High Latitude Blocking Over The NW Territories Combined with Long Wave Ridging North Of Hawaii Will Keep The Upper Jet Suppressed Into Northern Ca In The Mean
Tuesday May 24, 2011
Posted at 9:37 am by Howard
Yes…we still are being effect by a blocking pattern. The positive height anomaly north of Hawaii combined with above normal heights over the Northwest Territories will keep the upper jet stream in the mean suppressed over Northern Ca. That means that Central Ca will be subjected to periods of unsettled weather with periods of nice weather too! Today is an example of nice weather with highs in Mammoth expected near 60 degrees by afternoon. However, the short wave upper ridge responsible for the nice day will translate east tonight giving way to another chilly air-mass that will mainly effect Northern Ca as far as precip and much cooler than normal temps.
For Wednesday…..an upper trof will move through our area bringing another windy period with showers possible Wed afternoon and some light snowfall Wednesday night. The models still show the possibility of at least a moderate wind event Wednesday afternoon. The new Tuesday 12z WRF has the strongest gradient from Central Mono County south through the Owens Valley. The Owens Valley may really get hammered by strong down-sloping winds during the late afternoon and into the Evening hours Wednesday. The NWS has hoisted High Wind Watches for both Mono and the Owens Valley for Wednesday afternoon and night.
As far as the upper elevations….700mb winds peak about 45 to 50knots, so sierra crest winds will gust 90 to 100mph late Wednesday afternoon. The FROPA will occur during the early evening hours over Mono County. Some light snow is possibly Wednesday night with a dusting possible as the snow level drops to 6500 feet.
FIRST LOOK AT HOLIDAY WEEKEND:
The weather over the weekend is still “without” a lot of confidence. The American models (GFS) has the weather much milder then the ECMWF. Looking at this mornings GFS Ensembles from the 00z Tues run…the HT 500 mean heights are around 570dm in a cyclonically curved flow indicating that the weather may be breezy….cooler then normal but dry. The lowest heights in the trof over the far west is over Washington State. By Sunday, the jet does drop south with unsettled weather returning.
The ECMWF is a different bird. It has HT500 heights in its ensemble of 564dm….capable of showery, breezy weather for Mammoth. Air-mass temps would be some 6 degrees cooler and with the potential of more cloud cover, so it could be an additional 5+degrees cooler as well. The ECMWF has this positive tilt chilly trof plunging south through California through Sunday afternoon and it could be quite active. The trend of the ECMWF has the long wave trof reloading early the following week with a cold snow producing system sweeping through Mammoth the very end of the month. The GFS is much weaker with that trof.
Energy still coming off Japan:
In using Hovmoller’s Western Pacific surface cyclogenesis studies, the first cyclonically curved isobar crosses 140east on the 27th of May. The important issue is, that this system really bombs out. Thus….there is some serious support in the Dweebs estimation for the Tuesday/Wednesday storm a week away.
Stay Tuned to see how this all works out!!
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.