Sunday, December 27, 2009

Details on Christmas Eve Blizzard in Oklahoma

For details on the Christmas Eve blizzard in Oklahoma, see Roger Edward's photo above and his blog writeup at

Saturday, December 26, 2009

Cold Christmas

The Christmas Holiday has been quite cold here at the house with morning lows of:

Dec. 24 25F

Dec. 25 21F

Dec. 26 20F

Dec. 27 20F

This morning's low (on 26th) of 20F is the coldest since Dec. 28 2008 - when the low was also 20F. Very chilly for the desert but much warmer than many experienced the last several days!

Thursday, December 24, 2009

Winter in the Desert


Wednesday, December 23, 2009

Second Strong Storm of December Across Arizona

As was well advertised by both the short and long-range models, a strong storm pushed across Arizona yesterday and during the night. There is some snow lingering in the far southeast portions of the state. The subtropical moisture plume mentioned in Sunday's post did come across southern Arizona briefly (mainly as high and middle clouds with some virga, mammatus, and sprinkles - trace here at house midday yesterday) but was shunted east and south before the strong PVA moved into southern Arizona. The storm blew into the Tucson area yesterday afternoon with gusty winds and plenty of blowing dust, as shown above.
Highlights from the observations this morning:
It is difficult to assess the Pima County ALERT gauges this morning since higher elevation sites experienced a snow event and those gauges are registering "0". It does appear that the coverage was nearly a 100%, although a couple of sites in the far west part of the network might have stayed dry. Amounts ranged from around a 1/10" to a bit more than 1/2" - once again well-predicted by the models. Here at the house we had 0.32" and atmo had 0.51". Winds gusted at most southern Arizona stations to around 40 to 50 mph, not nearly as strong as with the event of December 7/8. I did note that Gutherie recorded 64 mph, Horse Camp Canyon had winds to 72 mph, and the atmo anemometer (75 ft above ground level) had several gusts around 65 mph.
Other observations of interest: snow occurred this early morning at Nogales, Ft. Huachuca, and Douglas, and during the night at Kingman. Phoenix and Scotssdale reported thunderstorms yesterday afternoon, and Prescott had thunder with snow. The models continue to predict that this S/W will will produce a blizzard-like storm for parts of the central and northern Plains on Christmas day.

Sunday, December 20, 2009

More on Tuesday Night/Wednesday AM Storm

Shown above is an Eastern Pacific IR image from 1400 UTC Sunday morning. At the present time there is a long plume of tropical and subtropical moisture extending northward into the S/W that will be digging down the coast. Thus, there is a nice "pineapple" connection in place. However, the NAM does not pick this plume up as the S/W digs. Rather, the NAM indicates that westerly flow around the base of the trough will shunt the low-latitude moisture off to the east and into Mexico. This connection should be monitored closely the next two days, since it has the potential to bring a more significant precip event to the Southwest than the model currently is predicting.

Interesting Weather Situation Developing for Southwest

After the huge snow storm in the East, attention for the next strong storm event will shift to the Southwest. This morning's (Sunday 20 Dec 09) NAM 500 mb forecast valid on Wednesday morning indicates very strong PVA across southern Arizona. Thicknesses (1000 - 500 mb) around Tucson are very near 534 dm, indicating quite low snow levels with this storm. All the models are very consistent and indicate that this strong S/W will swing rapidly into the Central Plains, producing a Christmas Eve blizzard. Thus, a very interesting event is unfolding for Southwest and Central Plains as Christmas approaches.

Wednesday, December 09, 2009

Strong Winds in Southern New Mexico

From Mike Hardiman in El Paso regarding the strong winds that impacted much of the state yesterday (Mike asks a good question below concerning the possible roll of the N-S Franklin Mountains in the localized occrrence of very strong winds east of the mountains).

Quite the wind event in the El Paso CWA today (Tuesday, December 8, 2009). Widespread damage in the Sacramento Mountains with 70 mph wind gusts at an APRS mesonet site in High Rolls, NM (elev ~6250) and 55 mph at a WxUnderground site in Cloudcroft, NM (elev 8850). Both were recorded before 9am and were the last obs reported before apparent power outages stopped the data flow. Lots of trees and powerlines down, some falling into homes.

The 12z RAOB from EPZ showed a strong inversion just above the mountaintop level of the Franklin Mountains which bisect the city of El Paso. Wind Gusts on the east (leeward) side of town topped out at 79 mph at an AWS site, which was well supported by 75 and 78 mph gusts at other mesonet stations. Wind blew down the signature canopy at Cohen Stadium (which looks eerily like Denver Int'l Airport), roofs blown off structures, debris breaking car windows, trees down, etc. Also, the Transmountain highway was shut down due to high winds blowing rocks into the road. Lots of residents reported a "tornado" despite just scattered flat Cu at 6000 feet. Interestingly, a plot of all the "mesonet" sites on the East Side shows one site reporting a SE wind much of the morning (everyone else was SW), before turning due West with that 79 mph gust, after which it remained SW. Don't really trust the siting of all these stations (combination of AWS Schoolnet, APRS, WxUnderground, etc), but the one site in question hasn't been noted to have wind direction issues in lighter winds. Can't help but wonder if a rotor or some sort of lee-side eddy wasn't at work here and may have aided in the damaging winds -- the worst damage was sort of clustered in the area of this cock-eyed wind ob.

A notoriously windy site at Aguirre Springs, NM, on the east slopes of the Organ Mountains near Las Cruces has a 97 mph recorded gust which destroyed a well-built hay barn. Widespread wind damage also occurred at White Sands Missle Range Main Base, 'de-roofing' the Police Station there, knocking out powerlines, injuring 2 people, and finally sending workers home early. WSMR's mesonet includes a station at San Augustin Pass (elev ~5700), through which US-70 links WSMR with Las Cruces. Peak Gust 116 mph. Hurricane force winds there are common in WSW high-wind events, but 100+ mph is still quite notable.


Rapid Deepening of the Upper-Midwest Cyclone

The cyclone bringing the blizzard and severe winter storm to the central US deepened rapidly during the night. At 00Z last evening it had a central pressure of ~994 mb. This morning it has moved to near Milwaukee (see above) and deepened to ~978 mb. Thus, the storm has been deepening at more than a mb an hour - very impressive.

Tuesday, December 08, 2009

Weather Watchers

Cows in southeast Nebraska watching and waiting for the blizzard to arrive.

Big Storm Blows into Central Plains

Very late post today.

Brief summary of various aspects of the overnight storm event.

Precipitation - at 7 am this morning about 75% of the Alert gauges in Pima County had measured precipitation in past 24 hours. Those that had not had rain were generally in the southern portions of eastern Pima County and most of those had light rainfall after 7 am. We had
0.24" in the gauge at 7 am here at house and had 0.02" more in the next hour or so. Heaviest rainfall report I noted at 7 am was 1.65" at CDO and Coronado (i.e. up on the northwest flanks of the Catalinas).

Snows were quite heavy at high elevations in the mountains and the photo above shows a bit of snow on higher peaks of the Catalinas at right side of photo.

However, the main aspect of the storm was the very strong wind gusts that swept across most of state - many areas in almost all parts of state had winds of 50 to 60 mph and max gusts were considerably higher. For example, the Gutherie RAWS station reported winds of 79 mph, Horse Camp Canyon had 73 mph, and the anemometer on the roof of the Atmo building on campus also had 73 mph. The only station that reported thunder was apparently Phoenix and the SPC storm reports map indicates a number of severe thunderstorm reports in Arizona last evening. This was a "sneaky" severe storm situation in that the severe winds were produced by the extreme synoptic pressure gradients and the thunderstorms were along for the ride!

The most interesting thing about the photo above is that there is considerable dust hanging in the air, even after widespread precipitation. This gives an erie cast to the photo and as the preciptation areas moved to the east they had a distinct brownish cast to them. Very strange morning reflecting the power of the windstorm.

The strong S/W that produced th overnight weather in Arizona has swept eastward very quickly and is now bringing a very major snow event to the Central Plains and upper Midwest, in addition to widespread blizzard conditions tonight as the low intensifies.

Saturday, December 05, 2009

Not Quite as Cold This Morning

Considerably high-level cloudiness moved into southern Arizona overnight helping keep temperatures a bit warmer last night. Low here at house was 24F. Low at TUS NWS observation site was only 35F this morning, in contrast to 32F yesterday. The exception was far southeast Arizona, where Douglas dropped to a low of 20F this morning, in contrast to their low yesterday's of 27F.
Difficult forecast situation for next week as fast, low-latitude flow will bring several S/Ws across Arizona with at least some moisture from Pacific. Situation is complicated by the strong, cold S/W trough to the north - making timing, exact locations, and possible amounts of precipitation hard to anticipate precisely. Pattern for next couple of weeks certainly looks el nino-ish!

Friday, December 04, 2009

Cold Morning Here at House

It was quite cold here this morning - coldest of the winter so far with a low of 23F. I noticed a lot of readings down in the 20s this morning across southeast Arizona. The coldest I saw at lower elevations was 21F at Sasabe. This was 14th freeze this winter here at house and 7th day down in the 20s.

Snow photo above is from Mike Hardiman in El Paso. he has taken a lot of nice shots of the snowfall produced in the New Mexico and big bend borderlands by the storm earlier this week (see below) and these can be viewed at

Tuesday, December 01, 2009

Jim Means reports from
Alpine, CA at 1270', 32.83N 116.81W and are Alpine 3W on the hourly roundups out of San Diego
Hi Bob,
We had an under-predicted storm here on Saturday. I got 0.70" at my house with pea-sized hail, and some places nearby had over an inch of rain, with 5 inches of snow at Mt. Laguna.
Nice start to the winter season--things are less flammable now (a prime concern at my house).


I tried to find recent photos from the snow event across southern New Mexico and the Big Bend country this morning but with no luck. The photo above shows heavy snow falling in El Paso yesterday (Mon Nov. 30th).

Yesterday 5% of the Pima County alert gauges had light precipitation and these were all in the Catalina and Rincon Mountains.

Clear and cool this morning with a low here at house of 31F. Fall (September, October, and November) closes out with only a total of 0.63" inches of rain here at the house.