Powder Forecast –Tuesday January 22nd, 2019
Ted Schlaepfer CCM —- Mammoth Mountain WeatherGuy
Dry weather is expected for the rest of the week and through the following weekend and likely into the middle part of the next week as well with seasonably mild temperatures this weekend. Dry weather may last rest of January with the next chance for snowfall right around the end of the month or early February with a continued chance over that first week. Powder conditions are not likely again until at least early February, but overall, there are no clear signs for the next the powder day.
Next update Friday 1/25
Snowfall forecasts are valid at the Sesame snow course (Main Lodge) for the prior 24 hours as reported in the 6-7 AM morning snow report.
**Snowfall forecast confidence ranges from very low (1) to very high (5)
Wed 1/23 = 0”
Thu 1/24 = 0”
Fri 1/25 = 0”
Sat 1/26 = 0”
Sun 1/27 = 0”
Mon 1/28 = 0”
Tue 1/29 = 0”
Wed – Fri 1/30 – 2/2 = 0 – 6”
January Snowfall = ~94”
January Forecast = 95 – 100”
Detailed 4-day Snowfall Forecast:
Wed 1/23 through Sat 1/26 — No snowfall expected all days.
A high-pressure ridge will build off the coast tomorrow (image below) and then slowly move eastward into CA rest of the week for dry weather. A weak inside slider type system will move southward through the back side of the ridge and east of the Sierra Thursday and into Friday to keep temperatures seasonable and produce a little breeze, otherwise skies will be mostly sunny.
The ridge will edge eastward in the wake of the passage of that system and peak in strength over CA and Mammoth this upcoming weekend (image below). That means slightly warmer temperatures with 30s up top and 40s to low 50s on the lower part of the mountain along with light winds. May even feel like spring for a few hours.
High pressure will continue to hold over CA and Mammoth into the middle part of next week (image below) for generally little change in the weather pattern. This pattern, ridge in the West and deep trough in the East, is related to the Sudden Stratospheric Warming (SSW) event that started in early-December and has now finally worked vertically downward into the troposphere where it has caused a split polar vortex with one lobe centered over the Great Lakes and another over Europe.
The people who study these events say they don’t believe the SSW this time will remain coupled with the troposphere like it did in 2014. That is important because if it remains coupled like in 2014 the atmosphere will remain in a stable configuration and ridge/trough pattern will persist for weeks.
The latest guidance says the pattern may break as early as the first few days of February. The latest ECM model (image below) moves an upper level low pressure system southward late next week and a cold front into CA for a possible round of snowfall for the first weekend of the month.
The GFS model has a similar trend as the ECM bringing a trough southward out of the Gulf of Alaska, but never brings it southward into CA. It instead develops a westerly undercut (image below) with multiple low pressure systems moving into CA off the Pacific over the first few days of the month for significant amounts of precipitation with almost 9” liquid for Mammoth (two images below).
Unfortunately, this pattern is currently not well-supported by the GFS ensemble mean (image below) with a flat ridge over the West Coast and CA and not a true zonal jet into CA (purple arrow). Many of the ensembles are showing a continued ridge along the West Coast and trough in the East.
And the CFS model (image below) has pushed back in time a few days the forecasted period of potential snowfall to almost the second week of February. With the MJO a non-factor right now and El Nino weak, there is not a lot of factors to consider that may sway the teleconnection pattern one way or another. Best hope is that the SSW doesn’t couple and a weather patter like we had in the middle January returns during early February. Fingers still crossed. WG