One word to describe this week is ARK. Some of you may need one by this time next weekend. A lot of factors are taking place in order to give us what is known as the train. Now on a normal basis this set up would be ideal for tornadoes in the state. The ONLY factor keeping us from that would be the lack of instability due to all the rain. There will be plenty of ingredients there for a multi-day severe outbreak. Down towards the Gulf Coast, this is a real possibility due to more instability along with the moisture return plus the shear. Three things we look for in a severe weather outbreak: 1. SHEAR 2. INSTABILITY 3. MOISTURE RETURN. This is an ideal setup because you have a storm system staying west of the state but in close proximity, high to the east steering the storm from south to north, and that high steering the moisture due north with directional shear at all levels of the atmosphere. The amount of rain that will be seen with this system would somewhat prevent any organized severe weather from occurring. The exception would be on Tuesday and possibly Wednesday as the low is closest to the state. As the low is very slowly moving north, there would be enough wind and upper level support to sustain organized severe storms. Tuesday in Southwest Arkansas where the highest tornado threat and hail threat would be with a lesser chance Wednesday in Eastern Arkansas with more of a wind treat. With the cold air aloft, these would be some serious hail producers as well as damaging winds. The tornadic side of the system is what lies in question. The NAM, the short range guidance, wants to give southwest into central Arkansas a high tornado condition index. I do not buy this yet with there being so many question marks still with the severe side of this storm. The other medium range model is not as enthusiastic but do support a small tornado threat, especially with the shear values so high on Tuesday evening. This could turn into a low cape high shear event, meaning you won’t need much instability to support severe storms with such a strong low. That is yet to be seen. Below are the maps showing the setups from different models as well as our thoughts as to where the best shot of severe weather will be.
The biggest story with this storm is the amount of rain. Most data, and some soundings around the region, have atmospheric precip values at nearly 2.5 inches, which if it does come to verify this will be near record levels. That is a very tropical air mass, something you would normally see over the tropical parts of the world. The flow around the Bermuda high will send ample moisture northward. This along with a stalled frontal boundary setup somewhere in the state will lead to days of rainfall. Most of the state will see at least 2 inches. This will be a training event, meaning storm after storm, system after system for 3-5 days until the high breaks down or the front dries out. We saw a similar setup in December where much of the state had 3-8 inches of rain in a few days, we all remember the flooding that followed. Do I think we will see that kind of flooding again? YES. Reason being the first couple of days the rain will soak up due to the dry ground in the Ozarks. After that, it will run and run into the rivers. There will be river flooding over most of the state after this event. Central and South Arkansas hasn’t really had much of a drought. These areas will flood fast. Flash Flooding is the biggest concern out of this week. Severe weather is there, but the amount of rain to come will cause major flooding issues. To what extent we do not know at this time. Below are our thoughts on who gets how much as of tonight. Yes, several maps have come out but now data is honing in on a location where the front will set up and meander for a few days.
What can you do to be prepared? This is something we will touch on in the coming days during severe weather awareness week but it does need to be touched on with this system. You need to have a plan of action just in case. Have a higher ground retreat in case of rapidly rising waters. Have an emergency kit if you get stranded. A GOOD EMERGENCY KIT: ~BOTTLED WATER ~CANNED FOOD ~FLASHLIGHTS ~BATTERIES ~EXTRA CLOTHES ~BLANKETS ~FLARES OR A WAY TO CONTACT SOMEONE ~IMPORTANT DOCUMENTS IN WATERPROOF BAGGIES These are just some of the items recommended in case you get caught in a flood or flash flood. Only you can prevent yourself from becoming a statistic. Know your surroundings and know roads to get to higher ground. Have a way to receive warnings and weather updates. You may not always be able to access our site in the event of an internet outage or power outage. NOAA weather radios are a great investment!! Most of all STAY ALERT!!!
Just some small tips from us and be sure to monitor later forecasts for any changes because there will be. One thing to note on the heels of this system, there is another we are watching for another flood and severe potential. So yes March will be active, welcome to spring in Arkansas after a mild winter. We will keep you up to date on the latest as we continue to keep you ahead of the storm!
~Senior Forecaster Derek
~Asst. Senior Forecaster Cameron
Euro showing setup for severe potential track of low, high to the east and the surface winds
NAM showing similar setup but with a high further east, This would be more supportive of a severe weather episode
Typical setup for severe weather with this type of track in the upper atmosphere. Track of low left vs high to the right. Bermuda high controls our weather a great deal
NAM tornado condition index for Tuesday PM showing very favorable conditions for tornadoes in West Arkansas. This is the most aggressive model and not buying at this time
Our thoughts on where severe weather would be most likely to occur. Greater chance will be Tuesday with a lesser chance Wednesday.
GFS run showing similar to the EURO and NAM on track, more wind drawing in more moisture, but high further west, less shear.
Latest thoughts on total rainfall amounts from Tuesday through Saturday