Weak splitting System On the Way for Friday…Then Dry warmer weekend as High Pressure Aloft Builds In through early next week….
Thursday April 3, 2014
Posted at 9:44 am by Howard
Quick Update to reflect that we have a little upslope going on this AM. NE flow coming into the Sierra, a product of both the upper trof exiting into AZ and the upper circulation around the high off shore that will be building in through Monday evening of next week. No measurable precipitation is expected. IE .01 or greater. Winds over the crest will be out of the NE today. They will be in the 40MPH range this morning than increase this afternoon and into the night. These moderate then stronger winds are only significant over the lip of the sierra. Although sierra crest winds will be significant again Sunday, it will be 10 degree warmer. The upper high will peak out over the top of us Monday at 5:00pm. Tuesday will be the warmest day with highs in the low 60s in Mammoth.
We will be storm free through next Wednesday……..
A weakening system is moving through the Bay area this AM is headed toward the Sierra this afternoon and tonight. It looks to be a fair weekend with warmer temps ahead. It will be windy over the “sierra crest” on Saturday, with lighter winds Sunday. Temperatures will be above normal next week with the upper ridge over head, early to mid-week. Mid 60s in Mammoth Wednesday.
The following are some comments from NWSRNO for impacts in regards to area roads….today/tonight:
LIGHT SNOW ACCUMULATIONS OF AN INCH OR TWO ARE POSSIBLE NEAR THE SIERRA GENERALLY ABOVE 6000 FEET THIS AFTERNOON AS SHOWER BANDS MOVE THROUGH, BUT ACCUMULATION ON PAVED SURFACES WILL BE LIMITED
TO ISOLATED LOCATIONS WHERE INTENSITY AND DURATION ARE SUFFICIENT TO OVERCOME TYPICALLY WARM ROAD TEMPERATURES FOR THIS TIME OF YEAR. SOON AFTER THE SHOWERS DIMINISH, ANY SNOW ON ROADS WOULD
MELT QUICKLY. BELOW 6000 FEET, SOME SHOWERS MAY PRODUCE SNOW OR PELLETS THAT WOULD MELT ON CONTACT WITH THE ROADS, RESULTING IN MINIMAL TRAVEL IMPACTS. BY THIS EVENING AS THE TROUGH MOVES EAST
ACROSS NEVADA AND DAYTIME HEATING IS LOST, MOST SHOWER ACTIVITY WILL WIND DOWN QUICKLY FROM WEST TO EAST.
Temperatures will run below normal until Saturday, when upper heights, rise in response to a pretty strong upper height anomaly peaking out over Northern Oregon late Monday Afternoon. Tuesday next week will probably be the warmest day as the upper ridge axis is east of us over the Great basin and a weak southerly flow sets up. Thus, Tuesday’s highs will probably be in the low 80s in Bishop and in Mammoth, low 60s. There is another weather system that may affect our area about Friday the 11th. The ECMWF Ensembles are a bit weaker with it today, and the GFS Ensembles weaker yet. So I am not too excited about it other than it may bring snow showers and cooling. That in itself is good as the days prior will be pretty warm.
More currently, the weather today shows up with a lot of high cloudiness. A quick look at the Satellite motion shows upper level warm air advection type moisture today making it a mostly cloudy day. There was a CAP at about 500MB on the OAK sounding confirming the inversion. Temps today will be tricky with the high clouds, so although the forecast is for highs in the low forties, it may remain colder. Tomorrow will certainly be cooler with the last system expected this week. It is a weak splitting trof with enough moisture and instability to kick up some showers Friday for a dusting to an inch. Otherwise get ready for a fab weekend. Of note there will be gusty NNE winds over the crest Saturday. This will last only long enough for the ridge to get established, so that by Sunday, the gradient’s should have relaxed quite a bit.
NCEPS CFS still insists that we are not done yet. That before the end of this month we are likely to get another foot or possibly two of snowfall, and that May will be similar. In May, there are signs that there may be a period toward mid month of a cold negative upper height anomaly over the Great basin for Freezing Temps as low as the Owens Valley. In that climatically, we usually do not see a lot more big storms capable of several feet beyond early May….. I will follow this, as that is planting season for the Owens Valley as folks are sensitive to hard freezes.
Note: The Climatology of May is quite different then April. The Desert are pretty warm by May and the effects of Continental heating create a stronger gradient on the east sides of digging trofs, pulling them eastward quicker. Thus long wave features have more bias toward a Negative tilt, creating more NW or inside slider type storms. These are usually windy systems with little in the way of preicp. However they can be very cold!!!