Archive for August, 2012

Weak Subtropical Ridge Builds into California Today for a little Warming…..A bit stronger West Coast Troughing Expected Next Few Weeks….So the Far West Portion of the Monsoon will end for the Central and Northern Sierra……

Quick Update Monday AM:

No change in the current pattern Sensibly…  Trofing off shore will eject west Tuesday night for a bump up in the SW flow aloft. So it will be a bit breezier Tuesday. The outlook for the week is for very dry conditions with slightly above seasonal highs.  Expect is mid to upper 70s in Mammoth through the holiday. Night time lows in the upper 30 to low 40s. SW breezes to 25 MPH. No precipitation in the forecast for the next 7 days.

It may warm up a bit next week as models hint at a westward shift in the upper ridge.

 

 

The Dweeber………………….:-)

 

Although a flat subtropical ridge is building into California today….the guidance is showing more troughing off shore over the coming weeks as we move through late Summer.  Daytime highs now in the mid to upper 70s will a drift a bit lower later next week. As a result, there may even be some night time lows in the 30s in the drier air after mid-week. Needless to say, with a stronger southwest flow aloft, monsoon moisture will be shunted to the east next week, well south of the Central Sierra. Furthermore…..Longer range suggests that because the western periphery of the subtropical ridge is coming at us from the southwest…..the AZ Monsoon is pretty much over for the Central and Northern Sierra for the next week or two. By then, the Climo suggest more troughing anyway.

So…with the exception of a maverick closed low split off from an approaching west coast trof, drifting across the Sierra to the south of us, or moisture from a dying hurricane headed north…….Thunderstorms if any, will be very isolated over East Central Ca.

Daytime highs now in the upper 70s will drift lower next week and remain mostly in the Mid 70s then during the first week of September drift into the 60s for a time, as stronger troughing moves through California around September 4th.

 

The Dweeber……………………………………………:-)

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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.

Weak Spliting off shore trof will allow a small upper low to drift through Southern Ca Wednesday/Thursday…..Expect a brief period of Airmass Modifacation to develop Wednesday for some Showers and Thunder…..Rest of the week looks dry with slightly above normal temperatures……Then Southerly Flow may move back into the Southern Sierra about Mid-Week………

Quick Thursday AM update:

Looking at the short,  medium and longer range Guidance…..Monsoon season for the Central Sierra may be winding down. The guidance is showing more troughing in the extended for the west coast which will tend to keep more of a SW flow aloft over the Sierra. This is a dry pattern for the most part. That is unless another of those little buggers closes off and comes in like yesterday.   Even so, PWAT will likely be less.Expect fair weather for the next 7 days with afternoon breezes into the evening hours.  Highs in the mid to upper 70 and lows in the 40s.

 

Longer range shows below normal temps beginning just after mid Sept associated with stronger trofing off the Pacific North West coast..

 

The Dweeber……………

 

 

Wednesday Am Update:

It was a pretty sleepless night last night as numerous thunderstorms developed over the southern sierra then moved over the south central sierra at about 1:30Am. This occurred as the weak upper level low that was supposed to come in over Paseo Robles came across Monterrey Bay last night…..Dynamic forcing, strong UVM and upper divergence occurred over the southern and south central sierra. Mammoth picked up .29 hundreds of an inch of rain and there were over 310 lightening strikes recorded over both the west side and east side of the Sierra. Certainly not good news for fire agencies…..

At this time, the upper low at 700mb is centered over the south central San joaquin valley. However dynamic forcing associated with the cyclonically curved upper jet has now pretty much moved into Nevada.   So isolated storms will be generated by heat today VS dynamically driven last night.

It will begin to dry out tomorrow Thursday and be fair through the weekend with highs in the upper 70s…..lows in the 40s.

 

The Dweeber…………………….:-)

 

 

Latest guidance is showing a split developing in the off shore upper trof. Latest 06z GFS has the upper center crossing near Paso Robles, Ca Wednesday AM,  between 12z and 18z.  At 500mb the upper center is 584dm. The track should take it SE through Kern County and the Mojave desert,  throughout the day Wed and into Thursday…..exiting about noon Thursday through the Ca/NV/AZ borders.

As the low approaches the coast late tonight and Wednesday morning………a rapid increase of southerly flow is expected into the southern Sierra and extreme south Central Sierra. Moisture and dynamics will briefly increase chances of isolated showers and thunderstorms. The deepest moisture should remain to our south over Southern Inyo County….then SE over San Bernardino counties. This looks to be a one day event for the high country of Southern Mono County as drier air works back into the high county Thursday. Temperatures will cool slightly to the mid 70s. Lows in the upper 40s.

Outlook through the rest of the week looks pretty nice with highs back near 80 with lows in the mid to upper 40s. Expect the usual afternoon zephyr breezes.  Next change in the pattern begins to develop the very end of this week or the following Monday as the upper high over the four corners redevelops and the toasty 594Dm at 500mb height line pushes west into SE California again this summer.  Monsoon moisture may surge one last time into the Southern Sierra for isolated TSRWs about the middle of next week with high temps back into the low 80s as we finish off the rest of August on a warm note……

 

 

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.

Stronger SE Push of Moisture Today Will Increase Odds of Rainfall in the Eastern Sierra….Precip Threat Continues through Saturday Night with Drying being Delayed Now Until Sunday Morning……Sunday will be a Bit Breezy with a Reduced Threat of Showers….Dry Weather is Expected Monday Through Wednesday Next Week….

Quick Update Friday:

Latest guidance shows a weak upper jet at 250MB over the northern Ca along with a VT max/ upper wave moving north off shore.  Monsoon moisture and air mass modification will continue through Saturday afternoon with Precipitable water increasing to over an inch here in the Mammoth Area by Saturday. Odds of measurable precipitation will increase to 40% for showers and thunderstorms today. Saturday is somewhat of a question as there is so much moisture that if we do not get much daytime heating there would less chance of thunderstorms and a greater chance of just showers. We call this condition (over-developed). Nevertheless, showers are still expected through Saturday night and there is always the possibility of a few of them to be locally heavy.

Daytime highs will average 75 to 80 and night time lows 45 to 55 Friday.  Saturdays highs will be cooler with the anticipation of more cloud cover, so low to mid 70s.  Again….Some showers have the potential to bring locally heavy rain later today Friday and into this evening. And again Saturday through Saturday evening. Storms are expected to push off to the east Sunday afternoon with increased SW flow aloft. There is a 20% chance of showers Sunday…..mainly before the afternoon.

The outlook calls for dry weather most of next week with the return of zephyr winds. Daytime highs will be mostly in the mid to upper 70s next week.

 

Next update Monday..

 

 

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.