Is it Warmer or Not as Cold?
/Practice makes perfect! For all of our station model plotters, let’s look at the north central USA. The large arctic high pressure system continues to dominate the central USA north into Canada. Notice the cold temperatures over the Upper Midwest. The cold dry air is producing generally clear skies. South of the map, Gulf moisture is spreading north from east Texas to the Mid-Atlantic states. Look for stations reporting light rain and drizzle. Look for reports of light fog downwind from the Great Lakes in the colder moist air.
Map plotted using Digital Atmosphere software from Weathergraphics.com.
Compare this surface map with yesterday’s (scroll down). The high pressure center has been nudged slightly east but a strong southwest flow has spread out onto the northern and western plains. A “warm-up” is underway. There is still light snow and clouds in the moisture laden air downwind from the Great Lakes and also from Kansas to Texas.
Can we really call what’s coming warmer? It will certainly be warmer. With a 35 to 45 degree rise in temperature from last nights lows it is certainly warmer but with the winds it will feel “not as cold.” There will still be a solid chill in the air. One thing is sure. We are toward spring and summer so warmer weather is just around the corner, one way or another.
Advanced Exercise. For station model plot users: What to look for on the map today.
Look for stations reporting light snow in Indiana, Kentucky, and Lower Michigan. What are the wind speeds and wind direction from the Dakotas to Nebraska and Montana? And check out the pressure tendencies. Where have pressures been rising and where have they been falling? Where are skies clear?
Hints:
Look for cloudy skies, then see where precipitation is falling.
For strong winds look where the pressure gradient (change in pressure) is greatest; where the isobars (thin dark lines) are closest together.
For pressure rising and falling look at the tendency symbols. The symbols are shaped to show steady, rising, falling, rising then steady, rising then falling, falling then rising, falling then steady. And skies are often clear under high pressure areas.
Finally, notice the general wind direction around the high pressure area. See if you can spot the clockwise motion.
If you want to learn how to read station model plots scroll up this page and click on the Station Model Plot link.