Saturday, January 30, 2021

Widespread Rain Last Evening

Morning sun just touching the campus at 7:35 am MST. Down at bottom is view of another snowy day in Flagstaff yesterday, along with a view of the lights of downtown Kansas City reflecting on the walls of the stadium early this morning.

The forecast showers came by last evening, passing here around 8:00 pm. Measurable rain (0.04" or more) occurred at all the ALERT sites (above and below), except the two most southern locations - Arivaca and Tubac. Amounts were generally around a quarter of an inch or less, but there were six sites with half an inch or more. Here at the house we had 0.12", along with a morning low of 34 F.

Friday, January 29, 2021

Showers Later Today

Heavy cloud cover over the Catalinas at about 7:40 am MST this morning. Snowy view of Baboquivari from Kitt Peak at a bit after 7:00 am, below.

Down at bottom are views of the setting moon west of Hermosilla, Mexico; and sunrise colors east of Granby Lake, Colorado (west-northwest of Boulder).

Models continue to forecast a windy afternoon and evening, as front approaches from west later today (see previous post). The 06 UTC WRF-GFS forecasts a single line of not very impressive showers moving across the Tucson area around 8:00 pm (above). Rain amounts forecast by model (below) range only from around 0.01" to 0.10". Time will tell, as we head head into the last weekend of January.

Thursday, January 28, 2021

Windy Then Wet Tomorrow

Forecasts here from the 12 UTC run of the WRF-RR this morning. Winds above valid at 3:00 pm and precipitation below through 9:00 pm tomorrow evening. 

Some Photos

The entrance line at West Yellowstone a couple of days ago (from Jack Hales webcam wall).
Tough sledding on I-80 near Donner Pass yesterday.
White-out in Mammoth Lakes, California, yesterday.
Wind turbines and multiple lenticulars near Arlington, Wyoming, yesterday (also from Jack Hales webcam wall).
Lenticulars over the Santa Cruz Valley before and after sunset on Monday the 18th (from Art Douglas).

Wednesday, January 27, 2021

Cold, Clear Morning After

Snow cover on the Catalinas at 7:37 am MST this morning. Images at bottom show south view from Kitt Peak this morning and huge amounts of snow at Forest Lakes (Rim Country east of Payson) yesterday afternoon.

Cold morning here at house with a low of 26 F. Received 0,08" additional rain here yesterday, making event total 0.71" - most rainfall in an event since last July.

ALERT amounts yesterday were generally light or less than 0.04" (north above and south below). Total event amounts for general Tucson area (second below) were generally over half an inch and more than an inch in Redington Pass area. The 2.24" measurement just southeast of Oro Valley looks a bit suspect.

The GEFS plumes here (from 06 UTC runs) indicate a brief and light event next Friday afternoon/evening, as well as a roller coaster ride for the temperatures this week.

Tuesday, January 26, 2021

Significant Precipitation - Finally

View from campus a bit after 8:00 am MST shows snow cover over the foothills this morning. Both the airport and DM observed light snow after midnight. Not sure if there were any flakes mixed in here at house.

The 500 mb analysis (above) shows the main trough is still off to the west and that temperatures are very cold, -32 C here at Tucson. While most of the precipitation is now off to our south and east, the cold temperatures aloft could still support some showers before the trough is kicked off to east by next digging short wave. The GFS 500 mb forecast below is valid at 5:00 pm this afternoon and moves the trough rapidly across the state today.

Morning special graphic above from the NWS for rest of day, and also alerts for a very cold night tonight.

ALERT precipitation observations for 24-hours ending at 6:00 am this morning above and below. Second below shows ALERT totals over metro area for the event. Totals here at house went: 0.21" in gauge yesterday am; another 0.09" by 5:00 pm; and another 0.33" during the night; total for event as of 8:00 am this morning was 0.63" - making this the biggest precipitation event here at house since July 23rd.

There were thunderstorms yesterday - mostly west to north of metro area, as per plot of detected CGs (above, from Atmo and Vaisala) for 24-hours ending at midnight last night. Photo below shows severe hail that fell in Phoenix area with sizes slightly greater than inch. There were also numerous reports of damaging winds in the greater Phoenix area from the severe thunderstorms.

Monday, January 25, 2021

Wintry Start Last Week Of January

Snowy vistas this morning at Mt. Lemmon General Store and downtown Flagstaff (bottom).

Precipitation from ALERT network (north above and south below) for 24-hours ending at 8:00 am MST. Amounts across main metro area ranged from around 0.20" to about 0.50". Only 0.21" here at the house this morning.

Powerful, cold 500 mb trough (above at 12 UTC this morning) continues over the western half of country.  A variety of watches and outlooks for hazardous weather cover much of the country (below). Heavy snow/winter weather advisories stretch nearly continuously from California to Washington DC.

Detailed NWS forecast for the airport (above) includes snow tonight and tomorrow, but with little accumulation expected at lower elevations.
Precipitation amounts at airport average around 0.60" inches in the GEFS forecasts, but only 0.10" in the 12 UTC WRF-RR this morning - note the WRF forecasts the donut hole effect. So quite a difference again between the models.

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!