Brought to you by Howard Sheckter
Archive for September, 2021
Upper Trof to bring fall weather the next few days with breezy cooler weather and a refreshing of our smokey skies…..Some thoughts about the upcoming winter……
Monday September 27, 2021
Expect cooler breezy weather through Tuesday with gusts in the 40 to 50 mph range at FROPA. Expect high temps cooling to the upper 50s/low 60s in Mammoth the next few days. Nights will chill down into the upper 20s and 30s. Upper Trof will push a mostly dry cold front through our area tonight, Monday night. Winds will be light again in Mammoth Wednesday with north breezes to 15 MPH. By Thursday, upper ridging builds in with the thermal trough shifting to the coast and so offshore flow looks to keep good to moderate air quality over our region into the weekend. By the weekend, a small upper low develops off the coast of Southern CA. It builds heights further over the Eastern Sierra and Great Basin into early next week with even warmer temperatures Monday through Wednesday. The low is expected to open and merge with a trough in the GOA for a return of cooler breezy weather as we move through the 2nd half of next week, in the week two outlook.
Thoughts about ENSO and the upcoming winter:
I have read several articles’ about the upcoming winter. Most give odds of a normal winters worth of precipitation for Central CA, pretty much the same as the forecast made for the winter of 2020/2021. We all know that was a bust for the Sierra. With one of the lowest snowpacks for the central and southern sierra ever recorded. Unfortunately, the accuracy of long range forecasting is not all that great as there is a big differences between a winter that is below normal and one that is historically low in precipitation.
Making the case for ENSO, odds are high again that La Nina will make another appearance this Fall and Winter. Odds are up to 70% A point one should know is that there is a bias for drier than normal winters in CA. for the southern portions, like LA and San Diego, but the odds diminish as you go northward. Northern CA odds for a wetter winter is quite a bit higher than Central CA. If you want to look at the odds, check out Jan Nulls Website of information regarding ENSO for California. He has an excellent climate page and puts relevance of the past, to our current California Drought. https://ggweather.com/links.html
Personal Thoughts’;
Some changes in the climate related teleconnections this fall to last.
- La Nina appears to be weaker than last year this time.
- GOA SSTAs are warmer, as well as the AMO. (two areas that will experience stronger high pressure aloft.
- QBO has moved into its negative phase as of last June.
QBO, MJO and higher probably of Sudden Strato Warm events are of interest according to some research papers.
A strong negative phase QBO suggests a weaker Polar Vortex with stronger blocking over the higher latitudes. Although the odds are highest for the channeling of the Arctic Express to be channeled down through the northern, central planes and Great Lakes regions, especially with a strong Bermuda high and strong high over the GOA, the increased probabilities of more sudden strato warming events are also in the cards. (SSW) The research paper also suggests that the MJO is 40% stronger and last 10 days longer. This all argues for several AR events for the west coast including Northern and Central CA, January, Feb and March. Wet Nina?
PS, The MJO progression and strength, was severely blocked last winter due to the cold water over the central pacific and strong upper convergence over the central eastern pacific.
SEE: https://ncics.org/portfolio/monitor/mjo/
Abstract
The stratospheric quasi-biennial oscillation (QBO) and the tropospheric Madden–Julian oscillation (MJO) are strongly linked in boreal winter. In this Review, we synthesize observational and modelling evidence for this QBO–MJO connection and discuss its effects on MJO teleconnections and sub seasonal-to-seasonal predictions. After 1980, observations indicate that, during winters when lower-stratospheric QBO winds are easterly, the MJO is ~40% stronger and persists roughly 10 days longer compared with when QBO winds are westerly. Global sub seasonal forecast models, in turn, show a 1-week improvement (or 25% enhancement) in MJO prediction skill in QBO easterly versus QBO westerly phases. Despite the robustness of the observed QBO–MJO link and its global impacts via atmospheric teleconnections, the mechanisms that drive the connection are uncertain. Theories largely centre on QBO-related temperature stratification effects and subsequent impacts on deep convection, although other hypotheses propose that cloud radiative effects or QBO impacts on wave propagation might be important. Most numerical models, however, are unable to reproduce the observed QBO–MJO relationship, suggesting biases, deficiencies or omission of key physical processes in the models. While future work must strive to better understand all aspects of the QBO–MJO link, focus is needed on establishing a working mechanism and capturing the connection in models.
More later as La Nina develops…..
Cool Breezy Weekend on tap as a strong late Summer weather maker dives into the pacific NW and Northern CA. Showers possible for the Northern Sierra with mainly wind and cooling for Mono County….More breezy weather possible late next week as Summer comes to an end…….
Tuesday September 14, 2021
Quick update for the Weekend: 9/15
Several runs of the Euro has a confluence of both the Polar and at least a weak branch of the subtropical jets on Sunday. This is a departure from the GFS runs that omits this merge as well as the polar jet being a bit further north in the GFS as compared to the Euro. If the Euro is correct, it may bring us some light rain or rain showers over Mono County Sunday afternoon or night. Additionally, gradients are tighter with the EC and so it is a windier scenario for late Sunday/Night.
As much as 15 degrees of cooling is possible now with a freeze early next week for many of the colder valleys. Mammoth and June may get down to close to freezing as well Monday AM with highs in the upper 50 to low 60s Monday.
_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________
For the inland areas of California, it’s been the warmest Summer on record, a departure from Coastal California, mainly influenced by the chilly waters of La Nina creating more temperate weather. This weekend is expected to be breezy to windy in the Central and Northern Sierra, as a strong late Summer Trough dives into Northern CA. Although some models bring the chance of showers as far south as Mono County Sunday night, at this point, it’s unlikely this far south by the majority of the model runs. What is likely, is a cool down of at least 10 to 15 degrees by Sunday along with breezy to windy weather Sunday Afternoon and night. This weather system is remarkable in that it has a “Very Strong” AR accompanied with it for areas like the Columbia River inlet along the OR/Washington coastal border. The IVT Plume is over a whopping 1200! in the Integrated vapor transport scale. As an example, the AR that affected Mammoth late last January which dumped 8 to 10 feet of snow was around an 700 to 800 IVT. So the forecast is for an AR some 35% to 50% stronger! Pretty impressive for a late Summer upper Jet, up in the pacific NW.
At resort levels, the days will cool down into the low 60s by Monday, while nights will cool down to the lower 30s by Monday AM…..20s are likely in the colder valleys. This is the first of the early fall systems that are common during the end of Summer and the first weeks of Fall. The further outlook shown by the EURO model, has a nice period of weather the middle of next week before another migrating wave, one that may get “cut-off from the westerlies, that may affect the west coast later next week.
ENSO: The latest updated “IRI Compilation of SST Forecasts for the Nino 3.4 Region” show a weak La Nina expected for this Winter. Last Winter we had a moderate La Nina.
The bias of dryness goes with a La Nina here in the southern Mono County area. However, not all La Ninas are dry here. Other teleconnections are more interesting! Such as the The quasi-biennial oscillation (QBO), which is a quasi-periodic oscillation of the equatorial, lower strato zonal winds which oscillate west to east, then east to west. All of last winter they were in west to east mode or in the positive phase which is highlighted by a deep Hudson Bay Low. There was a flip in the index last June to east to west or the “negative phase”. This is most significant I believe, as the Polar Vortex will tend to be weaker with the opportunity for more Meridional Flow, which tracks the upper jet along Longitudinal Lines, VS latitudinal lines. This can make for a colder than normal winter across the US, and with blocking in the right places, such as the EP region, (-EP) an upper jet that can bring more storminess to California and Nevada. Additionally, it is known that there are more Sudden Strato Warm events which again, creates more Meridional Flow and the potential for “ARs”. Read abouth the QBO here: https://en.wikipedia.org/wiki/Quasi-biennial_oscillation
Also: The effects of the negative phase QBO upon the *MJO https://www.nature.com/articles/s43017-021-00173-9
Last Year, the MJO weakened rapidly over the western pacific, and there was a barrier of cold water over the central pacific. The article in the above link from Nature Mag is encouraging I believe. One that may argue against many of the current drier than normal winter forecasts for the Central Sierra.
*Madden Julien Oscillation (air sea coupled region of rising and falling air near the Equator that can modulate the westerlies.
Dr Howard and the Dweebs………………….:-)
Record heat to end Thursday as moisture streams north with the chance of showers into Friday…A warm dry weekend to follow into the early following week…..A significant cool down is in the cards for the following weekend…
Wednesday September 8, 2021
SATURDAY 9/11/2021
Discussion:
Upper Trough continues to lift out with a drying trend. Two more weak trofs will pass through Sunday PM and Monday PM. Expect a light to moderate Zephyr during these trof passages then light breezes Tuesday afternoon. Stronger breezes are possible Wednesday and Thursday. Expect 3 to 4 degrees of warming today and another 3 to 4 degrees of warming Sunday. Highs mostly in the mid 70s through Thursday.
Pattern Change expected next weekend.
This mornings 12Z GFS Model deterministic run was much stronger with the Upper Jet into Pacific Northwest next Friday, then sagging it south into Northern CA Sunday into early Monday morning the 20th. The GFS and ECMWF Ensemble’s are not reflective of this mornings GFS 12Z Run’s strength yet. Will have to monitor this pattern change this next week for the following weekend. Currently, the possibilities offer anything from breezy cooler weather to windy weather beginning Friday afternoon through the following weekend. The mornings GFS also suggests first Northern Sierra Dusting next Sunday night. That at this point is a long shot as again, current ensemble runs are not in agreement with the depth of that Trof. More model runs he upcoming new week will be needed to increase any confidence in the depth of the weather system.
As always stay tuned……..
Dr Howard and the Dweebs……………………..:-)
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Both ECMWF and GFS has a pattern change as we approach the Equinox, Wednesday the 22st of September. The pattern may start as early as the previous weekend. At the moment, strong winds and cooling is highlighted, but our first dusting is not out of the question. Stay Tuned..
__________________________________________________________________________________________________________________________________________________________________
High temperature records continue to fall this week as the strong upper high from the weekend pushed into Utah today. The high temperature at the Bishop AP hit 104 for the 2nd day in a row breaking the old record of 100 set back in 1955. The high temperature in Mammoth Lakes hit 84 degrees both yesterday and today Wednesday. The track of this upper high will take it to New Mexico by Friday. SSE flow is once again juicing up the state with the chance of showers and possible Thunder both Thursday and Friday. It’s getting late for Monsoon Season here over the East Central CA. This may be the last of it, this far north. No doubt that some of that tropical storm moisture from off Baja will get entrained into the CA state for Thursday and into Friday. By Friday afternoon, SW flow will develop with gusty SW winds, and a drying trend will develop later in the day into Saturday. Highs will cool to the low 70s Thursday and Friday with more sunshine Saturday and Sunday for warmer days. A nice cool down is instore for the bishop areas as well, with highs cooling to the low 90s Friday.
It’s getting close to Fall and time to start watching the MJO. The “Week 2” outlook for the MJO shows pretty good amplification in phase four. In September, that means that cooler than normal weather is on the way, *later next week. The GFS is hinting at a pretty good trof at that time with strong winds. BTW…The EURO does not agree, so we’ll wait and see later this weekend to see what shakes out. CLIMO does show that we often get a chilly equinox storm around the 21st.
ENSO: NCEP’s Seasonal climate forecast from CFSv2 is not behaving well with the latest modeling showing a trend toward a stronger La Nina.
Dr Howard and the Dweebs………………………………….:-)
