Dry weather expected again Today and Saturday with moisture on the increase Sunday into Monday. Some stronger breezes Sunday PM and Monday…..The chance of measurable precipitation increases to 30% by Sunday into Monday……Drier air will move back into our area by Mid week with just a Slight Chance of TSRWs….

Saturday Evening Update:

 

PM 10 Count hit 175 PPM at 6:00pm Saturday. (Unhealthy) Make sure you keep windows closed and keep indoors.

Latest on Rim Fire:

Rim Fire Fact Sheet

31 August 2013

Day 15

Acreage: 219,277

Largest fire in the United States to date in 2013·

No. 1-ranked on national firefighting priority list

Fifth largest fire in California history

·Second largest to date in 2013: Lime Hills Fire, Alaska 201,809 acres

Personnel currently on incident:4,995

States that have sent firefighters or other personnel: 41 and the District of Columbia

Cal Fire geographical units that have sent personnel: 20 of 21

Uncontrolled fire edge: 107.4 miles

Completed containment line: 66.1 miles

Completed dozer line: 139.9 miles Proposed dozer line: 30.3 miles

Completed hand line: 5 miles Road as completed line: 16.3 miles.

Acreage in Stanislas National Forest: 156,185

Proportion of the fire burning within Stanislaus National Forest: 71.2 percent

Acreage in Yosemite National Park: 60,185

Proportion of the fire burning in Yosemite National Park: 27.5 percent

Acreage of state and private property: 2,907

Proportion of the fire burning on state and private property: 1.3 percent

Proportion of the Stanislaus National Forest within the fire perimeter: 17.4 percent

Proportion of Yosemite National Park within the fire perimeter: 7.9 percent

Size of the fire area:

Larger than the land area of San Francisco, Oakland and San Jose combined

Pounds of firefighter laundry washed:

10,534

Burned or damaged trees adjacent to power lines removed by Pacific Gas and Electric:

4,929

 

Quick Saturday AM Update

A wind shift from the west has brought the southern boundary of smoke from the Rim Fire into the Mammoth area over night.  Visibilities were about 7 miles this morning. The PM 10 count jumped from 20 parts per million yesterday to briefly 120 parts per million about 1:00am this morning.  By 7:00am this morning the PM 10 count was back down to 60 PPM. Westerly flow is expected to continue today and possibly into Sunday and thus so will the smoke. However. the upper flow is expected to back more to the south Sunday and thus push the smoke boundary back to our north as the day progresses.  Labor Day looks clear of smoke. Lets hope that varifys….

Dew points are very high in Southern Ca as deep tropical moisture lay to our south. The southerly flow is expected to pick up that moisture for an increasing chance of thunderstorms Sunday into Monday. Temperatures will be dependent upon cloud cover. Expect high 70s today low 70s Sunday and Monday. lows at night in the low 50s.

Fair, dry warmer weather is expected to develop by Wednesday or Thursday.

 

More later…………………………………>>>>>>

 

The Dweeber……………………:-)

Friday AM Update: 

RIME FIRE:

Acres Burned: 201,894 (315 square miles)
Structures Threatened: 4,500
Containment: 32%
Residences Destroyed: 11
Fire Start Date: August 17, 2013
Commercial Property Destroyed: 3
Fire Cause: Under Investigation
Outbuildings Destroyed: 97
Cost to date: $47 million
Injuries: 4
Total Personnel: 4,931

Weather Discussion and Summery:   Temps in the mid to upper 70s this weekend for Mammoth with Lows in the upper 40s and low 50s.

Over the next couple of days high pressure aloft will sit over the plains states while Trofing persists off the pacific northwest coast. Thus the upper flow will continue to be channeled from the southwest (Dry). This persistent pattern should continue another day or two before the upper flow back a bit toward the south and an upper jet approaches.  The pattern is dry here in Mammoth with Southwest winds continuing to carry dense smoke up into the northern portions of Mono County. Areas like Coleville will continue to be especially effected both day and night. Winds will be lighter today and so the smoke will be even more of a problem today and tonight up to the north of us.

By this weekend, the upper low in the pacific northwest will progress toward the northwest coast Sunday. This will bring an increase of zephyr winds Sunday and Monday to our area with gusts to 30 MPH possible. In addition….Amplification will allow monsoon moisture to spread north as well. Then there is that Rt Rear Entry region of the upper beginning to impact the 1/2 Northern CA Late Sunday and especially Monday.  The chance of thunderstorm’s will increase Sunday PM and Monday. Hopefully they will be wet rather then just high based with just mainly lighting….

By the middle of next week the GFS shows enough WSW flow behind the upper Trof to bring enough dry air into our region to take out any threat of thunderstorms. It continues to be the most progressive. The ECMWF weakens it and still leaves enough subtropical moisture over the central and southern sierra Mid Week. Taking the middle road…the Dweebs are calling for a slight chance of thunderstorm’s Wednesday and Thursday here in the Mammoth Area.

There will be a WX Update for Mono County Sunday morning….

Mid Level Southerly Flow Allowing Smoke to continue moving NNE away from Southern Mono County….Some increase in Moisture today may kick off a few convective TSRWs today and Wednesday but no real forcing in the mix…..Holiday Weekend will be nice first half then Breezy Sunday into Monday….

Thursday AM Update in Rim Fire:

Current Situation

Total Personnel 4,840
Size 192,737 acres
Percent Contained 30%
Estimated Containment Date Friday September 20th, 2013 approx. 12:00 AM

 

 

Tuesday: 

Rim Fire is 20% contained….179,481 acres burned as of this morning…..Future fire growth potential is extreme.

A slight westward expansion of the continental upper high has spread some warmth in the mid levels and has created stronger inversions for the next couple of days.  This means that areas down stream from the fire will have more concentrated smoke. Areas like northern Mono County and especially Coleville and Topaz are under a dense smoke advisory.  It’s probably a good idea for elderly folks with respiratory issues to find some cleaner air else ware.  Southern Mono County Air in areas like Mammoth and June Lake is pretty clean these days. 

Monsoon Moisture:

Upper flow at 500mb is SW, However upper flow at 700MB is South…thus mid-level moisture is allowed to move north today and bring a slight chance (20%) of TSRWs to the Mono County area. Deeper moisture is to the east of us and areas like the Owens Valley and south will have a greater chance of rainfall (50%).  The outlook is for little change in the pattern until the weekend when a storm pushes east through the pacific NW increasing the winds from the West. That system is Fall like with a 558 thickness pool. No doubt that some snows will fall in the Washington Cascades. As far as Mammoth goes, there will be an increase of wind Sunday PM from the west then a dry front following with NW flow behind it. This may for the “first time” any significant RIM Fire smoke or haze gets into the Mammoth or June Lakes area later Sunday PM and or Monday behind the front.

Longer Range Stuff:

 

CFS still suggests main High Latitude blocking over Western Canada and AK, with Hudson Bay Low east of its normal position. This would make sense in the westerly phase of the QBO. An undercutting jet into west coast during the colder half of the year and less blocking in the east may be the trick, thereby allowing the cold up in eastern Canada to keep flushing out off the Atlantic, western phase QBO style. This is should result in a more progressive pattern for the far west.  There is a bias toward the Pacific NW being a bit drier then usual, an indication of possibly the warmer phase of ENSO later in the winter? This would add up to a much wetter winter for California. The cold the Almanac is touting is not over the far west. However, some of that may back up over the west from time to time early in the Winter or late fall if correct.

 

The Dweeber………………………………………………..

Mammoth Clear and Virtually Smokless…..Upper Trough off Shore will give way to a little southerly flow increasing a chance of some Showers or Thunder for Tomarrow…..Very active pattern continues over Southern California Deserts as remains of TS Ivo interact with Rt Rear Entry of Upper Jet……

Quick Update Tuesday: 

Rim Fire is 20% contained….179,481 acres burned as of this morning…..Future fire growth potential is extreme.

A slight westward expansion of the continental upper high has spread some warmth in the mid levels and has created stronger inversions for the next couple of days.  This means that areas down stream from the fire will have more concentrated smoke. Areas like northern Mono County and especially Coleville and Topaz are under a dense smoke advisory.  It’s probably a good idea for elderly folks with respiratory issues to find some cleaner air else ware.  Southern Mono County Air in areas like Mammoth and June Lake is pretty clean these days. 

Monsoon Moisture:

Upper flow at 500mb is SW, However upper flow at 700MB is South…thus mid-level moisture is allowed to move north today and bring a slight chance (20%) of TSRWs to the Mono County area. Deeper moisture is to the east of us and areas like the Owens Valley and south will have a greater chance of rainfall (50%).  The outlook is for little change in the pattern until the weekend when a storm pushes east through the pacific NW increasing the winds from the West. That system is Fall like with a 558 thickness pool. No doubt that some snows will fall in the Washington Cascades. As far as Mammoth goes, there will be an increase of wind Sunday PM from the west then a dry front following with NW flow behind it. This may for the “first time” any significant RIM Fire smoke or haze gets into the Mammoth or June Lakes area later Sunday PM and or Monday behind the front.

 

The Dweeber………………………………………………..

 

 

 

 

As of Monday AM (Rim Fire) near Yosemite is now 15% contained…

Mammoth has been fortunate this go around to be north of fires burning to our south and well south of fires burning to our north. This is in contrast to late July when the Aspen Fire was active.

Again…..The Weather is beautiful in Mammoth unaffected by the Smoke from the Yosemite fire (Rim fire)

 

Now for the interesting stuff….

Large scale pattern highlighted by strong subtropical continental ridge over the nations mid section and late Summer Trof off the coast of the Pacific NW extending south down the west coast. The upper jet in the bottom of the Trof is enhancing precipitation by Divergence Aloft and surface convergence….interacting with remnants from TS Ivo over Southern Ca. Mts and Deserts dynamic lift along with deep subtropical moisture will create very heavy rain and flash flooding in the southern deserts today.   As the upper flow backs a bit more southerly Tuesday, some of the moisture may work further north into the Mojave desert and even parts of Kern County Mts and act upon the upper just that will by then come in a bit further north.   As far as Mammoth goes there is a chance of Thunderstorms Tuesday and evening from a brief surge of moisture. By Thursday the new 12z gfs guidance back the upper flow more to the WSW so if that verifies…..well go dry again…..Thursday into the weekend.

More later in that…

 

The Dweeber………………………:-)

 

Below is a fabulous analogy from Retired WSFO-RNO forecaster Tom Cylke, all you Weather Dweebs out there with more than a basic understanding of summertime convection. Tom has in the past written and published several abstracts on Summertime thunderstorm patterns that are regional to Eastern CA as well as areas of the Desert Southwest including the effect of outflow winds in the Las Vegas Valley. 

 

Below is a current discussion during the current real time pattern as well as well as a pressure cooker analogy that works great any ware in the Eastern Sierra or Great basin and or Desert Southwest during the Summertime.

 

Current heavy pcpn pattern over Srn Ca being dynamically supported by strong upper divergence and low level convergence coupling in RRQ of 70 kt SWly  jet across central Nevada (see latest SPC analysis of these fields). These jet patterns will typically form this time of year when thermal gradients (frontogenetic zones) tighten between the desert SW (4 corners high) and colder troughs moving into Pacific NW. You will also see a spin up of upper level winds at jet level in the north quads of tropical storms and hurricanes as they move north into northern latitudes. Deformation zones are in fact frontogenetic zones where the wind field converges the isotherms or thickness lines closer together resulting in a stronger jet aloft and stronger upper divergence values.  

The high PW values currently over the desert SW are being supported by this UVV from the strong coupling of Upper Div and low Conv.

Here is a good analogy for convection. A pot of boiling water.  The bottom of the pot is UVV, the sides are convergence, the water is PW, the steam is convection, the temperature of the water is instability( hotter is more unstable),  the boiling point is zero lifted index or positive CAPE values where free convection occurs. the sun is the flames of the stove. putting a lid on the pot suppresses the convection or steam by increasing pressure above surface of water (subsidence) but still allows temperatures, theta-e and CAPE values to increase until the lid is removed by divergence and subsequent cooling aloft allowing for explosively deep convection to occur. Remember with out the UVV or bottom of pot and low level convergence or sides of pot the water (PW) will quickly diminish.

 

Would be great to see the RRQ of a jet develop over the Yosemite fire. Keep looking at the SPC analysis to see the obvious correlations between Upper Div, Zero LI/pos CAPE, low level convergence and thunderstorms. Look at PW, K index greater than 30, theta e ridges to delineate higher base thunderstorms from the heavier flash flood producing variety.  Look at high CAPE and wind shear (ri number) to delineate Severe thunderstorms from other type of convection. High values of CAPE and helicity (low level cyclonic wind shear) will correlate to Tornadic thunderstorms. 

Tom