Interesting Difference Between Models This Morning

After an interruption of several days, I am now able to get back to the blog.

The large 500 mb trough that is off the west coast this morning has a very complex structure, with a number of distinct short waves embedded within the larger-scale feature. One short wave is forecast by this morning's NAM to be ejected across the Great Basin today and tonight with little amplitude. Although precipitation covers most of California this morning, all the way south to San Diego, both the NAM and the WRF-GFS run at midnight last night forecast only a bit of precipitation in far northern Arizona. By the weekend however a much sharper trough is forecast to approach the Southwest, and this wave may bring enough moisture with it for a precipitation event across much of Arizona. (Note that February to date has been rain-free and almost cloud-free here in Tucson.) The top graphic shows total precipitation forecast by the Atmo version of the WRF-GFS for the period ending at 10 am Saturday morning (February 19th) and indicates a large band of rainfall and high elevation snowfall moving into southeast Arizona. The NAM however is slower (bottom graphic shows its prcipitation forecast for the 60 hours ending at 5 pm Saturday), and keeps the precipitation over northern portions of Arizona through early Saturday night. Regardless, finally a possible weather event for the Southwest!

Extreme Cold This Morning In Oklahoma

Rodger Edwards reports: I'm about ready for such a change (re previous post about the predicted pattern change) after the last two weeks, some of the coldest and snowiest in recent memory in OK (including *the* coldest temperature in state history this morning at BVO: -28 deg F). That, and my geothermal heat pump quit working sometime last month thanks to a worn-out condenser coil that leaked refrigerant like a sieve, leading to a doubling of my electric bill and a 4-figure repair cost for a part that hasn't arrived yet. Supercell observation season cannot come soon enough, nor can a different longwave pattern than this!
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Addendum: The OK Mesonet shows two sites colder than BVO, including Nowata at -31 deg F! Nasty...


Here is the link to the image (now shown above - perishable, so you may want to grab and save it if using it):

http://www.mesonet.org/data/public/mesonet/maps/realtime/today.TAIR.min.grad.png

Hemispheric Pattern Change

Shown above are the GFS ensemble, 500 mb, means from 00 UTC last evening for: 24, 84, 144, and 240 hours (from top to bottom). The models continue to indicate a pattern change in the Northern hemisphere, especially over the Pacific and North America. The strong ridge that has been persistent over the eastern Pacific finally shifts eastward over the continent, allowing a trough to develop and perist for a week or more along the west coast of the US. Also of note is the forecast deepening of the near-polar cyclone over Alaska and the redevlopment of a weak trough west of Hawaii - as per earlier in the winter. So, perhaps we will finally see a bit more weather possiblities here in the Southwest during the next couple of weeks.

Tremendous Damage In Southeast Arizona From Extreme Cold

The extreme cold of late last week left tremendous damage across much of southeast Arizona. The most serious damage being frozen and broken water lines. Today (Monday February 7th) when I was out running errands, I encountered several places where water is still running into the streets from ruptured pipes. The top photo is from Jim Toth (who lives a couple of miles away in the foothills where the local microclimate is warmer than here at the house). It shows bougainvillea encrusted in ice after a drip irrigation line froze and ruptured spraying water onto the plant. Interestingly, here on our circle the bougainvillea had been dead and brown since December, when the cold killed them back to their roots. Jim has more details at:

http://weatherwilderness.blogspot.com/

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The lower photo is of fallen prickly pear limbs and pads - I have piles and piles of these, probably at least 1000 pounds worth, and I figure it will take me about a month to get it all cleaned up. The morning low temperatures here at the house during the first week of February have been: 27F; 18F; 14F; 11F; 20F; 24F; and 26F. Easily the coldest week since I started keeping low temperature records here. We were quite lucky not to have frozen pipes, as several neighbors on the circle did. Art Douglas reports two nights with 0F at his place in Ash Canyon and much damage in the Sierra Vista area.

Lot Of Strange Soundings In Northeast Last Evening

Many of the RRS soundings at 00 UTC 6 February 2011 from the Northeast US appeared to have problems. There were many smal layers aloft with super-adiabatic lapse rates - too many to show them all. I've posted three soundings above (from the Univ. of Wyoming upper-air page).
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Albany data (top) have a super layer just above 700 mb and a deep layer below that exhibits absolute, moist instability. An unstable layer was definitely present, since the observations indicated thunder and snow and graupel and/or hail.
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The data at Pittsburgh (middle) indicate a VERY low tropopause - I can't rule this out - but the sounding seems very strange wrt all of its neighbors.
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Sterling (bottom) has a number of shallow super layers aloft, a layer below 700 mb with noise in the RH data, and then extremely low depoints for rest of sounding above 700 mb.
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No need to ask where the most interesting weather in the country was last evening!

After The Blizzard



I have not been able to find time to post last several days but hope that things will be back to normal tomorrow. Above photo shows my sister's little dogs heading out along a special snow route into the back yard after the Great Chicago Blizzard earlier this week. Sister lives in Batavia, Illinois, and she said they had about 20" or so at their house - much too much for the little dogs to deal with on their own!

Cold Forecast By ECMWF Definitely More Accurate Than GFS!

Chicago Lake Shore Drive during "rush" hour last evening - credit: Brian Cassella, Chicago Tribune.

Photo at top just one of many from the Midwest last evening and this morning of the show-stopping blizzard.
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Last Saturday I noted in a post that the ECMWF 120-hour forecast for 1200 UTC tomorrow morning was much different than, and VERY much colder than, the NWS GFS forecast for same time. That ECMWF forecast is playing out to have been much more accurate, perhaps even a bit conservative, as very cold air overs the West this morning (Wednesday February 2nd). It looks as if the 120-hour GFS forecast may have missed the 1000-500 mb thickness near Tucson for tomorrow morning by around 250m! The middle two panels show the NCAR RAP analyses of the 1200 UTC observations at 500 mb and 850 mb this morning. The 500 mb height analysis indicates a closed low near the Four Corners, while the observed winds indicate an open short-wave still, with temps of -38C near Grand Junction (note the very cold surface temperatures in northwest Colorado). The 850 mb analysis captures the extreme temperature gradients over the Southwest. Coldest arctic air remains east of the Continental Divide, but it is also spilling southward from the Great Basin. A weak inverted trough still extends south-to-north just along and west of the Continental Divide. The weakening, blizzard cyclone in the Midwest is now centered near Detroit.
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The 7 am surface data plot from NCAR RAP is the bottom graphic - one of the more wintery charts I've ever seen for Aziona and New Mexico. Observations of note: Guadalupe Pass, Texas, -2F with snow and east-northeast wind gusts to 41 mph; El Paso and Deming, New Mexico, both 9F with snow; Nogales, Arizona, 17F; here at house 7 am temperature was 20F (looks like low was 19F a bit after 7 - airport was still dropping at 8 am with 26F). Will tomorrow morning bring all time record lows?

Helicopter Crash Near Tucson Yesterday

Yesterday around 11:30 am a Sheriff's Dept. helicopter crashed at the north end of the Tucson mountains. Three were injured and, sadly, the pilot was killed. The storms that I reported in preceeding post had developed over the Tucson Mountains, apparently just before the copter went down. The top image shows NWS Tucson radar, base reflectivity, right before 11 am local time - the strong cell of 50+ dBZ produced abundant graupel, and perhaps hail, and was the storm that produced strong outflow winds that came all the way east past the house.
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As today's blizzard batters the Midwest, an intense arctic front has rapidly moved south down the Front Range of the Rockies. The U of A WRF model forecasts very COLD temperatures with this front tomorrow and especially Thursday morning. The WRF forecasted surface winds and temperatures valid at 7 am Thursday are shown in the middle figure. The temperatures are all the more remarkable given the strong downslope winds forecasted. See Mike Leuthold's special WRF discussion from this morning:

http://www.atmo.arizona.edu/products/models/forecasts/wrf_disc.html
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The surface data plot from an hour ago, bottom, indicates a battle between a Pacific front and the arctic front, centered over western New Mexico. Note the 10F temperature at Guadalupe Pass, Texas, with 43 mph wind gusts from the east-northeast and ice needles. To the west, Deming, New Mexico, was holding at 50F with west winds gusting to 30 mph - an amazing convergence zone. Will be interesting to see how long it takes before the arctic air dominates and comes west across the Continental Divide.

Quite An Event Here At House!

What a surprise here at house. I was away to the Post Office and strong convection came winging in from the Tucson Mountains between 11:30 am and noon. Where I was, near River and 1st, there was a lot of graupel mixed in with the rain and some wind. When I arrived home, there was 0.75" in the gauge with some graupel still melting (final total 0.76"). Apparently this was pretty localized, since I noted at 12:30 pm that  only 10 ALERT gauges had had any precipitation (except up in mountains where it has probably been all ice and not detected). At 7:00 pm this evening, only 24 of the 93 ALERT gauges have had precipitation (again with the ice caveat). Gauge with highest amount was Rillito at Dodge (about a mile away to the east) at 0.20".
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So a big event for the house and regions immediately to the northwest of here! We have solar panels being installed and the three guys working on the project were just leaving when I got home. I asked them if there had been any lightning or thunder here and they said "No" just lots of rain and ice falling along with strong west winds. I also noted on the max/min thermometer that the tempersture had fallen to 39F during the heavy rain/graupel shower.
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Photo above shows snow showers trailing off the west end of the Catalinas about 5:30 pm this evening (Monday January 31st).

Spits Of Rain At House This Morning

This morning at 7 am there were a few spits of rain here at the house and some snow showers up on the Catalinas - these were gone by 8 am as top image indicates. The morning low at house on the last day of the month was far and away the mildest of the month, coming in at 44F.
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The morning 500 mb analysis from NCAR RAP (second image) shows that the leading 500 short wave is well into Arizona and Utah this morning, with some middle-level moisture ahead of and with this feature. A very cold 500 mb cutoff is over west-central Canada.
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The 1200 UTC NAM forecast this morning (bottom two panels) indicates that by 5 pm this afternoon the 500 short wave will have moved to northern Mexico and stretch northward across New Mexico. The forecast also indicates a piece of the Candian low breaking off and moving south into the western US. The model produces only some light showers today across southeastern Arizona, with quite light QPF amounts at 5 pm.
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Very cold air will hold sway during mid-week, and here at th house I expect to see perhaps the coldest morning of the winter - will have to see exactly how the cold, cut-off evolves!

Rain Here before End Of Month?

The 500 mb cutoff that has plowed through the Pacific ridge is now along the northern California coast. This system will open into a short-wave that will swing across Arizona  tomorrow. The big question is whether there will be much in the way of measurable precipitation in southeast Arizona. The top image shows heavy cirrus moving in this morning. The middle and bottom graphics show QPF forecasts for total precipitaion ending at 5 pm tomorrow afternoon (the 31st of January 2011). The NAM forecast from the morning 12 UTC initialization indicates from 0.10 to 0.25" of precipitation across the low elevations of southeast arizona; whereas, the U of A version of the WRF model (initialized at midnight last night - bottom panel) forecasts precipitaion for the same period to be more sparse with amounts across the metro area of zero to 0.10" and amounts of significance only at the highest elevations.
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Quick note - the 84-hour NAM forecast ahas trended very much toward the ECMWF from yesterday - see post below - with VERY cold thicknesses here by Wednesday evening - might there be enough moisture left to squeeze out some snow showers here in town?

GFS and ECMWF Quite Different At 120 Hours

The 120 hour forecasts from the operational versions of the GFS and ECMWF at 1200 UTC this morning (29 January 2011) are quite different over southeastern Arizona. The GFS at 500 mb (top) has a very cold 500 mb low over Oklahoma, with heights of about 567 dm over extreme southeast Arizona. Thickness values (middle - 1000 to 500 mb) are around 540 dm. However, the ECMWF (bottom) has the low over New Mexico with 500 mb heights over extreme southeast Arizona at the same time of about 546 dm (more than 200 m lower than the GFS!). The ECMWF thickness appears to be about 522 dm - a very cold value for this part of the country. Thus, while both models' forecasts indicate the change to colder temepratures, the ECMWF (if it proved accurate) would likely bring the coldest temperatures of the winter to this part of Arizona. Certainly something to keep an eye on.
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Also of note are the extremely cold thickness values in both model forecasts of around 480 dm over eastern Canada - Brrrrrrrrrrrrrrrr!

Quiet In Arizona But 93 Million Miles Away.....

Double whammy on the sun


John Roach says: A spectacular double eruption on the sun was captured today by NASA's Solar Dynamics Observatory. The eruptions happened nearly simultaneously on opposite sides of the solar disk, SpaceWeather.com reported. The plasma clouds produced by the event are expected to miss Earth, so there's no threat to us or to satellites orbiting the planet.

On the lower left in this image of the sun, a magnetic filament erupted, and on the upper right a departing sunspot produced the strongest solar flare of the year so far, an M1-class event. The double whammy may be more than a mere coincidence: Recent research suggests that solar activity is interconnected by magnetism over large distances, and that solar storms can go global.
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John Roach is a contributing writer for msnbc.com.

Slight Chance Of Showers Last Day Of Month

First - more ups and downs in the low temperatures. Wind went calm here at house and temperature at 7am was 26F - down 19F from same time yesterday. Airport dropped to 37F at the same time; down 8F from
yesterday.
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The models are indicating a slight chance for showers on Monday the 31st of January, which is the first chance of precipitation here in southeast Arizona since December 30th. The forecast panels above (all valid at 5 pm on Monday January 31st) are: NAM 500 mb from 1200 UTC this morning; GFS surface from 0000 UTC last evening; and 500 mb and surface from ECMWF last evening. The models indicate that a 500 mb cutoff/short wave will break through the Pacific coast ridge and then get nearly in phase with a short wave digging down the east side of ridge from western Canada. The ECMWF is a bit faster with this system than is this morning's NAM. The GFS and ECMWF hint at a chance of showers while the NAM indicates limited moisture coming in with the system from the Pacific. The ridge pops back up along the coast and a very cold high comes south for mid-week. But, finally something for weather watchers in the far Southwest!

Suprisingly Mild This Morning

East winds set up during the early nighttime hours across much of southeastern Arizona, leading to low temperatures this morning that were 10 to 15F warmer than yesterday morning. Mike Leuthold noted yesterday afternoon that the WRF forecast was predicting morning temperatures considerably warmer than the NWS forecast was indicating. He sent the plot above that shows WRF surface observations for 7 am this morning (27 January 2011). It looks like the WRF was just a bit too warm but quite close, and captured the 24-hour change very nicely. Some observations this morning: here at house at 7am 45F with a nighttime low of 34F (versus 22F yesterday); TUS at 7am was also 45F with a nighttime low of 43F. Douglas changes were quite interesting: 29F at 7am today versus 16F yesterday morning at 7 am! However a few spots were about the same as yesterday, or even a bit cooler, as per the RAWS observations at: Mt. Hopkins, Rincon, Empire. This warming event indicates, again, the difficulty of low temperature forecasting across southeast Arizona, especially when there's a large-scale pressure gradient favoring easterly winds during the night.

Not A Cloud In Sight

Very clear skies today as per the webcam views above - looking toward north from Kitt Peak and also from Computer Sciences, U of A. Has been essentially an entire month of "Chamber of Commerce" weather here in Tucson. The clear skies and low humidity have led to six more consecutive mornings at house with low temperatures in the 20s - starting last Friday morning the lows have been: 29F, 29F, 27F, 25F, 25F, and 22F this morning (Wednesday January 26th). Airport was 11F warmer this morning than here at house.

Tough Forecast Challenges Next 48-Hours

A surface cyclone is intensifying along the Gulf Coast (see surface plot top for 13 UTC from CoD weather page), currently centered near New Orleans. I don't seem to recall many Gulf of Mexico cyclogenesis events in recent winters, but this seems to be a classic situation. The low will intensify and race up the East coast, posing a variety of forecasting challenges.
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Situations like this pose a severe weather threat, especially if unstable, mT air is pulled onshore ahead of the cyclone as it moves east-northeastward. Florida is clearly at threat later today, but satellite imagery at 1345 UTC (middle vis and bottom IR) indicates fairly strong thunderstorms offshore - so the first forecast issue with this cyclone is whether or not the air feeding these storms will stay mostly over Florida or be pulled further inland this afternoon.
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Last night's model runs indicate a significant winter storm for the Tennessee Valley, as colder air is pulled southward into the system. The models also indicate a rain/snow line that lies close to the major metropolitan areas, especially in the middle Atlantic Region. This will lead to a sloppy storm with the forecast challenge being how much rain vs how much ice and snow.
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So, a couple of interesting days on tap, but at other side of country.

Another Big Storm For Northeast Next Week?

The operational members of the ECMWF and of the GFS both forecast another deep storm next week - Wednesday into Thursday. The above forecasts are at 120 hours from 0000 UTC on 22 January 2011 for 500 mb and surface pressure and are all valid at 0000 UTC on 27 January 2011. The ECMWF (top 2 panels) deepens the storm very dramatically and keeps it very close to the coast. The GFS (bottom two panels) deepens the storm further east over the ocean, with much less impact on the cities of the Northeast. It should be noted that many of the members of the GFS ensemble forecast also keep the storm closer to the coast, making the operational version somewhat of an outlier. Regardless, it looks like more snow for portions of the Northeast next week!

Looking Around At Webcams

Looking at Mauna Kea from Mauna Loa this afternoon - Friday 21 January 2011.

Very Persistant Blocking Ridge!

The blocking ridge at 500 mb over the eastern Pacific and western North America is proving to be very persistent. While this may make the MAP winter weather lovers happy back East, it is leaving the Southwest high and dry! I've posted above the GFS ensemble mean heights and anomalies for 500 mb at 60, 120, and 180 hours from 00 UTC last evening. The ridge hangs in there through the period and is actually very impressive by 180-hours, with height anamolies reaching around 300 m over west Canada! Guess the main thing I'll be recording in my journal rest of month will continue to be low temperatures.