Marginal Risk of Severe Weather Today - Central and Northern Alabama

February 18, 2020

At 6:30 a.m. the SPC added a marginal severe weather risk area for central and northern Alabama for today. There is a 2% chance of a tornado and a 5% chance for severe wind or hail within 25 miles of a point in the shaded areas, maps are below. This is a low probability event, but because my update last night stated there was no severe weather expected I don't want anyone caught off guard.

Stay safe.

Chris

Deep South Weather Outlook February 18-24

February 17, 2020

Synopsis: rain will continue on and off with no significant severe weather in the forecast for the next 7 days as of now. Northern areas could see some snow Thursday. Temps will stay warm until midweek and then start to cool down Wednesday night into the weekend with a few days of warmer weather moving in on Sunday or Monday. Friday and Saturday look like they'll be our nicest days, but cool.

Here's your forecast graphic:

Seriously, the wet weather pattern is going to continue for a while it seems, you can see the frontal progression and rainfall accumulation below. Here's a good article about the pattern we're in: Wet Pattern To Continue Across The Southeast This Week

It'll be seasonably warm until Wednesday night when it starts to cool down. The folks up north will be in the 20s a few nights and wont get out of the 40s during the day through Saturday. Closer to the coast lows will be near or well into the 30s Thursday and Friday nights with highs staying in the mid to upper 50s Friday and Saturday. The beaches should reach the low 60s on Saturday. Saturday night and Sunday wont be quite as cool. Rain will return Sunday and with it a few warmer days to start the week.

After a brief warm up around the beginning of next week we may see an extended cool period through the first few days of March if not longer. The long term outlooks haven't been that great so we'll have to watch to see if this holds.

I hope you all have a great week.

Chris

Severe Weather Outlook - February 12

February 11, 2020

The Storm Prediction Center (SPC) has backed off a little on its forecast for tomorrow, there is no longer an enhanced (orange) risk area. A good portion of our region is in a slight (yellow) risk category. Associated with that is a 5% tornado risk for some of us and a 2% risk for the rest of us. You can also see the wind risk probabilities. In case your curious a slight risk is "an area of organized severe storms, which is not widespread in coverage with varying levels of intensity." You can read more here.

Timing is shown in the upper image. Most of us will be asleep so make sure you have a way to receive alerts that will wake you up.

You can get an idea of how the event may look on radar below. I think the severity probability will start to lessen some after midnight into early Thursday morning but we'll have to watch it.

I'll send out an update if the event evolves significantly.

Timing graphic from the Alabama Weather Blog.

Chris

Deep South Weather Outlook February 10-17

February 9, 2020

This is a long one, but really just a lot of images. Read the synopsis for the CliffsNotes version. The beginning is a recap of our recent weather, followed by the weather for week.

Synopsis: more rain coming especially from Montgomery north. There's a chance for severe weather tomorrow for parts of Alabama, but a more significant chance that may affect us all on Wednesday. Temps will be above average for most of the period, especially near the coast, except for a few days towards the end of the week where we'll see some cooler weather. There are some hints at some winter precip for the northern most areas later this week and early next week, but the probability is very low.

Recent Weather Recap

For those that are curious, there were a total of 269 severe weather reports for last Wednesday and Thursday.

Rain was the big story. Many locations received much more than the 3 or so inches of rain (at most) that was previously forecast.

Winter precip was a higher than expected as well, especially in northern Georgia, but this was probably a treat for those of you that got to see it.

For the week to come you can expect the same pattern to continue with the next system moving in tomorrow morning. I think it may clear a little Tuesday night into Wednesday morning, but by late Wednesday or early Thursday wet weather returns.  For the weekend and early next week It looks like we'll see another 1-2 punch with the first system coming overnight Saturday or into Sunday and the second Monday or Tuesday. Higher rain amounts look to be from Montgomery north. With some areas exceeding 7 inches for the week, flooding is certainly a risk.

Severe weather is the other concern this week. Tomorrow and overnight Monday a portion of the Deep South is in a Marginal risk area for severe weather, with a 2% chance of tornadoes in this area. While there's a chance for thunderstorms Tuesday, severe weather is not expected. Wednesday is the day to watch, the Day 4 outlook has most of our region in a 15% risk area with a portion in a 30% risk area. We haven't been told any details yet, but all forms of severe weather are possible.

There's not much more to add about temperature than what I stated in the synopsis. I think only the northern-most areas will see temps below freezing a few nights towards the weekend.

I'll send out an update Tuesday regarding the severe weather threat for Wednesday. If you have any questions, or want more specific info for your area just let me know.

Have a great week.

Chris

Evening Severe Weather Update - February 5, 2020

February 5, 2020

In addition to the threat overnight, the SPC has placed a portion of the Florida Panhandle in an enhanced risk for severe weather tomorrow and a good portion of Alabama is also in a slight risk area. The primary threat looks to be high winds but tornadoes are also possible. Timing could vary an hour or two, but storms will approach Walton County around 6am and Bay County around 7am. Bay, Holmes, and Jackson Counties have closed schools for Thursday, Walton is monitoring but schools remain open as of this writing.

The image below is supposed to be a simulated radar animation, I'm not sure if it will work for everyone.

If there is a significant change to the forecast I'll send another update in the morning.

Chris

Mid-Morning Severe Weather Update - February 5, 2020

Just a few minutes ago the SPC updated the Day 1 Outlook to now include an Enhanced (orange) risk area.

The tornado threat level has been increased in this area as shown below. The black hatching indicates a 10% probability of strong tornadoes, EF2-EF5, within 25 miles of a point within the boundary.

We'll likely see a tornado watch issued for this area very soon.

At this time I don't expect to see a change in the risk level for the remainder of the day and overnight, but I'll send out another update if there is a significant change.

Chris

Severe Weather Update - February 5, 2020

February 5, 2020

A quick update on the severe weather threat. A good portion of the deep south remains in a Slight (yellow) risk area. You can see the potential timing below, note the very broad time range. The SPC is describing this as a 3 stage event: 1) storms forming in Mississippi and northwestern Alabama ahead of the front during the day; 2) storms developing nearer to the coast this afternoon and overnight; 3) storms that form along or near the front as it moves west to east, this will impact us late today and overnight. The three stage nature explains the extended time ranges, there will be multiple opportunities for severe weather.

The primary threat remains damaging winds, with tornadoes and hail also possible. The SPC mentioned that the threat level may need to be upgraded as the day progresses. The probabilities shown below represent the chance for each hazard occurring within 25 miles of a point.

The severe weather threat will carry over into tomorrow also, we'll talk about that more later.

If you don't know how to get severe weather alerts, read this for some ideas.

The source for the timing graphic at the top is the Alabama Weather Blog.

Have a plan, stay safe, and have a good day.

Chris

Weather Nerd Corner 6 - CPC Outlooks

Originally sent via email November 4, 2019, with some edits for grammar.

If you're curious, below are the NWS winter (December-February) outlooks.

The NWS also publishes several other temperature and precipitation outlooks from short to long term which you can see here: https://www.cpc.ncep.noaa.gov/. All of these maps are compared to climatological norms. So above average temperature in the winter doesn't mean it's hot, just not as cold as normal. Likewise, below average precipitation doesn't mean no rain (it could), just not as much as normal. Normal is currently based on averages from 1981-2010 (updated once per decade). We'll get an update to this at the end of next year which will be interesting to see.

One thing about the winter forecast maps, or any long term forecast for the most part, is they don't have any skill. That's not saying they're no good, but that they're really just an educated guess. Forecast skill is a measure of how well a forecast does compared to some reference, typically climatology (the past). Long term forecasts typically don't do any better than what climatology says. So if you were to compare a long term forecast to what normally happens for that time of year the forecast will be no better than if you guessed using history as a guide. I could make a forecast for next July right now and say it was going to be like most Julys are and chances are I'd be pretty close, compared to a forecast that says it will be above/below average temp or precip. Because of this some forecasters don't think they shouldn't be published, but people are curious and as long as you understand how they're made there's no harm.

Weather Nerd Corner 5 - Models

Originally sent via email October 18, 2019

Let's talk a little about models. I'm not going to go in to a lot of detail about the meteorology behind how they make a forecast. Instead I want to explain the process that happens each model run. There are many more steps than I am listing here, this is just a highly simplified overview.

Models do not just ingest data from observations every few hours, run some calculations, spit out a forecast, and then rinse and repeat. One of the main reasons for this is the huge lack of data, especially over the oceans. Data can also have errors. The first step in the model cycle is to produce a short range forecast, not the published one, but a first guess you could call it. The fundamental assumption of the model process is that the short range forecast is accurate. In other words we're assuming that we have a good model! This short range forecast or guess helps fill in the gaps where we don't have observations. This also helps keep some history from previous model runs so that the model isn't starting off fresh, it helps to maintain some run-to-run consistency.

Next, real weather observations are used to correct the short range forecast! This produces what is called an analysis, it is what the weather is thought to be like at time zero or the start of the model run. This is also called model initialization. From there the rest of the forecast is calculated out however far the model is programmed to do so and the results are published. The final step is that the next short range forecast is made to start off the next model cycle.

One thing to note about initialization is this can be a good way to judge how well a given model run may do. Meteorologists can look at the analysis/initialization and then compare it to what actually occurred at that same time by looking at radar or satellite data for example. If the model didn't do a good job initializing a system then you may not want to trust the forecast it produces for 24 hours from now.

Weather Nerd Corner 4 - Invests

Originally sent via email October 17, 2019

So what is an "invest?" Just as the name suggests, an invest is an area of interest, something that is starting to get an organized and could possible develop. It is starting to get organized but isn't a tropical depression yet (which gets a number such as TD 1, etc.). It allows meteorologists to talk about it without saying something like "that group of clouds over there." Numbering starts at 90 and goes to 99 and then starts over again. The letter designates the basin with "L" for Atlantic, "E" for Eastern Pacific, and "W" for Western Pacific.

Weather Nerd Corner 3 - Wind Shear

Originally sent via email October 16, 2019

The context of this post is wind shear only with regards to tropical cyclones. This isn't completely clear outside of the full email that it was original included with.

Since I've mentioned wind shear a few times I thought I'd explain it briefly. Wind shear, or more properly vertical wind shear, is when the wind changes speed and/or direction with height. Wind shear is bad for tropical cyclones for two reasons. One is that any surface low pressure system that is drawing in air needs a place for that air to go for it to grow and stay healthy. The only place that air can go is up. Tropical cyclones need an upper level feature that allows for efficient evacuation of rising air from the surface. Wind shear doesn't allow for this upper level feature to form above the surface low pressure center. Wind shear also doesn't allow the developing thunderstorms to stay close together and share heat with each other, instead it spreads them out and blows them away.

Weather Nerd Corner 2 - Operational vs. Ensemble Models

Originally sent via email October 5, 2019, with some edits for grammar and context.

Just briefly, here's the difference between operational and ensemble models. The main models used for forecasting are called operational models. An example of the GFS showing southwestern Caribbean tropical development I mentioned during today's outlook is shown below (look for the L surrounded by bright colors).

An ensemble model is a group of models run together but with slightly different parameters. I'll explain this more another day but the idea is to see what the majority of the models predict, in other words is there a trend. This is used to get a better idea if the operational models are correct or just out to lunch. The GEFS is the ensemble version of the GFS. It has 21 separate members. The Euro ensemble, called the EPS, has 51 members. Below is the GEFS output for the same period of time as the GFS model above.

You can see a cluster of red numbers near where the GFS is showing development. These numbers are low pressure systems from some of the 21 members. So in this case I would say that the GEFS is in fairly good agreement with the GFS showing tropical development. As a comparison only a few of the EPS members (not shown) show development for this system so for right now I'd say overall confidence is low.

Both of today's maps are from tropicaltidbits.com.

Weather Nerd Corner 1 - Forecasting, Weather, Climate, and Models

Originally sent via email - October 2, 2019, with some edits for grammar and context.

Today I want to talk about forecasting and models.

Forecasting is a complex process that I'm only beginning to learn. The main thing to understand is that our forecasts are only good out to about 3-5 days. It's not uncommon for confidence to be low in a forecast 1 day out. Sometimes we can have relatively high confidence in a forecast beyond 5 days if there's really good model agreement run after run and if climatology favors the forecast, but in general don't put too much stock in forecasts beyond 5 days.

Climate is what you expect the weather to be year after year for the same period of time for a given location. For instance in the middle of July we really don't have to look at the temperature or rain forecast, we all know it's going to be hot with a chance of thunderstorms. Weather is what you actually get. For example we are running well above average temperature-wise and below average for precipitation this time of year. Climate says it shouldn't be this hot and dry, but that is the weather we're getting. With this in mind this is why we can sometimes have confidence in a forecast out beyond 5 days. If our past experience (climate) for a given time of year agrees with the long term forecast then that increases our confidence. When models start hinting at us getting snow in the deep south beyond 5 days we have good reason to doubt that, even though it may be correct.

I'll end with a brief discussion about models. Our forecasting is heavily reliant on computer forecast models. I think we all get the idea, you give a super computer some data and a program spits out a forecast. I'll go in to some more detail on this in the future. In the outlook I emailed today I mentioned the GFS and Euro. These two models are for the most part the best operational global models. GFS is the Global Forecast System. This model is produced and run by the National Weather Service. It produces forecast products for the entire globe and it runs 4 times a day. Its data is completely free to obtain, not counting the taxes you pay to keep it going. Euro is the nickname for ECMWF which is the European Center for Medium-Range Weather Forecasts. It is also a global model with the main model running 2 times a day. ECMWF is government supported but they are basically an independent organization. Some of their products are free but most have to be paid for and they are expensive. I subscribe to a service that buys ECMWF products and then sells subscriptions to users like me so that we share the costs.

How To Get Severe Weather Alerts

February 4, 2020

How do I get severe weather alerts? This question came up the last time we had a severe weather event. Experts recommend having multiple methods of receiving alerts, here are several to consider:

-NOAA Weather Radio This is in my opinion one of the most reliable methods but it has drawbacks. It requires a special, inexpensive radio that receives severe weather and other alerts from a nearby station. The best advantage is that the system delivers immediate alerts. The radio sits idle until it receives a warning code, then the radio will sound an alarm followed by the alert message. Some disadvantages are that you have to have a radio near you all the time, this is possible but not the most practical. I have one at home but that's it. It's good for nighttime events where the internet or cell service may drop out without my knowledge or have some other technical issue. Another disadvantage is that the local NOAA radio station could go offline, planned or unplanned. I think most radios will show you on their display that they're not receiving the station. This is a really good reason not to rely on this method alone. They can also be confusing to program so that you only receive alerts for your area.

-Local TV and Radio If you happen to be watching local TV or listening to a local radio station during an event, severe weather alerts should automatically break in to whatever program is being broadcast and deliver the alert message. Of course you have to have the TV or radio on to hear the message. If you lack a weather radio, turning the TV or radio on when an event is near may be a good option.

-Cell Phone Alerts, or Wireless Emergency Alerts (WEA) If you have a WEA capable device and if you haven't turned the alerts off you should receive these automatically, assuming you have a cell signal. I'm not sure how well these work or for what kind of events. I'll have to pay attention next time I'm in an alert area to see how well this works compared to other methods. All you have to do is leave it enabled, so you might as well do so.

-Sirens My area doesn't have sirens. if your area does then this is a good backup method. Sirens can break down, or some other issue could keep you from hearing them.

-iNWS Mobile Alerting This is a system run by the National Weather Service that will text and email you alerts. You have to sign up online and enter locations you want alerts for and what alerts you'd like to receive. I get these by text and email for my home and work locations. There seems to be no delay between these alerts and those received by other methods. That being said you have to have a good internet or cell signal, remember to not silence your phone, and hope your phone notifications will wake you at night. This is a good method when you're not asleep and when you have good service.

-Apps There are a bunch of apps out there. At best this is a backup method for me, others may have better experiences. I'm not going to post which apps I use for alerts because frankly I haven't found one that I'm fully confident in. It seems they all have delays, some by several minutes or more. Delays aren't a good thing during a potentially life threatening situation. Do a Google search or look through your app store of choice. Make sure you look for apps that have good reviews and that have been updated recently and work with the latest OS updates. Don't hesitate to pay a few dollars for an app that looks good. In major markets there are apps developed by local TV stations, they would be a good option to try out. Of course you also need cell or internet service for these to work and have your notifications set so that you can still get them if you forget and leave your phone silenced. Another downside is you may find one you like today that works well only to find out the hard way it doesn't work next time you need it. This is why I don't rely on them. The developer may stop updating it or it just may not work for whatever mysterious reason software decides to stop working.  It's also pretty much impossible for app developers to make an app that works flawlessly with all the different devices and OSs that are out there. It seems like a never ending battle to find one that works good.

-Yourself Seriously, learn to spot the signs of severe weather, there are some links below. Pay attention to the forecast in your area so that you have an idea when to expect severe weather and what you might experience. If I know bad weather is on the way, I'm usually watching and waiting for it, even at night, especially once it is only a county or so away. Rarely am I surprised by an alert, but I'm a weather nerd so I don't expect that of most people. Keep an eye out on the weather, check out the weather radar every now and then if you know how to look it. Make sure you can find yourself on a map! It doesn't do much good to know that there is bad weather out there if you don't know where you are! Talk to your family and friends, find out what has worked well for them in the area you're in.

Shelter Solutions - Before The Storm

Survival guide: Recognize which clouds mean danger

Severe Weather - Ready.gov

I hope this is helpful. If you have any questions drop me a line here.

Deep South Weather Outlook February 4-12

February 3, 2020

Let me try again, this time with pictures!

Synopsis: expect the same weather pattern to continue for at least the next week and a half with rain every 2-4 days. Severe weather is possible mid-week but I don't think it'll be a major event. Temps are gradually warming as our days get longer, with no extreme lows or highs in the near future.

First up for today is an update on the severe weather threat mid-week. As you can see below there is a threat for the deep south from late Tuesday through Thursday. Timing is still uncertain but it looks like the worst of it will be from Wednesday night through Thursday night with the threat moving east over time. Nighttime events can be more dangerous so make sure you have a way of receiving alerts that'll wake you up. We'll have better info early Wednesday but I think the main threat will be damaging winds with hail and tornadoes also possible.

Also with this system expect a multi-day rain event beginning in northern areas with the heaviest rain Wednesday night and Thursday, some areas may even exceed 3".

On the back side the northern areas may see some frozen precip Thursday and Friday but if so not a lot of accumulation. It's a low probability event at this point.

After this system clears the area later Thursday or early Friday we'll see our next front Saturday. This one looks to mainly impact people from Montgomery north and should clear out late Saturday or midday Sunday, keeping in mind timing this far out is uncertain. Rain totals wont be very high from this one, probably less than an additional 0.5" of rain.

Beyond the weekend we'll see the next system Monday evening, perhaps followed by another Wednesday evening.

Regarding temps, expect above average highs through most of the week and near average highs from the end of the week through the weekend and early next week. Lows will also remain above average most of the week. After the front passes at the end of the week northern areas can expect near average lows and areas from mid-Alabama south slightly below average lows for a few days.

I'll send out an update on the severe weather threat early Wednesday.

Have a great week.