Thursday, April 19, 2018

NWS Wind Forecasts For This Afternoon


This morning a 500 mb short wave (above from SPC is 12 UTC analysis at 500 mb) is oriented south-to-north across California, with a surface cyclone over the LA Basin (visible satellite image below is from 7:00 am MST). The 500 mb system is forecast to close-off and move eastward across the Great Basin, bringing Arizona another very moisture starved system, but with wind and dust yet again.



Continuing to focus on the NWS digital, high-resolution grid forecasts, above shows the forecast wind gusts for 2:00 pm this afternoon. Below is the hour-by-hour grid forecast for the airport today, and the bottom is the text forecast for airport. Note that text forecast is same as grid forecast for wind, but with blowing dust added to text.

More on digital forecasts later today.



Wednesday, April 18, 2018

NWS Gridded Forecasts

I have been trying to understand better the gridded forecasts that are available from the NWS (millions of grid point forecasts updated every few hours). These forecasts are easily accessed from the Forecast Office websites under the graphical forecast links. The grid point forecasts cover seven days at 1-hour time intervals. The NWS contracts with esri to provide the graphics for the mind-boggling set of products being generated (i.e., environmental system research institute of Redlands, California).


Shown above is the current digital forecast for high temperatures today across our region.


Another graphic (above) shows the gridded digital forecasts for wind gusts valid at 2:00 pm MST tomorrow (Thursday, April 19th). The display below shows the grid point forecast extracted from the massive data base by clicking on a point location (the interactive forecast map provided on NWS web pages). The wind forecast is for San Simon, Arizona - a location where I-10 in eastern Cochise County is frequently closed during blowing dust situations.


How accurate are these deterministic, point forecasts out through 7-days? Good question, and my experience watching them leads to my subjective appraisal - not very good, especially at longer time periods - but sometimes distressingly bad at only a few hours. When I tried to access verification data for the gridded forecasts, I found that that NWS link is restricted for only visitors having a noaa.gov email - so no luck there.

My digging has been stimulated by a question from Jack D, currently located in southern Illinois. Simply put his question was: Why are the NWS point forecasts so bizarre?

More on this issue in next post.

Tuesday, April 17, 2018

Wind And Dust Cycle Continues


Dust still hanging in the air this morning - early morning RH has only crept up to a very dry 13 percent. The 06 UTC GEFS plumes for wind (below) key on another spate of high winds for Thursday. The 06 UTC WRF-GFS forecast of 10-m winds valid at 4:00 pm MST on Thursday (second below) indicates the same.

Down at bottom is commentary on the ridiculous state of NWS short-term forecast graphics - this will be first of several posts about the problems with grid forecasts and meteorological absurdities.



If one goes to the NWS TUS web page this morning he/she finds both of these graphics about a Red Flag Warning for today - obviously a very short-term and important product. The real warning area is above; whereas the point-interactive graphic (below) that brings up the supposedly "high resolution" grid point forecasts shows a much larger area. What I find inexcusable is that a click, say on TUS, indicates a Red Flag Warning in effect - but this is not so for Tucson. Such inconsistencies at very short-terms should be totally inexcusable - but apparently management in NWS at Regional and National levels does not care.


Friday, April 13, 2018

Wind And Dust Here; Wildfires Southern Plains


It was very windy across much of Arizona yesterday, as per forecasts, with gusts of 40 to 60+ mph common. I estimated gusts to 50 mph here during mid-afternoon, as blowing dust obscured the mountains (above). The GEFS plumes from 06 UTC forecast last night (below) indicate three windy periods at airport for coming week.

Nasty wildfires continued into the night over western Oklahoma - as per news blurb at bottom.




Thursday, April 12, 2018

Spring Fling And The Winds


The University of Arizona is holding it's annual spring fling carnival today through Sunday. This event includes many carnival-type rides, as per above, and various booths up and down the length of the mall. (Edited to add important correction: the carnival starts tomorrow afternoon on Friday the 13th and today is setup, preparations, and testing of the big rides.)

So they are possibly faced with keeping things together during today's strong wind event. The NWS grid forecast for the University calls for possible gusts to 47 mph this afternoon. Below is the 06 UTC WRF-GFS forecast for 10-m winds from Atmo, valid at 5:00 pm MST today. Forecast indicates a widespread wind event affecting especially eastern Arizona and western New Mexico.





Tuesday, April 10, 2018

Winds, Dust, And Temperature Swings Rest Of Week


Rapid changes during the rest of week, with strong winds presenting biggest problems. Above is from NWS webpage this morning, while below is 06 UTC WRF-GFS forecast of 10-m winds valid at 4:00 pm MST on Thursday. The NWS grid point forecast for TUS that afternoon calls for gusts as high as 44 mph. Blowing dust with last event like this shut-down I-10 for about six hours off to our east and into New Mexico. With the very high temperatures and strong winds there will probably be some impressive dust devils around tomorrow and Thursday. 


Monday, April 09, 2018

Corrections

Jack Hales reports:

Jack Hales has left a new comment on your post "Miscellaneous Photos":

Bob, That is an Eagle's nest. Here is a video I grabbed a few days ago.


http://blog.starvalleyweather.com/2018/03/22/bald-eagle-nest-on-the-snake-river/ 


Looks like I happened to grab the image when the eagles were away and a raven was standing in their nest.

Also - the Flying Saddle Resort (and webcam) are in Alpine, Wyoming - not Idaho as earlier reported.

Miscellaneous Photos

Not much weather to write about this area - near record highs this week bumping at 100 F, and windy Thursday as strong short-wave goes by to the north. Am beginning to worry that rain may not come again here until summer thunderstorm season begins.

Below are some photos from last few days.


From Jack Hales webcam wall yesterday. Above is along the Snake River in Idaho. My weak, old eyes thought there was a bald eagle sitting in the nest - magnifying glass showed that there was actually a raven in the nest. Below shows buffalo grazing below Electric Peak, Montana, which is just inside the northern portion of Yellowstone, NP.



Sunrise near Sonoita, Arizona, on Saturday morning (above) and a nice sunset here at house on April 4th (below). At bottom is a Northern Cardinal from my walk yesterday morning.




Wednesday, April 04, 2018

Note To Jack D

Hi Jack - my emails to you are bouncing back. Are you receiving any?  Bob

Yesterday's Severe Thunderstorms


Yesterday's surface cyclone tracked across the central and upper Midwest about 100 miles north of the path observed in 1925. The mesoscale details of the situation were quite different, however, and the storms yesterday (above from SPC) produced mostly wind and hail reports.

The chart below summarizes events from March, 1925 (inside red boundary) and also indicates the area of the Jumbo Tornado Outbreak of April 3, 1974 (gray boundary). Yesterday's and March 25 outbreaks affected similar areas - differences in Arkansas and east Texas related to the dryline which swept eastward south of 1925 low, but did not yesterday. (Image below will not enlarge, unless you go to  http://www.ejssm.org/ojs/index.php/ejssm/article/view/114/88 .)






Tuesday, April 03, 2018

Another April 3rd Tornado

Don Baker (NWS Retired) sent along the post below about an F-5 tornado that struck the USAF base near Wichita Falls, Texas, on this day in 1964.


Monday, April 02, 2018

Two Historical Tornado Outbreaks

The deadly, Jumbo Tornado Outbreak occurred on April 3rd, 1974 - 44 years ago tomorrow. 

See -  https://swco-ir.tdl.org/swco-ir/bitstream/handle/10605/261918/ttu_fujita_000182.pdf?sequence=3&isAllowed=y

While tomorrow's synoptic setting is not as potent as that associated with the jumbo outbreak, it does bear large-scale similarities to the conditions associated with the infamous Tri-State Tornado of March 18, 1925. Shown below are a couple of recent surface analyses for that event.


The chart above is a surface analysis for 7:00 pm CST on March 18, 1925; while chart below shows the progression of the surface low during the day, as well as the track of Tri-State tornado. The detailed legends for these charts can be found at:

http://www.ejssm.org/ojs/index.php/ejssm/article/view/114/88



Here are two model forecasts from 00 UTC last evening - above is the NAM surface forecast valid at 7:00 pm CDT tomorrow. Below is the ECMWF forecasts for 500 mb and the surface - also valid at 7:00 pm CDT tomorrow.

It appears that tomorrows large-scale evolution will provide an interesting analog of the conditions that occurred 93 years ago on March 18, 1925.