Saturday, May 23, 2015

Looking To The South


The eastern Pacific is very active, convectively, from 5 to 15 degrees north - above IR image is for 13 UTC this morning, May 23rd. The eastern Pacific tropical storm season "officially" began on May 15th. The current outlook from NHC (below) indicates moderate chances for each of two disturbances to develop into tropical storms - out by day 5 chances increase to 80% for the more northern disturbance, At very long ranges (216 hours valid 00 UTC 1 June), the operational ECMWF (at bottom) forecasts a tropical storm or hurricane to be south of Baja moving north. So, this may be the start of an interesting season over the eastern Pacific. I should note that the global models often cry wolf regarding tropical developments at ranges beyond 5 days or so.



Friday, May 22, 2015

Art's Precipitation Outlook - Summer 2015

Art Douglas shared his analog outlook for the next few months, and the precipitation portions are shown below for July and August, with June and September at the bottom. Art does his outlook using a process through which he chooses five analog years. The strong El Nino that is underway, and its temporal evolution, will play a significant role in determining how the next few months will go. Art's analog years are: 1957, 1972, 1982, 1990, and 1991. The El Nino influence can be fickle here in southern Arizona - 1990 was a stormy and wet summer but 1991 was very dry.  The persistent trough along the west coast has been related to the El Nino, and it has been associated with May snows in the Rockies and Sierras, as well as unusual wetness in far southern California.


The analog years end up indicating wet conditions mostly to our east and north for July and August (above). June (first below) years indicate wet over Arizona and southern California - this has been the pattern that has prevailed the last several weeks of May also. September analog years indicate a return to near normal conditions for Arizona. Also of interest will be the character of the eastern Pacific tropical storm season, with perhaps another very active year adding another wild card into the mix.



Thursday, May 21, 2015

Heavy Clouds This Morning - Thursday May 21st


A dreary morning at sunrise today - all images here are a bit before or after 7:00 am MST. View above is of heavy clouds over the Catalinas, and image below shows the widespread cloudiness over southern Arizona. On my walk this morning I could see middle-level buildups, mammatus, virga, and perhaps several very light showers to the south-southwest. The TUS composite radar image at bottom indicates a few echoes across eastern Pima County. 

There is a wildfire burning north of Sonoita in the grasslands - with about 2,000 acres affected so far. Hopefully this fire will be contained before winds kick up later today and tomorrow. The heavy clouds will limit the vertical mixing to some degree, at least this morning.

Later today I'll post Art Douglas' summer outlooks.



Wednesday, May 20, 2015

Joshua Tree National Park

Driving back to Tucson from northern California, we spent Monday night in Twentynine Palms. Yesterday morning we spent three hours driving through Joshua Tree National Park. This is a huge park that straddles parts of the Mojave and Colorado Deserts.


We entered the park at the Oasis Visitor Center (above), which is at the east edge of Twentynine Palms. The highway map just below shows the general location of the park, which is north of I-10 and east of Palm Springs. the second map below is from the NPS and shows the roads, camp sites, and etc. within the park. The most interesting geology, and also concentration of Joshua Trees, is in the northwest portion, while the southern, lower elevation portions are characterized by sandy washes, rugged outcroppings and ridges, and much creosote bush. It's quite a long drive from the I-10 entrance up to the most interesting parts of the park.




Here are several photos I shot in the northwest part of the park yesterday morning.  The Joshua Trees in this part of the park are quite dense and very large, with spectacular backgrounds. It was interesting that the highest portions of the San Bernardino Mountains, visible to the distant northwest from the Park, were still carrying snow cover from recent storms.

Joshua Tree is just one of our National Park treasures that seem to be under attack by some of the country's ill-advised and short-sighted politicians. The visitor books at the Oasis Center were interesting for the number of comments from foreign tourists - one family from Germany noted that this was their second visit in recent years to this amazing park.





Tuesday, May 19, 2015

Back From Trip

We have been away for a week on an expected trip to California and have just gotten back to Tucson a couple of hours ago. Here is a quick post regarding the persistent 500 mb pattern that is probably related to the ongoing El Nino.


The troughiness over the Southwest U.S. is forecast by the GFS ensembles to persist through the coming week. I show here the, 12 UTC this morning cycle, GFS ensemble 500 mb mean charts for above - 12h valid about an hour ago; below - 68h valid at 00 UTC 23 May; and bottom - 168h valid at 12 UTC 26 May. 

Unfortunately, the troughs affecting the Southwest have been very moisture starved, at least for southern Arizona. I did find 0.07" of rain in the gauge a bit ago and that was from the early morning event of last Saturday, May 16th.



Tuesday, May 12, 2015

Heavy Cloud Cover For Southeast Arizona


Heavy middle and high cloudiness covers all of southeast Arizona this late morning - above is 18 UTC visible satellite image and below is current view looking south from Kitt Peak.



Plot above is of solar radiation from Atmo. Note that there is almost no incoming direct radiation (green curve) this morning, attesting to how thick the cloud deck is overhead.

Monday, May 11, 2015

Weak Short Wave From Mexico Tomorrow


A weak middle and upper-level short wave will be approaching from northwest Mexico tomorrow. The 15 UTC water vapor image above shows the feature over over central Baja this morning. The early run of the WRF-NAM model at Atmo today is actually forecasting radar echoes associated with this feature to move across southeastern Arizona late tomorrow. The forecast below is of composite radar echoes forecast for 10:00 pm tomorrow evening (Tuesday, May 12th).



The model's forecast of precipitable water (above, also valid at 10:00 pm MST) forecasts little moisture with this feature - keeping amounts tomorrow around half an inch. The forecast soundings indicate high cloud bases, with a deep and dry boundary layer. However, the model somehow manages to get rainfall down to the ground, as per its forecast of accumulated precipitation through 5:00 am on the morning of the 13th. 

Given the lack of moisture at low-levels, my guess would be for an unsettled afternoon tomorrow, with perhaps a few sprinkles across eastern Pima County. South and east of here there may be some better showers that dampen the ground. More significant showers and thunderstorms are forecast for the Big Bend country and eastern New Mexico.