Slow warming trend in the forecast through Thursday…….Models are moving toward more summer troughing over the East Pac in the weeks to come…possibly opening the door to a tropical system next week….A surge of monsoon moisture coupled with moisture from Dolores is heading north into CA this weekend……
Monday July 13, 2015
Posted at 1:46 pm by Howard
Idea of any meaningful effect from Dolores are still in question this afternoon as the latest model runs keep her off shore. Stay tuned!
The Dweebs are reconsidering the idea of the Dolores effect upon Southern and Central CA. However, not from a wind or tropical storm idea…rather from a precipitation event. Both EC and GFS ensembles have been trending more in the direction of the most current deterministic runs today which does give Southern CA and Central CA rainfall, beginning as early as Saturday then on into early next week.
What we have here is a west coast long wave trof that is beginning to over stay its welcome. It has been weakening recently and is forecasted to continue in that direction the next several days. However, out over the western pacific, typhoon action is constructively phasing enough to create retrogression with the westerlies later this week. That action will redevelop the long wave trof off the west coast and is forecasted to pick up the remains of Dolores Saturday afternoon into Monday. This evenings 00z Tuesday GFS shows a double jet structure developing over South/Central CA for Saturday night and Sunday into Monday. It appears that an upper vort center (Remains of Dolores) will move on shore Saturday night with strong upper divergence at 250mb over the same. This may be akin to a strong easterly wave coming north around a ST high. but from the SW.
Of most importance, this will not be much of a tropical system, rather the remnant’s thereof, with an enhanced upper jet providing the ingredients for moisture and the possibility for a period of general rainfall over the weekend. Tropical storm Dolores will not be the story, as it will not be much by the time it reaches the Channel Islands. The real story will be the deformation and strong upper divergence from the two air masses combining to bring more rainfall for South Central CA. I.E. the upper jet spun up and the remaining VT center of Dolores.
It should not come to anyone’s surprise that it has been wetter than normal for the Central Eastern Sierra and extreme Western NV this Summer. But how much wetter than normal is the question. It may interest you that according the latest graphics from the CPC during the period 12th of May to the 10th of July, the isopleths show that precipitation was about 200% above normal here in Mammoth to as high as 500% above normal near the mountains around Hawthorne, NV. The CPC latest model runs show more anomalous rain this Summer in the coming weeks. The Dweebs will highlight where and when later this week.
The weather this week shows the upper trof over the State of CA weakening over the coming days with rising heights, bringing warmer weather into Thursday. There is a lot going on, on a hemispheric bases.
Here are some of the players.
1. The extremely strong MJO for July last week has moved into the East Pac and appears to be constructively interfering with the El Nino base state. Looking at the Rimm Phase Space today SEE: http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phase.Last40days.html
It is located in mid Phase 8 defying most of the dynamic models as it remain about +1 Sigma. If this were Jan or February, we’d probably have a major Pineapple Connection going on now!
We now have western pacific tropical storms that were caused by the combination of the MJO and KV over the western pacific last week, effecting China; another that appears to be going to constructively phase with the westerly’s near Japan. The Dweeb will have to keep an eye on the West Pac, as amplification and retrogression down stream is still possible, even in July! Yes, mid July and “I am” having a real hard time saying that.
For those that are concerned about TS Dolores. She does not appear to be of a concern for the west coast through this weekend. The big question is, which short wave if any will be the one to pick her up her moisture? The longer she remains over colder waters to the north , the less she will be a problem. So what happens over the Western Pacific (West Pac) with typhoons, will have a major influence upon the west coast Long Wave Trof next week and beyond. Both of todays 12z runs show Dolores in the Eastern Pacific well over shore, weakening, with high clouds shearing off to the east into CA. However, both Global models do pick up her remains “about” mid-week, next week and give parts the west coast some rain. There are a few models that try to bring her in very early next week but I am not buying into that at this time.
Here is something to think about. When and if the remains of Dolores comes into the west coast, it may not be her moisture that is most significant, it maybe the remaining vort center that would affect the state. Less emphasis on hurricane moisture and more on the remaining dynamics. If by chance, she gets picked up by “a strong” for July short wave trof in the westerlies, which is possible next week, then her remaining moisture and upper divergence will be important to watch for. One thing is certain, a strong convective envelope from MJO in Phase 8 has moved into the Eastern Pac and modulating tropical storms now and that is expected to continue into next week.
Expect a nice week with occasional high clouds thru Thursday. Then an increase of thunderstorms this weekend… Thus, monsoon moisture and upper divergence makes a return this weekend.
Dr Howard and the Dweebs………………:-)