Warmer Weather on the way as the Upper High over Co Expands Westward……Isolated Thunderstorms to Return over Mono County this Weekend into Next Week….
Friday July 20, 2012
Posted at 9:16 am by Howard
Monday Am Update:
Yesterdays storms dumped up to an inch of rain along the Highway 395 Corridor. Here at Mammothweather.com .09 hundreds and so Mammoth and northward was really the cutoff in the northward extent of the precip yesterday. Today the area of best focus is shifted north from Yosemite/Tioga northward. Again this is the area of best focusing…however, conditions are still favorable for Thunder and rain here in Mammoth and for that matter all of Mono County.
The Dweebs wanted to mention that there was in addition, lots of nocturnal activity on the west side of the sierra all night. An area of convectivity from about Merced that moved northward is now located over Lassen County. There were 1,000 of lightening strikes overnight on the west side of the sierra.
Showers develops this morning here in the Mammoth area. .02 hundred’s dropped here at the village at Mammoth. More rain is expected today. Temperatures will be in the 70s today here at the 8000 foot level. Dew-points are in the low 50s. FYI, Dewpoints in the 50s is an area moistures wise that is usually associated with Rain and Thunder in July.
The current thinking is that the weak Trof located near Monterrey Bay will pull mostly northward today. There is quite a bit of drying that has pushed into Western Ca already. This drying at 700mb will advance into the high country over night and into Tuesday for a dry and warmer day Tuesday. Tuesday highs will climb into the low to possibly mid 80s as 500mb heights are higher. Fair weather is expected to continue into Wednesday with an area of weak instability that may regenerate some isolated Thunder Thursday and Friday followed by a Dry and Fair weekend.
The longer range outlook for the early part of August is for an increase of wet thunderstorms for the high country.
Sunday AM update:
A moist pool of 700mb RH has pushed west and north overnight into Southern Ca then north into the Southern Sierra. This is from last nights collapsing thunderstorms over the desert southwest. The moisture has been pulled north due to an weak upper trof off shore that in itsself will pull well north tomorrow. The resulting upper flow is due south today over Mammoth. The stability indices from the WRF show a negative lifted of about -1.5 over the crest and about a -2 over the whites. Cape is 1000 J/KG so there will be plenty of buoyancy for thunderstorms…. However with all said we did have some air mass modification yesterday. Several rain shafts were noted behind Crowley Lake yesterday during the late afternoon.
Forecast: Isolated Thunderstorms late AM or early PM then Widely Scattered TSRWs especially mid afternoon. SW flow will develop later today that will tend to push the storms that will form over the crest east by late afternoon. The action will pick up near Crowly Lake and especially over and east of the Whites as lifted’s are as high as -3 over Western NV Expect a high of 81 today in Mammoth.
Saturday AM Update:
Warmer weather is continuing to develop over Eastern California as evidenced by warmer temps yesterday. The high temperature reached 76 degrees in Mammoth or some 7 degree warmer than the day before. Today Saturday will warm another 6 degrees and highs will push over the 80 degree mark again this Summer. With the extra heat comes air mass modification. Vertical motion in the atmosphere will provide a gradual moistening and so we are back in the regime of Isolated thunderstorms each afternoon and evening hours. The chance of rain or the amount of rain will be dependent upon both the amount of air mass modification and the lack of southwest flow….as if the drying flow is strong enough, that dampens the effects of air mass modification by providing drying each and ever day. So the thunderstorm forecast as far as coverage and location will be dependent upon the strength of the southwest flow…IE the weak trof off-shore. At the moment, the new 12z Sat WRF has an increase of “Precipitable Water” over Eastern Ca. So the current guidance does infer that Air Mass modification will be successful over the next few days from the point of view that it will be successful in increasing areal coverage in the next day or two.
Very pleasant weather continues in the high country. The high temperature at the Village at Mammoth was 69 degrees Thursday. There were a few showers around with lots of mid level cloudiness noted. The cloudiness was partially responsible for keeping highs nearly 10 degrees below normal. This mornings low diped to 52 degrees.
This mornings 12z maps showed no surprises. The upper high centered over Eastern Co will expand westward into the Great Basin becoming more east-west oriented with time. At the same time, weak trofing over the cold waters over the Eastern Pacific will act to suppress the effects of any serious moisture moving into Central Ca by its southwest flow. So monsoon moisture and its associated instability will remain mostly SE of our area according the blend of model guidance at this time.
With that said, we will warm up a good 5 to 10 degrees over the next couple of days with a few more degrees of warming Sunday and Monday. It is likely that a combination of the seasonal heat returning, along with some increase in moisture and instability to allow enough air-mass modification for Isolated or even Widely Scattered Thunderstorms to develop over the high country and especially along the Mono County convergence zone to the east of the crest, as Southwest winds clash with the southerly flow coming up from the Owens Valley. This is all typical July Weather. The Summer so far has been highlighted by the typical four corners high being displaced a bit far to the east. The Dweebs feel that this is in part due to the -PDO and over lying troughing over the Eastern Pacific. This seems to have occurred, “more often than not”, keeping temps over all, a bit cooler then normal for the Summer with less thunderstorms than normal. This has been a positive for the forest as there has been less dry lightening so far this Summer.
This weekends weather will be highlighted by another attempt by the Continental Upper High to warm us up again by expanding westward, while bringing a little moisture with some Dynamics in at the same time. Air-mass modification will likely allow an increase of thunder by Sunday for the high country and to the east.
No significant changes in our weather is expected over the next 5 to 7 days…… Expect High Temps to average in the upper 70s to near 80 and lows in the upper 40s and low 50s……..
Dr Howard and the Dweebs………………………………………….:-)
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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.