11:00 AM | **Severe weather outbreak later today/tonight and another threat likely early next week...tropics will also be a focus next week as upward motion increases over the Caribbean Sea**
Paul Dorian
An “enhanced” risk of severe weather exists for later today and tonight across portions of Oklahoma, Kansas, Nebraska, and Missouri. Map courtesy NOAA/SPC
Overview
The ingredients are coming together for a severe weather outbreak later today and tonight across the middle part of the country and there can be a repeat performance early next week. In fact, next week may turn out to be quite active on a couple of fronts with severe weather a possibility across the nation’s heartland and potential tropical activity in the Caribbean Sea. Today’s severe weather outbreak does include the possibility of tornadoes across such states as Oklahoma, Arkansas, Kansas, Nebraska and Missouri.
A strong upper-level trough (circled region) and its associated jet streak will enhance upward motion across the middle of the country later today and tonight likely leading to a severe weather outbreak that will include the possibility of tornadoes. Map courtesy NOAA, tropicaltidbits.com
Severe weather threat(s)
From a climatological point-of-view, the most active time period for tornadoes in the US comes during the months of March, April, and May; however, there is a (smaller) secondary peak that comes during the fall months of September, October and November. The general weather pattern that can lead to severe weather outbreaks is much the same in the spring and fall with cold air intrusions coming into the middle part of the nation from the north and west and warm, humid air flow from the Gulf of Mexico into the Mississippi Valley. It just so happens the spring season features an increasing frequency for the northward intrusion of the warm, humid air masses and decreasing influx of cold air masses from Canada while, during the fall season, the opposite holds true.
A strong upper-level trough (circled region) and its associated jet streak will enhance upward motion across the middle of the country early next week potentially leading to another severe weather outbreak. Map courtesy NOAA, tropicaltidbits.com
Today’s severe weather outbreak across the nation’s heartland is indeed quite likely to include tornadoes across such states as Oklahoma, Arkansas, Kansas, Nebraska and Missouri. A strong cold front will push to the east across the central Plains later today and early tonight and severe thunderstorms are expected to develop along and ahead of this system. In addition to the surface cold front, a vigorous upper-level trough and strong jet streak will help to enhance upward motion across the central Plains leading to a highly unstable atmosphere and wind shear will increase the chance of tornadic activity. Thunderstorms will be capable of producing large hail, damaging winds, and tornadoes with the highest tornado threat likely coming this evening (after dark) and into the overnight hours. A repeat performance is possible early next week in terms of severe weather in what is likely to be the same part of the nation or close to it (i.e., the nation’s midsection). Like today, there will be a cold air intrusion from the north and west clashing with warm, humid air pushing northward from the Gulf of Mexico. And, like today, this will all be supported by a vigorous upper-level trough that will deepen across the Four Corners region early next week.
The Madden-Julian Oscillation or MJO will move to more favorable positions for tropical activity to return to the Atlantic Basin during the first couple weeks of November. Specifically, a tropical system may develop next week over the Caribbean Sea as upward motion becomes enhanced in that particular area. Map courtesy NOAA
Tropics to come alive as more favorable conditions develop
Meteorologists track an oceanic-atmospheric phenomenon known as the Madden-Julian Oscillation or MJO which affects weather patterns across the globe. Unlike El Nino or La Nina which are stationary features in the equatorial Pacific Ocean, the MJO is an eastward moving disturbance of clouds, rainfall, winds and pressures that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average. The MJO was first discovered in the early 1970s by Dr. Roland Madden and Dr. Paul Julian when they were studying tropical wind and pressure patterns.
The MJO consists of two parts or phases with one being the enhanced rainfall (convective) phase and the other being the suppressed rainfall phase. The location of the convective phases is often grouped into geographically based stages that are numbered 1-8 by scientists. The location or phase of the MJO can be tied to specific weather patterns in different parts of the world depending on the time of year. The MJO creates favorable conditions for tropical cyclone activity which is why it is important to monitor during the Atlantic Basin tropical season.
Latest computer forecast models suggest the MJO will move into a more favorable activity for tropical activity in the Atlantic Basin during the early stages of November. As an example, the latest GEFS model forecast of the MJO features movement into Phases 8 and 1 during the first ten days of November which are typically associated with increased upward motion this time of year portions of the Atlantic Basin. After this current quiet period, it is quite likely that a tropical system may indeed form next week somewhere over the Caribbean Sea and if indeed that takes place, then we’ll keep a close eye on it to determine if it can spill out over the Gulf of Mexico.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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