Sunday, January 24, 2021

An Extended Winter Storm


Damp morning on the East Mall at Campus - assume that the setup and tents are for virus vaccinations. Some snow at the airport in Prescott shown at bottom. Showers here have been light, and I haven't had chance to see if amount was just measurable or a Trace. First tilt radar echoes below from 7:32 am MST.

Morning upper-air charts from Univ. of Wyoming - 500 mb above and 250 mb below. Second morning in a row with missing stations in California. (Note that the bad heights are still being reported at Chihuahua, Mexico, - about 30 m too low for many months now.)  The shading on the 250 mb chart does not have explanatory legend - my eyeball says light purple 75 kt; grayish purple 95 kt; and white greater than 115 kt - whats impressive is the HUGE area of the country with very strong upper-level winds. Probably will be a bumpy day for air travelers.

Surface plot above is from 7:38 am - note heavy rain report at PHX and snows in the Rim Country.
Forecasts from the 06 UTC GEFS here. Plumes above are for QPF at the airport, indicating break from tonight into tomorrow afternoon, and then a heavy continuation of precipitation Monday night and Tuesday. The plumes below are for snow accumulation at the airport - more than a bit mind boggling. Note official forecast is for little or no accumulation, which seems much more reasonable. This snow forecast assumes a 10 to 1 ratio of snow depth to water equivalent. Any snow around the extended metro area would be much wetter with considerably lower ratios.

The WRF-GFS forecast above from 06 UTC shows total precipitation amounts for period though 11:00 am on Wednesday morning. Below is the WRF forecast of snow on the ground valid at 11:00 am on Tuesday morning. The WRF has some snowfall across much of metro area - will be interesting to see how this verifies!

No comments:

Post a Comment