Upper Low that brought rains to the region the past 36 hours will move out of the Desert Southwest Today……The next Upper Low will approach Friday…..

Friday 8:30 AM

 

Some light rain occurred after midnight last night and .04 was recorded in the rain bucket.  Skies were cloudy along the crest and westward this morning with precipitation falling over the Central San Joaquin and Sac Valleys this morning.  The upper low was located just off the coast between Monterrey Bay and SFO. Latest computer model simulations have it almost stationary today, moving on shore about 5:00PM this afternoon. The Track is ESE and the best odds of measurable precipitation will be later this afternoon, tonight and into Saturday. The freezing level lowers to 8200 feet by early Saturday AM. This means we could have snow showers in town Saturday AM.  Although I do not expect any accumulation on our local roads, the high elevation trans-sierra passes like Tioga and Sonora are in jeopardy for between 2 to 6 inches over night into Saturday according to the NWS. So please contact CAL Trans road info for the latest.  Highs in Mammoth will be in the 50s today and Saturday. Lows in the low 30s Saturday AM

Temperature’s and the freezing level will rise rapidly Sunday and Monday!

 

The forecast for Mono County calls for Scattered Showers and Thunder storms today through Saturday.

 

Dr Howard and the Dweebs…..:-)

 

 

 

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May 23rd:  AM Update:

Yesterday was another wet day across the Eastern Sierra with thunderstorms and brief heavy rains. 24 hours amounts 8:00AM to 8:00AM were .25 hundreds. Storm total 1.06, here near the Village at Mammoth.  The upper low is broad and anti cyclonic over the inter mountain west and continues to move away from the sierra. Latest Rapid Refresh Model run from 1400Z shows most of the precip today developing east of the Highway 395, with just isolated showers over or near the sierra today. Further drying is expected Thursday before the next upper jet approaches late Thursday night.  As mentioned yesterday, the models; GFS, Euro and Canadian are trending a bit further south with this system with either the central sierra or southern sierra being its traversing point. This brings the possibility of both the front left exit region of the upper jet effecting Mammoth Thursday night into Friday morning and upper divergence from the upper low itself Friday night into Saturday. Both supply dynamics to the atmosphere in addition to the strong convective potential (CAPE), that the late May sun angle supply’s. IE, there is going to be areas of heavy rain somewhere over the Sierra from this pattern this weekend. Too soon to know where,  as it depends upon the timing of the upper divergence and where it sets up in relation to the where the upper low tracks through Central or South Central CA.  At the moment, it looks like that potential is most likely going to be to our north.  However, the freezing level is lower with this storm; 7500 to 8500 feet Friday night into Saturday and so there will be a period of snowfall possible during Saturday morning in the Town of Mammoth. It is too soon to tell how much. best guess is light amounts. Will update all Thursday AM or afternoon.

New: 9:05 AM….

Latest 12z Wed GFS tracks upper low over Mammoth Late Friday night and so little chance of any sustained upper divergence over Southern Mono County. Most likely well to our north….

 

Dr Howard and the Dweebs…………………………:-)

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It will be another day of showers and possible thunderstorms Tuesday as although the low pressure system that brought moderate to heavy rains to Mono County Monday, has moved into the desert southwest, our air mass remains moist from yesterdays rains. Daytime heating combined with the sierra terrain and a few spokes of vorticity will generate showers and a few thunderstorms today and this evening. Rainfall amounts will be considerably less than the past 36 hours. Further drying will occur Wednesday and Thursday with mainly isolated showers possible.  More sunshine expected Wednesday and Thursday means warmer temperatures and so Highs will return to more seasonal levels by Thursday (60s).

Upper Air:

Upper low at 500mb was located over Southern NV this morning and will lift NE into Utah this evening. Spokes of Vorticity will rotate around the Low today enhancing rainfall. The weather system will be out of the area Wednesday and so only air mass, diurnally driven precip is expected. It will be partly cloudy Wednesday and Thursday with a chance to slight chance of Showers and Thunderstorms.

 

Holiday Weekend:

Changes have been occurring the last two runs in the GFS model on how the next upper low, approaching the west coast Friday is being handled.  The new 12Z GFS is both slower, stronger, wetter and colder with this system.

Will take a look at the new 12Z ECMWF to see if it comes in line with the 12ZGFS later today. If it does, and remains constant the rest of the week….it could be quite wet again Friday, night and Saturday. Additionally, in that the weather system is slowing down, its timing will be tricky.   It will be cold enough for snow above 7500 to 8000 feet. Friday, Friday night into Saturday.

 

Note:   In that this is only Tuesday, this is still considered an outlook and subject to change.

 

Dr Howard and the Dweebs………………..:-)

 

Althrough Mono County Rainfall has been confined to areas north of Mammoth the past two days…..The pattern remains favorable for some showers Friday, Saturday and Sunday afternoon and especially Monday,,,,,

The closed low that brought heavy rainfall to the Reno area Tuesday was located over Eastern NV Thursday night and moved ENE out of the state by morning. The pattern that originated was classic in that Reno and areas mainly north of Mono County were in the favorable NE quad of the upper low that moved in over the Bay Area Wednesday morning. Upper divergence combined with strong daytime heating brought rainfall to many areas in Tahoe, Minden, Carson City and Reno. Amounts were between 1/2 to an inch of rain in many areas.  Thursdays rain showers did not have the forcing of yesterday as mainly residual moisture and daytime heating provided the lift.

Friday AM Update: Today Friday is looking a bit different as the Rapid Refresh Model now shows showers developing long the Sierra Crest south to the Southern Sierra. The focusing will be over the crest then drifting east of the crest late in the day. So there is a better possibility of showers or a thunderstorm in the Mammoth Area today, from mainly diurnally driven convection. Tomorrow Saturday, dynamic lift begins to show up again. On Saturday, a negative tilt open wave moves into Mono county. So far the models are not overly impressed with the pattern with some showers in the afternoon. I will update Saturday AM. The main feature will be what drops in late Sunday as the negative tilt trof over CA reloads and a closed low drops down the coast late Sunday night into Monday. Monday afternoon looks to be the most active rainfall wise for Southern Mono County, otherwise there is a chance of showers and thunder each afternoon but not to a major degree.

 

High temps will be in the upper 50s and low 60s while the lows will range in the very upper 20s and 30s.

 

The Memorial Holiday weekend still looks nice and warm but possibly breezy at times.

 

Dr HJoward and the Dweebs……………..:-)

Small Scale Blocking Pattern will Likely Lock in weak Long Wave Trof over the Great Basin….Chilly unsettled weather the result for the high country this week and possibly next…

A blocking pattern is forecasted by both the GFS and ECMWF. 5 Day 500mb means show upper Trof over the Great Basin while the daily’s keep Vort centers moving counter clock wise around upper low with NE flow into the Sierra. Showers and possible thunderstorms will most likely be diurnally driven with some nocturnal action at times.

 

Expect the chance of showers each day this week, along with cooler than normal temps. The weekend outlook still keeps the chance of showers, however temperatures return to near normal for this time of the year. (Low 60s) The snow level will remain high, between 9000 and 10,000 feet for the most part. There may be periods of grapple with the daytime convection.

Temperatures in the high country are likely to be below normal over the next 5 days

Daytime highs will be in the low to mid 50s while the lows in the 30s…

The Freezing Level is expected to rise over the weekend and so highs will approach 60 by Saturday.

 

Longer Range:

Long Range forecasting is dicing at best this time of the year…..Even two weeks out.  However, for those that want me to take a shot at it, the Memorial Day holiday weekend looks fair, with warmer than normal temperatures.

 

The Dweeber…………………….:-)