More Storms Plus Heavy Rains

First storm coming off the Catalinas at around 4:00 pm MST yesterday afternoon.

Plot of detected CG flashes (from Atmo and Vaisala) through 0703 UTC last night shows eastern Pima County totally covered.

Plots of observed rainfall across the ALERT network (for 24-hours ending at 6:00 am this morning) indicates that all sites had precipitation, with many reports over an inch and several over two inches. Here at the house we had 1.43", which is heaviest single event so far in 2024.

The reports from SPC for yesterday (above) show a number of severe wind events across south-central Arizona. I estimated gusts of 40 to 50 mph here; TUS reported thunder, gusts to 55 mph, and 1.83" of rain; DM had thunder, gusts to 32 mph, and 0.37" of rain; the rain gauge appears to be out-of-service again at Atmo, where winds gusted to 36 mph. Numerous sites around the area had temperature drops of almost 40 F around 6:00 pm.

The morning sounding from TWC/TUS (above) shows a deep onion shape, with quite a cool layer below 800 mb. Winds aloft are basically northerly, with strongest speeds up around 200 mb. The 500 mb anticyclone is centered over the northern GoC and is forecast to shift east-northeastward into New Mexico during the weekend.

The 12 UTC WRF-HRRR (above) forecasts just a bit of light precipitation through midnight in eastern Pima County. Given the widespread rainfall yesterday, and this morning's sounding, it should basically be a down day today. The current morning forecast from TUS NWS (below) seems a bit optimistic regarding rain POPs at the airport today and tonight. Time will tell.

Heavy Storms Along Rillito

Early morning view of the Catalinas today. View at bottom is from yesterday afternoon after the storms here.

Plot of detected CG flashes through 0733 UTC last night (above from Atmo and Vaisala) indicates afternoon storm activity in north parts of eastern Pima County.

ALERT plot of rainfall reports through 7:00 am (above) and from MesoWest (below) show heavy amounts along foothills and the Rillito. Here at the house we had a heavy storm  around 4:00 pm with gusts around 40 to 50 mph (estimated). There was a report of gusts to 68 mph at 4:15 pm 7 miles north of the airport (which is near to our location).

The 500 mb analysis (above from SPC) shows a huge anticyclone centered over the Four Corners region. The morning sounding from TWC/TUS (below) continues moist, with a deep layer of several old BLs above the surface. There is considerable mid-level CAPE, and winds aloft are northerly to northeasterly at around 20 kts.

Forecast above (valid through midnight tonight) from the 12 UTC WRF-HRRR run at Atmo indicates rains across the metro area with some spots having heavy amounts. Current morning forecast from NWS TUS (below) continues to indicate high POPs for the airport through Saturday.

Severe Storms Today?

View toward the Catalinas at 7:00 am MST this morning shows very hazy skies.

Yesterday was very suppressed over southeastern Arizona - see plot of detected CG flashes for 24-hours ending at 0735 UTC last night (above, from Atmo and Vaisala). There were no reports of rainfall across the entire ALERT network.

At 500 mb this morning (above from SPC) the large anticyclone appears to have two circulation centers - one over northwest Arizona and the other over southern Idaho. The morning sounding (below - also from SPC) shows that PW has decreased to about an inch and a quarter; there is a deep, old boundary layer; and only a sliver of mixed layer CAPE. Winds aloft are northerly to easterly at around 20 kts above 600 mb.

However, the SPC has outlooked slight chances for severe thunderstorms today over southern Arizona (above). The 12 UTC WRF-HRRR (below) forecasts heavy rains across the metro area through midnight tonight.

The morning forecast (above from the National Weather Service Forecast Office) indicates high POPs through Friday for the airport, along with gusty winds and blowing dust this afternoon and evening. The graphic below provides an estimate of the timing for the forecast storms.

It will be interesting to watch what transpires later today. I am a bit of a doubter, based on the poor thermodynamics indicated in the morning sounding.

Nighttime Showers

The waning moon setting west-southwest of campus at around 6:30 am MST this morning.

Plot of detected CG flashes (above - from Atmo and Visala) for 24-hours ending at 0703 UTC last night indicates active storms over eastern Pima County and parts of the metro area. Composite radar image (below for 0602 UTC) shows several areas of storms over metro area and to the west.

ALERT plots (above and below for 24-hours ending at 7:00 am) show scattered light amounts across much of the network. Here at the house we received 0.06"; TUS had thunder, a Trace and gusts to 37 mph; DM reported thunder and a Trace with gusts to 33 mph; and Atmo had 0.02" with gusts to 33 mph. Since I was snoozing, I don't know what the wind gusts might have been here.

At 500 mb this morning (above from SPC) the anticyclone appears to be centered over eastern Nevada, with north-northeasterly winds over much of Arizona. The morning sounding (below, also from SPC) shows PW has fallen a bit below an inch and a half; there remains considerable CAPE below 650 mb; and winds aloft are generally north to northeasterly at 20 kts or so.

The 09 UTC WRF-HRRR forecast (above valid through 5:00 pm tomorrow) indicates some rainfall in southeastern Pima County. The current NWS Forecast Office forecast for the airport through Thursday is shown below.

Another Stormy Day

The setting full-moon at 5:30 am MST this morning.

Plot of detected CG flashes for 24-hours ending at 0723 UTC last night (above from Atmo and Vaisala) shows that there were thunderstorms yesterday across much of Arizona and northern Mexico.

ALERT plots (above and below) show a large number of reports of rainfall across the region for 24-hours ending at 7:00 am this morning. While we had some rumbles of thunder, there was no rain here at the house.

There were quite a few severe wind reports scattered across Arizona yesterday (see SPC webpage), with several occurring around the Tucson area. I was inside and don't have a wind speed estimate for here. TUS had 0.10" of rain with gusts 51 mph, and DM reported 0.35" of rain with gusts to 44 mph.

The ridge continues over the West, with anticyclone circulation centers near the west coast of California and southern Idaho (analysis above from SPC).

The 12 UTC upper-air sounding (below, also from SPC) has 1.50" of PW, but continues with a fairly dry, surface-based layer that reaches nearly to 600 mb. Steering winds aloft are near 20 kts from the north-northeast.

The 06 UTC WRF-GFS forecast (above, valid through noon tomorrow) indicates much diminished activity over Arizona today. This is reflected in the current NWS Forecast Office morning forecast for the airport (below).

More Light Showers

View looking toward the Catalinas at 5:00 am MST this morning.

There were numerous CG flashes detected over eastern Pima County for 24-hours ending at 1113 UTC this morning (above). We had some rumbles of thunder here before dark.

Showers were widespread across the ALERT network (above and below observations for 24-hours ending at 10:00 am this morning. Here at house we had 0.05" sometime after dark; DM recorded 0.09"; and TUS had 0.02". Winds were quite gusty in late afternoon and evening: I estimated 40 to 50 mph here; the airport recorded a gust to 52 mph; DM had 44 mph; and Atmo had gusts to 42 mph.

This morning there is a large amplitude ridge over the western parts of the US and Canada (above), with circulation centers over western Arizona, northern Nevada, and southwestern Canada. The morning sounding continues moist, but with a deep, fairly dry layer below 600mb. There continues to be some middle-level CAPE. Winds are generally northwesterly to northerly with some speeds around 20 kts. Steering flow for any storms later today will be from the north.

Forecast from the 06 UTC WRF-GFS (above) indicates wet conditions over most of southern and southeastern Arizona for the period ending 6:00 pm next Thursday evening.

Current NWS Forecast Office forecast for the airport is shown below.