Saturday, March 5, 2022

Spring warmth brings spring storms, and don't put those sensitive plants out just yet!

What a week (in a great way)! High temperatures the past four days have looked more like April than March - 71, 77, 80, 79 - and we're on track for another day in the upper 70s today despite the arrival of high clouds ahead of our next cold front. Sunshine and warm high pressure overhead have contributed to these well above average marks, and we even tied a record on Thursday with that high of 80 degrees! 

That kind of weather has brought on a case of spring fever for many of us, but while a little spring cleaning and preparation is a great idea, don't start putting those plants in the ground just yet! More on that in a minute, but first let's talk about how this early streak of fine weather ends (because you know it will...).

This weekend - windy and warm

The arrival of high clouds and a very gusty wind today signal the approach of the next weather-maker that will undo the spring conditions we've had this week in favor of early spring storms. That front will drop to the Missouri-Arkansas border by Sunday morning, but stall out for about 24 hours before finally making a significant push through the area. The upper level pattern is responsible for the stalling, and ultimately its resumption of southeastward movement through the Mid-South. 

Surface weather map on Sunday morning shows a front stalling to our north and scattered rain around the area south of it. We'll still be in very mild air. (NWS)

Ahead of it, look for strong southerly breezes to continue this weekend and clouds to build as moisture from the Gulf of Mexico arrives on strong wind. That means very warm temperatures in the 70s during the day and 60s overnight tonight. With the moisture increasing, we'll see spotty showers around the area this evening and overnight. 

The HRRR forecast model radar for 5pm tonight through 6am Sunday shows spotty showers becoming a bit more numerous by morning. (WeatherBell)

By morning, it appears activity will become a bit more widespread as the front gets closer, but still scattered. A few thunderstorms could also mix in, mainly north of the I-40 corridor, on Sunday morning to early afternoon. These are NOT expected to be severe. By Sunday mid-afternoon, upper level high pressure builds briefly and squashes our rain chances a bit more heading into Sunday evening. Look for another day or wind gusts to 25+ mph tomorrow with highs again in the upper 70s. So to recap - spotty showers this evening, increasing to scattered coverage with a chance of lightning on Sunday, drying for while by late afternoon.

The rest of the day Sunday through Sunday night, according to the HRRR model. Daytime showers lift north Sunday evening, only to orient into a line to our north and west overnight. Much of the night could be dry. (WeatherBell)

Sunday night/Monday storms

Sunday night is when the cold front finally gets some assistance front a shift in the upper levels as a trough approaches. That will cause it to accelerate southeast. Rain chances respond accordingly after midnight Sunday night and peak Monday morning, likely starting during the morning rush. In addition, with upper level support, strong wind at all levels, and a modicum of "storm fuel" available thanks to warm temperatures (mid 60s) and dewpoints (low 60s) overnight, thunderstorms appear likely. A squall line is likely to form to our northwest overnight and move into the Memphis area, probably in a slightly weakened state owing to the time of day, Monday morning. Current broad-brush timing is 6-10am and will be refined. 

Switching to the NAM3 model to show what radar may look like from 3am to 3pm Monday. The squall line (which may look a bit different than this - the NAM3 tends to underestimate this far out) moves through  Monday morning in the 6-10am timeframe, then showers continue as temperatures drop. (WeatherBell)


A few storms in that line could be severe with strong wind gusts the main concern, though a non-zero spin-up tornado chance also exists. We're currently on the eastern edge of a Level 2 Risk of severe storms, with the largest part of the risk over southern MO in to AR.

A Slight Risk (level 2) for severe weather is forecast roughly from the Memphis area west for Sunday night and early Monday morning. Our main timeframe of concern is 6-10am. Strong wind gusts are possible and a brief spin-up tornado can't be ruled out. (NWS/SPC)

Once the line moves through, those gusty south winds switch direction to the northwest, dropping temperatures as showers continue. Monday's high in the upper 60s to near 70 occurs ahead of the front, with temperatures falling into the 50s quickly that afternoon, and 40s by Monday evening. 

Mid-week cooldown

That cooldown leads us to a period of below normal temperatures starting Tuesday. There will still be clouds around as southwest flow aloft will be pushing another rainy system through Tuesday night. Look for Tuesday morning lows in the mid 30s with wind chills in the 20s and afternoon highs in the mid 50s. Most of the rain Tuesday night falls to our south, but a consensus of models brings some light rain into the city. We'll keep an eye on it as there are outliers. By Wednesday morning, with lows in the low 40s, it appears the southerly storm track dries up and we get a couple of decent days. Wednesday's high will be in the upper 50s, while Thursday sees sunshine and highs in the mid 60s.

Late week Arctic blast

By late Thursday, we'll be watching an even stronger front dive out of the central U.S. towards the  eastern U.S. with a significant push of cold air behind it. Depending on the amount of moisture ahead of it, we could see some Friday showers, but the big news is likely to be a blast of cold air that reminds us we are not yet to our average "last freeze" date just yet (March 18 in the city)! By next weekend, early indications are that lows drop back into the 20s with highs in the 40s again. 

The European model ensemble currently predicts with near certainty low temperatures next Saturday morning being below freezing. (Probability of 32° or lower near 100%.) Better hold off on planting for a while! (WeatherBell)

It is not atypical for freezes to occur well into mid and even late March, though the duration of cold air gets shorter, and the warmth that typically follows a bit warmer than in February. So let's put the brakes on the spring planting for at least a few more weeks, then evaluate what the end of the month looks like before deciding on a time to plant.



Erik Proseus
MWN Meteorologist

----
Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Wednesday, March 2, 2022

"Spring" is here! But is it here to stay?

The calendar has turned to March and the start of meteorological spring (which was March 1, a convenient day for weather peeps to divide the calendar for calculation purposes) is clearly apparent as a cold end to February (remember than thunder-sleet last week?) quickly melted away under the warm sunshine! We've got more of this to come in the next few days, but is it here to stay?


Rest of the work week

Let's start with the short-term, which is a continuation of the past couple of glorious days, despite a weak cool front moving in on Thursday. That front will be dry - and to be perfectly honest, cloud-free - and have little effect on the temperatures. Overnight lows will continue to moderate as dewpoints slowly creep up. Look for mid 40s Thursday morning and mid 70s in the afternoon with light wind shifting to the north. Thursday night will be a few degrees warmer, thanks mainly to the arrival of some high clouds late in the night. Those high clouds will partially filter the sunshine on Friday and are a harbinger of things to come. However, it will still be warm and dry to end the week as high pressure rebuilds to our east, bringing back the south wind. 

This weekend

Those clouds on Friday will thicken heading into the weekend. Dewpoints continue to rise as southerly flow becomes deeply established Saturday. Wind gusts could top 30 mph and a few stray showers are possible towards the end of the day as a cold front approaches. Look for temps to again reach well into the 70s after only bottoming out in the mid 50s Saturday morning. 

It looks like showers will become more scattered Saturday night with very mild conditions - 60s all night long. As the front gets much closer to the region Sunday, we'll definitely see an uptick in rain chances. In fact, with dewpoints likely near 60 degrees and a front not far off, scattered thunderstorms are also looking like a decent bet. If you need some outdoor time this weekend to spring clean, Saturday is your best choice, though don't overlook that wind. We'll border on #SkirtAlert criteria and the Trash Can Meter will be well into the "Can done turnt over" range! 


The cold front will move into the Mid-South Sunday overnight, so expect higher chances of thunderstorms, heavy rain, and potentially a few strong storms with very warm temperatures. The Storm Prediction Center has issued a Slight Risk of severe storms for Sunday night over AR right up to the Memphis metro. Worth watching, but not overly concerning at this point.

A Slight Risk (level 2) of severe weather is forecast Sunday night from far west TN across AR into the ArkLaTex region. Stay tuned! (NWS/SPC)


Start of next week

The cold front is currently forecast to move through the Memphis area by both the American and European models on Monday morning. That could still obviously change, but for now, that's our best guess. It will likely be accompanied by thunderstorms, a few of which could be strong given the energetic wind field and favorable moisture profile. The main question mark lies in the degree of instability, which is always a question this time of year it seems. The timing of the front (morning) favors lower storm fuel. If it were to be delayed and we got to the 70s again Monday for instance, I'd be a bit more concerned.

The NWS surface map for Monday morning shows the cold front on our door step with a wide swath of rain over the eastern U.S. Colder air sits just behind the front. (NWS)

Once the front moves through, rain looks to stick around Monday with a bit cooler temperatures. We cold see temperatures dropping from the 60s in the morning to the 50s in the afternoon. Behind the front, a cooler airmass moves in, but compared to late February, it will be manageable. Look for partly sunny skies Tuesday and Wednesday and highs in the 50s with lows dipping into the 30s. The overall pattern still favors slightly wetter than average for next week, so I'm not convinced rain chances don't return by mid to late next week.

The NOAA/CPC temperature outlook for next Tuesday-Saturday shows most of the cold air to our west, but starting to creep east. After this week, 70s are probably gone for a little while.


What season are we in?



So are we done with winter? On the above (very accurate, tbh) list, I'd put this week of 70s at "spring of deception." I guess it depends on how you define winter. I do think we've probably seen the last of our chances of impactful winter weather (thank goodness!). That doesn't mean we can't see a quick shot of winter shenanigans mixing in behind a potent cold front for another couple weeks, but it's doubtful. Freezing temperatures behind us? We're likely not quite there yet. 

The average date in the city for the last freeze in the spring is March 18 - still more than two weeks away. It's later than that in outlying areas, and that is just the average. We certainly have had some very cold mornings around Easter before, even when it falls in early April. I would not start going crazy with spring planting yet, but in a couple of weeks, we should be getting close! 


Erik Proseus
MWN Meteorologist

----
Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: MemphisWeather.net on the mobile web or via the MWN mobile app
Download our free iPhone or Android apps, featuring SW+ Alerts severe weather notifications!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder