Upper ridge to build and progress over California Today and Tuesday…..Warmer days expected…..Midweek Storm a Fickle One…..Now includes a Subtropical Tap…..Snowfall amounts increased for Wednesday Night and Thursday AM……It looks to be a windy one as well…..
Monday February 15, 2016
Posted at 9:08 am by Howard
After a couple of mild days early this week…..The Dweebs have seen more model consensus indicating a substantial subtropical moisture tap, that increases the QPF from moderate to now possibly heavy on Mammoth Mountain Wednesday night and Thursday. Overall, snowfall amounts will be determined by how quickly the short wave moves through.
Both EC and GFS are showing a nice but brief subtropical tap of about 6 to 12 hours, that will act to prime the pump in advance of strong dynamics that will move through the Sierra Later Wednesday Night and Early Thursday AM. Additionally, this system is not likely to split. It will move right on through the Sierra with good orographic’s.
The storm will benefit the Central Sierra and Southern Sierra…Southern CA will see little if any precip. The WPC QPF is between 1.75 and 2.00 of water EQ, enough for a 8 to 15 inches of snow in town and 18 to 24 inches over the higher elevations by Friday AM. The snow level Wednesday afternoon is above 8,000 feet but will fall to 7000 by 4:00PM Wednesday and down to 5000′ by Thursday mid-morning.
For the folks that are planning on coming up to the Sierra the following weekend, it looks very breezy over the top with temperatures at 10,000 feet in the 30s. Highs over the lower slopes and in town in the 40s. Expect lots of clouds, but dry. Expect packed powder conditions as well, So if you liked the snow this past weekend, the snow conditions will be twice as good next weekend.
PS there is a smaller feature showing up Friday night into early Saturday AM that may bring a few more inches of snow to the high country toward the end of this week.
THE ENSEMBLE SHOW A FAIRLY STRONG AGREEMENT IN THE EVOLUTION OF THE DEEPENING DEEP LAYERED TROF…THAT IS SEEN WELL BY THE WARMING WITHIN THE WAVE WEST OF THE ATMOSPHERIC RIVER WEDGE BOTH WITHIN THE LARGE SCALE AS WELL AS WITH SOME OF THE SIGNIFICANT INTERNAL FEATURES. THE SHIFT NORTHWARD OF BOTH THE 12Z NAM/GFS FURTHER TIGHTENED THE AGREEMENT IN TIMING/ORIENTATION OF THE TROF AND WITH STRONG AGREEMENT WITH THE 00Z ECENS MEAN AND 06Z GEFS…CONFIDENCE IS SLIGHTLY ABOVE AVERAGE IN THIS SCENARIO GIVEN THERE IS STILL TIME FOR ADJUSTMENT OF SOME OF THE SMALL INTERNAL DIFFERENCES. THE 00Z UKMET/CMC ARE BOTH OUT OF PHASE TO NOT PREFER THEM IN THE BLEND AT THIS TIME.
Dr Howard and the Dweebs……………………:-)
Upper West Coast Ridge will weaken this weekend then redevelop off shore and build over CA early next week…..Mid Week storm looks to be a moderate one with no Subtropical Tap….
Saturday February 13, 2016
Posted at 10:26 am by Howard
Clearing skies were in process this morning and temperatures were running a few degrees cooler. North winds will be on the increase later in the weekend and into early next week as the west coast upper ridge redevelops over the far eastern pacific and builds over California Monday into Tuesday. As the Dweebs have said many times before, the Town of Mammoth is protected from moderate to strong North Winds because of the Topography. The Sierra Crest and north-south valleys are the exception where north winds can rip through Mono County south thru the Owens Valley. This looks to be a light to moderate north wind event for later Sunday and Monday. Holiday Travelers’ heading south down the Owens Valley Monday should get excellent gas mileage with tail wind gusts to 40 mph.
MJO: Although we have a moderate storm for Wednesday and Thursday, the Dweebs main attention is on the inter-seasonal outlook for the end of the month and 1st week or two of March. Some things are beginning to happen that are showing support to the MJO on the move. This morning, the Southern Oscillation Index (SOI) went negative at -14.17.
This index represents the gradient between Darwin over North Australia and Tahiti. When it is negative the winds are moving from west to east near the Equator in the southern Hemisphere.
In order for that to happen during an EL Nino you need to have convergence aloft or a general sinking motion in the Troposphere. It just so happens that the MJO as it leaves the Maritime continent north of AU, has sinking motion (Upper Convergence) in it rear. This gives notion that the MJO is progressive and now moving into phase space 6.
I expect the SOI to continue crashing over several days to come.
The border of Phase Space 7 and 8 is near the dateline and where the MJO, should it remain strong, will constructively interfere with El Nino. It will weaken as it moves towards an area south of the Hawaiian Islands in Phase 8. By the end of February, the MJO should be very near phase 7/8. This location often times forces the extension of the East Asian Upper Jet to the west coast.
Dr Howard and the Dweebs………………………….:-)
Omega Block in Place with highly Amped Upper Ridge over California…..February Thaw in Process….Mammoth Mountain Boasts 9 to 14 Foot Base!!
Monday February 8, 2016
Posted at 8:58 am by Howard
No surprises this weekend….The Dweebs are still working out the QPF for the mid-week storm….Will have a final on that most likely later Sunday AM on my “Plat Powder Email”…..when both GFS and EC come into better agreement…..
Fair partly and mild through Tuesday……highs in the 50s….Lows in the 20 to 30.
A Quick Update this AM to be followed by more detail on the Mid Week Storm for next week…..
A big question still remains on whether the Wed/Thursday storm will pick up or phase with a subtropical system that will spin up off the coast of Baja this weekend. This Subtropical system is the result of a short wave that is into the Eastern Pacific now, and is in the process of splitting with a remnant subtropical low getting left behind….. This Remnant Closed Low has the potential develop a lot of subtropical moisture via upper divergence in its NE quad, over a 5 day period. Should the incoming short wave Wednesday phase with that weak system, that would provide much extra moisture for the storm to work with, enhancing the QPF significantly….
The Dweebs will follow-up with a special update via the Platinum Powder email service for our subscribers over the holiday weekend…………….
This is a quick comment in regards to the new MJO data, comparing the GFS Ensemble to the ECMWF Ensemble.
The Screaming message here is that they have both come into much better agreement on the strength of the MJO in Phase Space 7.
This increases the odds for another AR event here in the Eastern Sierra during the last week of February and first week of March……………..
The GFS is showing a Sigma of greater than +2.5; The ECMWF has Sigma close to +2. The MJO is very favorable in producing an “AR” event on the west coast this time of the year if +2 Sigma or greater held to through Phase space 8/1 (Dateline)
Just finished listening to the Climatic Prediction Center discussion on the Tropics. It was indicated that the Western Hemispheric pattern evident this week is related to the “destructive interference with El Nino. There are several tropical modes involved in this destructive interference including Equatorial Rossby Waves in addition to the currently weak MJO. The result is a pause or weakening of the effects of El Nino and a pattern over the northern hemisphere that is atypical for this time of the year in relation to a strong warm ENSO. The thinking of the researchers is that the MJO signal will strengthen based upon the various models and do a repeat of what it did in early January where it became strong in late December in phase 7 then progressed to along the border of phase spaces 7/8 near the dateline. At that point it will “Constructively Interfere” with the ENSO signal and effectively greatly enhance El Nino. This is likely to occur between the very end of Week 2 and especially week 3. So the period beginning between the “19th through the 22th”. This is the end of week 2. Then all of week 3. ( 23rd through the 29th) The odds of an AR event will especially be enhanced during the last week of February. The early part of the first week of March look stormy as well for California. This all the while the possibility of east coast folks will be dressed in short sleeve shirts.
As another note, that does not hold much confidence for the February 18th storm making it through the Sierra…although the new Operational ECMWF this morning shows the storm as a strong one and progressive through the Sierra the 18th.
Its Ridge City over the far west. Daytime highs will remain in the low to mid 50s in Mammoth this week with some cooling and breeze going into the weekend. Night time lows will remain in the 20s.
Next chance for snowfall will be around the 18th. That system will most likely split and weaken. The Dweebs will have a better handle on it over the weekend. Hopefully we’ll get some accumulation.
Next possible Storm Cycle the last week of February into the first week of March…..The MJO is looking very strong according to NCEP’s GFS
It was truly a Super Sunday with near record highs in many areas of the state. Eastern CA will get its chance today and tomorrow with between 5 and 9 degrees of additional warming expected. The temperature forecast for Mammoth both today and Tuesday is 59 degrees with highs near 70 much of this week in Bishop and low 80s in Death Valley.
The Convective part of the MJO envelope is looking like it is leaving the Mid-Maritime Continent north of Australia. The SOI is becoming negative again and this maybe be due to the Upper Divergent area of the MJO moving out of that same area. In the front of the MJO, the Upper “Divergent” portion IE “its convective phase” is expected to continue moving east toward dateline. In the examples below, by using the MJO Phase Space, one can see that it will strengthen in Phase 6 into phase 7 in the NCEP model, however, remains relatively weak in the European. The two CFS examples hold the promise for more precipitation the end of this month. Both the ECMWF and GFS ensemble’s have been hinting of a storm “around” the “18th” of February. However, the short wave will still be coming into the mean ridge position but a weaker one at that.
CFS: 500 Mean Height Anomalies Weeks 3 and 4: http://www.cpc.ncep.noaa.gov/products/people/mchen/CFSv2FCST/weekly/images1/wk3.wk4_20160207.z500.gif
CFS: Precipitation Anomalies Weeks 3 and 4: http://www.cpc.ncep.noaa.gov/products/people/mchen/CFSv2FCST/weekly/images1/wk3.wk4_20160207.NA.gif
It is clear that GFS is much more bullish of a break through of the westerlies toward the end of the month than the European Model is at the moment. The Dweebs suspect that with as strong as the NCEP models are, currently showing this MJO in phases 6 then phase 7 at nearly a 3 sigma, the GFS will probably begin to show the late week 2 period as being very wet over California. However, without the ECMWF being in agreement at this time, one should be cautious about going to the bank on this one until there is more agreement. The NCEP models may be picking up on a tropical storm and not the true state of MJO. That would act to cloak the true picture of the late week two period.
The Dweebs will monitor the strength of the MJO and report tomorrow after the CPC briefing……
Dr Howard and the Dweebs……………………………:-)