Looking at the next 5 days, I have the average 500 mb height anomaly map over the whole US. This does a good job of painting broad specifics.
Looking very broadly, we can see a couple of main features – a strong high pressure over the Desert Southwest with a ridge extending into the Tropical Atlantic, Northwesterly flow across the Midwest and Great Lakes, and cooler weather over Southeastern Canada and the Northeastern United States.
Western US
Mostly zonal flow will persist across the Western US, with the main feature being a dominant ridge across the Southern tier of the area, bringing warmer than average temperatures.
Looking at the current 500 mb analysis, we can clearly see the ridge, as well as some systems riding the top of the ridge.
A weak upper-level storm system over Washington is present on the models, and may bring in some cooler air for the Pacific NW, but isn’t going to be much of a rain maker over in this part of the country. This system may have major impacts down the line, however. The atmosphere is set to be drier than average over the next couple of days, looking at the expected PWAT values.
This also shows us that more monsoon like moisture is coming to portions of Arizona and the Desert Southwest, as some portions of the region see dewpoints approaching 60F and monsoon conditions to hopefully continue.
Another storm system located in Iowa was responsible for producing severe weather across portions of Nebraska last night, and more severe weather may be on the table for this afternoon, though the chances are pretty low.
Looking at the GEFS expected departures from average for the next 5-7 days, we definitely see a few patterns.
The Southern half of the forecast region is expecting much higher than usual temperatures, due to a strong ridge over the area. As storms roll across the Canadian border, we will see daily fluctuations above and below the average, so things more or less even out and not much of a strong difference is shown.
Precip wise, the signal is definitely there for more monsoon conditions.
Lots of precipitation (relative to the average) is forecast across most of the Desert Southwest, especially over Arizona and Northern Mexico. This is good for them, but of course won’t be enough to alleviate drought concerns. Monsoon rains do account for most of their precipitation, though, so it’s good that they’re getting caught back up.
Eastern US
Looking at the other half of the country, it is certainly a bit more active.
The subtropical ridge is still stout and in place, and will dominate the weather for a good portion of this region. Let’s look at the 500 mb vorticity analysis to get a good idea of the current conditions.
That bright blob in Southern Alabama is associated with severe weather that occurred last night. Some of the damage appears to have been significant, with a swath of damaging wind reports down the I-65 corridor from Birmingham to Montgomery.
The Iowa system is visible on this view as well, and we’ll be watching the Midwest for severe weather today.
The more significant threat for severe weather comes tomorrow. I won’t go too in depth out of fear of the data changing, but we can go over some of what’s happening.
The 500 mb system currently located over Washington and Oregon, pictures earlier, is forecast to deepen and move to the East, and by tomorrow evening, we have a stout shortwave trough over portions of the Northern Midwest.
Upper level flow is moderately strong here, so we do have a risk for organized severe weather downstream of this trough, specifically over Southern Minnesota and Wisconsin.
I don’t have the latest SPC outlook, this one is from yesterday, so just keep an eye out in the area. Damaging winds and large hail appear to be the major threats at this time, but we will know more information later today and tomorrow. As of now, the SPC has an enhanced risk of severe weather, which is significant. There are a lot of details missing, but they’ve highlighted a large portion of Southern MN/WI for significant severe weather, so it’ll be interesting to watch at least.
More generally speaking, let’s take a glance at the overall forecast patterns.
The precipitation anomaly map is just about what you would expect-above average precipitation in the areas affected by these troughs and severe weather, while the areas baking under the ridge remain drier than average.
This is not good news for many areas in the Southeast that are currently already running below on water, and this pattern is unfortunately going to exacerbate pre existing issues.
Also not surprisingly, the temperature anomaly map is what we expect. 4-6C above average over the next 5 days for portions of Missouri and the Ozarks, as the ridge doesn’t plan on leaving any time soon.
Cooler weather is forecast further North, where the jet stream dips far enough South and allows some of the more mild Canadian air to infiltrate the CONUS. This is going to be few and far between though, and it’ll still be quite warm.
This general pattern is favored over the next few weeks, as all the forecast charts show pretty similar general conditions going into August.
The CPC outlook definitely reflects this, with warmer than average temperatures forecast basically over the entire CONUS. This goes to August 4, so the pattern doesn’t look to change much between now and then. What you see now is what you’re going to get!
