Beautiful Spring weekend shaping up with mild temps and light winds……The Last Gasp of EL Nino is on its way!………………….
Friday April 1, 2016
Posted at 9:18 am by Howard
No changes to the Dweebs Outlook with high latitude blocking increasing in the PNA region with time. The northern part of the trof that split last night is headed east into the Rockies today, while the bottom part of the split will spin up off the coast of Baja, MX this week. To the north of us, a strong upper height anomaly will develop near Vancouver Island. This upper height anomaly in the mean will remain in the PNA region for the next two weeks. This feature will work in tandem with the development of southern stream energy. Thus an extended period of unsettled weather is expected for mainly the southern 2/3rds of California.
We are coming into the time climatically, for Springtime Thunderstorms. Springtime thunderstorm patterns are highlighted by the development of slow-moving closed or cut off lows. At this time of the year, Strong daytime heating can combine with cold air aloft, making for a very unstable air-mass. (increased lapse rates) So more attention is given to areas of deformation, (Surface Convergence); upper divergence, (Cyclonically Driven Diverging Airflow between 18,000 and 30,000 feet) usually found in the NE quad of the upper low, Convective Available Potential Energy, (CAPE); and Lifted Indices. (LI)
Later this week, the upper low off the coast of Baja will be ejected by an upstream kicker, that will spread moisture and precip north via the Southern Sierra and deserts of Southern CA, early Friday AM. Mammoth maybe too far north for good upper divergence from that low, but the Owens Valley may not. (well see how the upper low actually sets up for the weekend by Wednesday or Thursday. The upstream kicker low will definitely bring some cooling to our area for lower snow levels Saturday. The snow level is likely to be at or above 9,000 Friday before coming down Friday night. Several inches of snow is possible over the higher elevations Friday through Sunday. This is not the typical Springtime thunderstorms pattern. Those usually set up off the Central or Southern Central CA. Coast. That may occur toward the following weekend….
Apparently…We are not done for snowfall for this season!
Upper Flow at 700MB (10,000ft) is still out of the east and will back more out of the NE and then North this afternoon and tonight. The winds over the crest should be light on Saturday. All this because the highly amped ridge off shore is building into CA, ATM. Temps this weekend in town look to be in the lows 60s. Night time lows in the upper 20s and low 30s.
Outside of a weak upper trof moving to our north bringing high cloudiness Saturday PM into Monday, the weather will remain mild and dry. This upper trof will no doubt bring a period of moderate wind to the crest later Sunday into Monday as it scoots east. Another upper ridge will build into Ca, Wednesday and be followed with warmer temps.
Some Comments about the MJO: In my platinum powder email yesterday PM, I discussed changes in the pattern coming up by the end of next week. Looking at the updated MJO Phase Space this AM, it was interesting to note that this was one of those unusual times that the GFS scooped the ECMWF in indicating a stronger MJO. When one model does that over the other, its week two forecast is more reliable! The CPC commented on that in their Briefing last Tuesday. I like their briefings because they know which phase space to use and thus makes for a better week two outlook or at least which model’s week two forecast is the best. In this case, it is the American models week-two forecast. Looking at the new update this morning at 8:00am, the ECMWF has come around to the GFS thinking and so I would imagine that it’s week two forecast on todays 12Z run will be more like the GFS. It is playing catch-up.
The profound statement from the briefing was that this particular progression of the MJO through Phase I, then into the circle of death will 1st; Enhance the El Nino’s effect upon the westerlies by “Constructively” Interfering with the El Nino Base state. Or in more simple terms….enhance it’s Convective Potential with the MJOs system of upper divergence in its nose. On a large-scale, this is occurring right now as the MJO is -1 deviation of normal in phase space 1. However, in the rear of the MJO as it progresses east will destructively phase with the remains of El Nino and that will likely put the nail in EL Nino’s coffin by May. The Nino Basins reserve of warm water is just about spent and an increasing amount of cold water subsurface has taken over. SEE: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/wkxzteq.shtml
What this all adds up to; is most likely the last MJO/El Nino modulated extension of the East Asian Jet undercutting the west coast upper ridge to the southern west coast of the CONUS this year; 1st with an incipient system associated with the pattern change the weekend of the 9th as a subtropical upper low ejects NE into Southern CA bringing showers to the sierra. This is the result of a strengthening belt of westerlies with a lead kicker trof, followed by the potential of a couple of good Sierra Storms and even a possible atmospheric river as well. All that sometime during the week beginning 11th then on through the end of the 3rd week of April. (Ten Days)
PS. The year 2015 will go down as the worlds warmest in modern times…
Dr Howard and the Dweebs………………………………..:-)