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Tricky forecast is changing
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Above you can see the NAM 48 hour forecast 500 mb flow. This shows a weak, positively tilted upper low moving into Texas and Oklahoma. You can tell that it is positively tilted by looking at the tilt from northest to southwest. If it were oriented northwest to southeast then this would be called a negatively tilted trough. A negatively tilted trough produces a lot of rising motion leading to rain and thunderstorms, or snow if it were cold enough. This storm, however is positively tilted which leads to not much lift. But, we must watch this closely because the tilt can change very fast. A great weekend forecast could suddenly become cloudy and rainy. I don't see any evidence of this right now.
If it stays positively tilted the weekend will be awesome. Have a great day!
Posted by at September 28, 2005 8:41 PM
I could swear I saw frost on some rooftops in Liberty this morning on the drive in to work, but didn't see any frost on the grass. None of the official obs from KCI or MKC indicated a dp at or below 32 degrees F this morning. Is it possible to have frost with a dp above 32? Since the "official" obs is taken 4 feet off the ground, is it possible the air at four feet off the ground was slightly more moist than the air 10 or 15 feet off the ground?
There were some scattered reports of frost this morning. And, yes the temperature and dewpoint could easily be two to as much as 7 degrees lower than the readings 5 feet above the ground. If it is 40 degrees at 5 feet 32 is possible, yet unlikely at the grass blades. The rooftops are rarely colder however.
Posted by: Pat Trudel at September 29, 2005 1:17 PM
haha... Have a Positively Tilted Weekend! Sounds fun.
Enjoy the forecasts, Gary and Team! Keep up the good work!
oh and... do you really have to move your fingers in a circle when pointing to a little icon? jes' curious! ;-)
If I move my fingers in a circle it is to make a point, otherwise I shouldn't be doing it.
Posted by: mike trainor at September 29, 2005 1:32 PM
Do you think that the first freeze will be earlier than last year? How about snow amounts?
It is too early. We will have an idea by early November. The weather pattern right now is favorable for cold fronts every few days. It won't take much to produce a frost as we move into October, but this is not a cold pattern. Once again it is about to change.
Posted by: Ben at September 29, 2005 4:37 PM
Hey Gary, when you move your fingers in a circle to draw attention to the icon on the map, do you move them in a counter-clockwise circle for a low and clockwise for a high?
Posted by: Dave Arnold at September 29, 2005 10:25 PM