More On The Satellite Images

I asked what was wrong with this image yesterday.

Comments I got went:

John Hinsberger has left a new comment on your post "What's Wrong With This Satellite Image?":

>From what I gather, imagery is no longer being generated at the Western Region level, but is coming from NESDIS. Hopefully, the county lines will come back again soon. 

Jack D has left a new comment on your post "What's Wrong With This Satellite Image?":

In my humble opinion, it is hardly Tucson centered. Not even if you consider the entire CWA. There needs to be much more coverage to the south and to the east, outside of cool-season systems, for which the Phoenix-centered image compensates, there is no coverage south of 31N nor as far as 108W. It "seems" to be centered just east of the jct of I-8/I-10 which is, in fact outside the Tucson CWA. 

Jack D has left a new comment on your post "What's Wrong With This Satellite Image?":

For what it's worth, you can get a more "customizable" version (lat/long, highway, etc) of the same image at the URL: http://www.ssd.noaa.gov/goes/west/wfo/twc.html 

Chris Reynolds has left a new comment on your post "What's Wrong With This Satellite Image?":

I do miss the old links.. I like this : http://weather.msfc.nasa.gov/GOES/ 

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All the comments are relevant, but I have been upset with the lack of county outlines, which makes geographical interpretation difficult. As per old version (different day) below:

While it is nice to be rid of the black void at bottom of image, the county boundaries were very useful to me. I have searched various sites and the only image I can find with county boundaries is from NCAR, as per:

But this is not very useful since it's centered over Hermosilla, Mexico. If anyone can steer me to a nice visible sector for Arizona with county boundaries, please let me know.

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Since I'm going on about this, I must say that I really dislike the IR and WV sectors now and the link that Jack D. provided is much better, given greater flexibility. The NWS link to western IR now produces:

I really dislike this Funktop enhancement curve - perhaps because of multi-decade familiarity with the AVN curve. The Jack D link lets you chose the old color enhancement, as per:

Both the NOAA enhancements are of minimal use, since they don't quantify the temperatures that correspond to the colors - very sloppy science.

Definitely Bit More Than Sprinkle Showers

More on the satellite question later today.

Moisture hung in through the afternoon yesterday and several bands of showers affected parts of the metro area and the Catalinas, as per ALERT data above for past 24-hours shows.We had 0.02" here with two periods of winds gusting 30 to 35 mph. TUS had 0.01" and DM had 0.02". Two sites in the Catalinas had nearly half an inch.

The WRF-GFS forecasts from 06 UTC continue to forecast very low PW, with values falling to 8 mm in metro by 7:00 pm MST this evening. However, the dry-out is short-lived in the model forecasts, with moist air returning from the east on Monday. The forecast below is valid at noon on Monday.

The evolution of features at 500 mb continues to be intriguing. Shown here are 500 mb forecasts (again from 06 UTC WRF-GFS, but on the 5.4 km grid) valid at 6:00 am - above on the 25th, below on the 26th, and bottom on the 27th. The closed low that develops just to our east digs southwestward over the GoC, but then moves northward toward southwestern Arizona. There will undoubtedly be showers and thunderstorms around parts of southern Arizona as all this evolves - but the details are certainly not clear at this time. The color bar has changed and is apparently one for winter - temperatures over us at 500 mb are forecast to be colder than -15C on the 27th, which could be very interesting.

What's Wrong With This Satellite Image?

The NWS Western region has changed the satellite images available through clicks at the NWS Tucson webpage. The above is the new (but definitely not improved from my perspective) Tucson zoomed high-res visible image. What's wrong with this new version?

Drying Out Slowly

Low levels remain very moist this morning, with heavy cumulus about and clouds hanging on the Catalinas.

Yesterday was very unusual regarding severe thunderstorms - all 23 reports from SPC were noted in a small portion of Utah - below.

The blended PW analysis for 12 UTC this morning (from CIRA, above) shows amounts now below 25 mm over southern Arizona. WRF models forecast slight chance for sprinkle showers before drier air moves in from northwest later this afternoon and evening. Below is 06 UTC WRF-GFS forecast for PW valid at midnight tonight, indicating amounts plunging to 10 mm and less over most of state. Weekend should be the coolest we've had in a long time.

This morning the middle and upper closed low is centered over western Utah (above is 250 mb 12 UTC analysis from NCAR), with a strong jet curling across parts of Arizona. Models forecast a strong vorticity maximum to dig down the west side of the low and become a separate closed low, as most of trough heads eastward. By early next week this southern low is actually forecast to be edging westward along the Borderlands (below is 06 UTC NAM forecast for 250 mb valid at noon next Monday the 26th). Will this feature manage to pick up moisture after the big dry out of next 24 hours? We'll just have to wait and see - but it will be the last hope for another rain event before the end of September.

Trough Over Great Basin Impacts Arizona Through The Weekend

There were isolated showers over southeastern Arizona yesterday afternoon - as per radar/gauge rainfall estimates above from Maricopa County FCD. Two ALERT stations in Oro Valley area had light rain amounts yesterday afternoon and Ron Holle reported 0.37" at his house up there. The view to the north from campus at 3:00 pm MST yesterday (below) shows the developing shower near Oro valley at far left of image.

The forecasts from the 06 UTC WRF runs at Atmo again forecast very slight chances for isolated showers over southeast Arizona this afternoon and tonight.

I show two 500 mb forecasts here from the 06 UTC WRF-NAM forecasts. This morning 500 mb temperatures over Arizona (above) are warm with temperatures of -2C observed at a couple of spots. However, as near as central California temperatures within the cold, short-wave trough are as cold as -25C. As this short wave moves eastward into the northern Plains during the next several days an interesting evolution is forecast by the model. A region of very strong cold advection develops to the rear of the trough axis and digs southward toward our area. By midday Sunday a separate closed cyclone has developed nearly overhead with temperatures colder than -15C; quite a change. The ECMWF model forecasts are quite similar, so it will be interesting to watch how the pattern actually evolves this weekend.

Beautiful Sunrise Today (21 September)

Meant to post this photo of sunrise today when I did the morning post but forgot.

The Paine Lingers Mostly As Low-Level Moisture And Mid-Level Heat

The NHC issued its last advisory on Paine at 8:00 pm MST last evening, as the storm had rapidly crashed, much as they had predicted. No rain here from Paine, and the WRF-GFS two days ago was very good with its forecast keeping Paine's precipitation swath far to our west. The IR image above is from 14 UTC and indicates only low, warm cloudiness left in area where Paine's remnant circulation is (northern Baja). However, the CIRA blended PW analysis (below for 12 UTC) shows a large pool of high PW air extending northward over the lower Colorado Basin and eastward to El Paso. Forecast question for the last day of astronomical summer is whether or not there will be enough CAPE this afternoon to fuel thunderstorms over parts of southern Arizona.

The SPC skewT plot of TWC sounding data from 12 UTC looks very promising (above) - PW of 1.60", substantial CAPE, and a nicely veering, Plains-type wind profile. However, the 06 UTC WRF forecasts from Atmo do not indicate anything across southern Arizona this afternoon, except short-lived, small storms that are very isolated. The models forecast decreasing PW and CAPE diminishing due to warming in middle levels. So, the models forecast that all that low-level moisture out there will go for naught. The forecast soundings for early afternoon in both versions, however, do look a bit more favorable for storms than the forecasts indicate - can only watch and see what the mountains are able to boil up later.

Unfortunetly, Paine has also left behind a large pool of warm, middle-level air within the core of a rapidly weakening short wave at 500 mb (the remnant short wave is actually the melded result of Paine interacting with the pre-existing cyclone that had been present to its north - destructive interference in action. Shown here are 06 UTC WRF-GFS forecasts for 500 mb winds and temperature - above valid at 6:00 am this morning and below valid at 6:00 pm this evening. The forecasts indicate continuous warming at 500 mb over Arizona through the day, which acts to cap deep convection, especially at low elevations. So it goes - good riddance Paine.

Paine Weakening Rapidly

Former Hurricane Paine has weakened very rapidly this morning and is hard to locate in the IR satellite image above. The area of high cloudiness produced by Paine is extensive, extending from northern Baja across Arizona much of Utah and Colorado. The Yuma composite radar chart from 07:30 am MST this morning (below) shows light showers remain mostly far to our west over southern California and the Colorado River Basin. Yesterday's 06 UTC WRF-GFS forecast appears to have been considerably more accurate than was the NAM version. The plot of CG flash density (second below, from weather.graphics and Vaisala) shows that, after the early morning storms yesterday near San Diego, there has been little thunderstorm activity, except out in the Pacific and far south in Sonora.

The 06 UTC WRF forecasts from last night are now quite similar - shown here are forecasts of accumulated rainfall through 06:00 am on the 22nd (Thursday morning). Above is the WRF-GFS forecast and below is that from the WRF-NAM. Main difference is whether showers to the east of the main precipitation area impact mostly Pima or Cochise County. Regardless, main impact from Paine will be far to our west and north.

Fooled By Ground Clutter

At the end of the previous post I referred to the radar data from Yuma and San Diego. I thought that storms had developed over the mountains of far southern California, based on a very quick perusal. I went back and took a second look and discovered that I'd been fooled by ground clutter from the Yuma radar (KYUX). The clutter may have been amplified by an inversion at the top of the moisture surge layer this morning. Regardless, I show some examples below from 1440 UTC to illustrate how caution is advised whenever one attempts to interpret radar data - all examples are from the CoD web page (link to right), which offers a nice variety of NEXRAD products to their users.

The KYUX VAD time series is shown above - it appears the top of the surge layer is about 2,000 ft ARL (above the radar elevation).

Above is KYUX base scan reflectivity, but when the 2.5 degree scan is examined (below), there is no echo over southern California. The area of high reflectivity at long range to the northwest is ground echo from the San Bernardino Mountains (these show up more frequently in the KYUX data).

The echo-top product is shown above (note that the high tops out by Palm Springs probably indicate that the radar's first side-lobe is also returning signal from the mountains). Although it is of little consolation, the ground echo is also fooling the dual-polarization precipitation type algorithm, which is indicating rain over southern California (below).

Finally, the storm-total precipitation product indicates that the precipitation algorithm has failed also in the clutter area, with totals as high as 3 to 4 inches indicated through 1440 UTC.

So it goes.

Low-Level Moisture Surges Rapidly Northward Up GoC

Paine has become a weak hurricane as it moves northward this morning. The current track forecast from NHC is shown above - NHC now forecasts the low-level circulation to make it a bit further north before it dissipates around 30 degrees north. Yesterday's discussion regarding the mid-level circulations of Paine and the 500 mb to its north remain valid (see previous post).

Low-level moisture has surged rapidly northward up the GoC during the past 24-hours. The plot of detected CGs below is for 12-hours ending at 5:00 am MST this morning (from Atmo and Vaisala) - thunderstorms have developed far north of Paine and impacted the San Diego area already. Additionally, the surge has already reached Yuma where the dewpoint temperature jumped from 44F at 3:00 am to 72F at 6:00 am.

The two panels here show the MIMIC total PW analysis from CIMSS at Univ. of Wisconsin. Analysis above is for 11 UTC yesterday, the 18th, while below is for same time this morning on the 19th. The push of very high PW up the GoC is shown very clearly.

The blended PW analysis from CIRA at Colorado State is shown below - also for 11 UTC. The CIRA analysis indicates that the gradient of PW is very strong along the Borderlands and that very moist low-level air will likely be pushing into much of southern Arizona during this morning.

The two variants of the WRF model run at Atmo continue to forecast considerably different precipitation outcomes from the affects of Paine. I've looked at the 5.4 grid forecasts from 06 UTC last night. The forecast of accumulated rainfall through 5:00 am MST on the 21st (Wednesday morning) above is from the NAM version of the model, with heaviest precipitation occurring in a wide swath across much of Arizona. The GFS version (below) for the same period keeps heaviest rainfall far to west in southern California and the lower Coloradao River Basin. Of note is that the GFS version develops thunderstorms in our area, well east of the main Paine band of precipitation. 

So Paine remains a bit of a coin flip locally but is certainly providing a rapid change in our local weather conditions. Current radar data from Yuma and San Diego would seem to favor the WRF-GFS forecast below at this time. The best chance for thunderstorms in our area may occur late tonight and tomorrow morning, before very warm air from Paine moves overhead in the middle-levels.