Variable High Cloudiness expected for the MLK Weekend….Temperatures to Remain Mild through the Holiday….Then Expect Cooler Weather Tuesday and Wednesday…..
Friday January 16, 2015
Posted at 8:38 am by Howard
Friday 1:25PM Comments….
Just had a look at some of the key teleconnections this afternoon.
The PNA is currently positive and is why we have such strong ridging over the far west. However, in looking at the PNA by the 26th…. It is interesting to note that the 12z 1/16/15 ECMWF on the 26 of January has the PNA index at about -2.5 Sigma from neutral. What I like as well is that the new GFS Upgrade T1534 12z run today has the PNA at -2 Sigma. The old GFS has been retired as of early this week. As far as the EPO index, the ECMWF goes from +2 Sigma today to -2 Sigma but the GFS Upgrade goes from +2 sigma to neutral for the 26th.
The (PNA) is the Pacific North American Pattern and in its negative phase is usually associated with more trofing over the far west. The (EPO) eastern pacific oscillation is associated with heights building over Alaska further west and is often times associated with retrogression. So things maybe moving in the right direction during the last week of January into February.
The updated forecast for the MLK holiday weekend shows variable high cloudiness through Sunday with Gusty Winds at times over the Sierra Crest, breezy at times in the Town of Mammoth. High temperatures will range in the 50s at resort levels and 20s and 30s at night. The further outlook is dry for the most part and cooler as well.
A blocking ridge of High Pressure aloft will remain off the Southern CA coast through the middle of next week. The upper jet favors Extreme Northern Ca, OR and WA. With the upper jet this morning over Northern Ca, gusty winds are occurring over the Mammoth Crest to 60 MPH. It is likely to remain quit breezy today and tonight over the crest. Another short wave will move onshore later Saturday. This will bring more breeze to the upper elevations as well as more cloudiness to the Mammoth area. However, these clouds have little in the way of moisture and outside of a slight chance of a shower, precipitation will remain 100s of miles to the north of us.
The short, medium and long-range shows well below normal precipitation through the end of January. However, with that said, there are increasing signs that during the last week of January and into February, that retrogression with the upper blocking west coast high and a gradual weakening of the Subtropical Eastern Pac Upper High will occur. This is according to both the new T1534 now operational GFS and latest runs of the ECMWF…32 DAY 51-MEMBER ENSEMBLE CONTROL (EPS) Note: There is no established pattern yet, just retrogression with many of the ensemble members.
PS There is no truth to the rumor that it will be dry through Mid February because the forecast skill for weeks 3 and 4 is no better than about 50/50.
Dr Howard and the Dweebs………………………………..:-)
On a bright Note….
Check out the latest CFC Forecast:
CFSv2 Forecast of Weekly Climate Anomalies
Wouldn’t that be nice!
Some Unofficial Mammoth Pass information provided by amateur Hydrologist Bob Sollima “Back County Bob” as it pertains to local history….
According to Bob…..
“At this time, we are about even with the 1991 year mid-January. 1991 was the second worst drought on record (for Jan-Feb)…then the March Miracle that year which propelled the water content to 75% of average at (water) year’s end on April 1st. If Mammoth Pass does not pick up any additional precip by the February 1st (2015) survey, we would be in danger of having the lowest February survey result in history…even less than Feb 1977. The 1977 winter at this location only gave us 8.6 inches of water content at April 1st TOTAL. As the Pass sits now, we have about 4 inches of water stored in the snowpack there…about 50% of what was there this time last year (2014) & about 50% of what we had at this time in (2012). 4 inches of water content (at this point in time) equals 1977. Average for this date is about 25 inches water.”
Great Basin Slider will kick up some wind over the crest and down through the Owens Valley….However….The Short…Medium and Longer range is still dry for Central CA…….
Tuesday January 13, 2015
Posted at 9:53 am by Howard
Changes in the medium range models today and yesterday show a stronger ridge over the North Atlantic. Arctic Air that was proged to spill further west later in the month will now likely spill south, further east. This makes for a warmer west and colder east over the next 15 days. A true +PNA pattern over the west. Upshot to all this is still dry……
After some traveling, its time once again to have a look at the main indices that are driving our Central CA weather. I just had a look at the Mammoth Pass information put out by DWP and it is as bleak as it was last year at this time. We are currently 21% of the normal amount of precipitation to date on Mammoth Pass and some 10% of normal for the entire winter, IE (April 1st)
Some of the drivers that correlate with this winters dry spell is ENSO. The (El Nino-Southern Oscillation) area of most influence is the Nino 3.4 region. It reached briefly just over 1C in December. Today the 13th of January it is under .5C or in a category that is well below the threshold for the positive effects of ENSO for California. The Dweebs would say that overall, the worst ENSO years for Central CA are the ones that are classified as weak El Ninos. Based upon many reports from the Dweebs, they are associated with Split Flow winters. IE the winters that bring coastal sections of CA precipitation and the interior drier than normal conditions. Although this EL Nino has yet to be called by NCEP. Today, the odds are, that it will not reach that criteria. It has faded quickly. However in the longer climatic time frame, Warm ENSO conditions are expected to return again later this spring and Summer and Fall according to the Scripps model.
Another longer time frame induce that has had an effect is the PDO. Pacific Decadal Oscillation became positive last year. The warmer than normal waters along the far eastern pacific supports upper ridging. However, without a strong enough and persistent “Warm” ENSO signal, the benefits of the +PDO were never reached just like during the winter of 76/77.
Comparing the track of the MJO through its phase space last fall from the same time frame in 2013, it showed the promise of a change for the upcoming winter. This evidently has turned out to be a false promise. As last fall when the MJO progressed into phases 1, 2, 3 and 4), There was no follow through for the following month. Sure we got snow, but the cycle ended after that with no movement to other favorable phase spaces. Remember that a strong MJO “Modulates the westerlies”
Here is a basic explanation of the MJO. The Madden-Julian Oscillation (MJO) is the major fluctuation in tropical weather on weekly to monthly timescales. The MJO can be characterized as an eastward moving ‘pulse’ of cloud and rainfall near the equator that typically recurs every 30 to 60 days. When the MJO is strong, (lots of Thunderstorms), and is located in the Indian ocean, it causes the PNA to flip negative and we often get a long wave trof over the eastern pacific. (Lots of rain in California) When this cluster moves east to the western pacific we ridge up as the East Asian jet retracts. This is what is going on now. If the MJO progresses east to the Date Line and remains strong, phase 7 to 8, the EAJ often times splits and under cuts the Eastern Pac Ridge and we get tropical connections or AR events in CA.
So far this year, signs are less encouraging. And is becoming more clear that for the next two weeks, the MJO currently strong in phase 6, will weaken rapidly into Phase 7. This effectively “Takes the foot off the pedal” of the East Asian Jet causing both retraction of the upper jet as it weakens over the eastern pacific and at the same time, allows for amplification of the eastern pacific ridge and some retrogression of the same. Remember that the eastern pacific ridge is normally the persistent feature in the eastern pacific, hence the term eastern pacific ridge. It is only when the extension of the EAJ occurs that the ridge gets flattened and precipitation moves on west coast. Of course retrogression of the Eastern Pacific Ridge to a position north of Hawaii is often the other way we get pacific storms. I think that the absence or the displacement of critical teleconnections are responsible for the absence of the North of Hawaii Eastern Pacific Ridge the past several years.
The upshot of all this, is that later this month there is a good possibility for the return of cold arctic air into the US with the possibility of some of that spilling west, similar to what we had around Christmas/New Years. Over all this is still as dry pattern for Central CA, (Unless one of these systems backs up west, far enough for the upper jet to become over water. We saw this over Christmas Eve when snow fell in Las Vegas and San Diego County. We also had a lot of the snow stripped from the peaks of the Sierra due to strong NNE winds. For Mammoth to benefit from this type of pattern snowfall wise, the center of the upper low if it forms, would need to back up well north of us, like Tahoe or Grass Valley, Ca.
The Sun is in a funk. Some scientists say that we are in a solar hibernation. This much weaker than normal sun spot cycle has peaked. The next phase will be the slide to the trof of the cycle over the next 5 to 6+ years. If history repeats itself, we do much better on the down side of the cycle, meaning that we have wetter winters on the back side of the cycle.
On a bright note; Mammoth Mountain has done a fabulous job with a combination of Snow making and natural Snow. With colder temperatures on the way later this month, Mammoth Mountain will be able to increase its coverage on a larger scale if warranted.
And……Looking down the road, even during our driest winters, the vast majority come back during February and March…..
In the meantime, there was hope that we would be in for a mini wet spell later this weekend and into the following week. The extended models have been back peddling on this notion. IE the upper ridge now building into CA will flatten Friday into Sunday. The upper jet will return to the Pacific NW to bring wet weather to that region for a short while. Looking at the guidance for the end of this week, both EC and GFS show the upper jet well into the pacific NW with 500MB heights above Mammoth about 576DM. This means that there is little if any chance of precipitation the end of this week and into early next week. Thus we go back to the all too familiar Ridge-Trof pattern like the past three winters… Then retrogression later next week will bring the opportunity of some colder air back into the Mammoth Area. Currently, there is a cold dry system progged for the (21st). Then….the end of the last week of January looks favorable for a weather system as well.
Dr Howard and the Dweebs…………………..:-)
Transition to (+PNA) Pacific North American Circulation Pattern underway with Ridge in the West and Trof in the East…..Short Wave System for Thursday will Weaken with clouds and some cooling….
Friday January 2, 2015
Posted at 9:31 pm by Howard
As of Saturday morning the 3rd….
A strong upper ridge is currently building with 500MB heights well into the 580s early next week. Strong Temperature inversions will be the theme. Expect highs this weekend in town climbing well into the 40s then 50s first half of the week. Winds will continue to be light. Early morning lows will range with single digits and teens along thee highway 395 corridor….The Town of Mammoth will be in the teens and 20s early in the weekend then 20s and 30s as we go into next week. The Upper ridge will peak out Tuesday with the Freezing level topping 14,000 ft during the day. Thereafter, a slow weakening of the ridge will take place through Friday where the Freezing level falls to 8K that morning. This is associated with a short wave that will bring cooling, clouds, some wind and a slight chance of showers. Heights rise again over the following weekend along with the freezing level. A temperatures inversion is expected to set up again. Thus the Long Wave ridge position will anchor over the 6 to 10 day and possibly even out to the 8 to 14 day period near 120West. Heights “in the mean” at 500mb will be in the low 570s. This is common during the month of January. Hence the term January thaw……Longer range charts weeks 3 and 4 of the ECMWF shows the possibility of the upper Asian Jet extending back to CA for more snowfall…..
Next update January 13th……