First day of meteorological fall will continue with the trend of above normal temperature’s…..High Humidity to our south will work northward for better chance of warm rains next week….Winter of 2018 looks likely to be very different than 2017

Sky conditions cleared out nicely over night and as a result, lows dropped down into the 40s this morning.  Upper level winds have become easterly as an egg shaped upper high is currently progressing east over Northern CA.  This upper high will become northwest-southeast orientated and allow moisture that is currently over Baja from TS Lidia, to move up through Southern CA. Eventually making its way into the Southern Sierra and north.  Both the southern and central sierra may benefit from wetting rains early next week. The Dweebs expect an out break of thunderstorms at some point. The call for wet storms will be tied into the timing of impulses of upper divergence that would move up from the SSE.  More on that later….

Temperatures will remain both above normal and will be dependent upon cloud cover into next week. Highs this weekend are likely to be in the low 80s with lows in the 40s then low 50s as the moisture increases. Longer range charts for Tuesday and Wednesday show a strong easterly wave over AZ that may pivot into CA then north into the Southern Sierra by Mid-week.  Of note, with the increase of thunderstorms, will bring the increase of lightning and possibly fire starts in the forest.  Lets hope the rains are wet enough to prevent that next week.

Climate:

The Dweebs are starting to look at some of the teleconnections that can effect the weather on a climate scale of time. This is the time frame of 30 days and beyond.  September will likely remain above normal in temperature. However., I do see the possibility of that elusive equinox cool down or trough followed by warming.

The key teleconnections are quite a bit different as compared with last winter.  There is cooler than normal water in the Bering Sea, VS last years warmer them normal SSTA.  The QBO has become East to West arguing for a deeper Hudson bay Low and the Pacific Decadal Oscillation is now neutral trending Cold for the west coast.   This all argues for more meridian flow for the eastern pacific and across the CONUS vs zonal flow from the pacific last winter.  It appears that from a temperature point of view, the Fall will become quite cold (November) with periods of Continental Air backing into the Great Basin at times this Winter. As far as precip, it is still too early for a call, but at the least, not nearly as wet as last winter.  Colder storms will higher snow to water ratios seem more likely. AR events, although still quite possible in an ENSO neutral trending Cold, will be far fewer in numbers. Last winter we has some 15 AR events. Normal is about 5.

 

Dr Howard and the Dweebs…………….:-)

As subtropical moisture moves out….The heat is on this weekend with record highs in jeopardy by early next week…..Long period of above normal temperatures expected with the chance of some thunder developing over the Labor Day Holiday…

Our weather pattern will transit to more of a late July and early August weather pattern with 500MB heights becoming quite high over the Great Basin and California. 500mb-1000mb thicknesses are expected by the GFS to reach low 580s over Eastern CA by late this weekend into the early part of next week. This will be good enough to tie high temperature records for the Bishop AP and Mammoth Lakes with low 80s in Mammoth and between 100 to 105 temperatures for the Owens Valley, early next week. Through the middle of next week, it is expected to be a dry pattern. However, isolated thunderstorms may begin to develop my mid week. Expect some of the best back country travel this summer this weekend into next week as the high elevation snow pack is nearing normal for this time of the year. Of course the Mosquitos are probably still active in the usual areas.  Once over night lows drop below freezing they will be gone too.

The high temperature records for Bishop Monday and Tuesday of next week the 28th and 29th are 103 and 105, set back in 2001 and 1950. It is reasonable to expect similar highs then. A anomalously strong continental high will be responsible for the heat this weekend, well into next week. Some changes are in store for the holiday weekend as moisture moves up from a dying tropical storm over the Gulf of CA. This may bring the return of mainly afternoon and early evening thunderstorm’s over the sierra that weekend,  As we all know, Mammoth is usually one of the last areas to get rain from summer type afternoon and early evening storms. I will have an update later next week on the progress of such a pattern developing.

 

Dr Howard and the Dweebs…………………:-)

Weakening Upper trof remains over the inter-mountain west with back side over California…..Weak Low pressure at 700MB will provide marginal instability to the sierra for a few isolated thunderstoms the next few days….Weather may become a bit more active over the weekend…..

Very light flow remains overs the Central Sierra this evening with a very weak low pressure circulation located over West Central CA at 700MB. There were plenty of high clouds today. However, little in the way of air mass modification. Looking at the Tuesday 18Z  GFS 0.5 Degree Model Output, , there appears to be a slow increase in the 250 MB upper divergence over Mono County through the weekend. At the same time, the convective available potential energy “CAPE” increases, especially over the weekend.  Air mass modification should take place Friday and Saturday with areal coverage of thunderstorms on the increase, especially Saturday and Sunday… Through the process, temperatures will rise a few more degrees this week….into the upper 70s. Lows in the 40s.