Mild And Dry With Some Gusty Winds

Pre-sunrise clear skies over our area this morning. Down at bottom - vivid sunrise colors at Skunk Bay on Puget Sound, Washington.

Severe thunderstorms and tornadoes across the Southeast on Sunday and Monday resulted in major damage and more than 30 fatalities. Storm reports from SPC for Easter Sunday below.

This morning's 500 mb chart (above from GEFS for 12 UTC) is dominated by large-scale trough over much of the continent and a blocking ridge over the eastern Pacific and Alaska. The MIMIC analysis of PW (below for 12 UTC this morning) indicates extremely dry air dominating over most of continental U.S., including our area.

GEFS plumes for winds at TUS (above) indicate several more periods of gusty winds into the middle of next week. Gusts of 25 to 40+ mph were common yesterday afternoon across all of southeast Arizona.

Forecast below shows total precipitation forecast by 00 UTC GFS out through midnight next Monday night. Our very dry April will continue for at least another week.

Easter Sunday 2020

Easter bunny in the sky - not my photo. Still some clouds and stratus around at sunrise this morning, as per image down at bottom.

Scattered light rains yesterday afternoon produced 0.04" here for the first rain of April. Amounts across the ALERT network (above and below) were mostly less than a quarter of an inch. Airport had 0.07" and Atmo recorded 0.03".

There were some embedded thunderstorms around, as per detected CG flashes through midnight (above from Atmo and Vaisala), but there was a big hole over our area.

Looks like a dry week ahead for southern Arizona, but some more precipitation for the north half of state - below is 06 UTC GFS forecast for total precipitation through noon next Sunday, the 19th.

Showers For Easter Weekend

Red sunrise this morning highlighted clouds over the Catalinas above. Below is view at 7:00 am MST of heavy clouds over the GoC southwest of Puerto Penasco, Mexico.

The morning 500 mb analysis for 12 UTC (above from SPC site) shows that the closed low has moved about as predicted for several days, and is centered about right over Yuma.

Visible satellite image from 7:00 am (above) shows clouds associated with the circulation - the closed middle and upper-level low will move along the Borderlands today, bringing us a chance for showers continuing into the night. Showers currently developing over mountains locally. Plot of detected CG flashes (from Atmo and Vaisala below) shows that thunderstorms have moved into far southwestern Pima County during past 3 hours.

The 06 UTC SREF  plumes for QPF at TUS (above from SPC website) continue showing 100 percent of the ensemble models predicting rainfall - but amounts continue to average only around a tenth inch or so. Thunderstorms would likely produce amounts somewhat higher, if they occur over parts of metro area. 

Regardless an unsettled start to the weekend, but clearing skies likely for Easter Sunday.

Finally, the SPC is outlooking a significant outbreak of severe thunderstorms for the Southeast tomorrow (below).

Waiting For Bit Of Rain

                                     

Pristine, clear skies in the view south from Kitt Peak this morning.

Down at bottom is current "Weather Story" from NWS at San Diego, where rains of 5 to 7 inches have already fallen over much of their forecast area. Very significant event underway for extreme Southern California as the 500 mb low this morning (below) remains over southern California.

Models continue to forecast the low to move south and eastward across Arizona tomorrow bringing us a chance of showers, and perhaps thunderstorms. Forecast above is from the 06 UTC WRF-GFS and is for radar echoes at noon tomorrow (Saturday the 11th).

Total QPF forecast from the same WRF run above through noon on Easter Sunday. Plumes below for QPF from the SPC plume viewer. Event continues to be forecast to occur tomorrow afternoon and continue into the night. Forecast amounts for southeast Arizona remain light - about a tenth or so posible at airport.

Showers Friday Night And Saturday Morning

Few clouds hanging on the Catalinas before sunrise this morning. Down at bottom: early morning rain at LAX and snow at Big Bear Lake (lake is in mountains east of San Bernardino at almost 7,000 ft MSL).

Closed low at 500 mb over southern California this morning forecast to wobble slowly eastward and come across Arizona Friday night and Saturday. The forecast above (from 06 UTC GFS) indicates low centered west of us over southern Arizona at 6:00 am MST Saturday morning. Forecast sounding for TWC at that time (below, from 06 UTC WRF-GFS forecast) has only a bit over half an inch PW, but with some CAPE - possible rumbles of thunder during the rain event.

Plumes for QPF at TUS (from the 06 UTC GEFS forecasts) are very consistent for rain at airport late Friday night and during day Saturday. Forecast amounts average about 0.15" - embedded thunderstorms could produce local heavier amounts around eastern Pima County. The 06 UTC WRF-GFS forecast for precipitation amounts through midnight Saturday night (below) indicates about a tenth inch at airport and higher amounts on the mountains. Models do indicate some snow at higher elevations of Catalinas and Rincons.

Gusty Winds Plus Rain By Weekend

Last evening's supermoon rising with some low clouds hindering views at times.

The 500 mb closed low is west of San Diego this morning (above - pretty much as fore cast by models last few days). Precipitation at this time (7:00 am MST) is focussed over Southern California (regional radar from NCAR RAP below). 

Low-level winds here this morning are southerly to south-southwesterly with speeds as high as 30 kts a bit above the surface - so gusty winds likely after some morning heating.

The 500 mb low is forecast to move slowly eastward along our Borderlands and be near Tucson by midnight Friday night (above).

As the low moves by forecast models indicate good chances for precipitation in our area area. The QPF plumes from 06 UTC last night average out to a bit over 0.10" at airport (above). The 06 UTC WRF-GFS is a bit more aggressive for amounts over eastern Pima County (below from 06 UTC run, with half an inch forecast for airport). Regardless, looks like good chances for our first rain here in more than three weeks.

Fair and Mild Start To New Week

Nice start to new week, but cooler with chances for showers by midweek. Down at bottom is Yosemite Falls in the snow this morning.

The 500 mb analysis this morning (from NCAR RAP - above) shows a closed low northwest of San Francisco. This feature forecast to move southward toward San Diego and meander around the Southwest into the coming weekend. Forecast below (from 00 UTC ECMWF) for 500 mb is valid at 5:00 pm MST next Friday afternoon.

The water vapor image from 1350 UTC this morning (above) seems to indicate two circulation centers in middle to upper troposphere - making the situation a bit more complex than indicated in analysis and forecast above. Remains to be seen how accurate the forecasts will be, given what appears to be a fairly poor analysis this morning.

The plumes for QPF at the airport (from 06 UTC runs) indicate a mis-mash of light rainfall possibilities into start of next week - all amounts are light indicating the moisture-starved character of coming event(s). 

Should be interesting to watch how all this actually evolves.

April 3rd 2020

Sunrise this morning from the Mt. Lemmon Sky Center.

Forecast for total precipitation this weekend (from 06 UTC WRF-GFS on 5.4 km grid) - West Coast wet but Arizona dry. Longer range GEFS forecasts (below valid at 12 UTC on the 9th) indicate a 500 mb cutoff to our west and perhaps some precipitation possibilities last part of coming week.

Look back - 46 years ago a huge tornado outbreak occurred - summary below from the late Ted Fujita (who referred to this day as the Jumbo Outbreak).

Recent Cloud Photos

Photos above and below from Tuesday morning, March 31st. These show fallstreak holes over the Catalinas. These holes can form  when cirrus ice crystals fall into a super-cooled water cloud layer - usually alto or cirrocumulus. Aircraft flying through the super-cooled cloud can also trigger freezing and formation of similar holes. Photo below by John Sirlin, forwarded to me by Mike Luethold.

Lenticular clouds yesterday afternoon. These formed at an inversion above 500 mb and were not anchored to mountains below (as is usually the case with lenticulars). Also got a large hawk in photo below.