Wednesday AM Update:

Just some fine tuning this morning to our forecast…..

Freezing levels expected at 00z Thursday (Wednesday PM) to be 10,500 feet late afternoon then 8700 at 00z Friday (5:00pm Thursday)

The Snow-level today Wednesday is above 9500….then lowers during the early morning hours Thursday to 8500 and then 7000-7500 by Thursday PM.

By the afternoon Thursday little if any moisture will be left. It still look to be mainly a rain event for the high country associated with the subtropical upper low Tonight/Thursday morning.

CRFC gives Huntington Lake .90 over the next 48 hours and Yosemite .65 the same time. So over the crest there could be 6 inches of heavy wet snow by early Thursday AM with possibly another inch or two of fluff on top of that.  This is above 10,000ft.

Based upon the guidance……only .25 to .30 occurs during the day Thursday after Sunrise……IE most of the precip that occurs is associated with the warm subtropical upper low.  It is thought that any backwash or wrap around associated with the southern upper low itself will be too far south of the Mammoth area for any significant up slope Thursday. With all this said, there is still the nose of a 130knot that will be making its way into Northern Ca Thursday late morning. Mammoth is located in the front Rt exit region of the upper jet. So it will be windy beginning later Thursday morning and especially Thursday afternoon. As the upper jet from the northern low translates east Thursday night into Friday morning winds will slowly diminish. The southern edge of the 70 knot Iso-Tach at 300mb is forecasted to be north of the Mammoth area by mid morning Friday. So it will still be breezy over the crest Friday and Saturday as the back side of the long wave remains over the inter-mountain west….but a nice weekend over the lower elevations of Mono County. Light breezes are expect over the weekend at the 7000 foot level with highs in the mid 60s. (Very Nice Fishing Opener) Need warm Jacket when the Flairs go off before Sunrise, then lighter ware late AM and for the afternoon.  Always good to carry a wind breaker for those afternoon breezes.



Here is the game plan…..

The Upper high now over the four corners area will weaken tomorrow morning. Yesterday was again, a record breaking day with another high temperature record for the Bishop area. It was 90 degrees Monday at the Bishop airport which broke the 1953 record high of 88. No records expected today with a high of 82 in the forecast. The High Temperature at Mammothweather was 68 degrees VS Sunday’s high of 71 which was a 20 year record.

Thunder and moderate rain showers developed during the afternoon do to the 2nd of two southerly waves that moved up from Southern California early in the morning.  The wave was stronger than the one that brought rains to Western NV Sunday late afternoon. No doubt that the record heat in the Owens Valley contributed to the lift!  In the Ol’ rain tip bucket a whole .06 was collected. However, in town to the east, there was much more rain with some water running through the streets.  The Dweebs do not expect another episode like that today. However, some less organized storms may still form over the sierra as a marginally unstable air-mass still exists………

Storms off shore:

Nothing has really changed. However quite the reservoir of tropical moisture well to the south off Southern Baja. Too Bad the majority of all that will not be a player over the next few days…..

Currently the upper closed subtropical low is moving slowly SSE. The upstream kicker will help to open up the the closed low Tomorrow Morning….as at 700mb by 15Z Wednesday a surge of subtropical moisture will flood into Central Ca During the Day.   The Upper jet will be aligned pretty much North/South over Central Ca Tomorrow Am. The Canadian has a VT Max coming through the Central Valley Wednesday. This would be a trigger for rains below 9500feet Wednesday Afternoon. (The Freezing Level is 10,000 Wednesday)  At the 700MB level a closed low opens up into a trof while at 500mb the trof remains closed with the majority of the dynamics staying close to the upper center.  This is one reason why the majority of the precipitation will go to our south as the real jet support with this system is well to our south. In fact, areas from Kern County south to the MX border may have heavy rain!

The bulk of the precip will probably be concentrated right near the upper low itself. This mornings 12z WRF has the upper low and main vort center coming in to the south of TJ, Mex. about midnight Wednesday night.

Now the second system will focus its QPF upon Northern California. The nose of 130knott upper jet comes into Northern Ca well north of the Bay area Thursday morning. The front left exit region is along the Or/ Ca border and the whole dynamic portion of the upper jet including the Rear Rt entry region stays well to our north. By the time the second system comes through little moisture will be left.

The Upshot:

1st system will be rain up to 9500 Ft Wednesday PM as the air-mass will get pretty saturated. Then gradual cooling after midnight will lower the snow level to 8000 feet by Sunrise. Then 7000-ft during the day Thursday. Snow showers a good possibility. As the air-mass dries out Thursday, the spread between the freezing level and the snow level will increase. The Freezing Level on Thursday is expected to be 8000ft so a snow level of 6500 to 7000 would not be unreasonable, however, there will not be much moisture left By the afternoon/evening. I do not expect a General Plow from both system as it will be too warm. Total QPF with mostly rain will be about 1/2 inch. So a lot to do about nothing…..  A few inches of snow is possibly over the lower slopes. The top of Mammoth Mtn might get 6 inches. The town maybe an inch or so…..

Will take one last look Wednesday AM…………..

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.