Archive for February, 2012

Split System To Combine Offshore To Give The Southern Portion Of California A Nice Shot of Precip…..Better Consolidated Upper Jet Mid-Week………

 

Sunday AM:

The stronger of the two Vort centers was located at 40N-131West moving SSE. The 2nd Vt center near Seattle….due to upstream amplification will dive south over the next 12 hours and aid to spin up the upper low. Main point is that both PVA/UVM remains well west of the Eastern Sierra. With RT/Rear entry region favoring southern coastal sections and the Mts of Southern Ca, north to Kern Co. Strongest 500/700mb upper flow is over Southern Ca.  Over all the system is not all that moist and outside of the Convective parameters being up a bit as the sun is higher in the sky now, The high country of Southern Mono county will probably not get much more then 2 to 5 inches including the crest.  (1 to 3) in town.  The Southern Sierra will do a little better with the Northern Sierra pretty much skunked. (A trace to an inch or 2 up there). The system is pretty cold though. Snow levels will lower to 3000 feet to our south. Bishop could see some snow showers….

The next upstream system for Wednesday is stronger.  The upper jet is more consolidated.

The Sunday 12z GFS has the nose of 120knott upper jet coming into just north of the Bay Area Tuesday night into Wednesday AM. This definitely favors the Northern Sierra. They will easily see 12 inches plus…especially for the resorts NW of Tahoe along Highway 80…Alpine Meadows and Squaw Valley, as there is more moisture with this system because of the better defined upper jet. However, with this said…..the system also moves pretty quickly east as well.  The upper jets Front/Left exit region is still to the north of Mammoth as the Trof swings through Ca. The storm looks windy and so March will roar in like a Lion….. Best guess for Mammoth at the moment…..3 to 6 inches depending upon where exactly the upper jet comes in. (Will take another look at it Monday AM)

With short wave ridging building in Thursday the weather will be fair Thursday and Friday with the following bringing more precip to the north over the pacific northwest.

Update Monday

 

Dr Howard And the Dweebs……………………………………..:-)

 

Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

NW Slider Moving To the East Now As Cold Front Slowly Shifts out of Southern Mono County…..MJO Stuck in Early Phase 2 is Not Good News……..

The Northwest slider that has brought cooling and moderate wind to the Mono region has shifted more to the east. Winds as a result have not been as strong as the main gradient has shifted more to the east then south as well. Temps today will reach the low to mid 40s while nighttime lows will be in the teens….  Winds will diminish this afternoon….

The next upstream system is coming in further south as its energy is a bit split off from the main belt of westerlies. This small system moves in Monday and brings us a little snowfall of a few inches (1-4), as it does have some over water trajectory. It is associated with two vort centers and will move out quick Monday night. At the moment, the Dweebs are not buying into the hype. And although the EC is wetter….CRFC and HPC only have a few tenths of an inch. CRFC puts most of the precip down into the MTs of San Diego. The problem with the Central Sierra is that the best Jet dynamics and forcing is to our south.  Will take another look at it tomorrow.

The following system for the 29th is definitely stronger.  However, the upper jet does not makes its way far enough south to give the Central Sierra a good shot of snow. Neither the front left exit region, nor the rear right entrance region effects Southern Mono County.

Tahoe will definitely do a better than Southern Mono County as it is swiped by the RT rear entrance of the upper jet. Now with this said..we will still gets some light snowfall.  1 to 6 inches…will update later next week……

 

MJO-PNA

The main concerns now is where the PNA Teleconnection is headed and why the models have been backing off…both on retrogression and amplification to a much larger extent.  The Dweebs feel that the problem has been with the MJO.  It has been stalled a lot longer in its present position of early Phase Space 2. Currently it is still pretty weak with most of the convection south of the equator….and not in the right location for a strong flip in the PNA to negative as has been forecasted by both the air-sea coupled models nor the Global models.  The convective portion of MJO is currently located 65E-70E. The PNA index is pretty much neutral today.

See: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna_index.html

CORRELATION OF MJO TO THE PNA

NEGATIVE PNA

20E      70E        80E      100E

.05      .135       .125       .125

POSITIVE PNA

140E    160E   120W

-0.05   -0.1    -0.14

According to the forecasts, the negative phase of the PNA should strengthen as the MJO strengthens and moves beyond 70E. With continued eastward progress the -PNA continues with the MJO’s active phase shifting eventually to the Maritime Continent.  The negative phase PNA would promote long wave trofing over the Eastern Pacific. Thereafter, if the MJO eventually shifts eastward, its convective phase would then shift into the western pacific…then toward the dateline. The PNA teleconnection would flip positive again with ridging returning to the Far Western US.

As you can see the MJO is stalled out at the moment. See: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

See its position with forecast:   http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/ensplume_small.gif

The models continue to forecast it to strengthen and shift east through the Indian Ocean. If the MJO performs as forecasted, odds are we will turn wet.  However, the MJO is not performing as the models indicate and if it does not strengthen and shift east as forecasted, we would most likely remain drier then normal.

At this time most convection is south of the equator and fairly weak.  More of the convection needs to get north of the EQ and grow in size.

You may watch the progress of active phase of MJO at the following link:

As you can see it is has recently left Africa.

Animation of daily IR and 200-hPa velocity potential anomalies

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ir_anim_monthly.shtml

 

The Dweeber……………………..:-)

 

 

 

 

 

————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Short Wave Tempo Picking Up With Series Of NW Sliders Headed Our Way…..Pattern Change For Precipitation Still In the Cards For Early March…..

Friday PM:

Quick Update to reflect lower winds expected over the ridges for Saturday morning. Gusts have been revised downward to 90MPH then decreasing during the afternoon to 60MPH. Winds in town in the 30 to 40MPH range.  Wind Advisories Hoisted for Mono County 1 Am to 10 AM.

Snow showers will occur Monday and Monday night now…not over the weekend.

 

Highs Saturday near 40

Lows in the teens.

 

Thursday Am Update:

Windy NW slider on its way for the high country Saturday with ridge top winds 120 to 135mph in the AM….decreasing in the afternoon. Some very light snow possible Saturday AM.

Next in Series of sliders expected Monday and another Tuesday.

Mammoth Highs over the weekend falling to the 30s and should stay that way through Mid Week.

 

Long range update:

CFS Air-Sea coupled model has pushed the above normal precip back to 2nd week of March. It may be correct as the MJO has definitely stalled out in early Phase Space 2. Once MJO begins to move again eastward, the Dweebs will have better visibility on when the Storm Door will open. Both the GFS and EC ensembles still consistent in strengthening the MJO and progressing it east into Phase Space 3. At that point we should flip to negative PNA. However, as long as the MJO remains stalled where it’s at, the PNA index would likely remain at least weakly positive.

With that said, it is still possible to get some energy south, down the coast for at least a small to medium system, during the first week of March. More later………………………………………The Dweeber…… 😯

 

Well…You would think that the Dweebs had back peddled on the idea of turning the pattern wet For March just because it has not been mentioned anything in the last few discussions…. On the contrary…were still on track!  Even the 6 to 10 day and 8 to 14 day outlooks from CPC has put normal precip into the Central Sierra during that time frame. I expect the 6 to 10 day to go above normal with their outlook within a week!

Got email today from one of my O’l favorite lead forecasters that has since retired from WSFO RENO.  Yea know…old lead forecasters never die…..they just fade away to their favorite Golf Course or spend time doing Soaring Forecasts when the wave is right!

The propagation of energy from the western pacific is back in action tonight via Hovemuller theory as three significant surface waves spin up off the coast of Japan in the coming days. Energy from the first will be coming through Saturday in the form of a northwest slider.  Mammoth might actually get a little light snow from it Friday night. With more short wave action following. The main message is for wind and cooling. Winds over the crest could reach 120 MPH Saturday AM.

The next Surface low spinning up with leading isobar crossing 140E occurs this Friday morning. The energy is forecasted to come through California Tuesday AM the 28th.  The next shot of energy through California would be the 3rd. The GFS’s timing is quite a bit different so it will interesting to see how it all works out.

I think that we are finally on the right track now. The tempo is picking up with strengthening surface lows coming off Japan. Eventually, the upper ridge off the west coast will retrograde westward with more serious systems that will effect California later in the first week of March.

For the past few days, the MJO has stalled out in early Phase space 2. The flip in the PNA usually comes in Late Phase space 2 into 3. So the flip is taking longer. It was supposed to occur in late February. By the time MJO gets to 3…(if it does) A full latitude trough should be set up along the west coast….. Remember, the global models do not get the tropical forcing into the models until about 5 to 7 day ahead…..So at the moment the PNA is still Positive like it has been for quite awhile.

Dr Howard and the Dweebs…………………..:-)

 

 

————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.