High Clouds Flowing Northeastward from TS east of Hawaii has shifted south this morning….That band will lift north back into Mono County later today…….Showers likely late Thursday Night into Friday followed by Fair weekend…….Perseid Meteors are on the way….El Nino Comments!!!!

It been a very unusually wet Summer here in the eastern central sierra. Isopleths suggest that precipitation is running about 250% of normal for Mammoth June through July.  The current pattern continues to favor more mid latitude trofing over the far eastern pacific causing temps to remain a bit cooler then normal for this time of the year.  This Friday, high temps will be between at 10 to 15 degrees below normal.

Anomalous upper trofing will prevail off the west coast the next 5 days.  The short wave trof responsible for suppressing the high cloud spin off from TC “G” has passed to the NE, and so that high cloud band will likely lift back into Mono County later today and tonight.  More importantly…..the next short wave out some 1000 mi WSW of Mammoth will approach the Monterey Bay by 12Z Friday AM.  The Wednesday 12Z NAM this morning shows 250mb Upper Divergence increasing over the Eastern Sierra Later Thursday night and on into Friday. Surface CAPE will increase as well Friday. Plenty of 700RH along with surface Dew Points over the region well into the 40s suggest showers and thunderstorms. Precipitation amounts will not be major.

A 500MB Vt max is noted crossing the Sierra late Friday morning as well. Again….Showers and or thunderstorms may develop anytime between Thursday night and especially through Friday AM and PM. 15Z 500/1000 thickness of 570dm suggest that precipitation may be in the form of some light snowfall above 11,500 to 12,000 feet Friday…..so there may be another dusting or an inch like what we had on the 9th of July.  This is not a major storm…but it will feel fall-like Friday with lots of showers and possible thunder with up to 1/2 inch of QPF.

The weekend outlook is better. It will be clear Saturday and Sunday with high temps returning to the low to mid 70s.  However, Saturday pre dawn lows may be well down into the 30s is some areas.

Next Week:

A tug of war between the west coast long wave trof and a continental upper high will fight it out next week.  Most likely given the time of year, the upper high will win out with temps returning to at least normal or above by Mid Week next week.  However, it is less likely that the Summer Monsoon well return through at least the middle of next week because of SSW flow aloft.  I expect a very significant change in the pattern, between by week 2 into week 3.

 

Perseid Meteor Shower:

In the Northern Hemisphere, the annual August Perseid meteor shower probably ranks as the all-time favorite meteor shower of the year. This major shower takes place during the lazy, hazy days of summer, when many families are on vacation. And what could be more luxurious than taking a siesta in the heat of the day and watching this summertime classic in the relative coolness of night? No matter where you live worldwide, the 2015 Perseid meteor shower will probably be fine on the mornings of August 11, 12, 13 and 14, with the nod going to August 13. On a dark, moonless night, you can often see 50 or more meteors per hour from northerly latitudes, and from southerly latitudes in the Southern Hemisphere, perhaps about one-third that many meteors. Fortunately, in 2015, the waning crescent moon comes up shortly before sunrise, so you’re guaranteed of dark skies for this year’s Perseid meteor shower. Thus, on the Perseids’ peak mornings, moonlight will not obscure this year’s Perseid meteors.

 

El Nino:

Even though the CFS v2 has pulled back a bit from its highs a week or so ago…who cares?   Do really want an El Nino 3.4 event of +3C anyway?  Super Nino Criteria is anything above +2C in the Nino 3.4 region for a few months.   California does not need the kind of Carnage  that an event of +3c for a few month would bring…….  It has endured enough…..So get a grip!

The two Strongest  El Ninos on record were 1982/83 and 1997/98  Neither one reached over 3C in the Nino 3.4 region over a month’s average….  I think 2.7C/2.8C was the highest anomaly for a weeks period.

Contrary to some “Dweeb Wantabes”…. We are still on track up through end of July 2015 close to 1997 in some ways:

Check out Bob Tisdale’s SSTA evolution below by clicking on the link. You only need to look at the Nino 3.4 graph to see how this El Nino is progressing

https://bobtisdale.files.wordpress.com/2015/08/nino-region-ssta-evolutions.png

 

MEI UPDATE:
NOAA ESRL MEI founder Klaus Wolter explains ,While the updated (June-July) MEI has dropped slightly (by 0.09 standard deviations in one month) to +1.97, it is now reaching the 2nd highest ranking, surpassed only by 1997 at this time of year. The MEI has hovered around +2 standard deviations for two months running, highest overall since early 1998.

 

Dr Howard and the Dweebs……………………..:-)

 

With a Persistent Upper Trof along the West Coast….Expect a dry week ahead with a Stronger Zephyr at times…..Rain out of the forecast for Mammoth through Thursday……

An upper trof will remain anchored along the west coast this week with a dry SW flow aloft.  For the most part this will be a rainless week with only a slight chance Friday and night….High Temps will average near normal for August with highs in the mid to upper 70s then cool to the lower 70s by next weekend….Expect Nighttime lows mostly in the 40s this week.  Afternoon and evening Zephyr winds will blow up to 30 MPH this week.

 

Dr Howard and the Dweebs……………………….:-)

 

El Nino:

Some folks have expressed concern about the CFS V2 with a drop in the index as of Late.  Have no fear of that.  The reservoir of anomalous warmth under the ocean and  equator over the eastern tropical pacific normally goes through a process of weakening and strengthening over time.  We had a weakening of the index back in early July and then a strengthening later in the month. The same process is going on now.  Looking at the wave structure, the index will reflect strengthening a bit later this month.  A lot of down welling has again occurred in the more west portion of the thermocline and that will ripple east and will eventually recharge the Nino Basin.   Looking at the SOI this morning it is a very strong -38. So “La Machine” is working well!  And…..The Walker Pump is quite weak…  I will graphically point this out soon…

 

Here are the animated graphics for the Kelvin Waves and the Thermocline:  http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/wkxzteq.shtml

1. Note how the warm undersea KV wave shrinks up and expands; IE weakens and strengthens.

2. Note the 28C (upper isotherm) in Thermocline in the lower graphic. Looking at the animated graphic, you can clearly see the west moving waves rippling through by following the rise and fall of 28C isotherm.   At the moment, it appears that there is another surge of warmth moving westward, recharging the Nino basin.  This additional warmth will be reflected in the CFSv2 eventually….  PS, the SOI was a -38 yesterday, an indication of the gradient west to east (Very Strong) keeping the surface movement of water, west to east along the equator….

 

Additionally…A Hovmuller time section of upper ocean heat content along the EQ at 300M in (C)

http://www.cpc.ncep.noaa.gov/products/intraseasonal/heat_tlon.shtml    Best to use Google Chrome as browser I have found…

 

Monday Night Extended Update:

The Dweebs looked at both the ECMWF and GFS Ensemble Control this evening.  The weather will remain breezy on and off this week and into at least next Monday. There is now some concern for the closed low coming into CA this Friday as the new 00Z run of the Hi Res GFS T1534 is showing the upper low coming ashore near Monterey Bay this Friday. A shift south of some 30 or 40 miles would make a big difference as far as precipitation over Mammoth Lakes.   More concerning is that the trend which is usually my friend in forecasting, is further south. So there is at least a chance now for some showers and isolated thunderstorms Friday the 7th. More later…..

Next week: The GFS, ESM Control moves the upper long wave Trof out Tuesday the 11th and retrogrades the continental high back over the Desert SW, for a return of the Monsoon. The ECMWF delays the warming until 13th; (The next Thursday) and then also retrogrades the Continental upper High but sets it up further south over AZ and NW.  This give us a warm up without the Monsoon as the upper flow remains SW and dry.

What does this mean? It means that we’ll likely warm up for by the 12th or 13th.  The issue of Thunderstorms is still a question.  After looking at the actual Ensembles of both global models, my personal take on it is based somewhat upon the Summer so far. So the likelihood of more thunder and rain showers is the best way to call it from this point in time, the 2nd half of next week.   Additionally, the upper flow looks more southerly instead of southeasterly, so the pattern may not be as robust for thunderstorms unlike the last two monsoon outbreaks.  Updates on all of this later this week…………

 

 

 

 

 

Two Short/Easterly Waves on the move from the south to influence weather over Mono County this weekend…

Moisture, mainly high level is increasing from the southeast where PWAT values are close to 2.00 in some areas. Over Southern Mono County at the moment PWAT is running about .7 so it has a long way to go before we get into the Soup….    Two short waves rotating around the Continental high will provide the extra lift for not only the possibility of daytime precipitation and thunderstorms but nocturnal precip as well.   The lower levels are still pretty dry this afternoon.  So the air mass is still in the moistening phase from the bottom up….then later tomorrow,  from the top down…  By Saturday, it will be pretty juicy out there. However, any heavy rain during the day will still be dependent upon how much sun we get early in the day.  The first short wave is headed up tonight…there will be another wave coming through tomorrow night into early Saturday AM.. If these waves were timed in the afternoon, Heavy rain would be almost guaranteed….  But that is not the case.

 

If you are a camper,  be prepared for some rain late tonight and a better chance again later Saturday night.

During the day, the sun will be the driver along with CAPE*

 

The Dweeber………………………:-)

 

Toms Corner:

*CAPE is Convective Available Potential Energy  and can be found on a Skew -T  diagram by lifting a parcel from its initial surface temperature and dew point to either the CCL (convective condensation level)  by heating or to the LCL (lifted condensation level) by mechanical lift (ie frontal or kinematic forcing). If the parcel continues to ascend at the wet adiabatic rate it will reach the LFC (level of free convection)  where the parcel is warmer than its environment and become positively buoyant such as a hot air  balloon. The difference in temperature at 500 MB or roughly 18000 feet between an ascending saturated parcel and its environment is the LI (lifted index). the LI is negative for positively buoyant parcels.  The CAPE is the total amount of buoyant energy in joules/KG calculated above the LFC to the tropopause or the integrated area between the moist adiabatic trajectory of the ascending parcel and environmental sounding. CAPE is directly related to updraft velocity and correlated to hail size and other severe thunderstorm characteristics. A weak high based thunderstorm will have CAPE values between 50 and 500 joules/kg while severe thunderstorms that produce large hail and tornadoes can have CAPES in the 3000-5000 joules/kg range.  A thunderstorm in a high CAPE environment with strong updrafts can survive in the  stronger wind shear needed to create a mesocyclone or tornado.  CAPE is strongest is areas of steep lapse rates and abundant low to mid level moisture.  Any process that increases lapse rates such at strong surface heating in the summer or cooling aloft by vertical motion will increase CAPE. Likewise any process that increases low and mid level moisture from the ground up primarily through vertical motion or from the cloud base down as a shower or outflow boundary will feed back into increasing CAPE values. CAPE is like gasoline for convection and without it, deep convection will not exist. To ignite the CAPE, some sort of trigger or lifting is needed for the parcel to reach the LFC . This trigger can be any type of low level convergence usually coupled with an area of upper level divergence.