A Splitting Trof along with small upper closed low will kick off a few showers later this afternoon and evening……The weekend weather will bring a mixed bag of Sun…Clouds and Some Isolated showers Saturday then warmer Temps by Sunday into Monday…..A more active pattern develops later next week……
Friday April 18, 2014
Posted at 11:53 am by Howard
It looks like the winds will be picking up Monday as the first in a series of short wave trofs begin their migration into California. The first system for Tuesday will really cool things down with highs Tuesday in the 40s, followings by nighttime lows in the 20s. The upper jet is mostly to our north with the RT rear entry brushing Mono County. Moisture appears to be sparse as well as the Dweebs are only expecting mainly snow showers and the possibility of up to 2 to 4 inches over the crest and an inch or so at 8000 ft by Tuesday afternoon.
Short wave ridging will follow Wednesday into Thursday with breezy weather especially over the upper elevations Wednesday and light breezes Thursday. Temperatures will climb into the 50s on Wednesday, then peak out to near 60 by Thursday.
As mentioned in my last posting, the following storm for next weekend is a different animal. A cold pool at 500mb of -27C and 700mb temps of -10C Saturday AM is over Mammoth Saturday AM. This is suggestive of a major system for the Central and Southern Sierra. The system will split a bit while coming in, as it becomes negative tilt. However, with the cold pool digging so far south, the most dynamic part of the storm will be more over Central CA as the models show a cyclonically hooked upper jet with Central CA in its front left exit region.
Based upon the 12z ECMWF guidance, this storm has a QPF of about an inch over the upper elevations. That is about a foot at between 10-12:1 over the crest. The GFS has between 1.5 and 1.8 inches of QPF and the bulls eye keeps moving around with various runs. The Dweebs will take another look at it in the morning….then track it the rest of the week….
The bottom line is the although this system is not nearly as cold as the storm that the Dweebs called a Platinum Powder alert on, it will still be good quality powder over the upper elevations!
Dr Howard and the Dweebs……………………..:-)
As we approach the end of the 1st 30 days of Spring, the weather has for the most part been above normal temperature wise, and below normal precipitation wise here in Mammoth. The Dweebs see a reversal of that pattern over the next 14 days. To begin with, more blocking is forecasted over NW Canada and this blocking is expected to build North Westward into Alaska, well into week two. The end result would be a more active pattern over the west with cooler than normal temperatures developing by midweek next week, and normal precipitation for the week 1 period then “above normal” precipitation for week 2 for Mammoth Lakes (IE the 25th through the 30th). The next weather system that will approach our area early Tuesday will bring gusty winds, cooler temperatures and snow showers. The Dweebs do not expect significant accumulations in town at this time. However, the two global models handle the short wave energy differently. The GFS is more consolidated with the upper flow with less splitting then the ECMWF which has a significant split in the flow just before the upper trof moves into the state. Mammoth would be significantly effected by a drier QPF, resulting from the EC’s model handling of the short wave energy. Thus for now…just expect a dusting in town with a few inches over the upper elevations. I will take another look at it over the weekend and comment Sunday. The following system for that following weekend, or the last weekend of the month looks to be a different animal. It will have the support of a strong upper block over AK and a strong upper jet over the North Pacific. Short wave energy is expected to dig a long wave, negative-tilt Trof over the Eastern Pacific and effect all of California with significant precipitation. This may be a protracted period of storminess for our state that following weekend, right on through the end of the month of April. The Climate Forecast Systems outlook based upon the CFS 06Z output from last night shows about 2.5 inches of QPF total for our area of the Sierra through the end of the month. That may be another two feet of snow over the upper elevations! It also extrapolates in its output, significant precipitation during the month of May, with as much as 1.6 to 1.8 inches of QPF for the Mammoth area. So we may not be quite done yet. Of note…the latest long-range guidance from the 12z Friday the 18th GFS output shows the storm coming in Saturday morning the 26th (Timing Subject to change) has a large cold pool of -10 to -15C at 700MB in the low off shore and at 500MB its cold pool is quite large at -30C. The upper jet at 300mb is between 130 and 140 Knots. That’s an impressive weather system for the end of April, that could dump a couple of feet over the crest…..should it verify like it is shown. In that the trof is negative tilt, the upper jet should slide south over the Central Sierra over that weekend, putting Mammoth in that favorable front left exit region. In the meantime, we currently have a mainly convective situation over Mammoth both today and Saturday due to the effects of a small closed upper low moving on shore today over LA. SE upper flow is indicated over the southern sierra this afternoon and that spells divergence aloft and a good chance of Thunder this afternoon. Infact…the best CAPE with 500 J/KJ are over the Southern Sierra and there is a good conv/divergence 850mb/250mb couplet over Death Valley. Several showers were beginning to crop up on radar over the southern portions of the Southern Sierra about 12:00PM today. The areal coverage should spread a bit north as the day goes on. Thus Mammoth may have a thunder bumper or two today, and this evening and again Saturday as some residual instability is indicated in the models for Saturday. The weather Sunday and Monday look warmer and then the winds to come up Monday afternoon and into that night with showers possible anytime after midnight Monday and especially Tuesday. Dr. Howard and the Dweebs………………………:-)