Yuletide Season Approaches…..Still No -NAO or -AO in Sight…..-WPO and -EPO to Rule West Coast Weather into the New Year and possibly beyond…..
Thursday December 5, 2013
Posted at 7:40 am by Howard
Friday Update: Mammoth temps Highs 20s today and teens Saturday…..low 20s Sunday
Lows below Zero Sunday AM again…..
Warmer Next Week:
Not much change but to slow the current system down 6 to 8 hours. QPF is slightly less than the previous storm but we’ll get more snow because it will be colder during the snowfall. Snow to water ratios are expected to be 20:1 over the Southern Mono County Sierra. Thus…….4 to 8 inches is expected in town with 8 to 12 inches between 9K and 11K. Although some light snow may begin later this evening…..Most intense period of precip will be 5:00am to 11:00am Saturday with showery WX during the afternoon into the early evening hours. Sunday AM will be very cold again with early Sunday AM temps below -0F. Temperatures at resort levels will moderate slightly by Monday AM with single digits..however, the high elevation valleys like Bodie will go -20 to -25. Like Thursday Am there is a surface gradient for the NNE flow over Mono Lake Sunday afternoon into Monday AM. So another Lake Effect snowfall is not out of the question for Mono City and Lee Vining. As the high pressure portion of the AK block progresses east into CA, There will be moderating temperatures Tuesday into Thursday with highs in Mammoth returning to the 40s and lows in the teens. The Freezing level is expected to temporarily rise to 9300 feet by Wednesday Night. Expect a brief reduction in air quality the middle of next week due to temperature inversions.
There after….the next weather system for late Thursday and Friday the 13th is being handled differently by the two most popular global models. The ECMWF has it as a coastal slider with less moisture then the GFS which actually brings in the western flank low from the current Omega Block which is most likely wetter. Either way the system will be fighting the trend….
Outlook: (Subject to change)
The trend according to the Ensembles is the transition from the current -EPO to its western cousin the -WPO. Once the -WPO sets up in the Bering Sea it is indicated to retrograde westward even further out over the Western Pacific. That will increase heights over the mid lattes of the eastern pacific. Without any cold deep trof in the Gulf of AK or BC to suppress the westerlies south week 3, the Anti Cyclonic tracked Rossby Wave Train will most likely remain too far to the north to bring us precip during weeks 3 and 4. This would be a return to milder weather for the high country. However, there are some ensemble members showing the possibility of the pattern reverting back to the -EPO which puts us back into the deep freeze and cold storms down the coast much like we have been having, toward the end of the year.
More later…………………….Dr Howard and the Dweebs
Looking at the latest teleconnections the next 6 to 10 days it is quite possible that the Positive numbers in the QBO and low solar are putting the KABASH on negative phases of the NAO and AO. The Dweebs like that as those teleconnections do not usually favor stormy weather on the central west coast. Easterner weather junkies love the negative of the NAO and AO as those telelconnection’s often create a blocking pattern that buries the cold in the east while the west is often times ridged up with the +PNA.
With the strato winds of the QBO blowing stronger west to east last month as compared to the month before, it is unlikely that long-term blocking will come anytime soon to the Greenland area this year. This is good news I think in a neutral ENSO year for the central west coast. Exception….the GEM has a block in the Greenland area but is the Maverick compared to the other models.
It appears to this WX Dweeb….that over the western hemisphere, the negative phases of the WPO and EPO are taking turns in their reign over the Pacific. As of late…..the GFS has shown that amplification has come to the -WPOs Eastern Cousin, the -EPO and an adjustment wave is slowly becoming more and more evident in the pattern, west of the BC coast. “It maybe” as the upper jet out over the pacific gets stronger climatically…..a stronger southern branch under these blocks will become confluent with the strengthening arctic jet later this month…..radically changing Mammoth’s landscape……
Snowfall Estimates Update:
Update on the QPF from the 00z Thursday ECMWF for the Friday/Saturday system (.70) for the crest. CRFC has .46 for Yosemite and .40 for Huntington Lake. The New 12Z Thursday GFS has .50
So it appears that this snowmaker will be similar in amounts to the last system that dropped 7 to 10 inches on Mammoth Mountain.
Looking down the road… is it quite evident that the highly amped upper ridge responsible for the Arctic Air will break down rapidly early next week and collapse in response to the Morph of the -EPO back to the -WPO. This will allow milder pacific air to invade the far west by mid week. Sometimes you can get isentropic lift type snowfall if there is a moisture channel, however this is not in the cards at this time.
The epo/wpo teleconnections are very similar in that they are blocking patterns highlighted by positive height anomalies over the northern latitudes and negative height anomalies to their south over the mid latitudes. The only difference in the teleconnection is location. The WPO is in the central and western pacific and the EPO is situated in around the Gulf of AK. When under the influence of the -WPO, the main upper height anomaly can be too far west for major storminess for the central coast with ridging instead. With the -EPO as are experiencing, the upper height anomaly is too far east. What we may get is a sort of hybrid of in-between…and if the southern branch of the westerlies is strong enough…..It may merge with the polar branch and become confluent. This can lend to a wet pattern for the central west coast with possible “AR” implication’s….
At any rate, there is lots of Winter Left and this candle is just getting lit…..
Dr Howard and the Dweebs……………………….:-)
Wednesday December 4, 2013
Posted at 7:39 am by Howard
Quick update for the Friday-Saturday Storm. Storm still looks very similar to the last system, except it will be colder and the snow lighter…..so it will snow more. Liquid EQ would be about .5 over Yosemite and probably . 7 or .8 over Mammoth Pass. The Dweebs still feel at this time that about a foot over the Crest is reasonable with 8 or 9 inches at the main lodge. In town, 4 to 7 inches so a good plow….
Will update amounts again in the morning if necessary………………………………………….
Skies dawned clear for the most part over Mammoth Lakes with very cold temperatures. The low temperatures here at Mammoth Weather.com was 3F degrees with yesterdays high 33. Temperatures were still the coldest in the upper elevations with a low of -11 at Tuolumne Meadows. That will change as sinking air allows the combination for the cold in the high country to settle into the valleys and radiational cooling to further release heat from the surface. Expect tonight lows to range from -5 to -15…especially in the colder valleys along the highway 395 corridor.
Today’s high temperature in Mammoth will be cold as modified Arctic Air remains in place. Highs are expected to be in the teens under clear skies. It is a dry 48 hour forecast.
The next upstream system is currently over the north coast of AK as it rounds the top of the upper high. It is another cold bugger! I like what it is doing as in comes down the coast Friday afternoon. Both 12Z NAM and GFS show the upper jet taking a nice quick Jog to the west off shore to pick up some moisture before in comes south along the central coast. The main VT MAX is depicted a good 175 to 200mi west of the Central Oregon by 00Z Saturday. the jet does become cyclonically curved a bit and so this should generate some good UVM and lift for moisture to get up into the Trop. A large consideration to remember is that yesterdays system’s precip began with temps in the low to mid 30s. This storm will begin as snow in the 20s then cool rapidly into the teens. The Snow to water ratios will be higher, possibly between 15 and 20:1 over the higher elevations. At the moment, the QPF is about .50 for this system over Mammoth. Double that and you get another 8 to 10 inches. if it ends up a little wetter, then we may get a foot. After the system winds down Saturday, it will be followed by another shot of Arctic Air Saturday. High Temps over the weekend will remain in the 20s with lows in the single digits or below 0.
Outlook for Next Week: (Subject to change)
Yesterdays 6 to 10 and 8 to 14 day outlooks were a bit wetter than normal for the Central Sierra. However, I have to say that I can not see where they are getting that from. While it is true that we may get some moisture from the west as the upper ridge collapses early next week over the eastern pacific. Precipitation would be light and isentropically lifted. It looks to me that the trend in the pattern is headed back to the -Phase of the WPO by week 2, which usually builds a ridge over the eastern pacific and is dry for our area. However, this time there may be a substantial southern branch of the westerlies undercutting that ridge with the potential for an “AR” event for the pacific NW. How far south the area of confluence goes is dependent upon the depth of the upper low (adjustment wave) that will develop in the Gulf of AK.
PS: Big day for mamothweather.com yesterday with 19,059 visitors……
Thanks for your interest everyone!
Dr Howard and the Dweebs………………………………:-)
After a Quick Shot of Light to Moderate Snowfall Tuesday….Modified Arctic Air Invades the High Country Mid Week and Stays into the following Weekend……
Saturday November 30, 2013
Posted at 9:54 pm by Howard
Tuesday Evening Update:
Upper trof axis slowed as it moved through Mono County as forecasted. At the moment the axis is near Lone Pine and will remain over the Owens Valley moving at a snail’s pace through the early morning hours…..reaching Kern County 12Z. Another ripple moves through in the northerly flow late Wednesday for another round of snow showers from upslope Wednesday night into Thursday AM.
The next important Arctic short wave dives south, and is west along the coast of the pacific NW Thursday night…….700mb RH in the NAM increases rapidly Friday with another round of snow by Friday afternoon and into Saturday.
This particular wave looks interesting. As the upper ridge that currently extends up into Alaska gets pinched off with the break occurring on tonight’s 00z Wednesday NAM at 45 north. If this break occurs in the ridge in this spot at that time, the timing may allow the next short wave to bow way out off the coast and cyclonically really pick up some moisture from the pacific.
However, the 00Z Wed GFS does not pinch off the Upper high at that time. What we get is another cold outside slider with a period of light snowfall Friday night. So it is too soon to get too excited about another foot yet.
It look like Mammoth Mt picked up about 8 to 12 inches past 15 hours. Actual tally in the morning from Mammoth Mt.
This particular system is through now….just some snow showers remaining. Do not expect much more than another inch over night.
Cold is now the main message with lows in the low single digits here near the village and -10 to -15 in some of the colder valleys.
Will update in the morning………………
PS I do not remember the models having this much difficulty in handling Pacific energy and the upper flow like it has this fall!! The spaghetti in the Ensembles is pretty unruly after about 7 days…..
I think that were all good on the snowfall prognostication for Tuesday based upon the last discussion. Tomorrow Tuesday Morning, the Arctic Front is expected to slow as it moves into Mono County and that should give us a bit extra Precip as reflected in the forecast amounts.
Looking down the road there will be several ripples in the flow that are out of the Arctic this week. Any one of them can potentially kick up some snow showers. There is one short wave in particular, off in the distance with this same pattern, that will come in Friday night worth watching. The Upper jet seems to have a double structure with it, with an apparent part over Water and the other coupled with it over land. That is expected to come into Mono County Late Friday night into Saturday. That may be good for several more inches then.
The longer range outlook is greatly subject to change, shows the possibility of the upper high pinching off into a closed upper high over AK, with a significant branch of the westerlies undercutting into the central west coast. If this works out, this may be initially, an isentropic lift precip producer, flowed by some dynamics (UVM) afterwards. This is not a forecast……just looking down the road a week away…..
Have a nice day>>>>>>>>>>>>>>
Dr Howard and the Dweebs…………………………..:-)
10:00 AM Sunday
Everything on track for a very cold week ahead with upper teens and low 20s in town. Even Tuesday’s weather will be cold with high temps near 27F……and that will occur fairly early in the day.
Strong winds will preceed the arctic front with gusts Monday afternoon through the night 30 to 50 MPH in town.
Snowfall: The new ECMWF QPF is out for Tuesday painting .6 over the crest and there is even a few isolated areas that show .80 Considering how cold the air mass will be and the higher snow to water ratios of at least 15 to 1, it is not unreasonable to expect 5 to 10 inches between 9K and 11,000 feet by Wednesday AM, and 3 to 5 inches in town. In a few of those isolated spots, up to a foot could fall.
Well, we could have had a bonanza of snowfall this week if earlier model runs would have stayed consistent. The Current Arctic Low off the coast of Northern BC will instead move into the Pacific NW then become east west orientated across the northern tier states. I have to say that by December, the longer range global models usually do a much better job a week away.
You would expect a longer range outlook in November to bust, but by late November that’s unusual. So until the Dweebs see better performance in the longer range, well stick to the short-term and medium range, highlighting that the extended guidance is an outlook rather than something that is more believable. It may be that during this winter, the longer range guidance is one that the Dweebs will use more cautiously.
As far as snow fall goes…light amounts are expected. Will fine tune in the morning….
What we lack in snowfall we will make up in cold weather…..Modified Arctic will invade Tuesday and by Wednesday we will struggle to get out of the teens at 8000 feet. Night time lows will range from the single digits to below zero in some areas. The cold will be prolonged into next weekend. No doubt there will be broke pipes in town……so do what you have to keep the house warm….
I do see another pattern change during the 2nd week of December….hope its a wet one!