UPDATE on winter weather chances and an Arctic blast

UPDATE (Fri., 3/1/19):

About 48 hours ago, the blog below was written, indicating the potential for some winter weather on Sunday afternoon, followed by a cold snap that would rival some we see in the middle of winter. This serves as a short update to that info (scroll down to the Sunday/next week sections below for the original post).

As of this afternoon, now less than 48 hours from the arrival of the Arctic cold front, little has changed from what I wrote below. We have a couple more models available that cover the time period in question, and the American GFS model continues to be the one that keeps precipitation around the longest versus the European model and now the high-resolution North American model.

However, we are narrowing in on what I believe to be the likely solution, and snow-lovers won’t like it. We will indeed see a scenario where cold air “chases out” the precipitation, meaning that the only way to get snow will be where the cold air catches up with lingering precipitation. That is most likely to occur north of the metro. By Sunday mid-afternoon, as temperatures are dropping into the 30s, rainfall will be departing to the east.

If we get any flakes in the metro (possible), we will still be above freezing and they will melt. It is not expected to drop below freezing until the evening hours when precip is gone. The NWS “reasonable worst case” forecast for snow on Sunday is below. It depicts the scenario that has less than a 10% chance of occurring. That forecast says 1-2″ of snow is the worst case (or best case, right teachers??) for Tipton County and points north. Even the unlikeliest of scenarios still produces less than an inch in the metro. In other words, it ain’t happenin’! (Don’t you hate our no-hype approach?)

As for the cold air… well, that IS happenin’! Next week will feel more like January than March. Plan on more hours below freezing than above from overnight Sunday night through mid-day Wednesday! Overnight lows will be closer to 20° than 30° Monday through Wednesday mornings and we may not rise much above freezing Monday afternoon at all. Couple that with a brisk north wind and the Arctic blast will feel like single digits Monday at the bus stop! Plan now to protect any outdoor vegetation that you want to keep starting Sunday night and lasting a few days. Expect the temperatures to recover pretty quickly though by Thursday and Friday (as precipitation chances return, of course).

Sorry for the bad news, but I’m ready for spring, so let’s get this out of the way and get ready for some spring thunderstorms and rainbows!


ORIGINAL POST (Wed., 2/27/19)


The past few days have been an opportunity to dry out, and while we end the week with rain chances, they are fairly low, and rainfall should remain fairly light. That will provide more time for the ground to dry out a bit and local streams, creeks and rivers to return to their normal streamflow – unless they lead directly into the Mississippi River! With the river nearing 40 feet on the Memphis gauge, portions of the Wolf and Loosahatchie River and Nonconnah Creek will still remain high as water backs up from the main stem.

A hydrograph showing recent and forecast river levels at the Memphis gauge on the Mississippi indicates a “flat crest” approaching next week with levels near 41′ for several days before dropping by mid-March. Today’s reading is about 39.5′. (NWS)


Thursday and Friday

A cool front is moving south across the Mid-South this afternoon and will bring an end to the mid 60s we’ve had today as it drops into north MS. There will be low rain chances this evening, but rain will remain light and many residents of the area will see nothing at all. With the front stalled in the region, we can expect more cloud cover the next couple of days, small rain chances Thursday morning and again Friday into Friday night, and cooler, but not cold, temperatures. Look for the mercury to remain in the 40s most of Thursday, then mid 30s Thursday night and lower to mid 50s Friday.

The National Forecast Chart shows rain chances in the area Friday as a front sits to our south. Notice that mixed precipitation or snow is not too far to our north as cold air is poised to move south by Sunday. (NWS)

Saturday

Models have had a hard time with the weekend forecast as Arctic air spills south towards the area and low pressure forms to our west and moves across the region. As of now, it appears Saturday may not be bad with most rain holding off until Saturday night and mild temperatures that once again climb back into the 50s to near 60. If you have stuff to get done outdoors, this is your day to do it!

Saturday night is when the Arctic front starts dropping into the area as low pressure moves along the existing front draped over the region. Rain is basically a certainty Saturday night with temperatures in the 40s.

Sunday

Sunday could get interesting. The speed with which the precipitation moves out Sunday, along with the surge of cold air moving into the region presents somewhat of a dilemma. Sunday morning will likely be wet, but the colder air will be plunging south on a brisk north wind. While the European model has been quick to push the precipitation out, providing for a dry afternoon, the American GFS model hangs some precipitation back in the afternoon and is a little faster with the cold air. It changes rain over to light freezing rain, sleet or snow Sunday afternoon as temperatures drop below freezing after a morning high in the 40s. The wind will also be brisk, meaning wind chills drop below freezing probably by noon and make it into the teens by evening. The GFS also is dry Sunday night though like it’s fancy European cousin.

The GFS model for Sunday afternoon projects a wintry mix of precipitation as temperatures plummet behind an Arctic cold front. The European model (not shown) is dry by Sunday afternoon. (WxBell)

If the GFS is right, we could see a light coating of freezing rain or a dusting to light accumulation of snow. We’ll need to monitor this situation carefully, as we’re still 4 days out, but it’s worth mentioning. Right now, I don’t expect we’ll see enough to have to worry about travel Sunday night into Monday. My gut tells me that this “cold air chasing precipitation away” scenario won’t yield much if anything. But I’ve also always said, “winter isn’t over until we get past the first weekend in March!” It appears this year, it might come in like a lion!


Next week

Unfortunately, this isn’t a quick punch of cold air and right back to spring warmth. I fear for the blooming flora across the region as a bitter airmass sinks into the region Sunday night through at least the middle of the week. We’ll easily see lows in the lower half of the 20s to start next week, perhaps for 3-4 nights, and a few mornings could see outlying areas in the teens. High temperatures may not get out of the 30s  Monday-Wednesday! Hopefully this will mark the end of winter, but the long-range outlooks suggest cooler than normal temperatures (but not necessarily that cold!) stick around into the middle of March. Plan ahead for any precautions you’ll need to take against a hard freeze for anything that is popping up out of the ground or blooming!

NWS forecast model temperatures for the upcoming 10 days. (WeatherModels.com)

I may try and get a blog update done on Friday for more clarity on the weekend, but will be out of town Saturday as I represent StormWatch+ at Tennessee Severe Weather Awareness Day in Nashville. We’ve already had an early taste of severe weather season last Saturday. Despite the cold, it’s also time to be giving some thought to severe weather preparation plans for this spring. This week is Severe Weather Awareness Week in Tennessee and Arkansas, while Mississippi had theirs last week.

Erik Proseus
MWN Meteorologist

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