Winter Weather Guide
POSTED: Thursday, February 3, 2011 - 1:04pm
UPDATED: Friday, February 4, 2011 - 12:50pm
The Jargon meteorologists use when describing winter weather can seem a bit confusing at times. Here is your guide to all things Winter.
First, let's look at the warnings and watches in effect for our area.
1. Dark Magenta(ex. E Baton Rouge, Pointe Coupe, etc) = Winter Storm Warning: Now-9AM Friday Morning - a mix of rain, freezing rain, and sleet is expected to worsen icing conditions in our area.
2 Pinkish-Lavender ( ex Tangipahoa)= Freezing Rain Advisory: Now-4PM Thursday-Periods of freezing rain or freezing drizzle will cause travel difficulties as roads will be slippery.
3. Purple (ex. St. Mary) = Winter Weather Advisory: Now-6PM Thursday = less than 1/4 inch of freezing rain will occur in the next 12 hours, causing a light glaze of ice to form.
Next, lets look at the differences between types of Wintry Precipitation.
1. Cold Rain: Liquid Rain Drops that are just above 32 degrees.
2. Freezing Rain: Supercooled liquid rain (below 32 degrees) that falls onto a surface that is at or below freezing.
3. Sleet: Frozen ice pellet that forms as a snow flake falls out of a cloud into warmer air (melts) and then into a layer of much colder air (freezes into a solid pellet)
***Not to be confused with hail, which is ice formed by an updraft in a super-cell thunderstorm**
4. Snow: Frozen 6-sided ice crystal that falls out of a cloud at or below freezing into an atmosphere that is also at or below freezing.
A "Wintry Mix" is any combination of these types of precipitation.
Freezing Rain is the most dangerous because it can instantly freeze on anything it makes contact with. Roads, trees, power lines, and bridges are all common areas where freezing rain can create very dangerous ice accumulations. When freezing rain lands on a road or bridge it instantly turns into "invisible" ice. So it's undetectable to drivers which is especially dangerous. All efforts should be made to stay off of the roads during freezing rain events. It is especially important to avoid elevated roadways like bridges and overpasses. Much like a convection oven cooks food faster by surrounding the food with heat. A bridge is like a "convection freezer" and gets much colder than surrounding roadways making it perfect for ice accumulation.