THE LAST DAYS OF WINTER...
THANKS FOR SUPPORTING WEATHER
MY SINCERE APPRECIATION...
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WINTER'S FINAL DAYS...
With about a week to go (for all practical purposes), winter has been on its last leg since the beginning of February. While you never say never, my belief is what's left of this one goes quietly out the back door with little in the way of cold and snow.
As for cold, we are positioned to get a taste of late winter chill come Saturday night and Sunday. The front responsible for the downturn actually arrives Saturday morning with a wind shift to the northwest. However, the true cold air lags a few hours behind keeping daytime temperatures tolerable in the 50s. Unfortunately, stout winds exceeding 30mph will cause temperatures to feel lower than they actually are.
Strong cold air advection cranks up Saturday night and Sunday with stiff north winds continuing. Some stratus (at the very least cumulus clouds) are likely at times. A flurry is possible in the north, but low levels are bone dry limiting that concern. Steady or even falling temperatures are expected most of Sunday keeping readings confined to the mid to upper 30s (Maybe 40 early in the south).
Sunday night and Monday will be plenty fresh. Lows Sunday night of 19-24 look representative with highs Monday again in the mid to upper 30s. Rather crisp!
Beyond day 4 (Monday), the upper level winds stretch and transitions again into more of a W/NW flow. That allows some moderation later next week but not nearly as much as we've seen in the past with the retreat of similar cold shots. In fact, it appears a fairly strong baroclinic boundary sets up near the area driven by cold Canadian highs. Some guidance is rather staunch in keeping the central Midwest on the cold side of the boundary. With time, energy does dig out a trough late next week creating the forceful interaction needed for storminess along the merger of the warm and cold air. This is not likely to happen until next weekend when the pattern turns active. Here's the thermal boundary next Thursday by way of temperature departures (readings 15 below to the NE and 10 above to the SW). Close to normal or a bit below locally.
Once established a week from now, the active period of storminess can commence. The EURO shows this for precipitation totals through March 30th. Most of it comes after March 23rd.
The idea I'm conveying for the final days of winter, (basically the next week) is that they look uneventful. Temperatures will go from below normal Sunday and Monday to near normal late in the week. Little if any precipitation is likely. After that though, the last week of March has the potential to be a wild one with multiple storms and perhaps a chance of snow for some part of the Midwest. Both the EURO and GFS indicate well above normal precipitation in the period March 23rd to March 30th.
SWITCHING NINO GEARS
As many of you know, this winter was highly impacted by El Niño. It will go down in the Midwest record books as one of the warmest on record. That said, a radical cooling of sea surface temperatures is occurring in the tropical Pacific. By May, June, and July, the El Niño is projected to flip first to a neutral phase and then a full-fledged La Niña
Bundling of Statistical models shows the potential of a moderate La Niña going into next winter. While that can mean cold snowy winters over the upper Midwest, it's typically less snowy and somewhat warmer here in the central Midwest. All La Niñas have their quirks, but for my region that's the most common occurrence. Plenty of time to worry about that.
Short term, the switch to La Niña late spring may impact the severe weather season (if it already hasn't). As you can see on the right, the number of tornadoes and hailstorms significantly increases over the eastern half of the nation during seasons with La Nina. This is due in large part to a strong west to east jet that enhances shear and thermal contrasts.
Even without a full throated El Nino, this winter (it's not even spring yet) has produced 4 severe weather outbreaks in my southeast counties. The latest event, the 13th and 14th was considered part of a regional outbreak. On the 14th alone, there were 772 reports of severe weather. 17 were tornadoes which produced 3 deaths in Ohio.
The featured graphic below presents an unofficial IEM accounting of the number of Severe Thunderstorm, Tornado, and Flash Flood Warnings active per minute during Thursday's outbreak. The maximum of 16 simultaneous Tornado Warnings ranked in the top 10 largest for March events since 1986
There's definitely some weather on the table but for anything of real consequence, we're at least 8 days away. With that, I call it a post. Have a terrific weekend and Roll weather...TS
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