July Grinds On

View above, with contrail streak, from a bit before 6:00 am MST. Thunderstorms mostly avoided Pima County yesterday, as did rainfall - plot of detected CG flashes for 24-hours ending at 0803 UTC this early morning (below, from Atmo and Vaisala).

The 500 mb plot is truly a mess this morning - the 250 mb chart provides a better depiction of current features. Three anticyclone centers of circulation extend from Arkansas to northwestern Sonora. An inverted trough in the easterlies is over the southern end of the GoC.

The morning sounding at TWC/TUS continues to be unimpressive - limited moisture, no CAPE and a chopped up wind profile. The 14 UTC plot of total precipitable water (below) shows higher moisture content lurking just south of 30 degrees north - need a feature to kick these values up into Arizona. Remnants of Bonnie are around 140 degrees west, while intensifying Hurricane Darby (now a high-end Category 3 storm) is just west of 120 degrees.

The 12 UTC WRF-RR forecast manages, somehow, to develop isolated nighttime storms over parts of eastern Pima County - forecast above valid at 10:00 pm tonight.

Current heat warning for today. from the NWS Forecast Office, is shown below.

Continued Dry Here

Storms around yesterday with a rumble of thunder here from the northeast. Just a sprinkle here - not enough to wet the courtyard.There were gusty outflow winds several times during afternoon and evening. Of note was a gust to 49 mph at the airport just before 8:00 pm MST.

Plot of detected CG flashes (from Atmo and Vaisala - above) for 24-hours ending at 803 UTC last night. Not the classic Tucson donut hole is very pronounced. Precipitation (below from MesoWest) is for 24-hours ending at 7:00 am this morning. Reports on the mountains, but with some isolated rain reports around metro area.

This morning's TWC/TUS sounding (above) is as bad as it can get - no winds, no CAPE. The 12 UTC WRF-RR forecast indicates only isolated storms over the mountains at 5:00 pm this afternoon. It's July but you sure wouldn't know it without looking at the calendar.

Chance For Showers

Pink cirrus and dark lower clouds about 5:15 am this morning. Very warm start to the day - when I returned from my morning walk at 6:30 am MST it was 82 F here. The plot of detected CG flashes (below from Atmo and Vaisala - for 24-hours ending at 0803 UTC) shows that thunderstorms returned to southeastern Arizona yesterday - perhaps a flash or two just inside Pima County.

This morning's sounding remains unimpressive, as per past several days. There are, however, some relatively strong east winds from 300 to 700 mb. If storms develop off to the east this afternoon, the steering flow will try to move them our way.

The 12 UTC WRF-RR forecast run at Atmo indicates that this is what will happen, with storms moving west over much of eastern Pima County. Forecast of composite radar echoes (above) is valid at 7:30 pm this evening. The storms produce strong outflow winds and some light rainfall - as per two forecasts below from same WRF-RR run.

At bottom is an outlook graphic for today from the NWS Forecast office.

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.