Tuesday Night, December 18, 2018
Chief Meteorologist Jason Simpson
Another soaking wet setup for the end of the week
December is usually the wettest month of the year in North Alabama, and the weather is living up to that billing this time! Another big-ticket round of rain moves through the region later this week: starting as early as Wednesday night lasting through Friday.
It’s still dry in the short-term. Tonight and most of Wednesday feature cool, dry air: lows tonight in the 30s (31ºF-34ºF in the cold spots, 35ºF-38ºF in urban areas) and highs Wednesday pushing 60ºF with a partly to mostly cloudy sky. Some of the rain later this week gets heavy, and there is still a chance it could end as a little bit of low-to-no impact snow as cold air blows in Friday.
Rain: when, where and how much? Most of Wednesday stays dry; however, some showers start sneaking northbound from the Gulf Coast in the early afternoon. Light, spotty showers are possible from around 8 PM to midnight; more persistent rainfall moves in overnight into Thursday morning.
This first wave produces about 0.15” to 0.50” of rainfall through midday Thursday, and then we see a break (isolated showers if any at all) Thursday afternoon and evening.
More rain develops overnight into Friday morning, and based on the ‘look’ of the features in play here, some of it could get rather heavy: another 0.50” to 1.50” of rainfall on top of what we have already measured by Friday afternoon. Some minor flooding is possible in areas that get more than an inch of rain Friday.
Snow chances? Your odds of getting a great parking spot at Bridge Street or Parkway Place Mall on Saturday afternoon are better than you seeing enough snow to accumulate in North Alabama or Southern Tennessee on Friday.
See how that works? The chance isn’t zero, but the odds are pretty low. We still think there’s potential for some brief change-over from rain to snow or a wintry mix, but the best moisture runs away from the cold air leaving us with very little to work with for snow production.
Weekend through Christmas: Once the rain (and snow) move out Friday evening, we are set for a nice, quiet weekend. Saturday looks chilly: lows in the upper 20s, highs close to 50ºF. Sunday brings some clouds and a very low chance of a few sprinkles or showers late: highs in the mid-50s.
Christmas Eve and Christmas Day look fairly ‘typical’ of late December; ‘average’ numbers for the 24th and 25th are around 52ºF for a high and 33ºF for a low. The ‘normal’ range around that is about 11 degrees warmer or cooler. In other words, it’s not unusual to have highs in the 40s, 50s or 60s on Christmas Day, and it’s pretty standard to be chilly in the morning from the 20s to the 40s.
This year’s forecast falls squarely in the middle of all of that. Expect chilly mornings, seasonably cool afternoons, and a low chance of some light showers. Total rain out? Not likely. White Christmas? Get out of here. No rain at all? That’s possible, but we do see at least some ‘chance’ of rain in the area for both Monday and Tuesday.
Tennessee Valley Forecast:
OVERNIGHT: Partly cloudy, not as cold. Some scattered frost. Lows in the 30s: cold spots 31ºF to 34ºF, in-town 34ºF to 38ºF. Light north wind becoming southeast by morning.
WEDNESDAY: Partly to mostly sunny early; clouds thicken in the afternoon and evening. Some showers are possible after 7 PM. Highs in the upper 50s and lower 60s. Wind: SE 5-10.
WEDNESDAY NIGHT: Showers possible 7 PM to midnight, rain more likely between midnight and sunrise Thursday. Lows in the mid-40s. Wind: SE 3-9.
THURSDAY: Persistent rain in the morning, showers thin out between 11 AM and 5 PM. More rain late Thursday evening into Friday. Mostly cloudy and mild. Highs in the middle 50s. Wind: ENE 6-12.
THURSDAY NIGHT: Rain likely again, and some could be heavy! Another 1/2” to 1” of rain possible. Temperatures steady in the mid-40s. Wind shifting NW up to 20 MPH.
FRIDAY: Rain likely in the morning. Temperatures peak before noon in the upper 40s then stay steady or fall in the afternoon. Some rain could mix with snow before it ends with little/no accumulation. Highs in the 40s. Wind chill in the 30s. Wind: NW 12-25.
SATURDAY: A morning freeze in the upper 20s. Clear and cool. Highs in the lower 50s. Wind: WSW 3-9.
SUNDAY: Fair and cold early. Partly to mostly cloudy with a chance of some showers in the afternoon and evening. Highs in the lower 50s. Wind: SSW 6-12.
CHRISTMAS EVE (MONDAY): Partly to mostly cloudy with some light rain possible early in the morning. Highs in the low-50s. Wind: SE 5-10.
CHRISTMAS DAY (TUESDAY): Showers possible. A seasonable Christmas Day with highs in the 50s, morning lows in the 40s. Wind: SE 5-10.
WEDNESDAY: Partly cloudy and warmer. Highs in the mid-60s. Wind: S 10-15.