Welcome to the first full day of fall in the Eastern Sierra…..Jack Frost Returns!!!! Temperatures seasonal today…….However, upper trof will push cold front through Mammoth Tuesday evening followed by snow showers Wednesday into Thursday……ALL GLOBAL MODELS IN SYNC FOR BEAUTIFUL FALL FOLLOWING WEEKEND WITH SEASONAL TEMPS…..
Monday September 23, 2013
Posted at 9:51 am by Howard
Slower improvement today then yesterday run….Some upslope this evening noted as well from the 12z NAM surface progs to 700mb. Few flurries possible if there is any moisture left. Warming trend with Sunny skies Friday into early next week. 500-1000mb thicknesses were south of 546DM this morning so temps may be a little slow to recover. Expect highs in the very low 40s today. Lows in the 20s tonight. Temps are expected to pop to the upper 60s by weeks end and possibly 70 by Monday or Tuesday. Longer range shows a series of storms with the upper jet well north into the pacific northwest. Precip from those may get as far south as Tahoe. However, don’t feel left out. 500mb Heights will remain well north of 570DM so freezing levels will most likely be above 10K. Well down the road into early October. There is always the chance that one of those Trofs may split with some energy coming into our high country. But it will be running into a pretty good high pressure block if it does……
Last of the September California Troughs is on the way. Winds will highlight the weather this afternoon and night along with much cooler temps Wednesday and Thursday. The 00Z Tuesday ECMWF had about .15 of QPF in our area over the crest or about an inch or two of snowfall there. In town just a scant expected between Wednesday at 5:00pm to Thursday at 5:00pm when the secondary upper jet makes a run for Eastern CA out of the NNW. Certainly nothing to write home about. Again wind and cooling is the prind point with daytime highs Wednesday and Thursday in the mid to upper 40s. Lows in the 20s with snow showers mainly Wednesday night and Thursday.
A ridge of high pressure will build into Ca Friday into Saturday shunting the next short wave to the north. However….Daytime highs may have to wait until Monday to reach 70 degrees again. Thereafter, the larger scale long wave upper low in the Gulf of AK will retrograde more to the west, then anchor to the north of the Hawaiian Islands later next week. Because of the wavelength, this brings Indian Summer to the high country the weekend of October 5th. Thereafter…The Climate Forecast System keeps above normal temps for California through a good part of October.
Maybe we can talk to the authorities and convince them to keep the Golf Courses open longer in October! 🙂
Interseasonal Dweeb Thoughts:
Wednesday AM Update:
Cool Pool North of Hawaii Growing while Warm +SSTA remain over the far Eastern Pacific
Odds increasing for a long warm fall for California and below normal precipitation into November……
This should not be a reflection on the Winter and Spring though, as with an El Nino, we can end up well above normal….
As a side note….this could be one rip roaring fire season for Southern Ca later in October
Long range CFS still has wet December……
There is a significant positive SSTA pool that has been moving slowly eastward and is now off the entire west coast except the immediately coast from the Bay Area South. SEE: http://weather.unisys.com/surface/sst_anom.gif
As the North American continent looses heat, the location of that warm pool may play a part in keeping a long wave ridge parked over the far west this Fall… Keep an eye on this pool to see how it develops or diminishes. Also a coupling cool pool is NNW of Hawaii (Troughing). This may couple with the warm pool to set up an Omega Block for the fall. Note, this is just something to watch not a forecast for a late Fall. Lots of other forces at work like the MJO which if strong enough can dominate. Other forces include the westerly phase QBO (less high latitude blocking) however, a weak Solar Max may increase the odds for high latitude blocking. One thing we do not want over the far west is a strong cold pool north of Hawaii, Warm Water in the far eastern pacific and high latitude blocking in NAO region. That spells strong + PNA and ridge city over the west.
Remember..it is still September and lots of time for the right combination of things to come together for a good winter out west…..
A snow capped Mammoth Mountain is a beautiful sight for the first full day of fall. Early morning risers this morning experienced frost on many roofs in town. Early AM temperatures dropped between 25 and 32 around town. High pressure aloft will bring a warmer day today. High temps today will be in the upper 60s which is seasonal for this time of the year. Temperature inversions will set up over night tonight and overnight temps warmer at elevations above 8000, possibly above freezing while lows below 8K at or slightly freezing.
The last in the series of Trofs will move into the high country Tuesday, bringing gusty winds, cooler temps and snow showers. Unlike the last storm, the significant precipitation with this system will be mainly over Northern CA Tuesday PM with the main upper jet remaining cyclonically curved with its axis remaining over Sacramento. Mammoth Lakes will be in the Front Rt exit portion of the upper jet which is really the wind corridor for this storm for us. As the upper trof progresses through Ca, there is a secondary jet that drops south through Eastern California Wednesday afternoon into Thursday AM. This occurs behind a dry front that comes through Tuesday evening. This mornings 12z NAM has a developing Vt center over Sacramento that drops SSE through Eastern Ca including Mammoth Lakes by Wednesday night. Although there is little moisture left at this point, there is likely enough for some snow showers over Mono County, especially along the Sierra where there is topographical lift. So the prind point is that in a NW slider…..with the main upper jet remaining to our north, the front when it comes through is usually dry, however often times a subsequent upper jet upstream will dig the bottom part of the trof south enough so that Mono County will get some snow showers behind the front with light accumulations if any.
Wind and cooling will highlight this weather system. High temps Wednesday and Thursday will be in the 40s while nighttime lows expected in the 20s Thursday AM and Friday AM. The weekend looks fair and warmer under building high pressure aloft. Seasonal temps are expected this weekend with highs in the upper 60s. Now that snow covers the higher elevations it will be a bit harder to get up to season temps until a good part of the snow is melted. The Dweebs have noted that snow cover even light amounts can keep daytime highs a bit below Climo when using other stations temps regionally as an algorithm.
The MJO composites for September for precipitation and temperature in California based upon the MJO in phase space 5 which shows above normal precipitation and below normal temps. This has certainly verified. The statistical dynamic model has the MJO progressing into Phase Space 6 next week which still has a below normal bias for Central Ca. At the same time the bias for above normal precipitation goes down to almost nothing. This also goes for early October. Thus the last week of September may have some cooler then normal periods, the bias for precipitation in the Central Sierra is very low through the end of the month. October beginning in phase 6 then weakly into Phase 7 would be more seasonal weather-wise, with out much if any precipitation. On another note, the Climate Forecast System has above normal temperatures for Eastern Ca by mid October…..
Expect regular updates through the stormy period Tuesday through Thursday….then the Dweebs may take a break for a while beginning next weekend until the next change is on the horizon.
Dr. Howard and the Dweebs……………………….