Wet Windy Weekend expected throughout Mono County…..Main Snowfall will be at elevations above 10000 to 11000 feet….Winds will Increase Tonight…However, for Southern Mono County…The strongest winds may end up being Saturday Afternoon…..Stormy Period to end Monday with the upper jet lifting north next week for a long stretch of Fair Warm Indian Summer Weather….
Thursday October 13, 2016
Posted at 2:22 pm by Howard
Strongest winds have verified further north with Upper Jet the same. Although the stronger upper jet has yet to enter CA and is is still on tap for Sunday, the NWS has seen fit to keep winds in Mono County at advisories levels. Plenty of rain is still on the way for Tonight and Sunday…
Friday AM Update:
High Wind Watch hoisted to begin 2:00PM Saturday through 5:00PM Sunday…This looks likely to be the windiest period for Southern Mono County
A deep upper low continues to sit off the coast of the Pacific Northwest this morning with a strong ~150 to 160 kt upper jet driving moisture from post typhoon Songa into Northern CA. Already some reporting sites on the north coast show over 6.00 inches of rain. This wet fetch should sag southward today with an associated front that will stall out near Fresno, CA tonight. The strong westerly flow, and slow southward movement looks likely to hold off any significant precipitation for mammoth until either late this afternoon or evening. Freezing levels will be high near 11K to 12K and so snow levels for this event will be mostly above 10,000 feet.
Precipitation amounts should range from 1/3rd to 2/3s of an inch by Saturday morning as the first wet swath passes thorough. Saturday morning looks less likely to have major winds as we are “in-between short waves”. The next wetter AR rolls in later Saturday afternoon with stronger winds as compared to Today. The upper jet will come in just north of Tahoe instead of over Oregon this morning. Precipitation amounts will ramp up beginning Saturday afternoon and heavier precipitation is expected Sunday as the main jet core from the pacific comes in. That jet is forecasted to be 180 knots at 250MB well off the west coast! WOW for mid October. The track on the new 12z GFS has the axis over RENO Sunday mid morning. It begins to lift north by Sunday PM on this particular model which goes against last nights thinking of it lifting north Monday. This argues against any dusting Monday AM in our town. This 2nd AR is expected to drop between 1 and 2 inches of Precip by Monday AM for our area.
Dr Howard and the Dweebs…………………….:-)
Main headline is for the possibility for periods of Damaging Winds, beginning Friday into to Sunday night. The way the Dweebs see it, in that the upper jet axis never really gets into Southern Mono County this weekend, this storm is mostly about wind and rain. With each incoming Jet Let, we will be in the front right exit region of the upper jet. Any snowfall below 9000 to 10000 feet will be brief and light over the mountains of Southern Mono County, early to mid Monday morning.
The QPF for the Models over Mammoth Mt are around .50 to .70 Friday afternoon through Friday night. (Freezing level is about 12K) Another system will bring about an inch of rain Between Sunday night and Monday mid morning. The Freezing level begins about 11,000 Sunday night and drops to 9500 by Mid Morning Monday.
Note; the snow level is usually between 1000 and 1500 feet below the freezing level.
Back to wind:
According to the models, there appears to be several windy periods over the weekend.
The first one is stronger from Tahoe north after midnight tonight into Friday AM. The 2nd connected jet-let drops to the Oregon/CA border by about noon Friday. That looks much windier for us than the first jet-let tonight over OR.
By Saturday morning the nose of 180knott upper jet punches into the Bay Area. This particular Upper Jet may be the strongest for our area Saturday afternoon into Saturday night! Next strong Jet-Let slated for Sunday comes in about 12:00PM and continues into the evening hours, but it may not be as strong wind wise, as the temperature gradient may be less with a little cooler air already be in place. (Well See).
Main concern is for dead trees on windward side of structures getting blown down locally. Wind’s will initially be more from the southwest then become more west to east later in the weekend. Residents throughout Mono County should do a walk around their residences and look for tall, dead or dying trees and have them removed as soon as possible, as the region is likely to have more wind events this fall.
Dr Howard and the Dweebs……………………..:-)
Beautiful warm weekend to be followed by clouds and cooler weather next week…..Atmospheric River to take aim on Northern CA beginning Thursday with heavy precipitation as anomalous upper jet sags south to the CA/OR Border…..
Saturday October 8, 2016
Posted at 12:37 pm by Howard
Some tweaks to the forecast for the up coming week. AR event is still on track for the Pacific NW and Northern CA with the southerly boundary of the AR now forecasted for Central CA. The are four points worth mentioning in the upcoming event.
- It is going to get quite windy in the central and especially northern sierra. Winds at 700MB will be up in the 50 to 65 knot range with the latter for the Tahoe region. With these warm event storms, it is not uncommon to have significant down sloping drawing strong winds to the surface as well. So the word is batten down the hatches prior to the weekend…..
- There will be at least two to possibly 3 branches of AR for California. The first reaching the Central Sierra Friday around noon through Friday night. That has the potential to bring about .30 to .60 inches of rain to the west side near Yosemite. Less on the east side. Precip amounts taper off radically between Yosemite and Huntington Lake.
- The freezing level will be around 11K to 12K so snowfall will only be over the very highest elevations. There after….it will take the final push or final short wave Sunday into Monday morning, that will bring the possibility of over an inch of precipitation to Mammoth Mt. There is colder air in that system…..Especially by early Monday morning when the freezing level drops to near 8000 feet. That should be good for a snow level of about 6500 to 7000 feet during to coldest period Monday afternoon. However….Most of the precip should be over by then….Most will fall Sunday night with a higher snow level. More fine tuning of amounts and snow levels later this week…
Very anomalous wet pattern setting up for Mid October…. And more importantly, the Dweebs really like the SSTA pattern setting up across the north pacific west to east. It is what I have been waiting for. Hope it holds for the winter! Watch the +PDO to see if it flips and stays for the winter! Next update for September will be coming out in a few weeks….
Forecast on track with unseasonably warm temperatures this weekend with highs in the low 70s and lows in the 20s and 30s. Little in the way of any breeze expected. Great weekend to get lots of fall foliage photos!
Another part of the forecast is on track to bring an atmospheric river event to the pacific northwest, south to Northern CA. With the upper jet axis over the Northern California/OR border during the wettest part of the storm, Northern CA is on track to pick up a bonanza of water for CA in its storage facilities of the various Dams north of Highway 80. The pattern that will be developing is part of the strong blocking that will develop over the state of AK along with the remains of Typhoon Chaba. The Pacific Jet will be forced underneath that block with short wave energy “piling up” the cold air in the Gulf of AK next week. As the Trof loads up, strong upper divergence focuses its moisture upon the pacific northwest with the enhanced pacific jet stream. Eventually the block retrogrades west, which unleashes a deep upper low pressure systems energy into the west coast. Subsequent short wave energy drives its remains into Central Ca, most likely just after the weekend of the 15th. With the block over Eastern Asia by the third week of October, very strong ridging will build south to north over the far west, ending the wet pattern, with a possible heat wave over California during the 3rd week of October.
Note: The wet pattern for Northern California that begins Thursday, will most likely be associated with rain not snowfall at Northern CA ski resort elevations. QPF amounts that the computer models are cranking out are pretty astounding with the Atmospheric River. Some areas may get between 10 and 15 inches of rain in the mountains around Shasta in the very wettest areas. Sure, there will be cooler air following the warm moist rain leaded air mass, that will be followed by lowering snow levels. And….it is possible that the mountains of Southern Mono County could pick up 6 inches to a foot between Monday and Monday Night above 7500 to 8000 feet with the final short wave. However, most of the precipitation will be rain throughout the event over Northern CA, not snow at elevations under 10,000 to 11,000 feet during the wettest part of the storm. Again….The best chance of some snowfall for Mammoth Mt will be Monday and Monday night the 17th….However…some showers are possible before that time frame.
According to the latest 12Z Saturday run of the ECMWF, the bulls-eye for snowfall for the sierra is near Sonora Pass where between 12 and 18 inches is possible at elevations above 8000 feet on the west side of the pass, Monday through Monday night.
More later from the Dweeber!
PS, I will begin my emailing’s of Platinum Powder reports about November 1st. In it will be speculation of the type of Winter I expect and future stormy periods and possible storm cycles. Be sure to sign up this month. If you signed up last year, you need not sign up again…
You are on the list!
Dr Howard and the Dweebs………………………:-)
Chilly Northwest flow to continue through mid week before weak ridging warms Eastern CA over the weekend….It looks like another spectacular weekend for the high country with slightly above normal temps….Cooler breezy weather returns by the following midweek…Storm Clouds are on the Horizon…..
Tuesday October 4, 2016
Posted at 9:58 am by Howard
Strong blocking over the State of Alaska, WNW to Asia will be the dominant teleconnection effecting the weather along the central and especially the NW coast. An AR event is probably in the picture at some point as Low Pressure in the North Pacific and the Pacific Jet taps a lot of moisture aimed primarily at the Pacific Northwest by the middle of next week into the weekend of the 15th… We may get some showers this far south. The idea though is that it will be warm as we are on the Anti Cyclonic side of the big upper jet. It is great seeing a very strong jet like this in early October!
A large broad upper Trof remains over the intermountain west with only slow east ward progress expected. In the back of this trough is an a potent for October upper low that will bring Snow and rain to the pacific NW today. Another system is rapidly approaching the West Coast this morning in the fast NW flow; an impulse will move through the intermountain west bringing an increase of breeze and further cooling especially tomorrow Wednesday after a slight bump up in temps today. High temps at 8000 feet will likely remain in the 50s through Thursday. Note, the stronger upstream system is likely to bring stronger northwest breezes over Mono and Inyo county Wednesday/night. This is a dry pattern for the Mono County.
The Weekend will be dry and warmer with highs in the mid to upper 60s….Low temps in the 20s and 30s in Mammoth Lakes. I expect little wind over the weekend.
At the moment, a small splitting trof is likely to bring some increase in wind and cooling early next week. Dry weather is likely to prevail as 500mb heights rise over the west.
The current pattern of high latitude blocking is a major feature for the western hemisphere as this block over the Northern AK extend northwestward to Asia. This is suppressing the westerlies over the extratropical north pacific. It has begun the rainy season for the pacific NW and is bringing an end to their fire season. In the longer range, the block is forecasted to retrograde northwestward a bit and weaken west of the Dateline. . This change in the teleconnection should still keep a stronger trof over the north-east pacific. This is still a dry pattern for Central CA. The big question is, will there be amplification of the eastern pacific ridge currently near the dateline later next week? That would drive the westerlies south into Central CA. It is pretty early in the season for that. So the Dweebs will wait and watch!
Although it is likely that the block will fall apart eventually bringing Indian Summer to the Sierra, since these patterns often times repeat themselves, a similar block is possible later in the month or early next month. That would have major implication’s for snowfall and winter weather conditions for Mono County.
As another point, the Dweebs are becoming more comfortable with the notion that this winter will be quite different from the last 6, that have been below normal in precipitation. The Dweebs are more excited about the prospect’s for a better, wetter winter.
This is based upon the rapidly weakening +PDO, a +QBO that will should flip to negative by about year’s end and the warm water pool over the eastern pacific setting up farther west. “If these trends continue, the Dweebs feel that Mammoth will enjoy a very good water year. The next 60 days will really tell the story on these important features.
Note: Generally the view is that when the QBO is negative the atmosphere is more favorable for blocking patterns to occur in the jet stream over the Northern Pacific …Northern Canada …Arctic and Greenland areas. With more blocking patterns you get more snowstorms and more colder outbreaks. However, research does not support that directly.
Dr Howard and the Dweebs………………….:-)