Archive for September, 2019

After a Beautiful Start to Fall….Weather pattern to turn cold over the weekend with snow showers possible….weather to remain colder than normal much of next week…..

High temperatures moved into the low 70s in Mammoth Wednesday and will remain in the low 70s for Thursday as well. However a strong cold front will invade the Eastern Sierra Saturday morning with much cooler temperatures, rain showers to begin with then snow showers possible developing later Saturday.  Light snow showers may continue through Monday AM.  Snowfall accumulation will be light. Somewhere in the 1 to 3 inches range over upper elevations… Will fine tune this again Friday.

 

The Northward expansion of the Eastern Pacific Ridge supports the coming highly amplified pattern that is forecasted by all global models. they feature a strong ridge developing just west of 140W, with a long wave trof deepening as a result near 120 west.  In that the upper low is centered over land, over water trajectory is limited and precipitation will be light. However, the system is anomalously cold for this time of the year. In fact the 500mb heights sigma is some -3.5 by Saturday night over Mono County. By early next week, the upper trof  shifts east and weakens allowing temps to rise somewhat by mid week.  It will still remain quite chilly at resort levels….there is another system and cold front that will come through Thursday or Friday later next week.

 

BTW;  snow levels will lower Sunday and Monday to the valley floors…  But don’t expect much Snow.  Hard freeze conditions are likely beginning Sunday night into Tuesday.

 

Is this the end of warm fall weather?….Absolutely not.

We will have an Indian Summer!!

 

Dr Howard and the Dweebs……………………….:-)

Cool Breezy weather for Monday with warmer weather mid week…..Global models trending drier for next weekend system….with cold showery weather more likely…..

9/24/2019:

Forecasting week two periods

Forecasting week 2 periods can be tricky as we all know. We can all use the ensemble members as well as the various global models plus an extra tool called the MJO.

When the Global models are all in agreement that a cold trof will deepen down the west coast, a lot will depend upon how west the long wave is for precip odds, as well as where and how the upper jet set up.. In the case of the last 7 days, three of the four global models showed the upper low remaining off the west coast, far enough for a good SW fetch and precip several sigma’s of normal.  As of this time, we have learned that a east ward shift in the long wave is going to result in a trof that will be plenty cold, but much dryer than what was earlier thought. To give credit due, the american GFS was more correct all along….with a more easterly set up.

 

Lets see how the MJO fared in the upcoming change for this weekend.

 

  1. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtm

a. The MJO has stalled in phase one.

2. Lets see by the composites what we can expect temperatures for this this time of the year

 

 

As you can see the composites are really forecasting this change to much colder weather quite well for this weekend.

 

3. Now lets see what the MJO show for precipitation;  (phase 1)

 

 

Once again there is a weak signal for precipitation as well for this time of the year with the MJO in phase one.

If the current guidance is correct for the weekend, we will have a cold weekend with well below normal temps and light precipitation according to the latest guidance.

 

Now here are the 200hpa lagged composites…  Not much help as you can see…  actually October might have been a better match.

 

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Monday AM 12-23-2019

At least the MJO forecast is correct in showing a cold 6 to 10 day period with a weak precip signal for CA. for Phase 1 in September.

Welcome to the first day of Fall…..

12Z GFS came in drier again this morning……And now the ECMWF is following suite with a cold cold weekend and snow showers. Don’t expect a lot of snow…But some 2 to 4 inches is certainly possible in the upper elevations over the weekend.

 

The trend suggests a cold showery weekend into early next week.

 

Dr Howard and the Dweebs………………….:-)

 

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The forecast remains unchanged for the next 5 days…..However, global models have been trending more toward the GFS earlier solution with the upper trof setting up further east.  The results of the trend would be more of a cold showery pattern for Mammoth next weekend and light amounts of snowfall Friday and Saturday the end of next week…..(1 to 6 inches).

 

Stay tuned….

Beautiful Weekend……Breezy Sunday PM…Then Fall to begin with brief heat wave Tuesday-Wednesday…..MJO Stalls in Phase one with Winter Like weather the following weekend….

9/21/2019

No changes in the forecast through Mid-Week.   IE.  Warming Through Sunday. A little cooler Monday and warming Tuesday Through Wednesday.  However, with a strong Trof coming in Friday and antecedent warmth due to the anomalous warmth mid-week, a possible wind event is in the cards for either Thursday or Friday. Critical Fire Weather?

Prospects for Snow the weekend of the 28th:

  1. Forecast Models ECMWF, Canadian and JAMA all show the same Trof in a position to give a healthy amount of snowfall that weekend beginning sometime Friday. The outlier is the GFS  which gives only light amounts (1-6 inches) as the Trof sets up further east. Snowfall amounts by the end of next weekend;  The ECMWF is the strongest with between 1 and 2 feet over the crest, with its control run last night. However, its ensembles only show up to 6 inches. (on Mammoth MT)
  2. What is so supporting in this extended range outlook is the fact that the MJO stalls out in Phase One, Which for this time of the year shows a California signal for Cold and somewhat wet.

Much More Later next week!!

 

Dr Howard and the Dweebs……………………….:-)