Monday, February 27, 2012

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.


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'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!

Saturday, February 25, 2012

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:

Wednesday, February 22, 2012

2/22 - 3pm - Severe Storms Possible Tomorrow Across the South

Let's start with today first. It's unbelievably nice outside! You can't get much better than this in February in North Mississippi. You may be thinking that we'll have to pay for this great weather with some sort of severe weather event, and you're correct. This warm, moist air will serve as the fuel for a few severe storms across the region tomorrow night (see right for the SPC's latest Slight Risk area).

The main issue with the forecast at this point is where and exactly when will these storms form? The computer forecast models are having a difficult time figuring out if a warm layer of air aloft will serve to suppress storm development during the evening. This layer of air, which is called the "cap", is something that storm chasers in the Plains have to deal with quite often but usually not something we deal with here in the Southeast. Even though the models are having a hard time with this, we'll likely see a squall line of storms (QLCS in weather nerd lingo) roll through sometime around or after midnight tomorrow night. These will likely carry wind damage and hail threats, but the latest data coming in suggests that we may even see a couple isolated tornadoes. This will certainly not be a tornado outbreak by any means because the wind shear profiles for that kind of thing just aren't there. The energy helicity index (a combination of rotation in the atmosphere and instability) output on the left from the 18z NAM shows that this squall line will have some tornado ingredients to work with, but not all that much.

Another reason why we won't see a more significant severe weather risk is because the amount of moisture that we'll have filtering into the region from the Gulf won't be as strong as previously thought. Dewpoints just above 60 (on right) are certainly enough to trigger severe storms, but something closer to 70 is needed for more potent setups. Check out the video below for more details on this system:

Saturday, February 18, 2012

2/18 - 2pm - Somewhat of a Snowy Fizzle

Last night's model runs were coming in very bullish for snow in West Tennessee on Sunday morning and I was even putting together a graphic very early this morning that had 2-4" of snow in Northwest Tennessee. As the 6z model runs came in there was a pretty stark change in the forecast all because of one fact: two waves in the upper atmosphere were not phasing (or joining forces) as quickly as previously predicted. This means that the cold air from the northerly wave will not inject itself into the southerly one until it reaches Nashville. Without this cold upper-air support, the chance for snow dwindles considerably.

While some light accumulations are possible in Northwest Tennessee tomorrow morning, much of the region should remain plain rain with some mixed in snowflakes. A brief burst of snow may happen later on Sunday morning as this system pulls out of the area, but even in areas with accumulation it should not cause problems on the roads due to above freezing surface temperatures. Areas north and east of Nashville, however, will see the accumulating snow and some of it could be on the heavy side.

Once the rain and snow is gone later on tomorrow morning we should be left with cloudy skies and cooler temperatures in the 40's across West Tennessee. There are a couple rain chances thrown in next week on Tuesday and Wednesday, but the rest of the week should be relatively warm and dry. Check out the video below for your complete forecast (Note: I left my TV tuner for my laptop in Mississippi so I don't have a longer copy of this video):

Wednesday, February 15, 2012

2/15 - 11am - Storms Tonight in Mississippi, Nice Weather Ahead

A line of showers and storms will move through Mississippi late this evening as a fast-moving disturbance makes its way through the region. With only marginal moisture and instability expected, the northern 2/3 of the state should see heavy rain and possibly a strong storm or two. Any severe weather should stay southwest of Jackson, Mississippi into Louisiana where these ingredients will be more plentiful. The Storm Prediction Center has issued a Slight Risk for severe weather down in that area as well, which you'll see on the left. Since there isn't much cold air behind the front that will be pushing these storms through this evening we should have a very nice Thursday with temperatures in the upper 60's here in the Golden Triangle. Another system may generate some rain for us during the weekend. Your full forecast is available in the video below:

Saturday, February 11, 2012

2/11 - 5pm - A Wintry West Tennessee Forecast

A front that passed through West Tennessee last night brought rain showers during the overnight hours and snow showers this morning across the region. These have since moved out of the area, but the snow came down in some heavy bursts at times even though there was really no accumulation. High pressure will provide the setup for a very cold couple of days with highs in the 30's and overnight lows in the teens. Yikes! Tonight could be the coldest night of 2012 so far, which really isn't saying much since we've been pretty mild as of late.

Monday's forecast is flat-out complicated. Warm air overriding the retreating arctic air mass in place from this weekend will set the stage for a storm that could put down snow, sleet, and even freezing rain. Most indications are that this will start off as snow across most of West Tennessee on Monday afternoon as the lower layers of the atmosphere moisten up, but this snow could switch over to a period of wintry mix later on in the evening as the atmosphere warms up more (notice the warm "push" at 850 mb - 5000 ft on the left). Once we reach a certain threshold of warming on Monday night into the wee hours of Tuesday morning, all the snow, sleet, and freezing rain should transition to plain rain and the wintry weather headaches will be no more. Before everything switches over to rain an inch or so of snow could be on the ground around the I-40 corridor, including Jackson, according to the latest forecast models. Areas in Northwest Tennessee will switchover to rain a little later on than I-40, so there may be up to two inches on the ground. This is nowhere near set in stone yet and I'm willing to bet we'll see a few small changes in this forecast before the weekend is over.

The models agree that snow will fall across West Tennessee on Monday, but there are differences in when exactly this warm layer aloft will come in enough to switch the snow and wintry mix over to rain. The 18z NAM seems the most conservative on snow amounts at this point, with only a half inch in Jackson on Monday night. It also suggests that we might avoid a wintry mix and switch immediately over to rain. There's even a brief shot of rain just before the snow starts on that model. The GFS is bullish on snow amounts with over an inch in Jackson with the aforementioned wintry mix period (depicted as freezing rain on the BUFKIT output to the right) before the switchover to rain. The main issues seem are the timing of the warm air intrusion aloft and how strong it will be. So while this won't be a huge winter weather event by any stretch of the imagination, a few travel issues may crop up on Monday evening as the snow and wintry mix is falling.

Check out the video below from this morning's newscast on WBBJ for more details on your forecast!

Wednesday, February 8, 2012

2/8 - 4pm - A Sunny Winter's Day in North Mississippi

How about that warm sunshine out there today? We still have a layer of thin clouds north of Tupelo and over the Delta right now, but south of there in the Golden Triangle we've cleared things out for the most part and temperatures got well into the 50's this afternoon as expected. A few of these clouds may move in to Starkville tonight, but that won't stop our low temperatures from bottoming out around the freezing mark.

High pressure will continue its eastward march into the eastern half of the nation for tomorrow, meaning a continuation of the nice weather we've had today. Tomorrow's highs may be a few degrees lower as cooler air continues to work its way in from the north, but most locations should clear 50 degrees. Even though some of the computer models have backed off on this a bit, our next front moving through on Friday night into Saturday could bring us a few showers on Friday night. The bigger story with this is the plume of cold air behind this front we'll see. It's possible that highs may not get out of the 40's this weekend, so a little taste of the winter we've missed so far in Starkville will come our way for Saturday and Sunday. Next week looks warmer again and we may even breach 60 degrees by Tuesday! Check out the video for your Mississippi State forecast:

Saturday, February 4, 2012

2/4 - 4pm - Storms Come to an End Across West TN

After a round of showers and storms this morning, a cold front is now moving across the Mississippi River into the state. The cold air and clouds with the storms this morning stabilized the atmosphere considerably, so storms will not re-fire this afternoon as previously forecast. This also means that our marginal risk for severe weather today is done. Instead a few areas of drizzle may pop up as the front moves through by this evening. After a few showers tomorrow, calm and mostly clear conditions should prevail for the rest of next week. Check out my forecast from this morning on WBBJ below:

This morning I walked into the studio and our weather center was completely gutted! WBBJ is starting to disassemble it to make room for our new set, which will include a shiny new weather center once completed. For now our weather operations are running from a temporary location just off-camera, which you can see in the panoramic photo I shot this morning:

Wednesday, February 1, 2012

2/1 - 6:10pm - Severe Weather in North Mississippi

After a rainy start to the day and peeks of sunshine this afternoon, we're tracking a line of storms moving through the northern half of Mississippi. There is a Tornado Warning out for parts of Carroll and Grenada Counties due to some rotation present in that part of the storm. Severe Thunderstorm Warnings are in effect up and down this line right now, mainly for the strong wind threat they pose. The environment is not favorable for these storms to maintain their strength over the eastern half of Mississippi, so they should begin to fall apart soon.

A Severe Thunderstorm Watch is in effect for northeastern parts of Mississippi until 11pm CST:

While I do not have a full Mississippi State weather forecast today, I did record a "weather tease" in my broadcast meteorology class today. This is just a 45 second preview of a forecast that would come later in a newscast. Check it out below: