Archive for August, 2020

End of August to be seasonal….Next Heat Wave Shaping up 2nd half of next week through Holiday Weekend….

Monday Night; August 31st.

All systems go for excessive heat event for California….

Quick look at new GFS 00z Tuesday Sept 1st, shows the same ugly 600DM at 500MB upper high over Nevada Saturday afternoon and it stays right around that strong through Sunday PM.  850 MB temps warm through Sunday.  The upper high weakens slightly early next week with its core shifting westward over Central CA by then.  High temperature records are definitely in Jeopardy this weekend into early next week. For the high country, the good news is that because it will be September, the lows at night will be cooler!  50s…

Highs in Mammoth will be in the mid 85 to 87 this weekend; lows in the 50s. Expect little change in the temps fr the high country Labor Day.


Bishop high temperature records this weekend are 103 Friday, 103 Saturday , 103 Sunday, 100 Monday  These were set in 1955. Bet some of these will be either tied or broken.


Dr Howard and the Dweebs…………………..:-)






Pretty typical weekend shaping up with isolated thunderstorms in the late afternoon and early evening hours. Highs will be in the mid to upper 70s, However, the lows are cooler now because of the drier air and longer nights as they are down to the 40s.  We have another heat spell setting up for CA. “Possibly”, not quite the strength as the one a few weeks ago, but one that may break records for the dates around Labor Day. 500MB heights may reach the upper 590s dm over California next weekend as that ugly 600+DM anti-cyclone sets up. This pattern is more interesting to me.  It is one that combines western hemispheric amplification with an extension of the Eastern Pacific high in the Gulf of AK SE over CA.  A quasi polar vortex is part of the pattern developing over Central Canada. So initially its the ridge over CA then the Anticyclone that develops later in the period around Labor Day.  Mid to possibly upper 80s now expected over the Labor Day holiday weekend in Mammoth, 100s in Bishop and 100 to 115+ in the valleys and coastal plain of CA, as desert air returns to the coast. Later in the pattern around Labor Day, isolated thunderstorms may develop. This is not a pattern that typically brings a lot of humidly to CA as the pattern evolves from the NW.  However, latest 12z GFS from 8-29-2020 does show a strong surge of PWAT (1.00 to 1.50) up the CA coast the send half of next week. So a lot will depend upon of the upper flow is easterly or south easterly. This new pattern once again, will be of major concern to fire weather experts….. Latest temperature departures suggest 15 to as much as 30 degrees above normal during the Labor Day holiday weekend from Oregon to Southern CA.

Again….The big difference of this pattern to the one that developed a couple of weekend ago, is that last time, a continental high set up along the Southern NV Utah border and 500MB heights were in the low 600s DM.  South-South East flow developed and the Vort train extended during that famous weekend, from southeast to northwest along the coast of CA, setting off a spectacular thunderstorm complex,  This pattern will be different as the upper high is progged to develop as part of the eastern pacific high pressure complex in the north pacific. A closed anti cyclone is progged to set up near Mammoth Lakes or Western NV at times. Easterly flow over Southern CA. will drive hot desert air westward to the coast. As the pattern evolves, there is some suggestion that a mega 600+DM at 500MB bubbles up over the far west.  It will be very interesting meteorologically…


Dr Howard and the Dweebs……………………..:-)

The last week of August should be pretty uneventful with warm sunny days….periods of haze and cooler nights….Meteorological Summer comes to an end….Heat returns to CA on September 3rd and builds through Labor Day weekend….100s in LA and Bishop….80s in Mammoth


The highlights of the last post was subtropical moisture that brought some thunder and brief heavy rain showers Monday afternoon.  Our highs have been in the low to mid 80s and have recently pulled back into the mid 70s. Yesterday Monday, we had southerly flow and that brought up smoke from the Sequoia Fire. Today’s SW flow effectively cut off that smoke train. However, particulates returned from the fires burning along the coast with smoke accumulating over the San Joaquin valley.   It is difficult to forecast future smoke outlooks as so much depends upon how effective fire suppression is. Today was a much better day for the fire fighters on the coast as onshore flow and a deeper marine layer helped much for the coastal range fires.   However, checking the air quality sites this afternoon, they were pretty awful over San Jose, north to the Bay Area, then ENE to Tahoe and Reno. So Air Quality has improved in Mono County and is worse to the north today.

Little change in the forecast is expected the next few days, with the bias of the denser smoke to our north.   The weekend outlook is fairly persistent.   Highs in the 70s with lows in the 40s.



The only change in the pattern that occurs is right around September 1st, when the eastern pacific high builds north into the Gulf of AK. This may pull down some cooler air from Canada. Will have to follow this as it represents a significant shift in wind direction. Hope it does not shift the smoke into Mammoth. Maybe the fires will be under control?

Of note, the westerlies really rev up across Canada next week. Significant snows fall in the Canadian Rockies, beginning this Sunday and continue next week… During the first week of September a chilly low pressure system sets up over Central Canada. Some of this cold air invades Montana and the Dakota’s by mid week next week and some Snows are possible for the Grand Tetons next week as well. Some models even pinch off some of that cold air into the Great Basin, but Climo-Support for that is not all that great, that time of the year.

The Dweebs still expect some good warm weather spells to occur in September.  The 2nd week of September shows promise for that…..of course the nights will become chilly….  Meteorological Fall Begins September 1st, next Tuesday.  Hope ya-all had a good Summer.  After all, it could have been worse.  We could have had long periods of dense smoke like a couple of summers ago.


Dr Howard and the Dweebs………………..:-)


Pattern Change initiates Dry SW flow aloft for drying trend into Friday…..Although little change in temps are expected for Mammoth Lakes…..Subtropical Moisture returns at weeks end…

RECAP:   Yes its been been very warm to hot across the State.  Down in Southern California, the protracted heat wave has caused misery for many. At resort levels at Mammoth Lakes, we actually had some very pleasant weather over the weekend with highs in the 70s.  That was because when we really moisten up, we loose a lot of in coming solar radiation and thus there was a lack of surface heating.  Mammoth did have some light showers, mainly in the late afternoon and early evening hours along with some thunder. Southwest flow was initiated yesterday. With more sunshine during the day, we got up to 84 degrees on Tuesday.  Nights in the 50s

Current Pattern:

The subtropical high at 500MB was centered over SW Utah this morning,  (597DM) and is progged to weaken through Friday over AZ to 591DM. So a 60 decameter drop.  This is in response to a trof of low pressure moving into Washington state today.  For Mammoth, although heights will fall the next few days, there will be more sunshine, as our airmass continues to dry from west to east. So the effects of airmass cooling will be negligible, with only a few degrees of cooling by Friday.  At night it will be a different story as the dry airmass  allows lows at night to pull back into the 40s.  Also, expect a resumption of  the Mono Zephyr, beginning today into Friday.   Another point to make is that there are a lot of fires burning to our west.  With the upper flow becoming more WSW. Expect smoke from the west to arrive later today or tonight….

For you folks in Southern Ca, there will be some 5 to 10 degrees of cooling which will begin today. By weeks end, coastal sections may be in the 70s, Coastal Plain in the 80s and Valleys in the 90s by the weekend.

Owens Valley:

Upper flow was still SSE this morning but becomes SW later today.  So today is the last of the Thunderstorms for a while. Drying continues in the Owens Valley through Friday..

Dew-points will come down a bit as well.


Hurricane Genevieve is nearing Cabo San Lucas. This tropical storm will move along the Baja Coast and weaken over time over the colder water.  Moisture will be released northeastward as the systems becomes a depression, with its remains exiting possibly over central or northern CA Monday Afternoon or night.  Although there may be some showers or thunderstorms from this system, main effect will be an increase of moisture for California, beginning Saturday over Southern Ca and Sunday and Monday for the rest of California.\

There is some suggestion from this mornings 12z GFS run that another Subtropical low will spin up, this time in the “COL”, and track toward CA mid week next week. That may be a good precip producer for the fires burning throughout Northern CA. This is a long shot at this point but worth watching…

We are getting close to the time when California may benefit from a dying Hurricane that could bring beneficial rains to the state. A Window is opening over the next few weeks….

Anyway…..It is worth noting that Meteorological Fall arrives on the first of September, so the days will become notably shorter in the next few weeks along with much cooler night

Dr Howard and the Dweebs……Covering the Eastern Sierra Weather for 40 years……:-)