this morning and may I add well off shore, is headed for Southern CA, where it will in counter a rich source of PWAT. This gets en-trained into the system and is expected to bring moderate with isolated areas of heavy rains to LA, between Monday and Wednesday. This storm stalls some-what during the day Wednesday before heading down the coast, thus not the more eastward through LA track like earlier progged.  This southward jog, will have the affect of limiting both the upper divergence, then upslope over our area during the Monday through Wednesday. However, the Owens Valley still looks to do well, especially the southern portion. This is a prime example of why forecasters are leery about precip forecasts 5 days out when you have a closed or cut off low, as higher than normal inaccuracies will exist in the storms track.

Later in the week, the models are converging on a solution of a storm track down the west coast again, similar to what we have had most of the winter. The last storm that dropped a foot on Mammoth Mt a week ago, was from a similar storm track.  However, the trof remained open long enough to get good upper flow through the Sierra. Will this trough remain open or will it wind up and head down the coast?  Only time will tell by the end of this new week. Beginning next weekend, the week two models are converging on a -EPO teleconnection of very strong negative proportions. a -5 to -6 DN.   So this means that very strong blocking will be developing in the Gulf of Alaska around mid month.  The AO Arctic Oscillation will be positive and so the Arctic looks to remain locked up, much like it has been all winter, but the PNA goes very negative.  So what does this all mean? The -PNA argues for colder than normal temps returning to the west and high country. The blocking may have two distant possibilities, one of undercutting of a branch of the westerlies and two, a track over the AK high and down the west coast.  So this is where the models will try to resolve there equations, in time and space…..Lots of possibilities and with any luck of the Irish, we may get a good storm…..;-)


Dr Howard and the Dweebs……………………….:-)