Archive for May, 2023

Strong Ridging just off the West Coast is forcing an elongated Trof in the upper levels over CA and Western NV with cooler showery WX Thursday and Friday….El Nino out over the EQ pacific will be perking up later this Summer…

Wednesday May 24, 2023

Posted at 2:40 pm by Howard

The Strong off shore upper ridge has set up some strong upper troughing over CA and Western NV. Although Southern Mono Clounty should be spaired today from major rains….The upper forcing should shift south Thursday into Friday with better action for the Mammoth and June areas. Expect showers and Thunder with even the sierra crest getting some snowflakes during that time. There may be some areas that will get 1/2 inch of rain, especially Thursday afternoon into the night and Friday looks unsettled as well. By Friday night, a part of the trof shifts east and we get a break in the weather for the most part Saturday. Another chance to slight chance of showers returns Sunday and Monday. Temps will be in the 50s in Mammoth Thursday, Friday with low 60s returning over the weekend with 30s at night.  There is likely to be unsettled periods of WX during the month of June as well.

 

EL Nino From the CPC:

So far, the subsurface warming of ocean water below north of the Equator has been modest with some suggestion that a Modoki type El Nino may be in order as the Nino 3.4 area show modest warming.  The Modoki El Nino tends to provide most of the warming near the dateline and possibility the central american coast.  There is a strongwarm pool off the Central American Coast so this suggests the possibility of a Modoki event. Many Modoki El Ninos bring dryer winters to CA.

This discuession below suggests a stronger surge of sub surface warming is on the way this Summer, with the intensification of El Nino as it rises to the surface. The potential sub surface warmer surge would be due to a strong downwelling Kelvin Wave event.  If successful, this change would give better odds for a wetter winter than the typical Modoki event for California.

 

Last Updated – 05/23/23
Valid – 05/31/23 – 06/13/23
An active Madden-Julian Oscillation (MJO) signal remains apparent in various atmospheric fields, and continues to project well on the RMM-based and CPC upper-level velocity potential based MJO indices. Recent observations have indicated that other modes are interfering with this intraseasonal signal. Notably, the large circulation of Typhoon Mawar over the West Pacific, and persistent anomalously strong upper-level westerly winds over the East Pacific have caused a slowdown in the eastward propagation of the MJO, which had been on the fast end of the 30-60 day circumnavigational envelope throughout much of the Boreal Spring. The confluence of these modes has resulted in a very strong westerly wind burst (WWB) along the equatorial West Pacific, co-located with the warmest waters of the West Pacific warm pool. This WWB is likely to generate a strong and breaking downwelling oceanic Kelvin wave, which would serve to reinforce and increase the influx of warmer upper-ocean water across the equatorial Pacific. Therefore the MJO slowdown and tropical cyclone activity over the Pacific increases confidence in a transition towards El Nino conditions.

 

 

Warming Trend to continue through Saturday…..Southerly Flow and impulses from the SSE will increase chances of Showers this weekend then cooler drier air expected early to mid following week…

Wednesday May 17, 2023

Posted at 9:48 am by Howard

It was a beautiful morning in the Mammoth Lakes today. Still a deep snowpack at elevations at and above 8500 feet. This snowpack will inhibit surface convection, however, there will be an increase in mid to upper level forcing, in the high country this weekend, and a better chance of rainfall. Our freezing level is above 13000 feet so no snowfall expected. Our Sun angle is now about the same as July 25th and thus good surface heating will increase snow melt and stream flows as we go through the weekend. Those fishing the creeks and streams need to be mindfull about several potential hazards associated with our water ways, especially during mid afternoon and evenings during the peak diurnal water flow periods.

(Weather Medium Range)

High pressure aloft will continue to build, both along the coast of BC, Canada and over Central CA through this Saturday. Warmer weather with an increase of snow melt expected. In addition this weekend, an area of low pressure will spin up over Northern Baja and the Gulf of CA in a weak Rex Block Fashine. Moisture and some upper level forcing will contribute to an increase of showers and thunder this weekend, especially over areas with out snowpack. However, all areas have the threat of some rainfall. It should be noted that as long as a dense snowpack continues over the high country, there is going to be a persistant limitation on the usual high temps and afternoon convection until it is gone.

Next Week:

The upper level ridge will shift east early next week with the long wave ridge redeveloping near 140West. This will redevelop a mid latitude trof over the far west and Great Basin during the 2nd half of next week. Expect breezy and somewhat cooler weather for the high country, especially during the second half of next week. Temps will return to normal or even a bit cooler than normal into the following weekend. Upper 50s to low 60s?  Also, if a closed low or cutoff low develops off shore, there may be some showers.  Beyond that we get into June and its too far off to tell.

El Nino:

Continues to develop over the central to eastern pacific EQ region. It will be a long time for any expectation for mid latitude forcing, if we even get it!

Well see later in the Summer.

Remember, the high latitude response is a positive PNA or strong upper high over BC west to the Eastern Gulf of AK. That is in contrast or the opposite of the -PNA during La Nina.

El Ninos here in CA tend to affect our area later in the Winter and so it may be a very nice warm dry Fall! ?

The Dweeber……………………:-)

 

Definetly a Warmer Weekend setting up as High Pressure Builds over Western Canada. In time, a cut off low develops over Northern California adding to unstable air and presenting the chance of some showers, mainly later next week. The Dweebs do not expect any snowfall on Mammoth Mtn as freezing level 13K….El Nino continues to develop with prospects for at least a moderate event with lower chances of a major event..

Friday May 12, 2023

Posted at 6:56 pm by Howard

Strong upper ridging is building north over CA and temps will rise to the low 60s in Mammoth this weekend, then mid to upper 60s later next week. Run off conditions once again will be brisk into next week.  Strong positive phase PNA pattern is developing as well; very El Nino like. Enjoy the warmer weather this weekend into next week, however, lots of build ups expected next week with the slight chance of showers.  Major snowcover over the upper elevations still keeping convection to a minium over our local mts.

As mentioned earlier, another cool spell is possible during the first half of June.

 

Here are comments from the CPC regarding ENSO:

Synopsis:  A transition from ENSO-neutral is expected in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter.

During April, above-average sea surface temperatures (SSTs) expanded slightly westward to the east-central equatorial Pacific Ocean [Fig. 1]. The latest weekly Niño-3.4 index value was +0.4°C, with the easternmost Niño-3 and Niño1+2 regions at +0.8°C and +2.7°C, respectively [Fig. 2]. Area-averaged subsurface temperatures anomalies continued to increase [Fig. 3], reflecting widespread positive temperature anomalies below the surface of the equatorial Pacific Ocean [Fig. 4]. Low-level wind anomalies were westerly during mid-April before switching back to easterly by the end of the month. Upper-level wind anomalies were westerly across most of the Pacific Ocean. Suppressed convection was observed over parts of Indonesia and anomalies weakened near the Date Line [Fig. 5]. While the warming near coastal South America remains striking, the basin-wide coupled ocean-atmosphere system remained consistent with ENSO-neutral.

The most recent IRI plume also indicates El Niño is likely to form during the May-July season and persist into the winter [Fig. 6]. The combination of a forecasted third westerly wind event in mid-late May, and high levels of above-average oceanic heat content, means that a potentially significant El Niño is on the horizon. While at least a weak El Niño is likely, the range of possibilities at the end of the year (November-January) include a 80% chance of at least a moderate El Niño (Niño-3.4 ≥ 1.0°C) to a ~55% chance of a strong El Niño (Niño-3.4 ≥ 1.5°C). It is still possible the tropical atmosphere does not couple with the ocean, and El Niño fails to materialize (5-10% chance). In summary, a transition from ENSO-neutral is expected in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter [Fig. 7].

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Additional perspectives and analysis are also available in an ENSO blog. A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 8 June 2023.

To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: [email protected].

Screaming message is, no matter what you read or hear, no matter how strong an El Niño events gets, it has to be a full basin El Nino which gives it the highest odds of it coupling with the westerlies and bringing a big wet winter to CA.

Another thought is, do we really want another big wet winter in CA?

El Niño winters usually are associated with positive phase PNA pattern.  This pattern often brings higher snow levels than last winter which favored negative phase PNA pattern.
positive PNA often times bring heavy wet snow events and higher elevation rain.

Again a lot of this will be determined by whether EL Nino couples with the westerlies. No one knows that yet.

Dr Howard and the Dweebs….