Archive for March, 2015
After another very warm day Monday….A slow change to near season temperatures will occur this week with periods of wind beginning Tuesday……Pattern Change this Week will Continue into the Following Week with MJO Support…..
Monday March 30, 2015
Posted at 8:06 am by Howard
No changes for the short-term with winds already up in the high country and cooling moving in. It will be breezy in town (TOML) both today through Wednesday with a high near 59 today and mid to upper 40s Wednesday. Night time lows will be in the teens in many areas by Thursday AM. The weather system responsible for the cooling will brings rains to the pacific NW and as far south as Northern CA. A secondary impulse will bring a slight chance of showers to our region Thursday AM. After that, a break in the pattern of wind before another stronger Trof brings winds and cooling back into our area by Saturday night and Sunday with wind 1st and then cooling Sunday into Tuesday. At the Moment, the favored global models are at odds with each other with the GFS Pretty dry and further north with the Sunday -Mon system, while the Euro continues the threat of snowfall for our area early next week. With that said, the EC did trend drier over night and I guess you could say more toward the GFS solution. So the system for Sunday Monday does not look all that great for snowfall at this time. However there is plenty of time for an adjustment either way. The Dweebs should have much better confidence by Thursday for the Sunday-Monday system. Evidentially the pattern will take more time to develop and thus the next storm cycle is most probably further down the road but not out of the question in April.
There was a depressing report that came out from the DWP this AM. The updated telemetry showed an inch of water up on the pass. I am sure that they will go up and measure what there is to measure manually today or tomorrow on several areas around the pass to come up with an average or the mean. I do not know which they use.
1 inch of water in the snow pack at this time is equal to 2% of the normal water in the snowpack for April 1st. That is deemed to be the end of the water year here on Mammoth Pass. As a comparison, the driest year on record showed MAMMOTH PASS with about 10 inch’s of water in the snow pack. You do the math…..
This is not only the driest year on record for April 1, but possibly a 1 in >100 year event. Just think, you were alive to experience history from a hydrological perspective. As a comparison, at the opposite end of a time scale, this is probably equal to or greater than a winter of
>300% of normal on the opposite end of the scale, or the equivalent to the projected historic ARC storm winter that may hit the sierra some day or a 1000+ inch winter. The infamous winter of 1969, the greatest winter on record according to DWP records going back to 1940 was 277% of normal. There are plenty of photos around town with the famous areal shot of the Main Lodge being close to buried. That winter is the high bench mark of all winters here in Mono County according to DWP records. I will also add this. Although the siege of storms began the 10th of January of 1969, there were plenty of good storms during the month of December 1968. I have researched the re-analyses 500MB and 250MB charts on that winter…….
Most astute WX folks know that model reliability is poor during times of pattern transitions. Especially in a drought year when there is the “possibility” of a pattern of wet and cold in a year of warmth and dryness. After looking at both the deterministic runs of the global models this AM and well as their ensemble members in seeing a pattern change for next week, one would look for other supporting evidence. Such evidence like the forecast of key teleconnection indice changes and other areas of support like the MJO within the Wheeler Hedon, phase space. Using the MJO to see where it is geographically, its strength as well as what and where both the dynamic and statistic models both locate it. The signal is tricky as it can be convoluted with other modes of lower frequency variability like kelvin waves and ERW which can constructively phase or destructively phase with the signal.
After the current episode of the MJO reached record strength on the 16th of March…it has weakened, but still remains a significant signal as it re emerges out over the Indian Ocean with a sigma of about 1.5. It is commonly accepted that when an area of enhanced convection moves over the Indian Ocean beginning with area 70E along or near the Equator south of a meridian that runs through Pakistan, then progressing east through the Maritime Continent and into the far Western Pacific to about 120E there is a “tendency for a Negative PNA state” or a long wave trof is biased to the far west of the CONUS.
What is interesting at this time is that:
1. The ECMWF model has a long wave trof carved out over the Far West next week coinciding with the forecasted location of the convective state of the MJO in phase 3. The Statistical model keeps the signal going into phase space 4, however the dynamic models weakens it rapidly thereafter….
2. This is the first time since last year that a moderate signal is forecasted to move through Phase 3. IE this has not happened in over 3 months. Although contrary to the dynamic models, it may hold together strong enough well into Phase 4 based upon the Statistical Model.
3. The Dweebs use the MJO at times for validation for the week two and week three-time periods which is more related to an interseasonal time scale. This is all in an outlook period or beyond any forecast time frame. So the idea of a wet week next week is a good idea, but too far out to be an actual forecast. Nevertheless it is nice to see last nights run of the ECMWF showing between one and two inches of water EQ for the Sierra west of Mammoth next week up until the 9th.
The forecast for this week shows a gradual cooling trend beginning tomorrow Tuesday through Thursday. There will be periods of wind and we will see the return of over night freezing temperatures on a regional scale by Thursday AM. Daytime highs will be in the 40s on Thursday. The following holiday weekend looks mild with the winds coming up on Easter Sunday. It is what happens beyond Easter Sunday that holds the possibility of a stormy pattern that following week….. (Week Two)
To reiterate my last discussion, there is the potential of the First Significant Cold Storm Cycle this year….next week depending upon how everything sets up including the timing…….. The new 12z ECMWF that is just finishing through 240 hours is looking more bullish today……I will comment further on this outlook late this afternoon….
Saturday March 28, 2015
Posted at 3:27 pm by Howard
Water Vapor loop over Central CA shows clearly the donut hole of the VT max moving into the Southern Sierra with Cu being forced to its ENE.
Cumulus build ups this afternoon occurred as expected. However, still no echo’s seen on the radar at this time. However, there is still more daytime heating ahead…thus the slight chance of a shower or TSRW in the forecast is good through this evening.
As in my previous discussion yesterday. I wanted to highlight the MJO that is actually 1.5 Sigma (Deviations from normal) in strength. It has just crossed into phase space 2 where it will spend a good part of the new week ahead. The Dweebs expect a cooling trend next week with stronger winds…..
The MJO is expected to cross into Phase space 3 Easter Weekend. The models have been touting for a while the possibility of a Storm over the Eastern Holiday weekend. The fact that we have support now from a moderate MJO over the Indian Ocean gives further support to the week 2 outlook for storminess because of the flip in the PNA to negative. At the moment, although it is too soon to think about a major system in the forecast. The possibility exists today, in my week 2 outlook for next Easter Sunday and into that following week of a major storm cycle. This is expected to be a cold pattern as compared to what we have experienced the past 2 months.
The MJO is expected to weaken as it moves east over the Maritime Continent with the PNA flipping positive again Week 3 and into 4.
Dr Howard and the Dweebs…………………………..:-)
It appears that finally the Dweebs are seeing a change in the pattern probably due more to the strong MJO which makes a run for Phase Space 3 during the later part of the first week of April…. I say that as the 6 to 10 day is bullish on the change to below normal temps. Using the ECMWF and the statistical model, they have amplitude’s of at least Sigma 1 or greater in phase space 3. So, as the MJO moves off the coast of Africa through the Indian Ocean, a flip in the PNA to negative is likely to occur. Thus there is support from the MJO composites in April in Phase 3 for cooler than normal temps over the far west when the Sigma is equal to or greater than sigma 1. This occurs beginning anytime around Easter Sunday and well into the following week. There may be some snowfall as well, but that is just a guess……Not based upon any guidance.
I still can not help thinking about the strong underlying antecedent problem of all that anomalous warmth over the Eastern Pacific trying to keep the ridge in place through.
Another Strong Kelvin wave:
More importantly the strong KELVIN Wave is beginning to surface throughout the Equatorial Eastern Pacific.
Once again this is going to be the big tease for California Weather for the next Winter….as the warmth (SST) fills the Nino Basin later this Spring and Summer. No doubt in this Dweebs mind that there is at least moderate El Nino on the horizon later this Summer and into the Fall. This big question like last year will be…will there be carry through into the following winter. We probably will not know that until later next Fall. One thing should be noted; that the Nino Basin has a head start on the warmth, as there is currently an El Nino Advisory in play. Weak El Nino conditions are ongoing now…..
The current Kelvin Wave will give a hot-shot of warmth to an already warm sea surface. For the folks that own beach front property in Baja….Better keep your Hurricane insurance policies current!
High pressure aloft will build over the region next few days leading to warmer temps and light breezes…..Another weak impulse moves through Saturday Night and Sunday for a slight chance of showers…….A zonal flow develops mid week to wrap up the end of March and the beginning of April…
Wednesday March 25, 2015
Posted at 8:47 am by Howard
Record high temps were recorded Thursday over the Eastern Sierra for the date. Bishop tied the old high temperature record set back in 1960 with 81 degrees. Today Friday, the high temp record of 79 degrees was set back in 1986. The forecast is for 84 degrees which will shatter the old record. Saturday and Sundays’ record high was 81 set in 1986 and 1969 respectively. Both of those high temp records are in jeopardy at the Bishop Apt this weekend. By the way the first 90 ever recorded in Bishop occurred April 1st, 1966. that high temperature record is not in jeopardy. For Mammoth, any high temperatures between the 26th and 29th in March in the low to mid 60s are record highs..
With a record low snowpack for this time of the year in the high country and antecedent temperatures running between 10 and 15 degrees above normal, the weak system coming in late Saturday into Sunday should really destabilize the local air mass, especially above the elevated heat sources of the high country. Thus mid to late afternoon showers and even a thunderstorm is not out of the question between Saturday afternoon and Sunday evening…..The freezing level over the weekend is forecasted to be about 12,000 feet, so it would be rain showers in town and being that it is convective, snow showers or thunder snow on Mammoth Mountain, similar to earlier this week.
It looks breezy to windy Tuesday and especially Wednesday. It will be cooler as well. A moderate strength upper jet will affect our area in two parts. One jet-let comes in Tuesday morning and the stronger upper jet comes in with 1000mb/500mb/ Thickness packing. So its going to be quite windy Wednesday. As far as moisture goes, the guidance this morning indicates the air mass is especially dry. So the Dweebs do not expect any significant precipitation at this time. With that said, 500mb heights drop to between 570DM and 564dm with the upper flow from the west to east. The position of the upper jet and its axis is right through Mono County Wednesday. So….there will be orographic’s in play, and thus there may be a few showers Wednesday. Right now I would put it in the slight chance category of 10% to 20% chance.
The outlook for Easter Weekend at this time does show a weather system for that weekend. However, it is too soon to say if it will bring any snowfall or just wind….
A dust on the crust occurred yesterday as a weak disturbance moved across the sierra bringing some light showers late in the afternoon in town and snow showers on Mammoth Mt. Today’s guidance shows heights aloft increasing with an anti cyclone developing near or over Central CA Tomorrow. The upper ridge gets flattened by a system moving to our north Saturday, then a weak Vt center makes its way though the Sierra Saturday night or Sunday, bringing a chance of showers or even a thunderstorm. Daytime highs will climb about 12 degrees by Friday with highs in the mid 60s Friday into Saturday. It will be a bit cooler Sunday with more cloud cover.
Next week will bring breezy weather by mid-week and windy WX over the upper elevations as the flow over the Eastern Pacific goes zonal. This is due to the forecast of the upper jet sagging south into extreme Northern CA while Central CA remains on the anti cyclonic side of the upper jet. Although Daytime highs will average warmer than normal, high temps will cool mid week to the upper 50s…at least. Night time lows will continue in the 20s and 30s. There appears to be a significant pattern change going into Easter Weekend……It looks cooler and unsettled….Stay Tuned……..>>
Dr Howard and the Dweebs……………………………..:-)