With March just a few days away and signs of spring in the air across parts of the U.S., this week will offer a few opportunities for some spring severe weather to break out. The first opportunity will arise Tuesday, especially into the afternoon through the night, thanks to a strong low pressure center which will strengthen over the border region of Colorado, Nebraska, and Kansas. This low will continue to push off toward the east northeast throughout Tuesday and Tuesday night bringing with it a cold front to its south which will be the main concern for the severe weather area this day. The Storm Prediction Center’s Day 2 Probabilistic Outlook depicts areas with a slight chance of severe weather over the location of the low pressure, between Nebraska and Kansas, as well as where that cold front will meet up with some nice warm and moist air from the south over eastern Oklahoma, Arkansas, southern Missouri and Illinois, and into western portions of Kentucky and Tennessee.

Ignoring where the models believe initiation of storms may occur, from my last few posts you may have seen the models have been doing a fairly poor job this far out lately, I will take a look at a few factors which may help define where this storm threat will be on Tuesday. A major concern on Tuesday will be how much warm and moist air can reach up north, especially to the more northern slight chance bubble. The GFS model for midday Tuesday shows some moist air reaching up north but dew points would still struggle to hit 50°F across that Nebraska and Kansas border region (shown below). Just taking this into consideration I would say the severe threat here will be minimal and really only exists at all due to the large amount of rising air occurring there from the surface low as well as some strong positive vorticity advection and warm air advection aiding in this rising air. Additionally, strong winds aloft due to a large 100 knot plus jet streak could help aid by creating some shear. Best threat over this region would appear to be some hail and potential for some damaging winds.

The larger threat for this day comes into play for the more southern area at risk for severe thunderstorms. Dew points across this region will reach and exceed the 55°F mark, especially across the southern portion of this threat area where dew points could potentially hit the upper 60s (shown below). Additionally, a large jet streak aloft with winds in excess of 100 knots will help aid by creating some shear which will especially be the case for the western half of this slight risk area. This area will also all be under some strong warm air advection and a low level jet will even form overnight across the Arkansas and Missouri area (shown below).


Taking all of this into consideration, I would expect this slight risk area to be the main concern for Tuesday and Tuesday night with a wide array of potential severe weather impacts. However, based on the data currently available I would suspect that the best chances for tornadoes exist in the southwestern zone of this slight risk area meaning a city like Little Rock should keep alert to this potential.
Moving into Wednesday now, the Storm Prediction Center’s Day 3 Probabilistic Outlook shows a large area of slight risk once again along this advancing cold front. I will not go into as many details about the potential threats here as it is still a ways out however I would like to point out the amount of moisture the GFS model is expecting this storm system to be dealing with.
A large area of 55°F and greater dew points will stretch from Mississippi across to the Atlantic Coast and up into North Carolina and even into southern Ohio. This will be quite a bit of moisture for this system to work with and should result in an overall greater severe threat on this day then the day before. The threat will also be enhanced by some warm air advection and a low level jet over Tennessee and Kentucky into Virginia.

Additionally, a jet streak will help aid in strong winds aloft and may really help create for some shear across parts of Kentucky and Tennessee which may be aided by a strong gradient in wind speeds aloft. With all of this in mind, I would expect that the SPC map is a good indication as of right now of where the threat will lie this day and night. Main threats from this event should be damaging winds but a few tornadoes may be possible especially across Kentucky and Tennessee where the severe weather indicators look to be most favorable at this moment.
The last chance for severe weather this week will result from a low pressure system forecasted to from over southeastern Colorado and move east into southern Missouri before beginning to move more northward into Michigan and Ontario. The threat for severe weather from this system could develop during the day Friday over parts of the southeast and continue right through the day on Sunday, pushing slowly to the east. While this event is still a ways out and a lot could change, the GFS model does depict a lot of moisture with this system with dew points hitting some pretty high levels over parts of the southeast and Midwest on Friday as shown below.

It could be a rough week for some, but it is that time of year again. Keep it tuned to this blog for more updates on the severe weather situation this week as they arise.