Another Upper Trof will push into the Pacific NW this weekend bringing some cooling along with stronger Zephier breezes…..Saturday through Monday…..Summertime Monsoon Still Shut Down for the Central Eastern Sierra with signs of a return before the end of the month….
Friday July 15, 2016
Posted at 8:10 am by Howard
Although the Pacific NW upper Trof has slowed some from last weeks forecasts…gradients are still forecast to tighten tonight and Monday. Gusty winds a good bet later tonight and Monday along with some cooler temperatures Monday. Big changes are in store for Eastern CA over the next one to two weeks. The European model has strong retrogression of the long wave features of some 20 degrees of longitude later this upcoming week. That will put the continental subtropical upper high over the top of us for another real heat wave. In fact if the current operation EC model should verify, we may have our 1st 90 degree high this year in Mammoth by the 25th. Of course if the seasonal wind kicks in, that would be a different story with relief via thunderstorms. The model develops a 600DM upper high at 500mb pretty much over the top of us by the 25th. Although a long way off, CPC is in agreement with their new 6 to 10 and 8 to 14 day outlooks. They show very hot temps over the state with the potential of new high temperatures records being broken in their 8 to 14 day outlook..
Further comments Monday AM the 18th;
The reason why we are seeing another bout of heat coming our way is related to the same system that is currently making for quite breezy conditions today. At the moment we have an anomalous upper trof off the coast of the Pacific NW that is associated with a stronger belt of westerlies across the North Pacific this summer. This is due to the fact that the Arctic is actually colder than normal is specific areas this Summer. This makes for a stronger and more persistent belt of westerly along the US Canadian border over the far west and westward over the North Pacific. That same belt of stronger westerlies, “when the dip in the upper jet is off the west coast”, forces the Continental Subtropical High east of its normal position for the Summer. This results in the Summertime monsoon coming out of Mexico further east with very dry conditions over the far western interior as well as very dry breezy weather in the high country. The European Model is becoming more consistent, Run to Run in the retrogression of the long wave features. The European is showing retrogression of about 20 degrees longitude over the next week. So the Dip in the upper jet will occur about 1500 further west by the end of the week. However…here is the interesting point of it all….. the westerlies remain strong to the point that the continental high in order to retrograde has to become stretched out westward underneath the westerlies, instead of being an oval bubble in its retrogression. The up shot is…..That we may not see any moisture backing with its retrogression. If the retrogression occurs like the EC is showing the end of this week and heights at 500MB rise to near 600DM over Central CA…..Bishop could hit 108 to 110 and Mammoth in the low 90s as our air mass would be bone dry and no moisture or occasional dynamics to inhibit the super high temps…..
Monday AM 11:10AM;
New 12Z GFS has similar idea to the ECMWF but with a twist. It develops a weak upper trof over the Northern Great Basin that keeps the Continental Sub Tropical High from becoming too strong like the ECMWF and thus too hot for CA. The GFS version is still a dry pattern through. It will bring hot temps but no records. Then during week 2 or the end of the month….strong SE flow develops in its configuration which allows both Dynamics and Seasonal Wind Moisture to invade CA from the SSE.
Eventually…. a lot of high and mid level moisture moves in to suppress the heat wave a bit. Additionally, pattern generated by the GFS would set up a lot of instability for thunderstorm’s with potential for areas of heavy rain by the end of the month of July. Only time will tell which model has the right idea.
The Dweebs will have a much better handle on the weekend and early next week heat wave by Wednesday or Thursday this week. It is a dry 5 to 7 day outlook. in the meantime
Dr Howard and the Dweebs…………………….:-)
Although there will be little temperature change today over yesterday…Another Upper Trof will push through the pacific NW bringing breezy afternoons and evenings, Saturday though Monday. A cooling trend begins Saturday with high temps from the current mid 80s down to the mid to upper 70 by Sunday into Monday. Nighttime lows will remain cool in the dry air with lows in the 40s this weekend before sunrise. The Hemispheric pattern retrogrades next week with the subtropical continental high moving and spreading west. This will first bring very warm temperatures back into the Mammoth area the second half of next week. Thereafter….As the upper flow backs more from the SSE during the last week of July, Monsoon moisture and dynamics will return, as the season wind brings the chance of summertime showers to the high country again.
Mammoth Lakes Temps:
FRI SAT SUN Mon TUE Wed Thur
SUNNY SUNNY SUNNY SUNNY SUNNY SUNNY SUNNY
84 47/77 48/75 47/76 47/78 48/78 48/77