LUBBOCK, Texas (KCBD) - After a couple of cold days in the viewing area, temperatures are on the way up. When you see them go up, like in our current 7-Day Forecast, this time of year it often means more than just a warm up.
Late fall through early spring, especially during winter, a typical weather pattern will bring a cold-weather system around the West Texas region every so often.
In a busy pattern, these systems may arrive every three-to-seven days. During a less active pattern, it may be weeks between systems that bring significant weather changes.
In between these systems our weather “recovers.” It goes from cold, sometimes wet, to more average temperatures, often dry. In an active pattern, this change can seem dramatic.
For example, in Lubbock Wednesday's high was 32°. It never got above freezing. Sunday's high is expected to be in the low 70s.
The recovery, the warmup, is because ahead of an approaching weather system winds shift to a direction or directions that tap warmer air. At the same time, this inflow pushes the colder air east, away from the South Plains.
As the next weather system — low-pressure area, trough, or cold front — moves ever closer, the wind will gradually circulate air from a warmer region into our region.
That warmer air may come from northwestern Mexico or the U.S. Desert Southwest. Both regions often, but not always, are warmer than here during Winter.
There's another factor that I will only briefly touch on here, and that is a wind with a westerly component.
The more due west, the more pronounced. It can be a factor, however, when southwesterly or northwesterly air arriving here from the west is moving downhill. It drops in elevation thousands of feet.
From the central mountains of New Mexico to Lubbock that drop may be 4,000 or more feet. Why is that important?
Descending air warms. All other factors being equal, it warms from about 3° to 5.5°F for every 1,000 feet it descends. The rate is about 3°F for saturated air while 5.5°F for dry air. So a change of 4,000 feet alone can add an additional 12 to 22° to our warmup.
By the way, when air rises, it cools. All other factors equal, at the same rates. If you would like to learn more about the process, search for "adiabatic lapse rate".
Immediately following the last cold-weather system, which brought wintry showers Tuesday and early Wednesday, air flowing into West Texas came from the north Wednesday and Wednesday night.
This resulted in another cold morning and chilly afternoon Thursday.
By Friday afternoon we will be between systems, the air moving in will have a southerly component, and that usually means at least slightly warmer.
By Saturday the wind will be southwesterly, which usually means notably warmer.
By Sunday the next weather system is expected to be winding up over the western U.S. The wind will be southwest to west, warming the area even more.
A cold front, based on current data, is expected early next week. Winds will shift to the north and temperatures will plummet.
The low-pressure area over the western U.S. may circulate moisture into West Texas. And the stage is set for possible wintry showers.
One more thing. The magnitude of the warm up often is matched by the magnitude of the cooling that follows. The more the warm up, the more the cool down.
For mid-February Lubbock’s temperature averages are 30°F for the low and 59°F for the high. Record lows are mostly single-digits, record highs are mid- to upper 80s.