Wednesday, April 11, 2012

Current Weather Conditions for Wednesday April 11th, 2012

Current Conditions
Temperature - 51 degrees Fahrenheit
Dew point - 22 degrees F
Wind direction - NNE
Wind speed - 3 mph, gusting up to 7 mph
Barometric pressure - 1030.22 g/kg
Cloud cover - clear

This is one forecast that I can say, I really wish I wasn't right about. Eau Claire did indeed see freezing temperatures and some frost overnight. The low in Eau Claire hit around 26 degrees F, which is not good news for fruit trees and a lot of other vegetation already in bloom. If your apple trees at home have already blossomed, temperatures below 27 degrees Fahrenheit can kill them. Severe frost can also do your apple blossoms in, although the blossoms may look fine the pistil (center tenticle like thing of the blossom) is likely dead. All of the apple trees I have seen in Eau Claire have already blossomed. However if your apple trees are still just budding, you're crop is likely unharmed as they can tolerate temperatures down to 24 degrees Fahrenheit. Since the temperature did not get drop terribly far beneath 27 degrees Fahrenheit the blossoms on the branches higher up on the tree are likely still healthy. But are we in the clear or we in store for another cold snap overnight?

Legend


Once again we are under a freeze warning into tomorrow morning. So we'll take a look at what is going to possibly cause freezing conditions overnight in today's post. Hold on, what is up with the tornado watch in the area where New Mexico, Northern Texas, Colorado, and Oklahoma all touch? Let's take a peak at that too.




I am introducing a new map to you all today, this is a 925 mb surface map. It does a nice job of conveying what general wind speed and direction looks like relatively close to the surface. In regards to the current weather conditions in Eau Claire it is evident that high pressure system you see in the first surface map is moving colder winds from Canada down into Wisconsin and Illinois. This is why clound conditions are so clear today, but this is also why we are at risk for frost overnight. Looking at both surface maps you can easily see the low pressure system southeast of the Rockies and the high pressure system east of Texas. These pressure systems are key in the development of these tornadoes, however the high pressure system over Illinois is also important. What is going on the low pressure system is drawing cold dry air over the leeward side of the Rockies, while the high the pressure system east of Texas is bringing warm moist air through Texas from the Gulf of Mexico. Meanwhile the high pressure center over Illinois is moving cold air from the NE, causing convergence with the warm air from the high pressure system east of Texas. Now what this has formed is a dry line. Remember we talked about dry lines yesterday? The convergence of the warm air and cold air from the high pressure system has created temperatures similar to those produced by the low pressure system. The difference is that the low pressure system has produced very dry air, while the converging air from the high pressure systems is moist. But let's take a look at upper atmosphere sounding and see just how unstable the atmosphere is.



Pretty darn unstable...KI of 34 and an LI of  -3.5, so thunderstorms are just about a 100 percent chance. I will keep you posted on tornadoes in the SW and frost dangers here at home.

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