Main focus for the short term is on the winds the next few days…then heavy snow on Wednesday/Ngt

FOR MONO COUNTY:

FROM THE NATIONAL WEATHER WEATHER SERVICE:

329 PM PST SUN FEB 13 2011

…HIGH WIND WARNING IN EFFECT FROM 7 AM MONDAY TO 10 PM PST
TUESDAY…

THE NATIONAL WEATHER SERVICE IN RENO HAS UPGRADED THE HIGH WIND
WATCH TO A HIGH WIND WARNING…WHICH IS IN EFFECT FROM 7 AM MONDAY
TO 10 PM PST TUESDAY.

* TIMING: WINDS WILL INCREASE EARLY MONDAY MORNING AND CONTINUE
  THROUGH TUESDAY NIGHT.

* WINDS: SOUTHWEST 25 TO 40 MPH WITH GUSTS UP TO 70 MPH AND RIDGE
  GUSTS UP TO 120 MPH.

* IMPACTS: STRONG AND POTENTIALLY DAMAGING WINDS WILL PRODUCE
  HAZARDOUS TRAVEL CONDITIONS FOR HIGH PROFILE VEHICLES
  …ESPECIALLY ALONG HIGHWAY 395. LOOSE OUTDOOR ITEMS SHOULD BE
  BROUGHT INSIDE OR SECURED BEFORE THE EVENT BEGINS. LOCALIZED
  AREAS OF BLOWING DUST COULD REDUCE VISIBILITY TO 3 MILES OR
  LESS.


Dweebs Discussion from this morning…..

Big WX changes still in the cards for Mono County as the mild weather pattern of the past several weeks gives way to a much colder and active pattern. The first concerns for the weatherman will be  the winds that will be increasing throughout the day Monday buffeting Mono County. There is the possibility of damaging winds by Monday night into Tuesday morning for areas along the 395 corridor. At the moment, there is a high wind watch for those areas.

So for Monday, winds will increase mainly along the ridges. 700mb winds on this mornings GFS indicated 40 to 50 knots from the SW, so 80 to 100mph winds over the crest is possible. Further increase in speeds is possible Monday night into Tuesday Am with 700mb winds about 60Knots.

Bufkit profiles from Penn State  incorporating Skewt is showing a critical layer at 10,000 feet  which will provide the mechanism for a Mono County down-slope event that should peak here in the Mammoth area  Tuesday morning, however, winds will remain strong all day Tuesday.  Although strong winds are not uncommon up on Mammoth Mountain, strong down sloping winds across highway 395 into residential areas such as Crowley Lake , Aspen Springs Ranch north to Walker are much less common….occuring just a couple of times a year. Westerly Wind gusts 60 to 80 MPH are possible Monday night through Tuesday Night in the “most wind prone areas”.

Precipitation:

CRFC indicated just a few hundreds Monday near Yosemite with the freezing level at 7500feet. Then .28 Tuesday with the freezing level at 7300. So Mammoth Mountain may get a few inches of Snow Tuesday, nothing for the town of significance.

It will not be until Wednesday for the Moderate to Heavy snowfall. The cold front will probably come through early afternoon. Snowfall rates will increase to 2 to 3 inches per hour during the afternoon. HPC  has a 2.84 bulls-eye near Yosemite for the 48 hours period between 4:00am Wednesday and 4:00am Friday.  Although it appears that the lions share of precipitation of this storm will be up in Northern California, Mammoth Mountain could pick up as much as 3 feet by Thursday. The snow will be Cold and Powdery from Wednesday afternoon through the following several days. Ratios will begin about 10:1 then increase to 15:1 to as high as 20:1 by Wednesday night.

The outlook still looks unsettled with cold showery snowfall into the next weekend. The Dweebs will continue to fine tune the details as we get closer in time. There are more storms that will effect the central west coast in the next week to 10 days. The focus of those systems are in question at this time.


Pacific Energy Update:

Looking at the latest western pacific cyclogenisis starting the timing when the leading cyclonically curved isobar crosses 150E. The following timing is as per (96 hr) Hovmoller from Canadian and GFS north pacific sfc progs.


00z 12th- 00z 16th Tues PM


00z 15th- 00z 19th Fri PM


12z 18th- 12 22nd Tues AM


00z 21st- 00z 25th Thu PM


This timing is for amplification energy and not for moisture timing which can be caused by warm advection overrunning ahead of the dynamic forcing. In most cases the Hovmoller timing is more in line with the PVA or cold front timing. 

PS thanks Tom…….Hope your having a good time on the east coast…….:-)



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.

Upper level winds on the increase this morning as short wave passes to the north……warmer today with increasing high level moisture Sunday afternoon

The high country is getting ready for a return to Winter after a very long dry spell.  As the Eastern pacific long wave ridge returns to the central pacific,  a deepening long wave trof will progress toward California early next week with the upper jet eventually digging as far south as Northern Baja, MX.  The first system will juice up our air mass Monday into Tuesday before a vigorous Cold front swings in from the west. At this time, it appears that all the ingredients are in order….. including strong orographics, deep moisture and strong UVM Wednesday to produce quite a winter storm.  Although precipitation will begin as snow Monday, it will be too warm to stick in town. Once the 1st short of energy comes through about Midnight….temps will fall with a better chance for some light accumulation on Tuesday. By Tuesday night the tempo will pick up with moderate snowfall a possibility then heavy snow likely Wednesday and a good part of Wednesday night. This is because that although the cold polar front is expected to come through during the afternoon, several trailing vort maxes along with the upper flow natural to the Sierra should keep an active pattern going into the night.   It looks like a good 3 feet possible on the plot by Thursday AM with the possibly of more snow over the Crest.  Currently…HPC is forecasting about 3.00 inches over our area by Thursday AM. Considering how cold the storm is in back of the front with several inches of snow falling post frontal….we should easily get 3 feet plus by Thursday AM. The Dweebs will be updating the QPF on a daily bases…

 Thereafter…..another system may effect the Sierra by Friday, however the upper jet by then favors more Southern California  then Mammoth Lakes. It may be that we will just be an a cold showery pattern.

One more Notation:

There will be a potential period of strong  and possibly damaging winds in some of the valley locations including Crowley between Monday and Tuesday. More on the strong wind possibility’s in a later discussion Sunday as more information arrives from the National Weather Service.



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.

Last really mellow day today then winds on the increase as well as temps this weekend…..Storm/Timing still good for next week!

All large scale features still preforming well as forecasted, with upper pattern morphing toward a temporary REX block near the dateline Sunday afternoon. This is always good for the generation  of tropical and subtropical moisture for storms to feed upon at a later time.

 The eastern pacific upper ridge continues to progress into California as it becomes squashed over the area Saturday. On a smaller scale…..heights increase over Mammoth this weekend as  a short wave moves through the pacific northwest. This has the effect of increasing winds at 700mb and so it will be quite breezy over the upper elevation Saturday and at the same time, temperatures will actually be warmer.  By Sunday afternoon…the ridge axis shifts east into the Great Basin and the door opens to high level subtropical moisture along with stronger gusts over the Sierra Crest. The new 12z Friday GFS has a lot of upper level moisture advection at 700mb (rh) rushing in during the afternoon Sunday….so it is possible that although Sunday morning may be mostly sunny……then by the afternoon cloudy. 700mb winds will continue to increase Sunday PM.

Synoptic scale timing: 

Just using the new deterministic 12z Friday GFS for timing. 700MB (rh) has slug of mid level (50%) moisture into the Sierra after midnight Sunday night increasing to 70% by Monday mid morning then up to 90%  by late afternoon Monday. Initially, this is moisture advection without any dynamics from the subtropical 1st short wave.  Nevertheless, orographically induced light precipitation is possible as early as Monday morning with the chances increasing during the afternoon.  The actual energy and dynamic lift from this 1st subtropical short wave comes through during the early morning hours Tuesday. Thereafter….a larger scale Trof deepens with a vigorous cold front coming through Wednesday afternoon with heavy snowfall both frontal and pre-frontal. Snow levels may drop to 3500 feet by Wednesday night.  700mb winds natural to the Sierra may keep orographically induced snowshowers  going up to about 9 to 10z (UTC) Thursday am.  It is still too early to really predict how much snow we may get. However, the Dweebs have a 1st call of 2.5 feet over Mammoth Mt. by ooz Thursday…..just a guess at this time.

Longer Range: 

The longer range models still has the long wave ridge in the mean back between Hawaii and the dateline which is good. However, the GFS is beginning to display typical characteristics of Spring with an incipient trend of cut off lows during week 2. Once we get to March which typically begins cut off low season, week 2 reliability begins to diminish.  Additionally…looking at the fantasy charts of the GFS, the energy coming off Asia and Japan becomes split.  This often times creates a split flow pattern for the west coast. Of course, where the split occurs is what is important.

Although March is typically a very wet month on the average, this is an La Nina year. La Nina winters are usually more intense but shorter precip seasons. It may be that Cut-Off low season will begin earlier this year?

Future timing of “significant energy” through west coast “week 2”.

1. Night of Friday the 18th

2. Thursday morning the 24th


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.