Current Episode of Moist SE flow to begin diminishing by Friday leading to a fair warm weekend……In the meantime, High Country Showers and Thunderstorms possible, shifting a bit east Thursday…Then Dry Friday through Sunday
Tuesday July 8, 2014
Posted at 10:52 am by Howard
There has been a nice moist SE flow pattern over the Sierra the past few days…however little in the way of a trigger for heavy rain until today…Today looks to be the best day for some substantial rain over Mono County….With POPs as high as a 60% Chance!
Scattered Thunderstorms will redevelop Wednesday…..However, without as big a trigger as today. Nevertheless, storms may form again and areas of heavy rain possible tomorrow. A weak trof of low pressure will begin to back the upper flow from the SSW Friday with even more SW flow Friday night into Saturday. The weekend looks fair and warm with highs returning to the low 80s by Sunday.
Outlook for next week:
The Subtropical upper high builds back into California by Sunday and remains the dominant feature next week. A combination of light flow aloft and daytime heating will result in the typical air mass thunderstorms with forcing mainly the typical high elevated heat source of the Sierra in addition to the usual surface convergence that is moves about on a diurnal bases. At this point, I do not see another Strong SE flow set up….that is not to say that one could not develop between today’s model runs and the end of the weeks runs for next week.
The latest numbers for the Nino 3.4 and 4 region are pretty anemic. The very strong Kelvin wave that moved across the pacific has run its course. This is at least, part of the system that created the very warm SSTA’s, South East from Pt. Conception to San Diego where sea surface temps are as high as 78 degrees off the San Diego Coast and positive SSTAs are also found south along the Baja Coast.
The latest weekly Nino data shows that during the time period of June 25th through July 2nd, all Nino regions of the Nino Basin have cooled with the exception of Nino Region #3. This was a direct result of the rear upwelling phase of the Kelvin Wave. As of late, a new but weaker Kelvin Wave is beginning to increase the sub surface temps and thus making an effort to renew the heat in the NINO basin over the next few months. The Down Welling phase in its nose is warming the subsurface heat content at longitudes of 160 East to 180 West.
At this Time…it is the opinion of the Dweebs that it is highly unlikely that we will have a “Super Nino”, one which SSTA’s are at, or above +2C in the Nino 3.4 region. However, even a weak El Nino (.05C) can bring a normal amount of Precipitation to Southern CA and a winter that is 80% to 90% of normal to the Central Sierra Crest. There are a lot of Split flow systems in a Weak El Nino and so coastal areas of Central and Northern CA can get a lot of rain while interior sections can get much less.
There is no real way to predict with much certainty what the winter will be like until the Early Fall, as by then, well have a better idea on how the Nino regions are doing heat wise as well as the other teleconnections that will be effecting the weather for the upcoming winter. One thing is known at this time….The PDO is positive and the QBO is negative which argues for another cold winter east of the Divide. The big question will be…Will the stronger than normal subtropical upper jet be strong enough to flush out the cold air from the Hudson Bay > east out over the Atlantic next winter…..
Dr Howard and the Dweebs…………………………….:-)
Dry SW Flow to Continue Thuough July Fourth With Moderate Zephyr Winds…..South-East Flow Develops later in the weekend as the AZ Monsoon Rapidly Shifts into High Gear Next Week……….
Thursday July 3, 2014
Posted at 9:06 am by Howard
Scattered Thunderstorms the next few days then drier/warmer over the weekend…………………………
Sunday AM Update:
Our first shot of Monsoon Moisture arrived late yesterday afternoon as evidenced by Altocumulus advecting from the SE over the Sierra. Dew Points are up into the mid 30s now, and with strong daytime heating, extra lift and higher heights, isolated TSRWs will break out from our first SE flow episode of the Summer. Our local air mass will continue to modify this week with the aerial coverage of thunderstorms increasing and high temperatures falling off by Tuesday from the 80s to the 70s. Both today Sunday and tomorrow Monday may be the warmest days this week, as more and more moisture increases within our air mass, and it clouds up earlier.
Guidance from earlier this morning showed a vort max over Southern Inyo County moving NW. This will have the effect of enhancing instability this afternoon and rainfall chances. With the orientation of the upper high over the Utah the next few days….more instability will enhance rainfall chances over time. Thunderstorms will grow wetter with the possibility of areas of heavy rains and flash flooding. Although the Dweebs will follow the developing situation closely, stay tuned to the National Weather Service for advisories as that will effect your outdoor activities this coming week. We could have “some” very active weather days this coming week……
Dr Howard and the Dweebs………………………….:-)
Here is your July 5th afternoon update for you Weather Dweebs…………………….
First of all……Near record crowds here in Mammoth this weekend. I though that I would sneak into Vons to shop during the Crowley Lake fireworks show and it would be slow. Not a chance…the line was backed up into the Produce Dept at 10:30PM.
Kudos To Larry Johnson for another very creative Float during the Parade Friday. It was a page out of Jurassic Park with a seeming live Velociraptor chasing down Old Mammoth Road, I guess looking for something to eat. T-Rex was in front of him and A brontosaurus was ahead as well. The neck of Bronto- looked like is was possibly some 30 to 50 feet in length! Otherwise the weather was perfect! Upper 70s…..and a nice zephyr breeze in the afternoon.
Over the next two weeks were going to remain quite toasty with a strong Subtropical Continental Upper High over the Four Corners states. From time to time, a weak trof will flush the Mammoth Pass with drier air. However, today’s guidance showed monsoon moisture pulsing back and thus winning the weak trofing fight for the Sunday through Tuesday Period.
The weak trof that has kept us dry the past few days is now lifting out and a pulse of Monsoon moisture will move back into the area Sunday with more afternoon clouds and a slight chance of some thunder. An increase in dynamics and surface convergence will occur early next week with the best chance for some rain about Tuesday. Thereafter……Another weak trof is expected to bring more of a zephyr Wednesday and Thursday with less of a thunderstorm threat, before the next surge of moistures moves in Friday into that following weekend.
Interesting enough is that as of this morning….NCEP’s Climate Forecast System Version 2 (CFSv2) is calling for precipitation to be +200% of normal for the Mammoth Area for the month of July. That means that we should get some meaning thunderstorms and rain this Month. As a comparison, August precip is expected to be near normal.
Here is your updated Temperature and *POP forecast for Mammoth Lakes beginning Tomorrow Sunday:
(POP)= Percentage of measure precipitation of at least .01 of More.
As you can see Tuesday has POPs of 30%
PTCLDY PTCLDY TSTRMS PTCLDY MOCLDY MOCLDY PTCLDY
56/80 55/84 57/80 57/78 54/77 54/76 51/75
10/20 20/20 20/30 30/20 20/20 20/20 20/20
Weak troughing along the California Coast will provide for moderate zephyr winds and slightly cooler temps the next few days…Daytime highs will cool to normal (78) today Wednesday and remain through Saturday July 5th. However, the AZ monsoon will develop rapidly in that region as the continental high builds west and the upper trof currently off shore is forced north. the Global Forecast System (GFS) shows a Southeast mid and upper level flow developing. 1st over extreme southeast CA Friday, then reaching into Southern Mono County by Sunday. Thus the gates to dynamics and mid and upper level moisture will begin to increase by Late Saturday or Sunday.
Initially, TSRWs will be isolated Sunday. However, as time goes by, our air mass will become more saturated next week as the convective process builds. This will have the effect of adding moisture within the system from the top down over time. The effects of the monsoon process, IE South East Flow should not be focused so much on Moisture Advection….but rather, an increase of Dynamics as small scale features within the upper SE flow create opportunities for enhanced instability. Sure there is moisture advection, however, moisture advection at 700MB without a lifting mechanism is like gasoline without a spark.
Initially, storms will form and be focused within areas of surface convergence. Meaning they will be high based with small areal coverage. As time goes on, our air mass will juice up from within the localized system/process. Eventually a combination of moisture advection and possibly deeper moisture will arrive, and if a significant trigger (Easterly Wave or Vort Center) moves up from the South or South East; heavier rains “may” occur next week.
I guess you can say that with the advent of the AZ monsoon…the transition to a full on July Summer Pattern is complete.
Dry through Saturday in Mammoth with afternoon buildups Saturday. Highs in the upper 70s today through Saturday with lows in the upper 40s….rising to the 50s by Sunday and well into the 50s next week. High temps next week will probably begin in the low 80s then cool due to the convective process into the 70s. Isolated “dry thunderstorms” or storms with narrow rain shafts are expected Sunday with the areal coverage increasing next week with the possibility of wet storms as well. The climatology is good next week for storms with wetting rains…… both 6 to 10 day and 8 to 14 day precip outlook has somewhat enhanced precipitation possibilities for the sierra through mid July.
Have a Save and Sane Holiday Weekend and Remember…..The discharging of Personal Fireworks in Mono County is illegal and especially dangerous this Summer! We have extreme fire conditions here. Mono County will have a great Fireworks display put on by professionals at Crowley Lake, Friday Night at 9:00PM…..As well as at the Village at Mammoth over the Holiday Weekend.
Dr Howard and the Dweebs………………………………..:-)
Overall….A Very Warm Week Ahead Can be Expected for the Mammoth Area with Today being the Best Day for Thunderstorms…It will be a Slight Bit Cooler Wednesday into Friday with Thunder to make a return next week…….
Tuesday July 1, 2014
Posted at 9:08 am by Howard
With the evolving ENSO state…the Dweebs read the latest discussion from the CPC in regards to weeks 1 and 2. Based upon the current Wheeler Hedon MJO chart, week 2 shows an emergence of amplitude in the Maritime Continent region suggestive of a weak negative height anomaly over the Pacific Northwest and weak trofing off the CA Coast. While the GFS week two 500mb heights in the mean hints of this. From the Sierra east, through the great basin shows nothing but above normal temps. In fact the ECMWF 500mb heights has the continental subtropical high parked more over the Far west with scorching heat for CA with an easterly wave in its underbelly headed for the west coast of Baja later “Week 2″. From an El Nino-ENSO summer stand point of view, to date, the Dweebs do not see the typical signs anymore of the expected air sea coupling that would promote the cool periods associated with west coast trofing and a displaced eastward, Continental upper high. So the stage is set for both a very hot summer out west, waiting for the other shoe to drop for an enhanced shot of Monsoon moisture and dynamics later next week.
ENSO: While Nino regions 1 and 2 show strong positive anomalous SSTA’s, as well as subsurface temps, the Central Pacific is stuck with SSTA’s of only + .05C, barely the threshold of EL Nino. Earlier in the year….A strong Kelvin Wave moved east across the equatorial pacific last winter-Spring, providing warmth to the Nino Basin, its upwelling rear has cooled the subsurface ocean temps in the central pacific region, putting the kibosh on any further warming. “If” another strong Kelvin Wave does not replenish the subsurface heat within the Nino Basin between now and the Fall, you can most likely kiss the wet effects of EL Nino for interior, central and northern CA. However, Southern CA may still be wet….. The El Nino would thus be a Modoki type ending up with weakly warm SSTA’s in the central pacific and a cooling eastern tropical pacific. That kind of winter is known for west coast “Split-flow” patterns.
There is still time for another Strong Kelvin wave to come east…lets keep our fingers crossed!…..
Tuesday PM Update:
Mono Zephyr began earlier then expected today with best Mono County surface convergence well east of Highway 395. Mammoth will now enjoy more afternoon breezes along with slightly cooler daytime highs. A drier air mass in now in place as well. Very pleasant weather will continue with daytime highs in the low 80s cooling to the upper 70s by July 4th. The heat is on again by the end of holiday weekend along with a threat of thunderstorms as early as Sunday….. More later as SE flow lurking next week….
July 1st Climo wise, begins a period that is considered the warmest two weeks of the year in Mammoth…..especially up until the 11th. This is because south to south east flow usually has not yet established itself in this region. SE flow contains the ingredients for a greater thunderstorm potential. So unlike like today’s Thunderstorms that are expected, which are high based and are more the result of strong heating of the elevated heat source of the sierra and the shifting area of surface convergence. Next weeks storms will likely be more associated with the far western flank of the AZ monsoon.
Climo wise, as the continental subtropical high sets up in the Four corners area, odds will increase for the return of South East flow, as we move in time from the 1st week of July to the 2nd. week. By the end of the 2nd week of July, the western edge of the AZ monsoon should be into full swing bringing both mid level moisture advection as well as the more significant spokes of dynamics. The heat generated early in the month of July will often times help set the stage for when the south east flow returns for greater instability. Especially when thermal trof is anchored just to the West of the Sierra Crest. So in conclusion…..watch out for next week thunderstorm wise…..
Current forecast discussion:
Today Upper Air analysis showed the upper highs axis over Eastern CA. The upper high has peaked in building….a weak trof is approaching the pacific NW. A small Vt Center has developed on the Northern CA coast between the approaching trof and the upper high over head. Although this small feature will not directly effect us, there will be some slight cooling in the upper levels enough to increase laps rates today with increasing instability. So today is that transition day that thunderstorms will form with lighting and some rain as the lid comes off our local air mass. Tomorrow will be a slightly cooler, more stable day air-mass wise, with an increasing afternoon and early evening zephyr into the days ahead.
Expect about 5 to 7 degrees of cooling over the next 4 days. A new warm up will begin next Sunday in the high country with the possibility of southeast flow beginning as early next week…..
Dr Howard and the Dweebs……………………..:-)