Excessive Heat Watch In Effect...from Thursday through at least Saturday...if not longer depending on the temperatures...I'm shooting for 96 THU-FRI with a couple of degrees off those highs through the holiday weekend. The air aloft certainly would support higher values. My negatives from going to the extreme is 1) we need to get rid of a lot of moisture in the ground, although the farther SW you get the drier it has been over the last 5-10 days or so. 2) Winds...they will be favorable for maxing out on THU but less so on FRI...3) Dewpoints...somewhat lower on THU...but coming up FRI-SUN as the surface winds drop off. Model data suggests 100-106...

Regardless the Heat Index should easily be above 100, if not close to 110. Remember those numbers represent the temperatures in the SHADE...in the sunshine add 10-20 and on  the pavement add more compared to the grass. It's going to be nasty out there for quite some time after tomorrow.

Rain chances look minimal...perhaps a few strays tomorrow on the KS side...then we'll be watching a front over the weekend that should belly up towards the IA border. While the season has seen, at times, the cap breaking, i.e. SUN night/MON AM...it may hold a bit stronger with less forcing this weekend. We'll need to see IF storms develop...there would be the potential for an outflow to be generated and move our way altering the forecast considerable later in the weekend.


The seasons 1st TROPICAL STORM has formed in the Atlantic/Gulf Basin. Arlene is her name and will bring heavy rainfall to Mexico and potentially S TX...this could be a good thing for the drought situation down there that I've blogged about for awhile! Here is the forecast motion...

Very disorganized looking. Arlene is forecast to intensify over the next couple of days with very slow motion

Rainfall forecast per the HPC...

Back to our weather...I noticed something over the weekend on the VISIBLE satellite pictures that was confirmed for me by one of my friends @ the NWS...take a look at the picture...

Notice up across NW MO...just east of the State Line. See the absence of clouds. Notice the orientation of the clear area compared to the cloud filled regions east and west of the clear slot. Now what int he world could possibly cause this to happen? The same phenomena that causing so much consternation up there now...the flooding and the expanse of the MO River. The river has become so large that it's having an influence. locally on the temperatures. The heat of the sun, bakes the land areas and cause the temperature to go up faster, on this date (SAT) that created cloud cover where the heat was maximized...however the sun's energy is absorbed by the water, and since expanse of water is larger that normal, this kept temperatures immediately around the water area cooler. The lack of heating by comparison kept the clouds from forming. So now the MO River is actually creating it's own microclimate up there given certain weather conditions!

Meanwhile on the flip side...check out this information from AccuWeather...fascinating...I remember seeing these extremes a month or two ago in W TX and NM as well...


The National Weather Service in Las Vegas, Nevada issued a statement yesterday saying they had reached a record "dew point depression" of 129 degrees (or: low humidity of 1%) when their temperature was 107 with a dew point of -22 F.

They explain on their Facebook Page:

"Las Vegas' largest dew point depression ever recorded was set on June 27, 2011 at 129 degrees. The dew point depression is the difference between the air temperature and dew point temperature. At this time the relative humidity was 1%. The previous record dew point depression was 120 degrees set on July 2, 2007. This makes June 27, 2011 the driest day ever based on the dew point depression!"

You can't see the maximum depression on the official data graph above, where data only updates once an hour, but they posted a picture of the 1-minute data on their Facebook Page:

Relative humidity readings below 10% were widespread over the Southwest yesterday, though the KLAS airport was the driest I could find on the Mesonet map.

Joe