Archive for February, 2014

Heavy Convective Snowshowers! 

Main Vort Center moves through at 4:00pm

An Amazing 6” snowfall in one hour!!!!!  Yes, between 3:00pm and 4:03 PM at the main lodge 6 inches fell according to the Plot at the base lodge! This brings the total to 18 inches at the main lodge and most likely about 2 feet on top.  More to come tonight!!!  At least another 6 to 12 inches by 10:00PM then another 2 to 4 by Morning Saturday. (On Mammoth Mtn)

As of 9:00AM:

At Mammoth Weather.com at the 8200 foot level I have picked up 7 inches of fresh since 5:00am.  It is Snowing moderately at the moment. Temperatures have warmed up to 31 degrees since it was 27 at sunrise, an example of the Warm Sector of this system. Once the warm front has passed, we may have a short break before the Upper Jet enhanced colder precip arrives by 12:00pm. I suspect that we are at the highs for the day today because of the following…..

Fous 73 numerical data off the 12Z NAM show 1000-500mb Thicknesses at Fresno (FAT) 552DN at 12Z; then lowering to 548DM at 18Z.  Thickness falls continue through the day/night. By 00z Saturday, 544DM then down to 542DM by 06Z Sat.   What is interesting is that FAT shows a negative Lifted of -2 by 18Z and 0 lifted by 00Z. So do not be surprised if you hear some Thunder this afternoon in the Sierra. Probably mostly on the west side. I Checked the Vertical Motion…..it shows +12 at 18Z with the negative lifted of -2 then +20 in the max at 0 lifted.   Thus this afternoon there is going to be some pretty vigorous rising air columns!  Thunderstorms over the southern SJV you bet!  Possibly some cold core funnels as well.  The southern San Joaquin Valley will not be a good place to be flying if you’re in a small plane today!

Otherwise the snowfall forecast for Mammoth through Saturday is unchanged.  12 to 18“ in town and 20 to 30“ over the upper elevations……

PS, The MJO seems to be trapped between Phases 7 and 8. So for the time being the East Asian upper Jet will continue to be strong, for possibly another week. This give support to the ECMWFs version of the extended showing another significant storm for Wednesday or Thursday next week before we ridge up for my Sons Wedding on the 8th!

The Dweebs are doing what we can for you Cliff!…………..;-)

The Dweeber…………………………..:-)

Sunday Morning:

MJO has made the jump to Phase space 7…thus unleashing the power of the Extended Asian Jet toward the west coast! All models working nicely together to bring the upper jet on shore over South Central California Wednesday night. CRFC just painted .70 to .75 for storm #1 with the snow level beginning about 7500 to 8000 Wednesday; then during the major part of the event Wednesday night to Sunrise Thursday the snow level will be between 6000 and 7000 feet lowering to 5000 by the time most of the precip is over about Sunrise Thursday. Expect snow showers Thursday afternoon and evening, with little if any accumulation.

Storm #2 is still favoring the Southern Sierra and Southern California with what appears to be the best storm of the Winter for Southern CA! We here on the east side of the sierra will still get some good snowfall amounts. However in this case, snowfall amounts 1 to 3 miles east from the sierra crest will fall off faster than the first storm because the upper jet is so far south coming in over LA/San Diego. The Upper Flow at 700MB is due South Friday PM and so it is not orographically favorable. Nevertheless, the crest will get between a foot and two feet as there is more moisture in this system.

Again….What is interesting is that storm #1 has less moisture, however, it is orographically more favorable as the winds at 500mb and 700mb are SW or natural to the sierra. It is possible that we here in town may do about the same from the wetter storm Saturday as compared to the Wednesday night storm.

Where will the big amounts be?????   In the Southern Sierra, and Mountains around Southern Ca. This may be the first precipitation for parts of the desert South West like Phoenix, AZ this winter.

Friday AM:

Lots of hype developing with the coming pattern change next week. I heard someone quoting me by saying 9 feet of snow!  First of all, if I really believed that a storm capable of delivering 9 feet, was approaching Mammoth a week away, during a drought year, I would not even think of saying that publicly and most likely would not believe it myself until it was within 72 hours away.

I am going to preface what is to follow by saying that at this time, the MJO has not moved out of Phase 6 yet.  If it does not progress through phases 7 and 8, we may not get what we think we will get weather wise later next week.  Again, watch the phase space map to see if the MJO is progressive!!!!!

What I do see here are 3 short waves, the 2nd half of next week into the first few days of the following week. The first wave will weaken as it moves through the mean ridge position ridge. That upper ridge will dampen and shift eastward Wednesday/night. This storm “at the moment” looks like it could give us . 5 to possibly an inch of QPF or 6 to 10 inches of snow by Thursday AM over the upper elevations. Snow levels will likely start high at about 8000 feet before lowering during the night Wednesday. It is the following storm that is of interest Friday into Saturday. It has a double-barreled surface low that will entrain a lot of subtropical moisture with it. Additionally, it will be intensifying as it comes in, not weakening. The biggest problem with this storm in forecasting estimates at this time, is that the upper jet will pretty far south of that ideal position that’s across Paso Robles, Ca. The wave as it comes in will have a shorter period of 700MB winds natural to the sierra and thus a shorter period of orographic’s. In fact the winds will be more SSW which tends to favor the west side of the Sierra more, with less slop over to the eastern slopes.

At 300mb, the idea is for the upper jet to trend further south with time and so the main energy may favor the Southern Sierra more and Southern California.  Mono County will likely do better than the Tahoe area for the biggest storm totals with the 2nd storm because of the position of the upper jet and mid level 700mb flow.

The 3rd or last in the series, will roll in about Monday of the following week. It is not impressive at all with light to moderate amounts.  There after, we will be well into the first week of March. At this time, it appears that the upper cut off high will retrograde westward across Siberia. Thus west coast 500mb heights will rise, during most of that following week. Teleconnections from the ECMWF focused upon that positive upper height anomaly day 15 suggests a storm track that will shift north again. By Wednesday the 6th, Northern California will get the following storm after the Monday system and the pacific NW then BC, can expect the following train of short waves.

For those that are wishful of a Miracle March, it is this Dweeb’s opinion that it is highly unlikely. However, with that said,  the 2nd half of March looks potentially wet again for the central west coast according to the inter-seasonal climate models.

As a comment, these are not cold storms because of their trajectory. However, they are not warm storms either like the ones with snow levels at and above 9K.

I expect the snow levels to vary between 8K and 5.5K over all.

By Monday, the Dweebs will fine tune snow levels and QPF……

Dr Howard and the Dweebs……………………..:-)