Unsettled weather to continue through this weekend and into next week as long wave upper trough remains a fixture over CA….
Friday May 15, 2015
Posted at 7:38 am by Howard
Monday AM: 920AM
Looks like another very active day today..
SPC shows a very strong 250MB Divergence-850mb convergence couplet over the Owens Valley at the moment associated with the 300mb cyclonically curved upper jet to the south. Best Surfaced Based Cape is located along the CA/NV border and SE Inyo County 500-1200 Joules per Kilogram (J/KG) according to the 14z HRRR 3km. (Rapid Refresh model) 850/500 crossover MULI lifteds are -3 over SE Inyo County. It all adds up to some strong thunder storms developing near Death Valley and to the NW of that area today. Best 850 surface deformation is over Southern Mono and south to Northern Inyo County. Good Thunderstorm potential over Inyo County Today…especially over the Southern Whites Mts…
The HRRR forecasts up to 300 J/KG over Mono County today and so air is not nearly as Buoyant and unstable. Nevertheless, deformation enhanced showers quite possible this afternoon for all of Mono County.
Dr Howard and the Dweebs…………………….:-)
Another system is currently moving in….snowfall to pick up later this morning and continue into tonight. Some thunder possible. Accumulations in town above 8000 about an inch with several inches over the crest today and tonight…..This pattern of on and off again rain and snow will continue through much of this coming week. It will be all snow on Mammoth Mt. More snowfall expected Monday in the shorter term…. highs in the 40s lows near freezing….
1. Increasing divergence over Mono County Today
2. 850mb deformation across northern NV
3. Strong 250MB Divergence over Mono County this afternoon
4. (Currently) storms are forming and training northward according to radar, north of Mono Lake along the south border of the Lion County and Mineral County line in Nevada. This is an area of strong 250mb upper diffluence.
Additionally, the SPC 850/250 differential divergence is showing an area of 850mb convergence near the Inyo/Mono County border with the 250mb divergence over Lyon County.
Here is an update on the current and extended pattern in general terms…
The Dweebs looked at GFS means this morning. IE days 3, 5, 8 and 11. The current pattern is likely to last through mid week. Looking at the larger scale, we can expect a continuation of the 500mb block over the NW territories of Canada through Thursday and the 500mb mean upper Trof over the far west. That keeps a rather unstable pattern for this time of the year with the combination of various areas of deformation and actual progressive areas of dynamic forcing aloft. The long wave trough is not as deep as it was with the system that brought up to 3 inches of rain over San Diego and 5 inches of snow to Mammoth MT last Thursday. Snow levels will likely not be as low with the exception of occasional lower level snow showers or snow pellet falls, due to the convective nature of the cells that form. So over the coming days there will be very active periods over the Sierra and Great Basin especially the Northern and Central Sierra eastward. Although none in the forecast, Great Basin funnel clouds can occur during some of the more active afternoons this upcoming week.
Beyond Mid Week:
GFS days 8 and 11 means, move the block westward over Alaska with the results of rising heights over CA. By the Memorial Day weekend the trend’s would suggest more of a diffluent upper flow pattern which is both warmer over California but still offers the chance of some at least widely scattered or isolated Thunderstorm’s. Mule Day temps would climb into the seasonably low 80s that weekend. A mid latitude ridge is suggested over the Rockies in the GFS by the 25th with still some difluence suggesting some isolated late Afternoon Thunder.
However… The ECMWF (Euro) wants to keep the pattern cooler than normal and unsettled through Friday next week. Furthermore……Cooler than normal temps will continue through the holiday, Precipitation will end by Friday night and so Saturday and Sunday for the holiday weekend look fair but some 6 degrees cooler then normal. (Mid 70s)
What the ECMWF does in the their 5 day means next weekend is to Morph the block over the NW territories’ into a full latitude ridge at 140 west by Memorial Weekend with a negative height anomaly over Los Angelus. In that the upper jet is progged N/S off the coast….Some periods of north wind becoming westerly early that following week is possible. High temps are currently progged to be about 6 degrees below normal for the bishop area, or in the “mid 70s” VS the GFS which is more low 80s. The ECMWF indicates a dry pattern for the Owens Valley Saturday and Sunday and into the next week with a warming trend…..
Dr Howard and the Dweebs…………………..:-)
Massive convection boiling north of the equator Wednesday with strong moist STJ tapping the moisture……Arcing across the Big Island of Hawaii then eastward into Extreme Southern CA/Northern Baja. SSTA’s now more then +1C in the Nino 3.4 and warmer east to well over 2C in the Nino 1+2 region. I am sure that the Anchovies are having a difficult time now down under…..
San Diego has receive between 2 and 3 inches of rain in the last 36 hours. .15 is Climo for the month of May.
If it Walks like a like a duck….Quacks like a duck…..But oh how I know……The key is to wait a few more months so not to step on the duck….. 😉
Although the right combination of dynamics did not all come together for Southern Mono County yesterday, Mammoth Mt did manage to pick up about 5 inches of new snow. A few more inches could fall today as well. The brunt of the storm is focused upon Southern Ca and especially San Diego where up to 2 inches of rain has fallen in some areas and more currently occurring….. Deformation zone set up yesterday was too far to the north of Mammoth, more over Northern CA and NW Nevada. The upper low at 7:00am this morning was located near Dayton, NV tracking east. Precipitation is actually moving south along the eastern slopes of the sierra over Alpine County and near Reno and some of that will wrap back into Mono County before too long….
We have two more systems to deal with. Both are warmer than each other, but possibly better from the possibility of Thunderstorms…..
High temps will remain cooler than normal through the weekend with below freezing lows in the morning…