Friday 8:30AM Update:

Main changes to the forecast for the weekend include the slowing of the storm, more emphasis of precipitation for the Central Sierra now instead of the Northern Sierra.  QPF for Yosemite is about 1.5 inches of H2O eq.  Mammoth Mountain is store for at least a foot of freshes over all. The upper mountain may experience some rain-snow mix with the onset of the storm’s precip Sunday. The freezing level is quite high at 11,500 at 10:00am Sunday, but will fall to 10,000 feet by 4:00PM Sunday. The snow level will be about 1000 feet below the freezing level. Expect precipitation over the upper part of the mountain will change to all snow during the afternoon Sunday while the lower elevations will experience most likely either rain-snow mix or very wet snow by late in the day….  The strongest winds will be Sunday.  These winds will be strong enough in some areas to cause some damage along the highway 395 corridor Sunday.   The colder portion of the storm will arrive for the most part after midnight Sunday with the freezing level crashing later Monday morning. Snow will begin to accumulation in the Town of Mammoth Monday morning with a plow needed during the day Monday. Between 3 and 6 inches is expected in the Town of Mammoth Monday. Highs in Mammoth Monday will be in the upper 30s in town.

Storm behavior:

  1. Storm will be moving into a record warm air mass,  Pressure gradients will be very steep and winds will be strong Sunday as a result.
  2. The trof will begin splitting Sunday with a closed center forming Sunday night well west of the Bay Area. The split will have the the effect of developing the bulls-Eye of precip further south over the Central Sierra. The closed center will come on shore over Monterrey and Mammoth will end up on the NE quad of its upper divergence. So Mammoth will greatly benefit from this change of the behavior of this storm. It would not surprise me if we got 1 to 2 feet on the upper mountain, but the forecast is for a warm storm 1st that will begin as rain on top of the mountain then change to snow within hours. The slowing of the storm and its closed center will allow a period of upslope Monday which will favor the Town with its easterly flow, and could prolong precipitation well into Monday.
  3. It will be much cooler after this storms passage with seasonal temps for Mammoth. Highs in the mid 40 and lows in the teens and 20s.


Longer Range:

Another splitting trof will effect the high country mid-week but will be dry. There is the chance that a closed low will develop from this storm off the Southern CA coast and become stationary, only to be picked up by a stronger Trof the end of next week…..Stay Tuned….the Dweebs got you covered………:-)





Although the Thanksgiving Holiday will be much milder than normal with a late November Heat Wave for the southern half of California, the next storm system this morning is showing up to be a potentially better storm than what was indicated the past 5 days for the period Sunday through Monday. The upper jet’s right rear entry region now favors the Central Sierra later Sunday night into Monday morning and the QPF by both ECMWF and GFS has this system showing the potential of bringing significant snow over the upper elevations later Sunday into Monday night.  Additionally, both Global models the ECMWF and the GFS  are more in line with the storm coming through in two parts. The first part with feature a warmer system Saturday and Saturday night with strong winds and the second portion colder for late Sunday afternoon into Sunday night. The models are also consistent in showing the snow levels falling rapidly behind a strong cold front early Monday morning. Although this system is still some 4 to 5 days away, moderate amounts of (6-18 inches) are showing up as a possibility for the very early next week period by the two global models this morning.

Again the Dweebs want to emphasize that the antecedent conditions of near record warmth prior to the weekend will precede this systems arrival.  Thus, exceptionally strong winds are possible to develop Saturday into Sunday over the high country.

In the meantime, enjoy the beautiful holiday weather this week. Expect highs in the upper 50 to low 60s, with lows in the 30s Wednesday through Saturday with winds coming up Saturday and rain turning to snow Sunday through Monday AM.


Happy Thanksgiving to all from

Dr Howard and the Dweebs……………………..:-)