Looking Ahead for the Remainder of March…..Next Possible Storm and What April May have in Store for us….
Sunday March 15, 2015
Posted at 8:16 am by Howard
The first system of the Spring will bring gusty winds and the chance of some light snowfall late Sunday night into Monday.
The weekend looks fair and breezy with winds ramping up Sunday and Sunday night over the upper elevations. Wind Advisories are expected Sunday night into Monday AM as a Strong short wave moves through Northern CA. Temperatures on Friday will reach the mid 60s then cool to the mid to upper 50s Saturday with further cooling Sunday into Monday. Highs early next week will be in the upper 40s near the Village at Mammoth. In that the models are trending further south with this system this evening, there is the chance of some light snowfall over the upper elevations early Monday Morning with showers Monday afternoon. Although snowfall amounts could reach a half a foot over the Northern Sierra, for the southern parts of the Central Sierra, amounts generally in the trace to an inch range are possible by Monday afternoon over the crest…. This was revised from last night due to the models coming in drier…
It will be warmer between Wednesday into Friday….
St Patty’s Day Update:
The Dweebs have been watching the MJO Phase Space intently that indicate a very strong MJO now over the Central Pacific. Although there appears to be no connection to an “AR event” in the Dynamic Models, the MJO is very strong and has crossed into Phase Space 8, providing westerly wind bursts along or near the equator, pushing warm waters from the western pacific eastward. It will be interesting to watch how the ENSO signals including the ONI develop over the next few months. With the Nino 4 and 3.4 region already warm, priming the pump for a warm event will not be nearly as difficult as it was last Spring, coming off La Nina.
The Dweebs have been touting for several weeks now that the seasonal change is well under way with the first days of spring this coming weekend….. You can see it, even in our local forecasts with a chance of thunder Wednesday and Wednesday evening over the Eastern Sierra. The reason for this is that air masses react differently once daytime heating from an elevated heat source like the sierra, is added to even weak troughing. Capes increase as the air mass becomes more unstable just because of the combination of cooler air aloft, upper divergence or diffluence….plus the added rising air from convection.
The record strength positive PDO for the months of Dec, Jan and February, is most likely the biggest reason why the winter has been so dry and so warm for the golden state. This unusually warm water over the far eastern pacific, has supported strong long wave ridging aloft along the west coast. This system very effectively blocked storms most of the winter, giving California, one of the warmest and driest winters on record, similar to the winter of 1977!
As mentioned earlier, the Continental US, IE “CONUS” is warming up. This is/will have the effect of “diminishing the effect” of the anomalous warmth over the eastern pacific by switching the heat source from the ocean to the continent this Spring., this has a good chance of breaking the cycle, for at least as long as the westerlies remain far enough south before they weaken during the month of May….. So in other words, although March has not come back wet, there will still be an opportunity for April to…..
Interseasonal Models weeks 3 and 4 are supporting this notion with a change in the pattern the end of March with a strong under cutting upper jet into the west coast about April 1st…..
Dr Howard and the Dweebs…………………………………………………;-)
It was a record-breaking day across much of California yesterday. High temps over Southern CA reached low to mid 90s over much of the coastal plain. This was due to a combination of the persistent ridge over the west coast, heights and 500mb-1000mb thickness considered, a mild offshore Katabatic flow which was not associated with any great basin chilly surface high and probably as important now, the fact that it is Mid March, the sun is higher in the sky akin to late September, and able to heat the surface more thoroughly.
Bishop was warm as well with a high of 78 yesterday. That was no high temp record as the current record STANDS AT 84 set in 2007. It should be noted that during the cooler season, Bishop’s high temperature records are usually only broken during the more dynamic process of convergence aloft from an upper jet that causes Down Sloping winds along the lee side of the sierra katabatically…
Katabatic winds are the same as Santa Ana Winds as they both heat by compression adiabatically, at a lapse rate of 5.5F per thousand feet. Remember that there is a no heat transferred outside of the Adiabatic process. It is contained within.
You would not use the colloquial term Santa Ana winds for Bishop or the Owens Valley as the term has no relevance. That last prime example of Katabatic winds in the Bishop Area occurred during the beginning of the Round Fire when down sloping winds pushed temperatures up at the Bishop Airport that day into the low 80s……That was a new record for that date. The term Katabatic refers to a system meaning running down hill. Santa Ana winds are down sloping winds as well. Other areas outside of Southern CA like the eastern slopes of the Rockies can use the term Katabatic winds. However, they frequently they use colloquial terms like Chinook or Foehn winds. However, they are the same and pretty do much do the same thing….Warming by compressional heating through the adiabatic process.
In that Spring is about one week away…The Sun is higher in the sky and the differential heat sources of Pacific Ocean will have less or a different effect upon the upper pressure patterns over the far west. Storm’s will perform differently. They will in essence, yield to the more dominant heat source of continental heating rather than the anomalous warm water along the west coast. As the Dweebs have mentioned before, this is why weather patterns and WX systems often times change behavior in springtime as compared to winter.
It is possible that over the next few weeks that storms will have an easier time getting through the west coast upper block and bring us badly needed precipitation, here in California. The Dweebs see a few precipitation opportunities, indicated by several models and their ensembles with the dates like next weekend or between the 21 through the 24th as such an opportunity. That is one period of time as well as the very end of March. So may be that March will go out like a Lion this Spring, at least it is a possibility today.
Dr Howard and the Dweebs…………………..:-)