Weak Little Upper Low Getting Nice Kick From Upstream System Near Dateline….Longer Range Models Are Suggesting Change!

All short term models this morning are continuing the trend of a nice little system bringing light amounts of snowfall to the Eastern Sierra Sunday.  QPF was boosted by CRFC to between .5 and .6 between Huntington Lake and Yosemite for Sunday. That’s probably good for 6 to 8 inches over the Crest and 3 to 5 inches in Town.  The system is slowing down and so although Snow may begin falling as early as Saturday night, it is more likely Sunday morning. The upper ridge behind the small upper low will Amp along 135west and allow another short wave to drop down the west coast from Washington State. The new 12z GFS has the front left exit region of an 110knot upper jet approaching Mono County Monday morning and so although not in the forecast at the moment…some possibility of some snow showers may redevelop later Monday morning or pm. 

Thereafter, there appears to be an Arctic front that will back door us Tuesday/Wednesday. Its a cold bugger too with 500mb-1000mb thickness of 522dm along the Mono County Border Wednesday morning!  If this verifies….There will likely be some snow coming off Nevada NE to SW. (Up-slope)   I do not believe the the models have a real good handle on it all yet.  The main message here is that slow retrogression is occurring the first week of February and stronger amplification with further retrogression is in the models the second week of February. 

The Hemispheric Pattern Is Looking to Change!

Stay Tuned!!!

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.

East Coast Storm to Move Off Shore Opening Up The Wave Length A Bit….Snow Showers Possible Sunday…..Retrogression Now In The Cards…..

There is the beginnings of a possible change in the pattern this morning…. One that won’t immediately bring us significant snow, but one that, at the least, begins the process with retrogression of the longer range.

In the short term….. The big east coast storm is now moving out to sea and the wave length is opening up across the CONUS, thus the west coast ridge will temporarily weaken.  The ECMWF has the 2nd weak upper low sliding down the west coast rather then moving into the pacific northwest diving toward the Rockies. This is a major change in the way the EC handles that weak system. The importance of this, is that now, it is at least closer to the thinking of the 06z and 12z GFS and this mornings 12z NAM. Now all the models generate at least a little light snowfall over Mammoth Sunday. It is not expected to be much…..possibly a dusting to an inch or two, but at least something.  Of more importance is the notion that in back of this weak short wave is the sharpening of the west coast upper ridge back out to 135 west, next week. This may be more significant as we go into the month of February as some sort of retrogression in the long wave is the most likely scenario prior to either a storm coming into the Sierra from the Gulf of AK or some undercutting of the westerlies. However with that said the deterministic 12z run of the GFS progresses the long wave back to the west coast again next week. However, a significant number of both the ECMWF and GFS ensembles create retrogression to 140W.

Additionally toward the end of week 2, the GFS REXes up over the Aleutians at 160w by the 8th.  This is some thing new and will have to be watched……as if it is persistent and strong enough, the down stream effects would be profound.  All the models are saying, is that a change is coming in the next couple of weeks. However, it does not mean significant snowfall for Mammoth yet.

————————————————-
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.

No Change In The Current +Phase PNA Pattern Across The Western Hemisphere….Small Feature May Give The Sierra Some Snow Showers Weeks End

+Phase PNA all the way….That is about all that I can say…..Today.

Actually;

Not a lot of excitement out over the far west. The little feature coming in Saturday night into Sunday would be regarded as nuisance weather a few weeks ago. Today it is big news, as if it comes in like like last nights 06z GFS and this mornings 12z ….it might bring in some snow showers Sunday afternoon and night……Wow!  However, the ECMWF model has it well east of here. Officially, there is nothing in the forecast from NWS precip wise for this weekend.

High temps in the Town of Mammoth will be the  low to mid 50s through Friday, then mid 40s Saturday and then upper 30s to low 40s Sunday and Monday.  Over night low will remain in the 20s until the end of the week when they will cool to the teens into Monday. Sierra Crest winds will be pretty light after today/Ngt until the weekend.

Unfortunately, the current pattern is really entrenched with a very cold and deep Hudson Bay Low well anchored and effecting the eastern CONUS with the other anchoring upper low south of the Bering Sea. This may end up being one of the coldest eastern winters since the mid  70s!

When will winter come back?  Well….its hard to say when. However, it will come back.  The second half of February is a good guess. A better guess is March when the Sun is higher in the sky which will eventually break up the thermal anchoring  Hudson Bay Upper Low.  

We’ve been here before….

The good news is that the Sierra still has a tremendous snow pack!

Interesting recent note from Jan Null past lead forecaster from WSFO SFO:

“Second, through the end of December, San Francisco had 11.65 inches of rain.  Looking at the long term history for San Francisco, this would be the 36th wettest first 6 months of the rainfall season.  What has happened in the past with these wet starts?” 

There have been 40 years when the July through December rainfall in San Francisco was at least 11.00 inches. Of these only 6 ended up with below the 160-year seasonal average of 21.89 inches.  

The Dweebs Comment:

So there is still a lot of good odds that this winter will come back or…….about a 15% chance that it will be dryer then normal….(for the bay Area)

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.