Monsoon Moisture Along with some dynamics to bring an increase in Thunderstorms Sunday into Monday…..Otherwise Fair and dry through Saturday with Seasonal temps….
Thursday July 16, 2015
Posted at 9:40 am by Howard
Will make this as quick and clear as possible this AM:
At the moment, up at 300MB there is a weak WSW/ENE upper trof or boundary that gets pinched off into an upper low off the central coast this afternoon. This boundary has acted as a barrier in the northward movement of moisture. You might have noticed some wind in the afternoon from the west. This has been part of it.
This E/W trof will disappear today. The 12Z NGM creates a lot of CAPE over Mono County and the fact that we are becoming on the NE quad of the upper low off shore will add to the coupling by creating Upper Divergence.
Expect Thunderstorms to develop this afternoon and into this evening mainly south of Bridgeport. The Remains of Dolores will come in adding to the dynamics with additional moisture Monday into Tuesday. If there is plenty of sunshine both days. Heavy wet thunderstorms are possible with flash floor potential…not only during the daytime hours but Monday night and Tuesday as well. Dry weather will return Wednesday into Thursday with an unseasonably cool and breezy trof……
Thursday Night: A quick look to compare the 00z GFS QPF with the 00z ECMWF shows the GFS a lot drier. However, the ECMWF is quite wet with the Combination of Dolores and some dynamics near the area. So at this point, it could go either way as far as heavy rainfall. Odds are good we’ll get some rain. Question is will we get a lot of rain….The IOP is Sunday into Monday. ENSO: A combination of an Atmospheric Kelvin wave that translated east, strong westerly wind bursts late June and early July along with twin cyclones on each side of the equators near 160E, did its magic 3+ weeks ago. This is all being reflective in the further recharge of the Nino Basin and the boost in the CFSv2 indices’. El Nino looks Super! ……. 😉 Update Friday afternoon: ————————————————————————————————————————————————————————————————————————————————————— Last nights GFS Models continue to down play any significant effects from weakening Hurricane Dolores this weekend. Although some remnants are certainly picked up by a weak mid latitude circulation off the central coast of CA, the stronger upper jet over CA that was earlier forecasted by the models for this weekend does not appear in the picture anymore. Looking at the 06 Z GFS from late last night, both the 300MB and 250MB upper winds and jet structure is further east now favoring Arizona and New Mexico. So it is in those areas where you will find the best “Upper Divergence” for precipitation this weekend. Additionally, I did not see any impressive CAPE over the Eastern Sierra in the model as well. So the odds as of this point in time, for major thunderstorm action is greatly reduced. Just possibly some widely scattered action is currently expected Sunday into Monday. With that all said, there will be a big push of Monsoon Moisture from Mexico as well as remnant moisture from Dolores. This may end up a being classic example of lots of moisture but no wide-spread convection because of the lack of significant upper divergence necessary to create a significant thunderstorm pattern over the weekend. The Dweebs will be watching for any sign of a wave or vort max from the SSE flow later this weekend to generate dynamic lift. Additionally, there is some suggestion that Dolores may morf into or become part of a weak mid latitude upper low early next week. If a mid level upper low develops and its NE quad favors Mono County, that would be a localized situation that would make a difference in thunderstorm coverage for Mammoth Lakes about Tuesday of next week. The Dweebs will take another look at it Saturday AM or sooner if necessary. Longer Range: Another potentially strong upper trof for July will descend from the G of AK about Wednesday or Thursday of next week. This would bring a return of a dry air-across the region as well as some cooling with stronger afternoon west or SW winds. There is one more hurricane worth watching for later next week. At the moment, just like this weekend system, the models show the upper trof to the north shifting east before the window of opportunity of the next TS get close enough to CA to make a big difference. That of course is subject to change as we are out in time a long period. ENSO/MJO The transitory convective envelope of the MJO should be out of the Tropical Eastern Pacific “during the 1st week and into the 2nd week of August. So the emphasis of tropical storm action may shift into the Gulf of Mexico if the MJO is strong enough to make a difference. At the same time, the suppressed state of the MJO will have moved into the eastern tropical pacific, with possible destructive interference with the EL Nino Base State. The result would result in less TS action for the tropical eastern pacific developing sometime during the 1st week of August. Again, this is only if the MJO remain strong enough. All systems are go for a strong El Nino event this Fall and Winter for at least the Southern half of the State. Dr Howard and the Dweebs……………………………:-)
Beautiful Eastern Sierra Weather on Tap for the next few days…..Moisture from Dolores in doubt again as she spins up…slows down and most likely will miss the window of opportunity of getting picked up by a weak west coast trough….
Wednesday July 15, 2015
Posted at 8:11 am by Howard
Beautiful weather will continue here in the high country with highs in the mid 70 and lows in the upper 40s……Moisture from Dolores in doubt again as she spins up, slows down and may miss the opportunity of being picked up by an approaching trough. Will take one last look at it tomorrow AM…
In the meantime expect fair days with the usual afternoon clouds and isolated TSRWs over eastern portions of Mono County… Highs in the mid 70s lows in the upper 40s…
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………………:-)