3/22 - 4:30pm - Heavy Rain is Gone, but Warm Temps Remain!

Heavy Rain

Did you get drenched? I think we all did. The rain over the past 24 hours has been tremendous, especially across Mississippi as inches and inches have fallen from the pesky system that has been slowly churning through the Plains and now the South. Check out the estimated rainfall map from today below to see what I mean (the totals for West Tennessee are underdone but you get the picture of who saw some tremendous rainfall earlier today!) Most of the rain is now east of West Tennessee and North Mississippi, but a few showers remain and will continue this evening.

More rain will fall tomorrow afternoon as another piece of energy from the same system rotates around the Mid-South. The area in red with the directional arrow coming from it is called a vorticity max. Usually the area where rain and storms develop is east of the vort max as it moves along. Tomorrow's rain won't be as heavy as today's by any stretch of the imagination and it will be more of a scattered nature than today's washout. Once this rain is all said and done by Saturday morning we should be left with a very nice weekend and temperatures warming back up through the upper 70's across West Tennessee and North Mississippi.

The Big Picture

Let's zoom out more and look at the system that's been causing all of this rain as a whole. What we have is an upper-level low in the Plains that is slowly moving eastward. An upper-level low like this one is basically a ball of cold-air that gets cut off from its northerly source because the jet stream kicks north leaves whatever is in the base of the former trough behind. It moves slowly because the jet stream, which usually drives big weather features, is absent from the process after the low gets cut-off. The satellite and radar images coming in from area where the low is are striking... you can see very well the rotation of the low pressure center, which makes it look like a land-based hurricane.

The jet stream being way up north is also why it's been so warm lately. In the winter the jet stream usually dips down from Canada and brings cold air to the USA. Areas north of the jet stream remain cold due to the influence of an arctic air mass while to the south of it there is usually a warm, moist air mass. This winter and now into this spring the jet stream has not really come down from Canada to the eastern half of the nation. The West has had it come down a few times though, which meant snow and cold temperatures for the Pacific Northwest and even down through California. The reason the jet stream stayed so far north is that La Nina (colder than usual ocean temperatures off the coast of Peru) remained pretty consistent throughout the season. In an El Nino pattern, the jet stream comes down to the US with a vengeance.

Record Warmth

The above-average temperatures from this pattern will persist for quite a while it looks like. A cursory glance at some of the long-range models shows that the jet stream will remain somewhere close to this northerly position for the foreseeable future. With that said, comparing this year and month to years past is incredible. This March so far has been the warmest on record in Jackson, TN and Tupelo, MS and the second warmest in Memphis. Jackson is running 10.6 degrees above average for this March. Comparing the year so far to years past, this is the warmest year so far in Memphis and Tupelo, and the second warmest so far in Jackson. These are remarkable numbers and we'll likely see more of these records flash by as the warmth continues. A running list of how this year's heat compares to previous records is available from NWS Memphis.

3/14 - 11:55pm EDT - Record-Breaking Warmth

The warm weather we've been seeing across the region hit record-breaking levels this afternoon. Here is a list of some broken temperature records today:

Jackson, TN: High 84° | Previous Record 80°

Memphis, TN: High 82° | Previous Record 80°

Chattanooga, TN: High 83° | Previous Record 81°

Louisville, KY: High 82° | Previous Record 80°

Paducah, KY: High 82° | Previous Record 78°
Evansville, IN: High 82° | Previous Record 77°

Indianapolis, IN: High 81° | Previous Record 79°

Many other cities in came close to breaking records, especially in Alabama and Middle Tennessee. The ridge over the Eastern US that's funneling all the remarkably unseasonable temperatures into the area will stay put through the weekend, but a few shortwave disturbances aloft will bring storm chances to much of West Tennessee, North Mississippi, and even into Central Kentucky tomorrow and Friday. These storms will be more organized than the spotty ones that developed in eastern portions of West Tennessee and even up through Western Kentucky this afternoon. The crazy-warm temperatures are going to last at least another full week as this strong ridge stays put, so I think to say that spring (or even summer) has sprung before winter officially ended!

3/7 - 7:45pm - Heavy Rain, Just in Time for Spring Break

A cold front moving Mississippi on Friday will bring some heavy rain to the area, but this will come after some warm temperatures in the mid 70's and showers on Thursday in Starkville. Temperatures will only get into the 50's on Friday as the front moves through, but the weekend should be warmer as southerly flow returns highs into the 60's. A few showers may linger into Saturday, but Sunday and Monday look to be very rainy right now in the Golden Triangle. The bulk of the rain will move out on Tuesday, but multiple shortwave disturbances aloft will trigger more shower chances throughout next week. By the time we're done with the heaviest rain on Monday we could be talking about well over two inches of rain accumulation. A lot of folks are saying "of course it would rain" for the start of spring break here at Mississippi State. Parts of West Tennessee could see three or more and the Delta region of Mississippi could go four inches plus according to the HPC's outlook on the left. That's a pretty big rain event!

Today's Mississippi State weather forecast video is not a typical one because our broadcast meteorology class did some challenging exercises today. My video below features a graphics lineup with few slides thrown in that I did not know about until they popped up on the screen. This is a great way to practice ad-libbing and prepare for situations when weather graphics programs malfunction on air. I think I was able to hold it together pretty well considering that I had to navigate a weather show that had no numbers in it and some redundant graphics. Check it out!

Tomorrow I leave with the Mississippi State University Distinguished Scholars on a trip to Atlanta, Georgia. We'll be there for the next few days touring the city and visiting a couple universities. Should be a fun trip! I'll be on my way to Louisville after we get back to enjoy the rest of my spring break. It's been almost two months since I've been home, so spring break is a welcome reward for all the hard work I've been doing lately!

3/3 - 9pm - A Much Quieter West Tennessee Forecast

West Tennessee was spared from the bulk of the severe weather yesterday. As the cold front pushed through last night much cooler air filtered into the region and we'll see more seasonable weather for the next few days. It will also be quiet compared to the last couple of weeks, so be sure to enjoy these few days of sunshine! Check out your latest forecast from this morning's edition of Good Morning West Tennessee Saturday on WBBJ below:

3/2 - 12:30am - Severe Weather Outbreak Likely

A potent severe weather setup looks likely this afternoon and evening for Tennessee, Kentucky, Alabama, Mississippi, and even parts of Indiana and Ohio. All the ingredients are coming together for what could be a sizable tornado outbreak in these areas, especially around Middle Tennessee and Central Kentucky, maybe extending into Indiana too. We've had severe weather in some of these places just earlier this week, but this setup looks to be even more potent than that. Cities like Louisville, Lexington, Cincinnati, Nashville, Bowling Green, KY, Huntsville, Jackson, TN, Tupelo, MS, Starkville, MS, and Birmingham need to be on the lookout today.

Risks and Timing

The Storm Prediction Center has outlined a Moderate Risk area for severe weather tomorrow in an expansive area of the South. This includes a 15% tornado risk. Storms will likely erupt early this morning as a warm front surges northward and bring a hail risk to West Tennessee while not-as-strong storms will affect the most of the remainder of Kentucky, Tennessee, and Mississippi. These storms shouldn't be a huge deal, but a few might reach severe limits.

A brief break in the action throughout the mid and late morning hours should provide enough recovery time for the atmosphere to recharge and re-fire storms around noon. These storms will try to get going in West Tennessee and Northeast Arkansas, but will gain strength as they hit areas of greater surface heating to the east. These are the storms that could be very bad in a lot of areas. The worst tornado threat throughout the afternoon will be in Central Kentucky and Middle Tennessee, but there's a secondary area that could have tornado problems in Northeast Mississippi into North Alabama if a little more low-level wind shear comes into play. The Storm Prediction Center's latest severe weather outlook seems to pick up on that secondary tornado risk area by extending the Moderate Risk down to East Mississippi and Alabama. Straight-line wind damage and hail will be possible throughout the South tomorrow, so even if you're not in an area where tornadoes will be likely you need to be on the lookout for severe storms. The storms should move out quickly tomorrow evening once the cold front accelerates southeastward through the region.

Details

The reason why Central Kentucky to Middle Tennessee will be the area for maximum tornado potential tomorrow is because of an alignment of a few factors. For one, the fastest upper-level winds will be centered right over this area tomorrow afternoon. When you couple that with almost southerly winds (may be a bit southwesterly at times), you get not only a high difference between wind speed aloft and at the surface, but also a difference in direction. This is called wind shear and it's crucial to sustaining a thunderstorm and allowing it to become strong enough for tornado development. The southerly winds at the surface will help what's called low-level wind shear, and that's usually a pretty big factor in who gets tornadoes.

These southerly winds will also be bringing in moist air from the Gulf, which is the fuel for these storms as they develop. While the best moisture will be over Mississippi, Alabama, and Tennessee tomorrow, it will still be ample for serious severe weather in Kentucky. This moisture will bring some serious atmospheric instability to the region. When you couple this instability with helicity (the tendency for the atmosphere to rotate), you get what's called the Energy Helicity Index (EHI). This is a decent indicator of where the best tornado ingredients will be, and as you can see on the left, the values are particularly high tomorrow across a pretty vast area from Mississippi through Kentucky. Supercells appear likely in Tennessee and Kentucky, but Northeast Mississippi may have more of a mixed supercell/squall line of storms scenario due to less wind shear. This could be an entirely linear squall line event across Northeast Mississippi/North Alabama tomorrow if wind shear under performs. While squall lines don't harbor as many strong tornadoes, it is still a very real threat that needs to be monitored.

Safety

Before severe weather

• Make sure your cell phone is charged in case you lose power
• Have flashlights with fresh batteries ready to go. Your cell phone should NOT be your primary flashlight
• Your NOAA Weather Radio/Cell phone alert app should be ready to alert you
• Make a central meeting location for family members should you lose communications after the severe weather passes

I've said before that I like iMapWeather Radio on the iPhone for weather alerts. This is not any sort of endorsement, but it is an app that I use and it just works.

When a Tornado Warning is issued for your area

• Get to the lowest level of your home, apartment, or office
• Stay away from windows and try to get to the center of the structure you're in
• Evacuate mobile homes and get to a safe, sturdy building immediately
• Make sure you are wearing sturdy shoes
• If you have time (have these ready to go before a warning is issued), put bicycle helmets on the kids and yourself. Quite a few deaths were caused by head trauma in last year's tornadoes.

Please heed ALL warnings. This is a dangerous severe weather setup that needs no playing around with.

2/27 - 4:15pm - Two Shots of Severe Weather This Week

This will certainly be an active week across the Southeast as two storm systems cause trouble for many. The first of these severe weather events will affect West Tennessee and North Mississippi on Wednesday and the second should move through on Friday.

Wednesday

At this point it looks like we'll be tracking storms moving out of Arkansas into West Tennessee and North Mississippi on late Tuesday night after a few showers and possibly a storm pass through during the day on Tuesday. While these storms could have some potency over Central Arkansas, the thinking at this point is that they will weaken overnight as they lose the heating of the day. The best wind shear for these storms will be in the Jackson, TN area as they move through on Wednesday morning into the early afternoon ahead of a cold front, but without much of the needed instability that daytime heating helps to generate the storms shouldn't be too intense. They may very well reach severe limits with some wind and hail, but I think the worst of the storms will be more in Middle Tennessee where they'll have time to re-fire during the heating of the day. The Storm Prediction Center has 30% Slight severe weather risks over Arkansas into extreme West Tennessee on Tuesday and then has the same risk area in Middle Tennessee/extreme Northeast Mississippi on Wednesday. The worst severe weather will effectively leapfrog most of West Tennessee according to these two outlooks, and that looks like a fair forecast right now given the timing of the storms over the region.

Further south in North Mississippi the situation should be about the same, but with a little less wind shear support for severe storms and a later timing for them to move through (later Wednesday afternoon) since the cold front will stall near the MS/TN border for a while during the day (see left image from the 12 NAM). The NAM and GFS models agree that North Mississippi will have higher dew points (more moisture) than West Tennessee, but without great wind support this shouldn't lead to a noticeable increase in storm severity. I should point out that both locations could see a possible isolated tornado or two, but this should be a very low chance given the lack of good low-level wind shear.

Friday

Friday's severe weather event is not a clean-cut as Wednesday's is at this point, but it's looking more and more like this one will feature more intense storms. Another cold front passing through on Friday night will provide a focus for what could be a couple lines or clusters of storms. Right now the GFS and European computer models agree that this will likely not be a tornado outbreak because of the lack of low-level shear much like Wednesday's event, but the two models can't agree on how much moisture makes it northward from the Gulf. The GFS has 65 degree + dew points making it all the way into West Tennessee on Friday whereas the European is not as optimistic. This also plays into who sees the best instability too, so it's not clear right now as to who will see the most severe storms on Friday. It is safe to say that West Tennessee and North Mississippi may have to deal with high winds and maybe even some hail on Friday, and it will likely be more intense than Wednesday based on current data.

Southeast Severe Storms Symposium

To those who are attending the 10th Annual Southeast Severe Storms Symposium at Mississippi State University on Friday and Saturday, we will go on as planned even if there is severe weather in the region. While many meteorologists who will be presenting may not be able to attend because of the risk for severe weather in their respective coverage areas, we should be able to have most of them present their sessions to the symposium via Skype. I'm leading a group of meteorology students who will be live tweeting the symposium on the official Southeast Severe Storms Symposium Twitter account @SESSS12. Be sure to follow us!

2/25 - 5pm - Simple Weekend Forecast, Then Things Get Complicated

After a cold front moved through Thursday giving us cooler temperatures for the last few days we'll finally begin warming things back up again in West Tennessee as high pressure begins to channel warm, southerly winds back into the region. Jackson should get above 60 tomorrow with sunny skies while Monday could be even warmer in the mid 60's with a few clouds. We'll get enough of this warm, moist air in the region to begin turning our attention to the threat of strong storms on Tuesday evening. The Storm Prediction Center has already put West Tennessee and North Mississippi in a risk area for severe weather on Tuesday on their extended outlook (right).

It's not entirely clear how this will play out right now, but the latest data suggests a threat for damage from straight-line winds. The worst severe weather will likely be in Mississippi where moisture will be more plentiful. My main concern at this point is where winds near the surface will be during this event. A secondary disturbance (called a prefrontal trough - see left) could be not only a trigger for storm development, but it may very well turn winds across West Tennessee and North Mississippi out of the southeast. This would increase low-level directional wind shear and hence increase the chance for tornadic activity on Tuesday evening. Again, it's still too far out to make an accurate assessment on this so we'll be watching throughout the remainder of the weekend and into next week. There may be a shot of severe weather as we head into Friday as well, so the pattern will certainly return to an active state after this nice weekend. Check out my forecast from this morning at WBBJ below: