Tuesday, April 24, 2018

Light Showers Before End Of Month?

First time in a while for an am cloud photo - iridescence (sun dog?) at 22 degrees north of sun but no clouds to south.

As high pressure moves south over the Plains late in week, moisture increases on its west side. Shown above is 00 UTC WRF-GFS forecast (on the 5.4 km grid) for PW valid at 6:00 am MST on Saturday morning (28 April). Highest values remain along and east of Continental Divide but moisture does increase some into southeastern Arizona.

The GEFS plumes for QPF reflect this moisture gradient - shown below from top to bottom are: QPF forecasts for Tucson (top); Douglas (middle); and Deming, New Mexico (bottom). 

So, a bit of possible weather activity to monitor rest of week.

Sunday, April 22, 2018

Earth Day Number 48

Walt Kelly's famous Pogo poster done for the first Earth Day back in 1970.

I went off to Colorado State to work on my Masters in 1972 and was shocked by the terrible air quality and noxious brown cloud. Back then the only city with worse air pollution than Denver was LA. Over the years much progress has been made due to a number of changes that were driven by air quality regulations that were put into place along the Front Range - as per the two images shown here - 1970s vs this morning.

Let's hope that the common sense of the majority will prevail during this trying time and that our air quality will not be allowed to deteriorate back toward what it was in the last century.

Saturday, April 21, 2018

Not Much Ahead Weatherwise

This morning the 14 UTC IR satellite image (above) indicates a system west of northern Baja. The MIMIC TPW analysis for same time (below) shows little with this system - indicating mostly middle and high clouds, as per many recent systems. The models forecast this system to weaken rapidly and move across northern Mexico tomorrow - perhaps some clouds locally as this occurs.

Second below is the GEFS average 500 mb height forecast valid out at 00 UTC on 28 April - strong, bent-back ridge over the West - so not much hope for any meaningful rain again this month.

Down at bottom is photo of Harris hawk atop a pole near Country Club and Allen this morning - note the little finch keeping an eye on the much larger hawk.

Thursday, April 19, 2018

Jack D's Email Re Bizarre Point Forecasts

I know they (HQ) are wanting more automation in forecasts so “staff can dedicate more time to warnings and community outreach”. In AFDs around here (southern Illinois), they pull no punches. I have heard “Forecast Builder” mentioned many times as well as “Forecast guidance” from Central Region HQ.  Today is the first time I have seen a forecaster ADMIT they have been constrained by automation.  He clearly favors the drier solution based on his expertise, but has to be “beholden” to the “consensus model blend” and POP values into the weekend.  I have heard “CONSALL” thrown around lately and I would bet this acronym is this blend he is talking about..........   
  Area Forecast Discussion 
  .LONG TERM...(Thursday through Sunday)
  Issued at 327 AM CDT Mon Mar 26 2018
  Forecast confidence continues to deteriorate through the extended
  portion of the forecast. Confidence is especially poor for the 
  weekend into next Monday. 
  Due to the disparity in timing of surface features,
*******and the  consensus model blend we are beholden to these days,*********
  the forecast details, especially winds, are not very representative of any 
  solution through the weekend. We have lots of PoPs all the way 
  through the weekend, but the drier ECMWF is the favored model at 
  this point. Look for lots of showers/rain Thursday, Friday into 
  Friday evening, and then late Sunday into Monday. Saturday through 
  most, if not all, of Sunday should be dry.
 Note - southern Illinois was dry and mostly clear on the Sunday mentioned above (Easter Sunday).

Jack Henz sent this link which provides some insights:  https://www.weather.gov/mdl/nbm_home

Examples of bizarre point point forecasts with meteorologically improbable changes in sensible weather at short time intervals (1 to 2 hours) are shown below:

Beckley WV
Snow and sleet likely before noon, then rain, snow, and sleet likely between noon and 2pm, then rain likely after 2pm.

Scattered rain showers before 9pm, then a chance of rain and snow showers between 9pm and 10pm, then a chance of snow showers after 10pm.

Sun Apr 15 forecast for Wed Apr 18th for Madison WI
Freezing rain and sleet likely before 9am, then rain likely, possibly mixed with freezing rain between 9am and 10am, then rain likely after 10am.

FCST point NE Montana
Rain showers and sleet likely, possibly mixed with freezing rain before 2am, then snow showers likely, possibly mixed with sleet between 2am and 3am, then snow showers after 3am.

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.