The irony of writing about flooding from 34,000 feet above the Sonoran Desert doesn’t escape me at the moment, but here we are. I wanted to provide a Tuesday late day update on what’s ahead in the Southern Plains and Mid-South. Yesterday, we noted some thoughts about Mississippi River flooding and tied it back to another round of heavy rain potentially this weekend. The good news is that the hardest hit areas, such as Kentucky, southern Indiana, and Tennessee should escape significant issues if the current forecast holds between now and Monday. But, we are likely to see new issues crop up across Missouri, Arkansas, southeast Kansas, Oklahoma, or even northern Texas. This is reflected in the current flood hazard outlook.
The experimental flood hazard outlook from NOAA shows widespread river flooding continuing after the rains of a couple weeks ago, as well as an upcoming area highlighted for days 4-7. (NOAA)
The area highlighted over the Plains and Mid-South is the area we’re keeping an eye on for the weekend and early next week.
The current NOAA rainfall forecast centered over Missouri shows good odds of 2 to 5 inches of rain over the next 7 days. Other than some variations in exact placement among the various models (which you’d expect to see), this is fairly stable confidence outlook.
Roughly 2 to 5 inches are expected over a wide area from Oklahoma through Illinois over the next week. (Pivotal Weather)
We’re starting to see some solid probabilities of 4 inches or more over the next week or so show up in this area now on the European ensemble’s 51 members. Almost half of them are in that territory now. So confidence in a fairly decent rain event are growing.
About 40 to 50 percent of European ensemble members are forecasting 4 inches of rain or more over southern Missouri through next week (PolarWx)
Exactly how much rain falls and how serious any flooding will be is yet to be determined. We’ll obviously have severe weather to consider too. Currently that looks like an issue Friday through Sunday, possibly into Monday to the east. Whatever the case, we’ll continue to monitor this. Flooding is a point of interest for me personally, so events like this catch my eye.
The southern half of Mississippi River will experience moderate to major flooding in the days ahead, albeit well under levels seen in other flood events in recent years.
But the addition of potentially significant rainfall in portions of the Mid-South this weekend (Oklahoma, Missouri, Arkansas) could add to Lower Mississippi flooding risks.
Flood situation on the Mississippi
About a year and a half ago, dire concerns were raised about salt water intrusion into the water supply of the Mississippi River because water levels had gotten so low. Thankfully that threat passed, and for the most part, things have been rather ho-hum in the Mississippi. We’re beginning to see signs of change now, however, as all the water from the multi-day rainstorm earlier this month dumps into the Mississippi River.
River gauges along the Mississippi and nearby tributaries that are expected to be in moderate or major flood stage over the upcoming days. (NOAA National Water Prediction Service)
None of the rises on the Mississippi look to be anything outlandish. For example, at Hickman, Kentucky, just downstream of where the Ohio empties into the Mississippi, there is major flooding expected, but still about 9 feet shy of the record from 2011.
The Mississippi at Hickman, KY will remain stable in major flood through the weekend. (NOAA)
Farther downstream at Osceola, Arkansas (just north of Memphis), the river is slated to be at a level of about 37.5 feet, which multiple floods have topped in the last 15 years.
The Mississippi at Osceola, AR will stay stable in major flood but well shy of levels seen in 2011, 2016, 2018, and 2019. (NOAA)
The story repeats down past Memphis into Mississippi, where the river will rise to moderate or major levels but nothing too absurd.
Down in Baton Rouge, the river will continue rising this week, eventually projected to crest around next Wednesday at levels similar to what had been seen in May of 2017 (and lower than levels reached in 2011, 2016, 2018, 2019, and 2020).
The Mississippi in Baton Rouge will crest sometime next week just over the mark into major flooding but lower than levels seen in 2018-2020. (NOAA)
Back to the rains in the Mid-South
One interesting element about the river forecasts is that they only contain rainfall forecasts in the next 24 to 36 hours or so. So, we assume 0 rain falls after, say this Wednesday. Which brings me to an interesting possible storyline that could develop in the Mississippi. Over the upcoming holiday weekend, a cold front is going to push into the Ohio Valley and Mid-South again. There will likely be some degree of severe weather with this, though exactly how widespread or significant remains to be seen.
Forecast surface weather map for Saturday morning, showing a cold front pushing into the Mid-South and some disturbances gathering across the Southwest. (NOAA WPC)
One thing I did notice this morning while going over my forecasting is that the ridge of high pressure setting up over the Southeast is expected to flex again this weekend. In fact, on Saturday morning, the European ensemble has about an 80 percent probability of the upper-level high pressure being in 99.5th percentile for this time of year. In simple language: It will be strong. Similar (but far less alarming at this point) than what we saw a couple weeks ago.
The probability is high that the ridge of high pressure over the Southeast will be quite strong this weekend, likely slowing or stalling the Mid-South cold front. (Polarwx.com)
So the combination of a cold front slowing or stalling as it runs into a southeast ridge would likely lead to an increasing risk of heavy rainfall. Unlike last time, where the bullseye was extremely widespread but focused on Kentucky, at least the initial odds this time favor Missouri and Arkansas. About 40 to 50 percent of the 51 European ensemble members show 3 inches or more of rainfall over northwest Arkansas through early next week, with 20 to 30 percent showing 4 inches or more.
Another round of possibly significant rain shows increasing odds this weekend from southern Missouri through Oklahoma. (Polarwx.com)
What does this all mean? For one, it means that the upcoming weather story will perhaps focus once more on the Mid-South or southern Plains. Secondly, it could mean that the forecasts for the Mississippi River, particularly those down into Louisiana have some risk of increasing in the days ahead. Or, perhaps the river will just stay high for longer, an entirely feasible outcome. Whatever the case, after a quiet week last week, the weather is beginning to look interesting again.
As a meteorologist, weather in general fascinates me. I worked two years in California about 15 years ago, and when I took that job, everyone teased me, saying the weather was “so easy” to forecast. And, yes, about 80 percent of the year, conditions are pretty stable overall. There is nuance to that. Most people may not realize a minor difference in temperature from day to day, but it’s something that can be reflected in power usage. Same goes for wind or solar output in terms of forecast weather for wind farms or solar facilities. But what always kind of fascinated me about the West was water.
So far, 2025 has been a mixed year in the Western U.S. On the one hand, California snowpack is doing great.
Sierra snowpack is running about 120 percent of normal in the north and 85 percent of normal in the south. (California DWR)
It’s been a late season bonanza up north, with snowpack levels sitting at 120 percent of average north of Lake Tahoe. The central Sierra are a little less well-off but still close to normal. The southern Sierra have not had their best winter ever, but even still snow water equivalent is around 85 percent of normal. There have certainly been worse years in California.
It’s when you get into the interior West that the problems start. Take Colorado. Their peak snowpack is likely to be the lowest since 2018. The northern part of the state has done well with near average snowfall this year.
Colorado’s snowpack as of April 8th as a percent of the 30 year median. (USDA)
The Colorado River headwaters are also running near average, but southern Colorado, particularly the San Juan and Upper Rio Grande basins are in bad shape. Snow water equivalents are running about 60 percent of the median right now, or well, well below average.
The story improves some in Utah, where the basins are a little noisier, but in general not in bad shape outside of southern Utah. Similar story in Wyoming and Idaho. Not great, not terrible. Oregon? Fantastic winter. Washington? Less so. But for Arizona and New Mexico, it was a dreadful winter.
Snow-water equivalents compared to the median are running way above normal in Oregon and way below normal in Arizona and New Mexico. (USDA)
Flagstaff, Arizona has seen 51 inches of snow this winter, compared to a normal of 86 inches typically. In Albuquerque, they’ve had 1.68 inches of rain since October 1st, compared to 3.38 inches on average. It’s turning out to be pretty bad. Snowpack is particularly important because as the seasons change, that snow melts and it feeds the rivers of the West and subsequently the reservoirs, farms, and hydroelectric power that is scattered about. The relationship is not 1-to-1, where 100 percent of snowpack means streamflow of 100 percent. Even though the upper Colorado Basin saw decent snow, with nearly 100 percent of normal, the forecast streamflow from CLIMAS is only 84 percent of normal.
New Mexico reservoirs are in very poor condition. (CLIMAS via Laura Paskus)
For the Rio Grande it’s even worse, with the CLIMAS streamflow forecast being only 52 percent of normal! Laura Paskus, who writes an excellent blog focused on New Mexico recently shared the image above from the CLIMAS March report showing reservoir levels in New Mexico. They are not good. At all.
Suffice to say, there have been glimmers of hope in recent years from some strong winters — but the underlying problems are not going anywhere in the West. There is still a shortage of water, and there is high risk that this will only get worse in future years. Absolutely reckless and illogical decisions like releasing water in California earlier this year may not seem like a huge deal on the surface, but every single drop is precious in the West. As it is, the situation regarding water is already tense. The states that utilize the Colorado River are up against a clock to come to an agreement on a joint management proposal by May. A quasi-handshake agreement that had been in place with Mexico for a shift in water delivery to Tijuana from the Colorado was rejected for the first time in 80 years this year because of complaints that Mexico is not supplying enough treaty-mandated water to Texas from the Rio Grande.
All this underscores the very, very tenuous situation in the West. I hope to include some additional coverage or words on this topic in the future here because this problem is not going to go away anytime soon, and if anything, it’s going to continue to worsen. Water doesn’t recognize borders of states or countries, which makes it an especially challenging and precious commodity to wrangle.
Nothing about this forecast on the surface is especially notable or alarming or fascinating. It’s simply a slightly above average forecast.
But what is somewhat notable about their forecast is some of the under the hood items they address. First, we are likely to be coming out of a La Niña event, something we discussed last back in February. But as the CSU team notes, we don’t know for sure if we’re headed for El Niño or ENSO neutral (La Nada) conditions. ENSO neutral summers combined with warm water temperatures “typically provides a more conducive dynamic and thermodynamic environment for hurricane formation and intensification.” In other words, hurricanes like those background conditions.
We do not yet have a “plume” from the C3S suite for April, but the March plume skewed slightly toward El Niño development.
Multi-system ensemble of various forecast models predicting a trend toward positive sea-surface temperature anomalies this summer, possibly giving a slight edge to a developing El Niño event. (Copernicus)
If we get to El Niño conditions by late summer or fall, that does not guarantee that conditions will shift to become more hostile to hurricane development. But that may take the edge off a bit. However, if we “hang” near the neutral line or even in weak La Niña territory, any hostile conditions may be apt to stay away, ensuring a busier season than usual.
In addition to the forecast for named storms and such, the CSU team also does try to convert that seasonal outlook to a prediction of U.S. landfall risk. Indeed, with a more active season expected, the odds of a U.S. landfall are also higher. They have a 51 percent chance of a major hurricane landfall on the U.S. coast, compared to a historical average of 43 percent. The odds on the East Coast are 26 percent, compared to 21 percent typically. And in the Gulf of Mexico, the landfall odds between the Florida Panhandle and Brownsville are 33 percent versus a 27 percent average.
According to the CSU team, all model guidance is pointing to an above-normal season. Water temperatures remain well above long-term averages across the Atlantic. As we noted earlier this year, however, this is not last year’s Atlantic sea-surface temperature profile. But it’s still quite warm.
March 2025 minus March 2024 sea-surface temperatures, showing year over year warming in the Caribbean, Gulf, and mid-latitudes, but not in the tropical Atlantic. (NOAA PSL)
From the map above, you’ll notice that the eastern Atlantic has cooled markedly since last year, however the Gulf, Caribbean, and northern Atlantic Ocean are all warmer. The fire that was burning all last summer in the eastern Atlantic is still smoldering, but it has been somewhat extinguished. The Gulf and Caribbean are another matter. The Gulf is warmer than 2024 by a good bit but still lags 2023. While the Caribbean was warmer than 2024 in March, it has since cooled some in April, taking it back under 2024 levels. Water temperature conditions can change quickly, but the bottom line is that the Atlantic, with the exception of the eastern basin are in the upper echelon of warm years at this point. The warmer overall waters in March in the eastern North Atlantic (north of the tropics), along with the warm Caribbean do correlate to active hurricane seasons.
The bottom line is that the underlying data support the idea of an active hurricane season — but not to the levels feared last year. But there aren’t very many red flags at this time arguing against that outcome. At least last year, we had the expectation of a developing La Niña to help grease the wheels a bit, and a slow development could have slowed the hurricane season a bit. This year? There’s no real glaring red flag that says the season will bust. But hurricane seasons always have surprises. Hopefully this year’s involves calm.
Colorado State’s seasonal hurricane forecast is just that, a seasonal forecast. Should you plan your life based on this? No. But they generally have good skill. And their skill in the last 10 years or so has been great. You still have a few weeks, but it’s time to start thinking about, refreshing, and planning for the season ahead. There’s a lot of uncertainty this year in terms of FEMA and federal response to storms, so it probably behooves you to plan that kit even a bit more than usual. We have tips on our preparedness page, which we will go through and adjust any broken links when we have some time in the coming weeks.
