2:40PM Thursday

The Trend is my friend……


Just a quick note to say that the new 18Z GFS  brings in the low a bit more north with the 18Z run, so it may be converging more toward the Euro solution.  This would move the deformation line northward in the Sierra, (Central Sierra) increasing the chances for Up-slope snowfall later mid week next week.  18Z gfs actually has up to an inch of QPF in this run. That’s probably over done but it is much better than early runs which were pretty dry.



12:00PM 14th..Star Date 5780

You got to love the EURO for the west coast…The GFS is finally coming around to the EURO’s thinking of early this past week with the development of a closed low that spins up off the Northern CA coast and and then rides the rail of the coast SE.  But you all knew that some 5 days ago right?  Although there is still time for some adjustments, the idea is that mainly the coastal communities, and some what to the east as far as the western slopes of the sierra could pick up some badly needed rains next week. And although this is not a wet pattern by any means….The pattern is a familiar one.  To a large extent it, “Initially” leaves out the Eastern Slopes of the Sierra with any moderate or heavy snowfall…..Possibly some light snow.  This is while in comes down the coast.  However….If the Euro is correct later next week, the system comes in just north of LA and “if” that verify’s, the Southern Sierra and Mammoth could be in for some good beneficial up-slope snowfall. Today’s Euro Guess is (2 to 4 inches), but that could change in the coming days.   By the way the GFS takes the track of the close low way down south and would not be beneficial to our area at all….


Stay Tuned!!!


Dr Howard and the Dweebs………………:-)


7:00AM Wednesday

Latest model runs show a lot of cooling next week with good snow making weather, especially the second half of next week. As far as dynamics, the GFS is still pretty dry with not much hope for any snowfall here in the Eastern Sierra.

The Euro is hanging on to the idea of an off shore coastal slider, without any coupling of a short wave coming down inland from the Pacific NW this time. This certainty is a dry chilly scenario for the Northern Sierra. And one that, depending upon its track down the coast, could bring showers or rains to the coastal communities of California, later next week. As also mentioned, if the low moves inland far enough north over Southern CA, Mammoth could pick up some up-slope snow.  This is the best that can be said this far out.

Otherwise, there appears to be further strengthening of the polar jet later this month and the chance of a better storm from the west the end of the month.


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


11:00 PM the 12th

The more I see the Euro the more I like the way it is handling short wave energy as it approaches the mean ridge position. It is with a pattern like this with the mean ridge position over California and along the coast of BC that split flows rule the pattern over the far Eastern Pacific.  I am buying into the Euro now with an upper flow pattern that will become more split over the next two weeks. In my Oct 25th discussion, I wrote about a pattern of split systems with the over-water portion breaking off and forming quasi cut off lows that would spin up off the Northern CA Coast ‘possibly’ missing the Northern Sierra with the main precip, then heading southeast down the coast and moving inland near LA. In a pattern like this, the coastal sections are favored for rainfall and Southern CA as well. Most of the precip for the Sierra from the west would fall on the west side, if the lows are close enough to the coast. However, as the systems come east, to our south, if they come east far enough north like Ventura County, Mammoth and the Southern Sierra can pick up upslope from such a pattern. At the moment, we need to get closer in time to the event.  It looks now about the middle of next week. Wed-Thur)  There are two short waves that the Euro splits.  One is expected to spin up off the coast off Northern  California, interacting with a subtropical low off the coast of Baja. However, more importantly, the split Trof that digs into the Pacific NW may dig back WSW across the Northern Sierra to phase with the cut off west of SFO.  Lots of possibilities….  If that happens, below is a possibility for the Northern Sierra;

  1. If the upper trof digs WSW across the northern part of the state, its circulation may get over-water trajectory and pick up enough moisture before it phases with the cut off low to give the southern portion of the Northern Sierra a good shot of snowfall. Or it may not. These are the fine details that have to be worked out. The Dweebs will be watching where these close or cut off lows form off the west coast.  Sometimes 50 miles can make a huge difference whether we get snow or not. Chances are good that there is going to be more than one this month.
  2. My good friend Tom C, retired WSFO RNO, reminded me a few days ago that as we get into December, the upper jet grows stronger and as a result,  there is more consolidation in the upper flow and less splitting.  Lets all hope so!

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


Although the global models are quite a bit different from each other next week, they all suggest a further weakening of the west coast ridge to allow significant cooling into our area.  The GFS is most aggressive with the cooling with more of a Great Basin trof, while the EURO phases a short wave moving across the North Pacific with a good sized subtropical low well west of Baja. The former would bring at least 20 degrees of cooling later next week with even some light snow showers possible, while the Euro suggests a closed, cut-off type system that would benefit the coastal sections with some rain with more uncertainty further east.  It would depend upon how close to the coast the cut off forms.   In a discussion some two weeks ago, the Dweebs highlighted that this was going to be a Fall/Winter that would be more challenging for the forecaster, especially for the Sierra as there will be splits and closed, or cut off lows.  At least through the Fall, the exact placement of these features will be key to whom gets the precip and whom does not.   Either way it will get more interesting next week, the upshot is that again, this is not a wet pattern as shown by the guidance at hand for the state….although the coastal areas could get wet.  More tomorrow late AM…after a few more model runs….


4:38PM Tuesday

In the CPC discussion today, the forecaster made it clear that there is no direct relationship of the IOD (Indian Ocean Dipole) and the current mid latitude flow or amplitude over the Northern Hemisphere. However, he did acknowledge that it was possible that the MJO was showing up stronger than it should be, in some of the models due to the enhanced ongoing convection over the Western Indian Ocean, due to the very strong IOD. He also acknowledged that he was not sure which models were correct between the other models and the ECMWF which has been much weaker with the strength of the MJO, in Phase 8/1.      


The Dweeber……:-)