Thursday, January 26, 2012

Something On The Horizon? Edited to add: And Then It Was Gone!

The 168-hour forecasts from the 00 UTC operational runs of the GFS and the ECMWF once again have significant differences in their 500 mb forecasts, valid at 5 pm MST on February 1st. The GFS (above) has a flat ridge over much of the western U.S. The ECMWF (below) forecasts a closed low digging south along the California coast - the first hint of a possible weather-maker in the Southwest for a number of model runs. Height differences along the southern California coast are nearly 200 m. So, something to keep an eye on as January draws to a close.

Edited to add: The digging short wave in last evening's ECMWF vanished as quickly as it appeared. The 168-hour forecast from 12 UTC this morning is shown below, with no trace of that California closed low. Perhaps it will return in the evening run?

Tuesday, January 24, 2012

Tornado Outbreak Of January 24, 1967

On January 24, 1967 - 45 years ago today - there was an unusual winter outbreak of tornadoes that struck in Missouri, Iowa, Illinois, and Wisconsin (see track map above). There were 30 documented tornadoes on this day. Six of the tornadoes were rated F3 and two were rated F4. There were 7 deaths and 268 injuries during the outbreak. One of the last tornadoes of the day (around 7 pm) was an F-4 that struck across the northern portion of St. Louis, Missouri - track is shown below. This tornado passed very near Lambert Field (the St. Louis airport) and the Weather Bureau Office (which was then located in the old terminal building on the northwest side of the airport). An aerial photo of some of the damage is shown at bottom. The NWS St. Louis Office has a story and more information at:

This is a very memorable event for me - I started work (my first full-time job after college) at the St. Louis Weather Bureau the morning following the tornado. The office was in a state of near chaos when I reported for work, and an investigation team had just arrived from kansas City. I was stuck off at a desk, away from the action, and told to answer phone calls as best I could - what a strange and exciting first day of work.

Commentary From Mr. Pickwick In Oz

An excursion away from the weather. Mr. Pickwick (Guy Weller) is a bookseller in Katoomba, Australia (in the Blue Mountains west of Sidney). He, and his computer, "Hannibal," provide political commentary and astoundingly accurate predictions regarding U.S. politics and elections. I've been following him for over three years now on a booksellers' chatboard. His blast below regarding the U.S. media and the current political situation is something I can't resist posting.
### However I felt that they would have been torn apart on some of their messages by the senior British political journalists. The other candidates seemed very lightweight and it was hard to believe that they were standing for a leading position. ###

Hi PhBooks,

This is a feature of US politics. Their media there is extremely wet and a sort of MacDonalds Media - it has no real teeth or spunk like the British media. All soggy beef and second-rate melted cheese dripping over inedible buns.

The candidates there can say and do more or less as they wish, and the media clucks and coos like so many geese in the yard - hisses a bit, and rushes about with flapping wings, but does NOT get savage at any point, or go in for the kill. Add to this the more or less complete incompetence and - dare I say it - ignorance of the US media and so-called political pundits, and you have a political commentary system which is more or less out of Walt Disney.

Hence your astonishment, which I share, but which I have long since learned to absorb and largely ignore.
Whereas you in Britain and we in Australia expect (and get) strong beer from our political journalists, in America they expect merely a milkshake from theirs.

The excruciating ignorance and lack of knowledge of their own political systems, history and political methods from US journalists and even their so-called "pundits" simply beggars belief on many occasions, and leaves those of us used to more sophisticated and knowledgeable inputs from our media folk sometimes quite bewildered.

The systems of "polling" in the US are so absurd (as Hannibal and I have demonstrated on several dozens of occasions in here, including several over the last month or so) as to render them perfectly meaningless, and even a little dangerous in that these ridiculous "surveys" can actually influence end-results over there to some extent (smaller than fondly imagined by their media).

In all, when it comes to US political reportage and associated polling etc., you are talking a circus rather than a piece of coherent theatre. The USA is horribly mis-served by its political media, and this fact helps feed second-rate candidatures, such as we are seeing in this GOP race at present.

None of Mitt Romney, Newt Gingrich, Rick Perry or Michelle Bachmann could survive for more than a week of media exposure in Britain or Australia - all would simply be laughed from the room for the clowns they are. Mitch Daniels would survive our far more intensive media analysis, and funnily enough, so would your "lightweight" in this one, Rick Santorum. Huntsman probably would endure under our spotlights as well.


Guy Weller (Mr Pickwick)

Current System Produces Only A Bit Of Weather

This morning has dawned mostly clear, but with low clouds still sitting on top of the Catalinas (above). The webcam up there indicates a dusting of snow at Summerhaven. The Pima County ALERT network indicates 6 stations had .04 to .12" during the night - plus a few stations probably had some snow that wasn't indicated by the ALERT gauges. So about 10% areal coverage for this "event" with precipitation occurring at high elevations, much as predicted by yesterday's WRF-GFS.

This morning's NAM analysis of the 500 mb data indicates that the vorticity maximum with the short wave actually got south of the border, as opposed to yesterday's forecast that it would be over Tucson at sunrise today. As Chuck Doswell commented yesterday, this short wave will head toward south Texas, where low-level, moist air from the Gulf of Mexico is flowing on-shore (see current surface plot below). So, possible January severe thunderstorms again, after the devastating tornadoes that hit in Mississippi and Alabama on Sunday and Monday. More on January tornadoes a bit later today.

Monday, January 23, 2012

Another Fast-Moving 500 mb Short Wave To Cross Arizona

The 500 mb short wave that is near San Francisco this morning (NAM 12 UTC analysis above), is forecast to dig southeastward and be nearly over Tucson by 12 UTC tomorrow morning (below)

This system, while currently producing considerable rain across California, is forecast to be fairly dry as it moves across southern Arizona tonight (23 January 2012). The early run of the WRF-GFS at Atmo forecasts only light sprinkles over southeastern Arizona at higher elevations - see below for the WRF precipitation forecast through noon tomorrow. So it looks like more clouds and some gusty winds this afternoon and tonight, and perhaps some spits of rain.

The system that moved across Arizona Saturday afternoon (see previous post) produced an unusual, January outbreak of severe thunderstorms and some tornadoes yesterday over the middle Mississippi Valley and parts of the Southeast - SPC storm reports are shown below.

Sunday, January 22, 2012

High Winds Yesterday Afternoon And Evening

As the 500 mb short wave (mentioned in previous post) moved rapidly across Arizona yesterday it produced widespread strong winds, some areas of blowing dust, as well as some light precipitation at northern locations. This morning suspended dust hangs in the air - see above image looking north toward the Catalinas. Wind gusts of 35 to 60+ mph were common at higher elevations across all of the northern and eastern portions of the state. Art Douglas reported high winds at his location near the mouth of Ramsey Canyon, and sent along observations from a nearby weather station - below:

Weather Conditions for:

N0NBH Sierra Vista, AZ (AS557)
Elev: 4646 ft; Latitude: 31.50228; Longitude: -110.26040
Current time: Sat, 21 Jan 10:10 pm (MST)
Most Recent Observation: Sat, 21 Jan 10:02 pm MST (MST)
Time Temp. Dew Relative Wind Wind Altimeter Station Precip Quality
Point Humidity Direction Speed Setting Pressure 24 hour Control

(MST) (f) (f) (%) (mph) (inches) (inches) (inches)

21 Jan 10:02 pm MST 57 31 37 W 5G62 29.94 25.252 0.00 OK
21 Jan 9:53 pm MST 57 30 35 WSW 10G56 29.94 25.252 0.00 OK
21 Jan 9:43 pm MST 57 30 36 W 9G44 29.94 25.252 0.00 OK
21 Jan 9:34 pm MST 57 30 35 WNW 10G63 29.94 25.252 0.00 OK
21 Jan 9:24 pm MST 57 31 37 W 9G49 29.94 25.252 0.00 OK
21 Jan 9:15 pm MST 57 32 38 W 9G55 29.93 25.243 0.00 OK
21 Jan 9:05 pm MST 58 34 40 WSW 8G38 29.93 25.243 0.00 OK
21 Jan 8:56 pm MST 57 35 43 W 12G42 29.93 25.243 0.00 OK
21 Jan 8:47 pm MST 58 36 43 W 13G50 29.92 25.234 0.00 OK
21 Jan 8:37 pm MST 58 36 44 WSW 13G48 29.92 25.234 0.00 OK
21 Jan 8:28 pm MST 58 35 42 W 12G54 29.92 25.234 0.00 OK
21 Jan 8:18 pm MST 58 35 42 W 9G64 29.92 25.234 0.00 OK
21 Jan 8:09 pm MST 58 35 42 W 11G64 29.93 25.243 0.00 OK
21 Jan 7:59 pm MST 58 33 39 W 10G48 29.93 25.243 0.00 OK

I read on the Albany MAP talk board that winds were very strong across portions of southern California. A PGA golf tournament in Palm Springs suspended play due to damaging winds at all three courses. Nothing of note at several of the low elevation stations, including here at the house.

Saturday, January 21, 2012

Fast-Moving 500 mb Short Wave

A fast-moving, short wave at 500 mb will move eastward across northern Arizona tonight (Saturday, 21 January 2012). The vorticity maximum with this wave was near San Francisco this morning, with widespread midde and high cloudiness spilling to the east and southeast far ahead of it. The heavy clouds cover all of Arizona at 8 am MST this morning, except for the far southeast (see visible satellite image below)..

The blended PW image below (at 5 am MST) shows a distinct plume of subtropical moisture extending from west of Hawaii into central and southern California, where rains and mountain snows are widespread.

The morning forecast of the NAM model predicts limited precipitation by 5 am MST tomorrow morning across far northern Arizona (see above). The midnight run of Atmo's WRF-GFS (below) forecasts a bit heavier precipitation across the Rim Country for the same period. Regardless, looks like we'll mainly be watching clouds zip by down here in southern Arizona, although there may be some sprinkles, and mammatus during the late afternoon. Next Pacific short-wave comes in late Monday and may dig further south than current one - so something to keep an eye on.

Monday, January 16, 2012

Damp Morning With Snow At Highest Elevations

The 9 am (MLK Day 16, January 2012) webcam shot up at Summerhaven on Mt. Lemmon (above) looks like they had a sloppy, wet snowfall during the night. Down here in the north part of Tucson we had light showers that began during midafternoon yesterday, and light rain during the night. Data from the Pima County ALERT network indicate a widespread event with almost complete areal coverage of measurable precipitation, but with amounts mostly less than half an inch. There were 13 stations, on and near the Catalinas, that had more than half an inch and one station on the north side of the mountains with over an inch. Here at the house the gauge has 0.26" in it this morning. So, we avoided, just barely, going longer than a month with no rainfall. Just looked at the latest ALERT map (below) for the Catalinas, and it is now showing three stations with more than inch of rainfall.

Sunday, January 15, 2012

Couple Of Questions

Sarah Truebe asked:

...Can you direct me to a resource on mammatus clouds? I noticed them yesterday, and I think I've only ever seen them before under anvil clouds of thunderstorms. Why do they form in other contexts? Thanks!

Sarah, mammatus can form on clouds that are not associated with thunderstorms, as they did yesterday. Usually, though they are associated with deep convection and thunderstorms. Yesterday there was instability in middle-to-upper levels and there was convection aloft with fairly high cloud bases, but with no lightning or thunder, and, eventually, just  a few sprinkles. Such events are fairly common here in southeastern Arizona.

The question of why they form is much more difficult. You can find any number of simple explanations on the internet, but these are usually not very accurate. The real answer is that we're not really sure of what exactly causes mammatus clouds.
The preceding link is to a technical paper on mammatus (written by 11 authors and mentioning discussions with 19 other atmospheric scientists). They conclude that there is no definite answer as to causes, but there are a number of possible mechanisms, as well as "...more research is needed."

Chuck Doswell asked:  Is that your bluebird photo?

No, Chuck, I grabbed it from an internet site. I did know what kind of bird it was though, thanks to my field guide. I don't take very great photos with my little, simple digital camera. Yesterday was even more frustrating than usual. Batteries slowly faded and I lost six or so photos, which were undoubtedly my best shots. I had taken photos of sevral spectacular live oaks down in the gullies and lost every one of them.

Hiking Yesterday West Of Highway 83

I took a short hike yesterday on public lands that are still open near the proposed Rosemont copper mine. Was surprised to find significant work underway, even though final approval for the mine has not yet been granted. Rumbles and noise of heavy equipment, working in the planned pit area, echoed through the hills. The terrain is quite diverse out there with live oaks and large juniper in the washes, giving way to scrub and open rock along the western ridges, with abundant grasses and smaller juniper across the middle and lower elevations out toward Highway 83.

Even though there has been no precipitation for almost a month, the north slopes of the Santa Ritas were still carrying noticible snow cover (above - top). As moisture streamed in from the western Pacific, there was heavy middle cloud, much mammatus, and virga hanging over the mountains (above - bottom). Here at the house we had a distinct, but not very strong microburst, from a precipitation streamer that produced a couple of spits of rain. This morning there appears to be a nice flow of low-latitude moisture being pulled northward by the 500 low west of San Diego. So, we may get the first rain in a long while, as this low weakens and is picked up the stronger trough to the north-northwest.

Of note while I was walking was a bright, brief appearance of a Mountain Bluebird - see below.

Saturday, January 14, 2012

A Week Of Cold Mornings Along The Rillito

I have been extremely busy on a project the past several weeks and have not had time for many posts. Here's a quick one concerning how cold it's been here at house during the past week. The lows for the past 7 days, beginning with this morning (Saturday, January 14th), have been:

24, 24, 32, 28, 26, 24, and 25  - in comparison the official Tucson lows at airport have been:
38, 32, 42, 38, 37, 32, and 39 - with the differences between the airport lows and here being:

14, 12, 10, 10, 11, 12, and 14    showing the airport lows averaging about 12F warmer than here.


Wednesday, January 11, 2012

Cool And Dreary Winter Morning

It has been a cool and dreary morning here at the house (Wednesday, 11 January, 2012). No winds and dirty air, after a morning low of 28F. Heavy cirrus and middle cloud, with some virga, are spilling over the top of a weak ridge over southern California. See current visible satellite image below.

Views below are from Kitt Peak (looking south) and from campus (looking north). No precipitation since December 19th, but lots of cold mornings - 13 of them down in the 20s. Not at all clear if the 500 mb cutoff low west of California will give us a chance of rain in a few days.

Sunday, January 08, 2012

Cold Front Brings Significant Cool-Down This Afternoon

A strong, but fairly dry short-wave trough at 500 mb has been digging southeastward across eastern Arizona today. The temperature has just managed to struggle into the upper 50s here in Tucson this afternoon (Sunday, January 8th, 2012) - a cooling of nearly 20F relative to yesterday. This morning was the coldest of 2012, with a low of 25F here at the house. Temperatures have been freezing, or below, every morning but one of the year so far, with three mornings in the 20s.Afternoons have been balmy, however, with highs in the 70s each day - until today. New Years Day set a rcord at 80F.

Surface plot for 4 pm MST (below) shows that the precipitation with this system is mostly over New Mexico, where strong convergence, as well as upslope flow, is producing a region of both rain and moderately heavy snow from El Paso north to Las Vegas.

Wednesday, January 04, 2012

Afternoon Walk Along The Rillito Wash

Just back from a walk along the Rillito Wash (3 pm MST on Wednesday, 4 January). Saw 4 of these guys, western Bluebirds, flying along in a little group or mini-flock. Seems to be the first time I've seen them along the Rillito, although I've seen them before out around Sonoita. It's quite a warm afternoon with the current temperature around 75F. Was down to 31F this morning. Morning lows continue to run 10 to 15F colder than the official Tucson lows at the airport. It certainly is Chamber of Commerce/ snowbird weather here.

Monday, January 02, 2012

Warm Night At Airport

Winds have been gusting 25 to 35 mph at TUS since about 3 am this morning. The time series of T and Td (above) shows the flat T curve after 11 pm last night. The low at airport was 58F and was 15F warmer than yesterday's low of 43F - quite a surprising warm up. Here at the house the morning low was 34F - up by 5F compared to yesterday. But, it was a very serious 24F colder than the official low. At 9 am it remains calm here at the house, but expect winds will break through any time now. Given the relatively small terrain gradient from the airport to north side of the city, the 24F temperature gradient is quite amazing.

The low at the RAWS station on Mt. Hopkins was only 54F, while the low at the Empire RAWS station was 44F. Photo above shows the Empire RAWS site (I took the photo on the 31st) with the view looking west-northwest, directly toward the north end of the Santa Ritas, i.e., directly toward the site of the proposed Rosemont Copper Mine. This mine would be mostly on Coronado National Forest lands; would be one of the largest copper mines in the world; and would destroy the scenic beauty, and much of the ecology, of one of the most beautiful landscapes of southeastern Arizona. Ironically, the mine would be owned and operated by a Canadian company, in partnership with several entities in Korea!

Sunday, January 01, 2012

Best Of The New Year To All

The year ended here at the house very dry, and with cold mornings. From 21 December through this morning (1 January 2012) there was only one day that did not have lows below freezing (the 22nd at 34F). The eight days from the 23rd through the 30th of December had lows in the 20s, with 6 days at or below 23F.

This morning the low here at house (2350 MSL) was 29F. The current temperature at the airport (TUS) is 80F, making this a day with a diurnal temperature range of more than 50F. This is quite something with the sun angle so low. We've been running 10 to 15F colder in the mornings than the official TUS lows at the airport.

This morning the cold est air was at low elevations that have some cold air drainage. The following lows occurred at RAWS stations nearby - Rincon (8209 MSL) 44F; Mt. Hopkins (7120 MSL) 53F; Empire (4658 MSL) 36F; and Sasabe (3500 MSL) 34F. The official low at TUS this morning was 43F. The photo above shows the Mt. Hopkins RAWS, station at lower middle of image, with the view looking north at the Hubble telescope on the peak of Mt. Hopkins.

Art Douglas reported similar temperatures over in the Huachucas and San Pedro River valley. Art had 56F at 7 am where he's renting (near Ramsey Canyon) and Coronado NM Headquarters had 53F. A weather station in the bottoms of the San Pedro, east of Ash Canyon, had freezing and Elfrida (north of Douglas) has 29F.

No precipitation here since the 19th of December, but the ECMWF is indicating at least some possiblities for next weekend - so we'll wait and see how things evolve. Meanwhile, it is continuing very warm during the afternoons.