TGIF Everyone….

As we come to the end of July, The Dweebs have come to the realization that its been an A-Typical Summer. The June Gloom season has lasted much longer than usual along the southern coasts of California. LA has not had any significant heat waves so far. The waters off the Southern CA coast are much cooler than normal. The Sierra and Southern Deserts has yet to experience deep SE flow. The AZ Monsoon season has been anemic at best.

Weather Type:

The large scale weather pattern over the West and Southwest has been highlighted by a stronger than normal, persistent upper trough off the coast of the Pacific Northwest. This trough has in the “long range means”, displaced the Subtropical High to the east. It has warped its configuration to where the upper flow along the west coast has been vigorous WSW. In the wintertime, that may be normal. But in the Summer?  By this time of the summer we usually experience much lighter flow aloft or southerly flow.

The results of the enhanced WSW flow over Southern CA has been steeper pressure gradients between the deserts and the coast.  Stronger onshore flow leeds to more persistent June Gloom along the coast. Stronger westerly winds over coastal waters creates up-welling, resulting in colder SSTs and then feeds back to even stronger differences in air pressure and intensifies and deepens the marine layer further.

A positive result that is beneficial from the strong up welling, is that more nutrients are lifted upwards in the seas which can be beneficial to fish population.

Short, Medium and Longer Range:

No sensible change is expected in Sierra Weather through next Tuesday.  Expect an enhanced afternoon and early evening Zephyr in Mammoth. This will suppress high temps by as much as 5 degrees from what we would expect from the current 500mb height structure this time of the year. High temps will range in the very low 80s with night time lows dependent upon the micro climates of Mammoth as they relate to breezes during the night.  Lows may range up to 10 degrees cooler in areas like the Mammoth RV Park verses Snowcreek where it may remain somewhat breezy all night. As an example, In the meadow last night, it was breezy enough to keeps lows limited to 62 degrees, whereby in the more eastern sections of the city limits, lows were in the low 50s.  These spreads are likely to continue the next few days. Our air-mass is bone dry now. So be especially careful with fire. No campfires are allowed in the forest now. Only in approved campsites.

Longer Range:

An extension of the Eastern Pacific Trof develops while the upper ridge weakens over the SW. As the cap comes off and heights fall….instability develops with a pattern similar to what we had some 10 days ago with isolated to scattered thunderstorms. High Temperatures will cool to the 70s later next week. Lows in the 40s and 50s.

Still no sign of the AZ monsoon….

 

Dr Howard and the Dweebs……………………..:-)

 

 

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Tuesday July 28th:

This looks like the Summer without the Monsoon

Latest guidance continues the trend of dry weather in the high country with little if any convection expected this week. A strong subtropical high develops over Southern California today that is east-west oriented. This system builds the heat over the state without any import of SE moisture. In addition, strong subsidence will put a lid on any convection as the freezing level hikes to 17,000 feet, both Wednesday through Friday. High temperature records will be in jeopardy toward the weekend in the high country and over the weekend for the Owens Valley.  Additionally, the Trof over the pacific NW will weaken temporarily, then strengthen again, increasing the gradient for a bit stronger Mono Zephyr during the afternoon and evening hours. Thus you will be able to opened the windows in the evening and let the west wind blow some of the heat out, a little later in the week. This Ridge shifts more east with time into AZ, as the Eastern Pacific Trof strengthens. This allows some cooling next week. However, the trof in the Pacific Northwest keeps the SW flow going, so not much more than isolated TSRWs expected when the heat breaks. Eventually, we get a weak closed low set up again, off the Central CA coast like this past weekend, for the return of high based thunderstorms. However, this is not the AZ monsoon!

 

Dr Howard and the Dweebs………………………:-)