12/2 - 4:15pm - A Needed Shot of Rain on the Way

A few brief showers scraped across northern portions of West Tennessee this morning as expected. The disturbance causing those morning showers has left behind some cloud cover across the region with peeks of sun here and there. More of the incredibly warm weather that we've seen for the past few days arrives tomorrow just in time for the Jackson Christmas Parade at 6:45pm. 75 still looks like a good bet for a high temperature during the afternoon as we start the workweek on Monday.

Much of the area is experiencing moderate drought conditions right now. Even though the growing season is pretty much over it is still important for rainfall to keep up so that we don't have an already-in-place drought come spring. The good news here is that we have a chance for a good soaking rain on Tuesday with over a half inch possible in most places. The front causing this rain will leave behind only slightly cooler temperatures in the 60's, which is still warmer than average for this time of year. The next round of rain on Friday and Saturday is the one to watch as it could bring much, much cooler weather to the area next weekend behind it.

Check out the video below from yesterday night's newscast on WBBJ for your full forecast!

11/12 - 2pm - A Frigid Fall Return in Progress!

The clouds are clearing earlier than expected across Mississippi, which is good news for those looking for a more picturesque day outside. Unfortunately this will not save us from an incredible drop in temperature this evening across the Golden Triangle. The cold front that came through earlier this morning is allowing northwesterly winds to bring in an arctic air mass that will help plunge us to around the freezing mark by early tomorrow morning. If you're looking for something a little warmer than that, just wait. Temperatures will break into the 60's again by Wednesday as sunny skies continue to stick around through most of the week. Your full forecast with all the details is available in the video below!

8/27 - 9:30pm - Update on Isaac's Expected Gulf Coast Landfall

Tropical Storm Isaac is teetering on the edge of becoming a hurricane this evening with winds of 70 mph as of this writing. The threshold for a Category 1 hurricane is 74 mph. The storm motion has slowed down over the past few hours, now moving northwest at only 10 mph. Issac continues to run into issues that prevent it from rapid intensification, which is certainly good news. The latest issue is a batch of dry air that is currently being pulled into the center of the storm. Without an uninhibited source of moist air the storm cannot form a defined eye or intensify very well. The dry air is why Isaac is lopsided right now with most of the intense winds on the south side.

How long will it be until this dry air is finished working through the storm? Probably a few more hours, possibly lasting into the early morning hours tomorrow if current model forecasts are correct. Speaking of models, the current track from the National Hurricane Center takes Isaac right into the Eastern Louisiana/Mississippi Coast areas late tomorrow night into early Wednesday morning as a weak Category 2 storm with 100 mph winds. With the lack of organization we're seeing right now it may only be a Category 1 at landfall. The latest computer model tracks, the spaghetti plots as you've probably heard about and seen over the past few days, have tightened up on a landfall location somewhere around New Orleans. It's worth noting that some of these models are now trending eastward after a massive amount of successive westward jogs in recent days. It doesn't appear that this landfall will take place further east than Biloxi, Mississippi given the current motion of the storm and model data, but the exact landfall location won't be the big story with this storm.

Storm surge exceedance probabilities

The big story here is how big and how slow this storm is. Sure, there will be some wind damage along the coast as the storm makes landfall, but the large area that Isaac covers means that quite an expansive area along the Gulf Coast will experience other effects from it. Storm surge at or above ten feet is possible in locations from New Orleans to Pascagoula, MS and rainfall amounts over a foot are forecast over much of Central and Southern Mississippi and Eastern Louisiana. Isaac will slow down even more than its current speed once it gets over land so heavy rain will be a good bet across much of the Gulf Coast states until we get into the weekend. Inland flooding will be a problem with the deluge that Isaac with unleash on the region as it crawls northward.

Rainfall through 7pm CDT Saturday

As far as local effects in North Mississippi and West Tennessee, Isaac will bring very heavy rain and winds with gusts in some cases near 40 mph. Starkville, MS may be looking at a six or more inch rainfall scenario through Saturday evening and areas in West Tennessee like Jackson will likely see more than three inches of rain. This highly depends on Isaac's exact track so some areas will see much more rain than others.

With just about any landfalling hurricane you can expect the threat of isolated tornadoes, and Isaac will be no different. The turning of winds with height in a hurricane or tropical storm create favorable wind shear for tornadoes to form in stronger parts of it. Due to this potential threat, the Storm Prediction Center has issued a Slight Risk for most of Mississippi and parts of Louisiana, Alabama, Georgia, and Florida.


So overall we're not looking at Isaac to be a major hurricane at landfall, but the effects from it will be widespread due to it's large size. It's a good thing that folks in a wide area are preparing for this storm since it could be a long haul given the slow motion that's expected from it.

5/25 - 11:50am CDT - A Grand Finale

Ever since earlier this week we've had our eye on today's setup in Central Kansas. The moisture return, a low developing over Southwest Kansas, and upper-level wind support all kept us coming back to look at the models to see how it was shaping up. For a while it looked like the cap, or a layer of instability-inhibiting warm air aloft, was going to surpress storm formation but now we're seeing a situation where there will be just enough break in the cap to allow for a few isolated supercell storms to form. To get surface heating today to break that cap we need to clear out the clouds across Kansas first. A push of dry air at around 10,000 feet is currently moving from Southwest Kansas to the northeast and is eating these clouds for breakfast as you see in the satellite image to the right. We expect this to keep moving throughout the day and hopefully it will clear out the clouds in time to get some serious surface heating going.

The big story here today is the moisture return. For the first time this week we are seeing a situation where dew points will surge into the mid to upper 60's. Yes! This much-needed moisture will be the fuel for storms this afternoon and should give us a much better show than the moisture-deprived low-precipitation storms we've been seeing lately. While we don't have this moisture in the area quite yet, it's streaming in like crazy right now. Strong easterly and southeasterly winds are blowing this moisture into Kansas from Missouri and Oklahoma and will continue doing so throughout the day. Having mostly easterly winds in Kansas right now is a very good thing because this is creating just about optimal low-level shear for rotating supercell storms.

Speaking of wind shear, this will create quite a bit of helicity, or a corkscrew-like rotation of air in the atmosphere. When you combine helicity with instability in an equation you get the Energy Helicity Index (EHI). As I've said before I think that indicies and parameters can be distracting since human analysis is always better than a formula, but EHI seems to be fairly reliable since it is so basic and relies on two very basic ingredients. This afternoon's EHI values in Kansas will be the highest we've seen out here this season according to the Rapid Refresh model. That's some great news for storm chasers because higher EHI values typically correlate with enhanced tornado potential.

The Storm Prediction Center has a Slight Risk for severe storms today from Iowa to the Texas Panhandle and within that a 5% tornado risk in Kansas. This is quite the change from the previously non-severe "general thunderstorm" outlooks that they had been issuing for today because of the concern that strong capping may inhibit storm development. Today is our last chase day out here for Tour 3 and my last day out here until I come back for a week in June. If we could see some good storms today that'd be a great end to the first part of my trip! Tonight once we're finished chasing we'll be traveling back to Oklahoma City where I'll fly back to Louisville from tomorrow morning.

Follow up-to-the-minute reports on our chase on my Twitter and Facebook accounts!

5/23 - 11:50am CDT - Nebraska or Colorado?

Today we're in the Cornhusker state of Nebraska in search of severe storms. Yesterday's chase in what ended up being extreme southern South Dakota was short-lived as storms that formed up that way south of Murdo, SD quickly dissipated due to a low amount of moisture and contamination of their inflow via a layer of clouds that formed to the south of them. The storm we chased had a nice structure for a few minutes and even put down a bit of a wall cloud before it fell apart.

A cold front situated across the center of Nebraska will be the focus for storms this afternoon. The band of clouds on the satellite image is roughly where the front is located right now and it will slowly sag south and east today. A low forming over Eastern Colorado/Western Kansas should help back the winds out of the east this afternoon here in portions of Nebraska and that will increase low-level wind shear needed for rotating storms as that happens. This low will also create easterly winds in Northeast Colorado, so that may be a secondary target area for today.

We're already seeing some easterly winds beginning to set up in Nebraska this morning and we'll be watching where those develop this afternoon as well. Dew points are still quite low this morning in the upper 50's, but more moisture should move in this afternoon and bump up dew points to around 60 or higher. This is still a bit low for good storms, but we'll probably be better off than we were yesterday in this regard. Dew points in Northeast Colorado won't have to be as high for good storms thanks to the elevation there.

The environment today is rather "capped" as we say, meaning there's a warm layer of air above the surface layer that's prohibiting storm development. As surface heating gets going later this afternoon and into this evening there should be enough energy for updrafts to break through this cap and form storms. This means that storms should be fairly isolated at least starting out, which is a good thing since isolated storms are more organized, more likely to produce a tornado, and easier to chase. Some of these isolated storms may become supercells, and that's exactly the thing we're after since they may produce a few tornadoes today. Storms may condense into one or more lines of storms later this evening as the cap quickly erodes after dark. The Storm Prediction Center has a Slight Risk for severe weather today from Colorado to Minnesota and that includes a couple areas of 5% tornado risk. There's a chance we may bug out on our plans for Nebraska and move to the secondary area you see there in Northeast Colorado, so stay tuned.

Follow up-to-the-minute updates today on my Twitter and Facebook accounts!

5/20 - 11:45am CDT - Texas Panhandle Today

We're on the road from Oklahoma City to the Panhandle region of Texas where storms are likely to form today. Right now we're watching a clear area on satellite near a cold front situated just south of a line from Childress to Lubbock, TX. This clearing should help to build instability for storms to form as heating from the sun is allowed to reach the surface. Winds and dew points at the moment are not terribly favorable, but the most recent RAP (Rapid Refresh) model does have surface winds turning more easterly during the afternoon bringing in more moisture.

Even though winds at the surface will likely be favorable, winds aloft at 18,000 feet (500 mb) will be weak and westerly to west-northwesterly. It would be preferrable to have winds at that level that are fast and from the southwest, so not having much of either of those components will be a limiting factor. Storms that form this afternoon could have some large hail and winds, but the tornado threat at the moment looks marginal given the lack of upper wind support and possibly lower dew points.

Given these factors, the Storm Prediction Center has decided to forgo issuing a severe weather risk for the area today and only has a general storm risk with mention of some isolated instances of severe storms. The trick today will be to find these isolated instances wherever the best environment for these sets up this afternoon.

The latest updates on our chase are available on Twitter and Facebook.

5/14 - 12:45pm CDT - Pressing Further Southwest in Texas

Today we're continuing on southwestward in Texas where fast westerly and northwesterly winds aloft and moist, easterly winds at the surface will combine to create a potential for severe weather. These winds should create enough shear for supercells among some scattered storms and more specifically there is a chance for a couple tornadoes down this way. There are a few clouds on the visible satellite view right now from ongoing storms in the region, but areas closer to the Mexican border near Marfa and Fort Davis are pretty much cloud free. There is a field of cumulus clouds we're driving toward south of Marfa that may serve as a focus for development, so we'll see how that pans out. In any case we have lots of direct sunlight and instability already building for storms later this afternoon.

The Storm Prediction Center has issued a Slight Risk for severe weather today across extreme southwest Texas where we're at and they've even included a 5% tornado risk area. This is the best setup we've had so far this week, so we remain hopeful that we'll see some great stuff today! There aren't many roads around the area so this will be a challenging chase day even though the ingredients appear to be coming together pretty well.




Follow me on Twitter and Facebook for the latest today!

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.