Upper Ridge Builds Onshore Tonight then Progresses East……Westerly Flow Develops Tuesday…..Next Storm’s a Creeper with Easter Weekend in Jeopardy…..
Sunday March 24, 2013
Posted at 12:06 pm by Howard
Quick Sunday Afternoon Update: 12:30pm
New 12Z ECMWF has the upper cut off drifting north to a position west of Monterrey by Sunday Am (130W-36N). By Monday a kicker trof descends out of the Gulf of AK and nudges to the upper cut NNNE to a point about 128W-39N by Monday AM. This is quite the change from earlier runs! Thereafter, the kicker Trof drives the upper cut off down our throat late Monday afternoon into Tuesday morning as it opens into a sharp tight dynamic system. The Dweebs like deece’…..:-) Well see how the models handle all this in coming days……..lots of time for things to change either way…..
It was a beautiful end to a Winter that was over-all pretty good to the locals in town. Much less was spent on snow removal by the HOA’s . The private guys with contracts did well again like last year, while the hourlies did not. Sorry Guys……
This is the first weekend of Spring…and now forecasters have to treat their forecasts differently with the addition of the higher sun angle. Daytime convection must be considered in every forecast now during active patterns, especially with cold air aloft systems on a synoptic scale, (within 620Mi). Thunderstorms will highlight some of these systems with closed lows that favor good upper level Diffluent/Divergent features. Here is a good link http://www.spc.noaa.gov/exper/mesoanalysis/ to use this Spring during active patterns.
This leads the Dweebs to chat about the next system that looks like quite the creeper. This mornings GFS showed an incipient wave located 350 miles west of the dateline at daybreak. The front aligned north south over the dateline. The wave is expected to travel east to a point some 1600 mi north of the Hawaiian islands by Tuesday night. Thereafter, it splits off from the westerlies as it heads SE toward the Eastern Pacific. This is due to the persistence of blocking in the eastern pacific that has been there most of the Winter in various degrees. Today’s 12z deterministic GFS has it east of 140W and south of 40N Daybreak Thursday while it spins up to occlusion…then true closed low fashion, with REX design. The 12Z Sunday 24th GFS run had the upper closed low drifting east to a point some 400Mi west of Santa Barbara by Saturday Daybreak.
For the Central Sierra it is important to add the convective component to the possible scenarios which will be dependent upon the placement of the upper low on a synoptic scale. Closed or cut offs which are common now this time of the year, and their placement is difficult within 72 hours, let alone a week away. Additionally, today’s 12z GFS also showed a subtropical jet that develops along 20N and lifts NE underneath the California low Friday. It appears to “couple” with the systems upper jet as well to add more moisture to the mix. So there is the potential for some heavy snowfall some where between the Southern Sierra north to the Central Sierra. Lets hope the system gets positioned just right for Mammoth Mtn!
In the meantime, nothing much is going to happen the next few days. The Clouds will increase Tuesday into Tuesday night with a passing wave to our north. The wave will kick up the wind here locally, but the “system is pretty wimpy”. There will not be much of any cooling either except for the effects of less sunshine. The aforementioned storm will begin to advect in moisture as early as Thursday and so showers could begin anytime then on……………….
Longer Range: There does appear to be another system headed from the NNW/SSE into California the following Tuesday, but this could be an inside slider…..too soon to tell.
Next Update Mid Week………………………….>>>>>
PS. Hats off to Geoffrey McQuilkin of the Mono Lake Commitee for his assistance on getting Mammoth Weather’s data system back on line…..
Dr Howard and the Dweebs……………………….:-)