10:15AM Thursday the 3rd.

Yesterday, a system droping south from the mid-west to the Texas Panhandle spread cooling through the desert southwest where it reached the Eastern Sierra over night.   As a result, it was a cooler morning in Bishop CA with a low of 18 degrees and Mammoth with a low of 16.  Today, as the result of that same cooling, it will be about 8 degree cooler with a forecasted high of 50 in Mammoth Lakes.

As mentioned in my discuession below, the west coast ridge is in control. However, with that said, there are at times when there are weaknesses in the ridge that can allow short wave energy to makes its way to various areas. In our case, the weather the end of this week shows just that. Although the models handel a small area of low pressure differently. They both agree to the idea of around .01 to .03 inches of precip as indicated in their quantitative precipitation forecast. (QPF) for as early as Sunday afternoon or as late as the following Monday.  Its a small feature, but one that both the GFS and ECMWF models bring a much cooler thickness pool over head between Sunday night and Monday. As a result, Monday will see highs down into the 40s.

Long Range:

Looking at last nights GFS ensembels 5 day means, the current planetary Rossby Wave Train across the Central and Eastern Pacific eastward to the East Coast shows a strong negitive tilt, negitive height anomaly (Long Wave Trof)  near the Dateline with a positive tilt mean ridge position over the Far Western States and another trof stretched out from the Southern States to the SE. Over the next 7 days, the trof over the central pacific retrogrdes a bit west while the trof over the SE progresses east.  This causes deamplifacation of the pattern over the west, that results in a split flow pattern of which,  results in a trof over Northern Baja. This does not get us where we want to be pattern wise.

Over time, (Week 2) the upper height anomaly over the west, retrogrades off shore to 135W. (mid month)  We are then back in a pattern of NW sliders much like in November. Storms on this track can give us light to moderate snowfall if current guidence varifies. We on the east side of the Sierra normally do not get big storms with heavy precipitation from NW sliders or from lows that spin up and drop south down the west coast.

Inter seasonal:

For whats it worth, the Climate Forecast System (CFS)  Shows Preciptation developing over Norththern CA during the 3rd week of December with that field shifting south into Central CA the last week of this month.  This time frame is out of the relm of the week 1 and week 2 extrended forecasts from the GFS ext and ECMWF.  The MJO forecasts are of no help for signifacant precipitation during that time frame.


Stay Tuned…..Keeping one step ahead….:-)


Our pattern over the far west is about as dry as one could be for December…..The MJO Phase 4 and 5 composites teleconnects to a ridge over the far west. Being that the MJO is forecasted to stall over the Maritime Continent, prospects for the continuation of dryness is indicated for another week, possibly two..   However, even so, there are a few possibilities of some light snowfall.  Both the GFS and the ECMWF to a weaker extent, drops a cut off low south through Northern NV late Sunday night into Monday and another around the 11th of December through inland Northern CA. These are not storms from the west as the active storm track remains well to our north. Rather, small amounts of energy, progged to come through an area of ridge weakness. The track if one would develop would be either the colloquial inside slider, or the California slider that are inland, west of the Sierra Crest from Northern CA. These systems if they do develop, are for the most part, moisture starved and without any pacific moisture tap. However, they do offer the possibility of light amounts of precip. (1-6) inches, if they are positioned favorably.


More Later………………:-)


Dr Howard and the Dweebs……………..:-)

Reporting and WX Forecasting for
Southern Mono County Weather since 1980.