Just wanted to give everyone an update on the heavy rainfall that will head this way overnight tonight and lasting into Thursday. This will not be a continuous rainfall, though there may be several rounds of scattered storms that will produce heavy rainfall at times. Our first cold front will work its way south later tonight before stalling out just to our North across the Wisconsin-Illinois border. Since we are stuck on the south side of the front, a very moist air mass will prime our atmosphere to develop thunderstorms that could produce heavy rainfall totals. 1-2 inches is possible over the next 48 hours, but some areas may receive closer to 2.5 inches.  Flash flooding should not be a major concern, only because we’ve had a nice dry spell for the past several days which should allow for most of the rain to be absorbed. Just be aware for water over the roadways due to clogged drains and do not forget your umbrellas.

Posted under rain, weather

Virga or fall streaks are a form of precipitation that evaporates before it hits the ground. Low humidity and high temperatures can cause rain to evaporate completely right after its release from a cloud. At high altitudes, the precipitation falls mainly as ice crystals before melting and finally evaporating.
Virga also has a role in seeding storm cells. It seeds the storm with small particles from one cloud that are blown into neighboring supersaturated air and act as “food” for the next storm cloud to start forming.
Virga can produce dramatic and beautiful scenes during a sunset. The light can be caught by the streamers of falling precipitation and light it up into so many beautiful colors.

Posted under science, weather

This summer has seen some very high dew points, at times into the middle 70’s making things feel very sticky. What if corn had something to do with our moisture content…well it does! During this summer’s wet growing season, a large amount of moisture evaporated off the leaves of cornfields through the midwest. Combining southerly gulf flow with this evapotranspiration, this is why we see so much humidity during our summers.

Now that the growing season is coming to a close, crops aren’t shedding as much water into the atmosphere. Despite southerly flow, this is one cause of our recently drier air.

Posted under weather

I’m running out of weather kids so send me your pictures. When you send me your pictures, make sure that the picture is medium resolution and no objects (hands, hat, fingers, etc.) are blocking the kid’s face. Just attach the picture to an email to either weather@wrex.com or ckahlbaum@wrex.com.

Posted under weather

We will be in a holding pattern over the weekend all thanks to Hurricane Danielle. Our high-pressure system will gradually move over Pennsylvania on Saturday and then comes to a halt. Why you ask?  Hurricane Danielle is blocking the High from moving further East. Therefore, we’ll gradually heat up for the next couple of days and our humidity levels will stay relatively low over the weekend. Our pattern starts to change by the beginning of next week, where we may see an increase in afternoon cloud cover into Monday and Tuesday. This is because of the continuous southern flow that will allow our dew points to increase back into the upper 60s.

Posted under weather

Altocumulus Castellanus (ACCAS), named for its tower-like pillars that billow upwards from the base of the cloud. Castellanus are the clouds that storm chasers look for on the morning of severe weather. Chasers look for these because they tell us that there is evidence of mid-atmospheric instability that is needed to supports supercell thunderstorms. They may be an indication of heavy showers and thunderstorms, if there is a lifting force at the surface that can connect to the unstable layer in the mid-levels. If they do interact, the Castellanus clouds may develop into cumulonimbus storm clouds.

Posted under science, weather

Radiational cooling is the reason why our temperatures cooled down during the overnight hours. At night there is no heat coming from the sun, so any heat acquired during the daytime releases into the atmosphere. The low temperature of the day occurs just around sunrise.
The best combination of radiational cooling is with clear skies and light winds. When skies are clear at night it helps the daytime heat to escape into space. When clouds are present, the clouds will push some of the heat back to the surface. Now if you add the light winds, the air is not mixing with warmer air aloft, so your temperatures will be much cooler at the surface.

Posted under weather

Have you ever wondered how many types for clouds there are?We have all heard of the three main categories, Cirrus, Cumulus and Stratus. However, there are so many different forms, features and species of each cloud that are used to describe the kind of cloud that you are looking at. Clouds are divided into the three categories based on the Latin words, which refer to the process of development. From there, each of these categories has several cloud genera. Ten cloud genera are obtained by cross-classification of the stratus and cumulus categories. They are separated by the prefix cirro, alto and low. Examples: cirrostratus and altocumulus. When looking at a species of clouds, that would be the individual or special cloud formation in one of the genera. For instance, the super-cool lenticular cloud (UFO Cloud) is species of cirrocumulus, altocumulus and stratocumulus. There are 13 different cloud species. The last classification before we get to the category all by itself is the main cloud features. This one we have all seen or at least heard of maybe in one of the blogs. Mammatus on the list of main cloud features as well the pileus cloud. Cloud features are usually created from how they are formed, which would bring the total in this classification to 21. Last but not least is the storm associated clouds. This is where you would find your funnel clouds and anvils. There are about 50 different types in the list and they have to do with stormy weather.

Posted under science, weather

We get to greet an out of town visitor of the rest of the week all thanks to the placement of our high and low-pressure systems. A cool-dry Canadian air mass will move into our area and likely result in the coolest overnight temperatures that we’ve seen since last spring.  By Wednesday night, our high-pressure system moves overhead and lingers on into Thursday.  This reassures us with temperatures staying in the mid to upper 70s, but it’s our dew points that will stay in check in the upper 40s and lower 50s. It might be jacket wearing weather for Wednesday because of the gusty Northwest winds up to 20 mph.

Posted under weather

We have been advertising a significant cool down coming behind a frontal passage on Tuesday for some time now, but indications of a warm up next weekend are beginning to fall into place. On the maps below, I have overlaid the GFS forecast temperature at 850mb (about 1,500m) with the jet stream position. By midweek, we will have northerly flow behind the frontal system that will bring very low dewpoints and fair temperatures. As we go a few days beyond, a shift occurs and returns us to southerly flow which will increase our humidity and temperature just in time for the weekend. I forecasted a high in the middle 80’s for Saturday and may have to look into upper 80’s on Sunday. Enjoy the taste of fall Wednesday and Thursday.

Posted under weather