First Week Of July

There were a few clouds hanging over the Catlinas this morning. After a wet start to July we've now had seven dry days. Plot below of detected CG flashes (from Atmo and Vaisala) through 0103 MST last night shows Arizona completely devoid of storms yesterday - a rare occurrence for this time of year..

Surface dewpoints have dropped into 30s and 40s last couple of days - as per the morning surface plot above - quite dismal.

The 500 mb level (above) is almost devoid of significant features across the southern parts of country and there is little in the way of height gradients. The morning sounding from TWC/TUS (below) is also a mess - PW less than inch, no CAPE, and light and variable winds through the troposphere. It can only get better this weekend.

Analysis TPW (above for 13 UTC) shows high values extending over half way up the GoC, and perhaps an MCS will move over the GoC tonight and help push the high moisture values northward. Hurricane Bonnie is at 120 degrees west, moving westward.

Meanwhile, the 12 UTC WRF-RR precipitation forecast through midnight (from Atmo below) indicates more of the same - a very dry day today for Pima County.

Little In Way Of Weather Fireworks

Some cumulus were bubbling over the Catalinas at 5:30 am MST this morning.

Thunderstorms mostly avoided the metro area again yesterday - see plot of detected CG flashes above for 24-hours ending at 1203 UTC this morning (from Atmo and Vaisala).

ALERT plots (above and below for 24-hour rainfall ending at 7:00 am) show mostly reports of light amounts northwest and south of the metro area - nothing here except a slight sprinkle in afternoon. Note the lone report of over an inch out near Picture Rocks, as well as a report of 0.75" west of Green Valley.

This morning's TWC/TUS sounding above is very moist and quite unstable - looks promising. But, the 12 UTC WRF-RR forecasts drop the PW to about an inch before noon, and the CAPE vanishes. Plot of 14 UTC TPW (below) shows the drier air to our southeast .

Forecast from today's 12 UTC WRF-RR of precipitation through midnight tonight (above) keeps most of southeastern Arizona suppressed. The 06 UTC GEFS plumes for QPF at the airport (below) indicated early morning showers at the airport - these did not materialize. The rest of week is nearly flat-lined, with little rain indicated through next Monday.

July Fourth

Pre-sunrise skies in Tucson this Fourth of July made for scenic views.

Plot of detected CG flashes (above from Atmo and Vaisala) is for 24-hours ending at 1253 am this early morning. Thunderstorm activity yesterday avoided the metro area and stayed mostly over or near the mountains. Map showing ALERT precipitation (below) through 7:00 am MST this morning indicates rain recorded (very light amounts) at only 5 sites.

This morning's TWC/TUS sounding (above) remains little changed from past couple of days. Warm temperatures from about 350 to 500 mb are killing any CAPE (500 mb temperature a very warm -4 C).

However, the 12 UTC WRF-RR forecast somehow cools these temperatures and allows considerable CAPE to develop this afternoon. The result in the model forecast is several heavy storms over parts of metro area (forecast of composite radar echoes below is valid at 6:00 pm this afternoon).

Second below is current NWS forecast for today and tomorrow.

Heavy Storms Yesterday

Heavy thunderstorms moved into the metro area from the Catalinas at mid-afternoon. Gusty outflows of 45 to 55 mph produced some tree damage i the north part of the metro area. Above photo is from just before 4:00 pm MST.

Plot of detected CG flashes (from Atmo and Vaisala) above shows activity for 24-hours ending at 0833 UTC. It was a much more active day than was forecast, with considerable thunderstorm activity across the eastern 2/3rds of Pima County.

Alert plots from the network show significant amounts (many over an inch) from the western Catalinas southward across much of the city. Here at house we had gusty winds of 45 to 50 mph with the storm, as well as 0.75" of rain. This was the largest amount of rain for a single event since September 21st, 2021. Other amounts noted: Atmo 0.30", DM 0.14", and TUS 0.02" with gusts to 43 mph.

Morning sounding from TWC/TUS above has an onion shape after yesterday's storms - the CAPE from the SPC analysis appears a bit large. Winds remain light and varible below 300 mb and if storms develop to our south to southwest anvils should over the city. Regardless, the day following a significant rain event is usually largely suppressed. Which is what the 12 UTC WRF-RR forecast through midnight (below) indicates.

But, what a start to July!

Friday July !st

Middle clouds and some mountain cumulus before sunrise this morning.

The maps above and below show total June rainfall across the ALERT network. The range was very large: 5.20 inches at Mt. Lemmon to zero at many sites. Total here for month was only 0.09" - which fits with the large metro region with little or no rainfall.

Plot above showing detected CG flashes for 24-hours ending at 0803 UTC this morning indicates little thunderstorm activity over the area, except for an isolated storm near the airport. ALERT plot below shows rainfall ending at 7:00 am this morning. The airport reported thunder and 0.07", but DM had 0.51" along with a thunderstorm gust to 43 mph. Atmo reported 0.03" and we had zilch here at house.

The 500 mb pattern (above) remains an unorganized mess across southern half of country. The morning TWC/TUS sounding below continues very moist, with light/variable winds below 300 mb, but with an increase in CAPE today. Sounding looks favorable for storms, except for the strange dry layer around 850 mb.

The 12 UTC run of the WRF-RR at Atmo (second below) forecasts a nearly classic Tucson donut hole for precipitation through midnight tonight. Would be nice to get a heavy storm from the Catalinas drift into our part of town this afternoon/evening.

Light Shower Here

Hazy, dirty skies this morning at 7:20 am MST.

There were scattered thunderstorms around southeast Arizona yesterday afternoon and evening, and then some light showers around parts of metro during early morning hours. Rainfall for 24-hours ending at 7:00 am this morning shown here: above from ALERT network where 17 sites recorded 0.04" or more and below from MesoWest which shows quite a few reports of light amounts or a Trace across much of metro area. We had 0.01" here at a bit after 3:00 am. Plot of detected CG flashes (second below - from Atmo and Vaisala) shows a distinct lack of flashes across a significant portion of the metro area.

The morning 500 mb analysis (above) shows weak height gradienst and a chaotic anticyclone across southern portion of contry - one weak anticyclone center appears to be off to our southeast in northern Mexico. The morning sounding has increased moisture below 600 mb and some CAPE, with continued light/variable winds aloft. The sounding appears more favorable to me for lower elevation storms today. However, the 12 UTC WRF-RR forecast for rainfall through midnight tonight indicates little shower activity for Pima County - time will tell.

Down Day Yesterday

Touch of pink over the Catalinas at about 5:15 am MST, just before sunrise.

Scattered thunderstorms occurred across the western two thirds of Pima County yesterday, but totally avoided the Tucson area (plot of detected CG flashes above from Atmo and Vaisala for 24 hours ending at 0803 UTC this morning). Was definitely a down day, as predicted by the WRF-RR (see post below). Across the entire ALERT network there were only three reports of rainfall - below ending at 7:00 am this morning.

There was no morning sounding from TWC today. Above shows sounding forecast for 4:00 pm this afternoon by the 12 UTC run of the WRF-RR at Atmo. The sounding has a very deep and relatively dry boundary layer (BL), a sliver of CAPE, and light/variable winds through the troposphere - not very promising.

However, the model forecasts storms in eastern Pima County, as per composite radar echoes below valid at 5:30 pm. Precipitation forecast from the same run (second below) indicates scattered light rainfall across the metro area, with a strong cell apparently hitting the airport - note the 0.40" there. So, hopefully a bit more active day - I'll watch to see what transpires.

Few Showers Around

Some cloud color over the Catalinas before sunrise this morning.

There was very limited thunderstorm activity over Pima County yesterday - plot above shows detected CG flashes for 24-hours ending at 12 UTC this morning. The airport did report thunder during the mid-afternoon, as well as 0.04" of rain. Nothing here.

The Alert network sites (below for north and south portions) indicated scattered, mostly light amounts over the mountains and southern portion.

Yet another morning sounding with limited moisture below 700 mb (above), some CAPE, and mostly light and variable winds aloft. We really need a feature that will move some low-level moisture up the GoC - as per: an MCS into the middle GoC, a TS near the south end of Baja, or an inverted trough (IT) moving west across northern Mexico.

The forecast for precipitation through midnight tonight (below, from 12 UTC WRF-RR) looks very dismal.