Some Saturday afternoon clouds on the News 2 City Cam

Our normal high this time of the year is 86, and we didn’t even touch 80 this afternoon. That was partially due to a few clouds that capped off our afternoon temparature. Tomorrow, we’ll start to warm back up under a full day of sunshine, but humidity will still be low for this time ofthe year.

What can I say? Enjoy the weekend! It might be a little cool if you have plans at sunrise (like fishing).
Now what would make me think of that?

By the way, check out the New Nashville Weather Channel on Comcast Digital Cable Channel 185. In less than 5 minutes you get Stormtracker, regional radar, local temperatures, City Cams, and the 7 Day Forecast, along with a briefing from the members of the News 2 Storm Team.

What more can be said about the upcoming weekend weather? Lots of sunshine, low humidity levels, pleasant afternoons and cool evenings. Record lows for this weekend are in the mid 50’s (we won’t be more than a few degrees away at Nashville International!) Next subject…

Kevin’s Class Question:
How do snowflakes make their shape? (Jackie in Crossville)

Snowflakes are made of ice, they can be one ice crystal, two or several stuck together. By growing snow crystals in a laboratory, scientists have found it all depends on the temperature and humidity as the crystal grows in its environment. The actual shape depends on the temperature inside the cloud. They tend to form simple shapes in low humidity and more complex shapes in higher humdity. The shapes have evrything to do with what’s called branching and faceting (a subject for another day.) Here’s a picture to show you how they organize:
http://www.its.caltech.edu/~atomic/snowcrystals/primer/morphologydiagram.jpg
Amazing to think someday, we’ll be actually not only how much snow will fall, but what type of snowflakes!!!

Kevin’s Class airs Friday mornings during the 5:30 am half hour of News 2 This Morning. Feel free to e-mail me your weather question at weather@wkrn.com

Enjoy the weekend!!!

This weather couldn’t be better. A second front is promising a great weekend. Notice on the 7 Day Forecast above some 50’s for overnight lows.

Only thing is, well need some rain next week. Maybe Wednesday or Thursday. But those chances don’t look that big right now.

Tough to knock out the humidity this time of year, but Mother Nature has done it! Timing couldn’t be better…the beautiful weather starts just before the weekend (for those who are feeling a tad ill…hint, hint!) and continues right through the weekend itself! Can’t help but think; why couldn’t this have been the forecast for last weekend with Bonnaroo, CMA Music Festival and the race at the Speedway. But who’s complaining? Certainly not me!!!

With the quiet weather pattern it’s a great time for installment #2 of…Secrets Revealed! This is where we let you in on one of the ways we forecast the weather (even though we don’t use a sliderule or an abacus, there is actual forecatsing going on here, surprised?)

Today we will show you a technique to forecasting high temperatures!

Here’s a run of the raw computer model data for today:

OUTPUT FROM NGM 00Z 16-JUN-05
TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5
BNA//563721 -1298 113111 75261912
06000593420 -0600 093411 73241811
12000823427 -0802 123514 70181510
18000523338 00204 123208 70231509
24000432663 -1605 113312 70241609
30000432057 -0706 113615 69221509
36000421929 00507 143504 66201407
42000322124 -1405 123106 68241608
48000332434 -1704 113211 69251808

This is just one of 5 to 8 computer models we look at every day, but will suit our purposes here. This raw data tells us anything from preciptation, to winds, to pressure to relative humidity. It also can help us forecast the high temperature. The time code is the first numbers on the left and go in 6 hour increments. Now, look over to the column labeled “T1.” This is the projected temperature near the ground every 6 hours. In the first 24 hours of time, find the highest T1 temperature, in this case it would be 24. This is in degrees Celcius, so we’ll have to convert it to Fahrenheit.

Here’s the link to the website to do that for future reference:
http://www.onlineconversion.com/temperature.htm

This puts our 24 degrees Celcius to 75.2 degrees Fahrenheit. As I said before this is “near” the ground. In most situations the temperature rises the closer you get to the ground, so you have a add a few degrees to this number. How many degrees? That’s where the forecasting comes in…it depends on the time of year and how much sunshine. Here’s my guideline: On a day of…

An all day rain: you may have to subtract a few degrees (73)
Some sct’d showers: close to the T1 max (75)
Just cloudy skies: add one or two (76-77)
Partly sunny: add three or four (78-79)
Mostly sunny: add four to six (79-81)
Very dry air and sunshine: add as many eight (83)

This doesn’t factor in the wind direction or wind speed, that can also take the base number a degree or two in either direction.

That brings us to today…I have forecasted 84 degrees. I am going with the dry air and sunshine regime (add 8.) But as you’ll notice I added 9, so don’t be surprised if I’m a degree to two too high with my prediction…I figured the strong June sunshine (longer daylight hours) may give me that extra boost.

Didn’t think that much thought went into it, huh?

Yesterday, our dew points were in the 70’s. That’s the type of humidity that you would see in Houston, New Orleans, or in Florida in the summertime. Today our dew points are in the 50’s and you can really feel the difference.
Click on the “June Archives” about half way down on the right hand side, and scroll down for my blog called “So How Can The Humidity Be 41%, It Feels Like 90%”. It explains why dew point is a better indicator of humidity than relative humidity.

By the way, check out the New Nashville Weather Channel on Comcast Digital Cable Channel 185. In less than 5 minutes you get Stormtracker, regional radar, local temperatures, City Cams, and the 7 Day Forecast, along with a briefing from the members of the News 2 Storm Team.