Enjoy the next few very nice days ahead as major pattern change takes shape…..Undercutting storm track may pick up some badly needed moisture from TS Rosa for good precip producer next week…….

9/27/2018 AM Update

Forecast models have come in considerably drier this morning with precipitation for the Tuesday and Wednesday time frame. TS Rosa will not, as of this time, be a player in contributing any additional moisture to the system for the Sierra next week. That closed low approaches the coast Monday, then drops SE along the coast Tuesday and Wednesday. Rosa’s moisture looks destined to affect Northern Baja to AZ, which is more climatically favored for this time of the year. As mentioned below, it is still September and models do not do as great a job in the medium range as they do during the winter. Nevertheless, this mornings guidance still suggest that at least a quarter of an inch of precip is possible and that would translate to a few inches in the high country.  This may flip-flop several times in the coming days so back country travelers do not let your guard down…..  All in all, it looks like at the least, a good dusting for the high country!


Stay tuned!


Dr Howard and the Dweebs………………….:-)




Although High pressure aloft will strengthen the next few days bringing warmer temperatures. The upper high is expected to build north over AK over the weekend as a vigorous belt of westerlies for Late September and Early October undercut and drive into California. With antecedent warmth well established over the Eastern California, there is no doubt that at least moderate to possibly strong winds will develop on Saturday. Pray the Aspens hold on to their leaves this weekend! 🙂


The pattern is complicated as Hurricane Rosa, now gathering strength west of Manzanillo MX, is expected to track NW,  west of Baja, CA.  Although this storm by the end of the week will be weakening as it moves over colder waters, its moisture is suggested to get somewhat entrained into the southern part of the westerlies. It is not completely known how much of it will get into California at this time, but the models are starting to turn wetter. There is also a cold part of the storm expected to come in Monday night or Tuesday. This would no doubt bring significant snowfall for the backcountry with any additional moisture from Rose.

The principle point here is that anyone planning a trip to the back country, leaving this weekend and traveling next week will need to have their winter gear ready! Snow, Winds Chills, hypothermia are all possible in a snow storm in the high elevations of the backcountry. Some model simulations bring up to a foot in the back country and if more moisture gets involved from Rosa, those amounts would rise. If the opposite occurs, then less snowfall would be expected.  The Town of Mammoth will have much lighter amounts. Especially on the roads that are very warm from the Summer. Will update later this week on snow amounts in town if appropriate.


Going this strong with a forecast of the possibility of snowfall in the backcountry in late September is dicey.  Forecast models are not as trustworthy as they would be in December through Mid March timeframe, However, I have to say that as of this time, the Global Models all show snowfall in our back country beginning Monday night and for several days thereafter…..so stay tuned to future developments…  For those of you that are headed for the backcountry, you need to keep especially informed…


Dr Howard and the Dweebs……………….:-)

First week of fall to end on a Summery note then cooler, breezy weather developing over the weekend…..First week of October looks cooler than normal with showers possible…..

Dweebs were back at it this morning with our first fall forecast. Of note, the MJO is amplifying in phase space 8 and is expected to track east into phase space 1. This area of tropical forcing moves through the Western Hemisphere and Africa next week. Highlights of this action now, are the intense mesoscale clusters developing from the ITZ, drenching parts of the Hawaiian Islands.  In looking at the IR Satellite & 200-hpa Velocity Potential Anomalies for the 25th of September, this is possibly in reaction to a developing Wave-1 configuration and strong upper divergence centered SE of the Hawaiian islands over the ITZ. This is likely in relation to the developing MJO projection into Phase Space 8.

This would be classic Pineapple Connection, a form of an AR) for west coast except that it is late September and the results from the jet stream are much weaker. However, they are substantial enough to build Upper High now off the coast of the Pacific NW, Northwestward, forcing the Negative Phase of the Eastern Pacific Oscillation blocking pattern (-EPO). This results in the undercutting of the westerlies and a relatively minor closed or cutoff low for Northern California Sunday. Sensible weather for Mammoth will be breezy, cooler weather and a chance of showers early next week.  As a note, There is a TS that will track up the Baja Coast this weekend and as a long shot, get entrained within the Trof off the west coast. This pattern is only remotely possible at this time as model simulations do not favor it at any significant degree…..However, it is possible.  San Diego would benefit at best, but more likely northern Baja CA to AZ and possibly Las Vegas early next week.

Longer Range outlook for October favors periods of cooler than normal weather with some possible cold storms, during the month. Mammoth will likely get a few periods of snowfall during the month of October.


Dr Howard and the Dweebs……………:-)

Last week of Fall to fair and mild with dry weather expected through the 24th.



Last week of summer to finish on a quiet note with season temperatures and breezy weather at times….Some high clouds expected on Tuesday along with some stronger breezes. High temps this week will range from the mid 60s to low 70s…..Lows in the 30s and 40s.

Next update on the 24th….


Dr Howard and the Dweebs…………………….:-)



The Jet stream over the pacific NW will sag south into Northern California the next few days bringing gusty winds tonight into Wednesday night. Temperatures more seasonal for this time of the year will develop by Thursday and into Friday with some warming returning over the weekend. Nighttime lows will cool well down into the 30s at resort levels. A modest warm up is expect this weekend and into next week.


Hurricane Florence is going to be a big problem for forecasters and South Atlantic states governor’s as the latest modeling shows the storm losing its steering winds, prior to landfall…. Good luck in predicting where this one goes!


The Dweeber…………..:-(