Looking Ahead To Friday Evening

The 500 mb analysis this morning (above from SPC) indicates an anticyclone is over northeast New Mexico, with a band of 20 to 25 kt east winds from El Paso to Tucson, along with quite cool temperatures in mid-levels. The pattern is a bit chaotic with a weak trough inching across southern California and an inverted trough far to the south over west-central Mexico. The inverted trough will likely help increase thunderstorms over northwest mexico and also play a role in the large increase in PW forecast by the models - this begins today and continues through Friday night. See the 00 UTC GEFS plumes for PW at TUS below. By Saturday the PW here is forecast to reach to around 30 mm (1.2 inches) and hold steady through rest of forecast period. The same forecast for QPF at airport (second below) indicates periods of light showers, and probably thunderstorms, from Friday evening (the 29th) through the Fourth of July.

A forecast skew-T for TWC (above from 06 UTC WRF-GFS at Atmo) valid at 5:00 pm MST on Friday shows an interesting sounding with west-northwesterly winds through the well-mixed boundary layer and southwesterly winds above (due to the slight eastward progress of trough over California). The forecast mixed-layer CAP is just over 800 J/Kg due to increased BL moisture and cool mid-level temperatures continuing to hold off much warmer air out to the west.

Forecasts here are from the 00 UTC operational GFS and are also valid at 5:00 pm on Friday - above is 850 mb and below is 500 mb. The flow at 850 brings higher PW from GoC anticyclonically into southeastern Arizona (a situation that occurs frequently during summer). The 500 mb is chopped-up but is open to low-latitudes, which allows the push of low-level moisture into Arizona.

All-in-all, it appears that we'll have interesting weather to watch as June draws to a close. 

Moisture And Perhaps Storms Return By End Of Month

A slow-moving 500 mb trough moves into the West by the weekend - above is GEFS average 500 mb forecast (from 00 UTC last evening) for 12 UTC on 30 June (Saturday).  This opens up the Southwest to flow from low-latitudes and allows higher PW to return. The return of moisture will be helped by outflows from convective systems over northern Mexico. The forecast below of PW is from the 06 UTC run of the WRF-GFS at Atmo and is valid at 6:00 am MST on Saturday. The model forecasts a distinct Gulf Surge at that time.

The 00 UTC run of the WRF-GFS (on 5.4 km grid) forecast of total precipitation through 5:00 pm on July 3rd is below. Most rainfall is forecast for high elevations, indicating an increased threat for dry lightning over many lower-elevation parts of southeast Arizona.

At the same time as all of this, the Eastern Pacific tropics continue to be quite active - second below is five-day outlook from NHC this morning.

Not Paying Attention

, capturing the pronounced shift to hostile westerly winds above 700 mb.

Walk this am was definitely toasty and muggy - quite a change! Should have been paying more attention yesterday. At 6:30 am MST it was 82 here at house and when I checked, dewpoints were in the 60s F from Tucson to Puerto Penasco to Yuma. The TWC 12 UTC skew-T plot above shows that moisture increased (during past 24-hours), reaching an inch this morning. Southerly winds below 700 mb have produced the increase in low-level moisture.

The MIMIC TPW below is valid at 5:00 am this morning captures the increase up the GoC. The 06 UTC WRF forecasts for 12 UTC (both the NAM and GFS versions) were considerably too dry below 700 mb - by about 6 to 7 mm. The rest of soundings forecast were accurate

The 1330 UTC visible image (above) indicates some cloudiness over the Mexican mountains, while the 12-hour plot of CG flashes below (ending at 06 UTC, from Atmo and Vaisala) indicates all thunderstorm activity was far removed from our Borderlands - so convective outflows not at play in our moisture increase.

Forecast question for today is whether or not there will be some high-level buildups over the Sky Islands this afternoon. Series of web cam views of Catalinas for past week (bottom three images) have not seen a cloud of any type since last Sunday! But the haze due to the moisture increase is clear this morning.

Last Week Of June

Cooler and greener locale to our north-northeast - sunrise at Durango, Colorado, with the Historic Strater Hotel dominating image.

The synoptic pattern continues to favor strong thunderstorms and heavy rains over much of central and eastern U.S., while keeping things terribly suppressed here in Southwest. Above plot shows detected CGs across CONUS for 12-hours ending at 12 UTC this morning - certainly an active night (from Atmo and Vaisala).

Forecast below is from 00 UTC WRF-GFS forecast run at Atmo and shows total precipitation forecast through 5:00 pm MST on June 30th - I didn't feel there was need to show the color scale, since black is black is zero.

Finally photo below is of a metal sculpture of a bat family bicycling along the Loop trail at the Campbell Ave. bridge over the Rillito. The bridge is the summer home for thousands of Mexican free tail bats, which swarm out in the late evenings to feed during the nighttime.

Little Hope For Coming Week

The rains of last Friday and Saturday quickly gave way to typical hot and dry June weather. The high temperatures from Sunday through yesterday at airport ran: 93, 99, 99, 102, and 106 F. The grounds over in the park by the Rillito seem as dry and dusty as they were before the rains.

The 500 mb analysis above is from the 00 UTC run of the operational GFS model. The subtropical ridge stretches across Florida, westward along our Borderlands, and on to the west north of Hawaii. We remain under the dry flow around the east Pacific lobe of the high, and tropical disturbances are blocked far to our south by the ridge. The subsidence with this anticyclone has been keeping our skies deathly clear - below is visible image centered on Arizona at 6:00 am MST this morning. The "June gloom" under the oceanic stratus over at San Diego would be welcome break for us desert dwellers.

The GEFS forecasts (mean of the ensemble members for 00 UTC on 27 June above and 12 UTC on 30 June below) for 500 mb continue the blocking ridge overhead through much of next week. However, by the end of the month the models forecast a Pacific trough that breaks the ridge and opens to lower latitudes to our west (below), which is certainly what I'd like to see happen. 

The NHC 5-day outlook at bottom indicates the possibility of tropical storm activity west of Mexico by the time the break in ridge occurs. These forecasts are for a very-long time range, but the trend is good, compared to what we're currently observing.

Rains Santa Rita Abbey/Summer Solstice

Sister Pam at Santa Rita Abbey sent this photo, which was taken Saturday afternoon (June 16th) during a heavy thunderstorm at the Abbey. She reports 2.00 inches of rain from Friday mid-day through Saturday evening. The heavy thunderstorm dumped 1.40 inches of rain during a short period Saturday.

Today is the summer solstice for the northern hemisphere and will be our longest day of the year - shorter days begin immediately but temperatures continue nasty hot.

Brief Pre-Monsoon Burst Just A Memory

The Pacific lobe of the sub-tropical  high now dominates the Southwest with very hot and dry conditions this morning. The 500 mb analysis for 12 UTC this morning (above from SPC) shows very warm (hot) temperatures over all the Southwest of -2 to -3 C, which is very nasty. The morning TWC plot below shows the warm air and only about 10 mm of PW.

MIMIC total precipitable water analysis (TPW - above for 12 UTC this morning) shows the dry conditions over the Southwest and northern Mexico. There is a small region with high PW pushed far south - from end of Baja down to Cabo Corrientes. Detected CG flashes (below, from Atmo and Vaisala) for 12-hours ending at 06 UTC last night (20 June) reflect this sorry state of affairs.

Down at bottom is the operational GFS forecast of total precipitation for  the period ending at 06 UTC on the last day of June. Situation about typical now, with hopes for the real monsoon to begin first week or so of July - but the short-lived burst was a great relief from the heat and drought that prevailed since February; now just a sweet memory.