Slight to Moderate Chance of Severe Weather Today Across AL and FL Panhandle

June 24, 2020

There is a Slight to Moderate risk of severe weather this afternoon and into the evening for most of Alabama south of Huntsville and the Florida Panhandle. Damaging winds and isolated tornadoes are possible with the greater tornado threat located in southwest Alabama and the western Florida Panhandle. Activity will start to decrease around sunset but some isolated storms will linger into the overnight hours.

Stay safe and have a good rest of the week.

Chris

Tropical Weather Update

June 21, 2020

Synopsis: the Tropical Atlantic has been pretty quiet since Cristobal but that will likely change over the next few weeks. Below is the Eastern Pacific 5 Day Outlook and as you can see activity is picking up. This kind of activity often foretells future development in the Atlantic but sometimes the East Pacific gets busy and then nothing happens over our way, we'll just have to see.

There is a teleconnection called the Madden-Julian Oscillation (MJO) that circles the global tropics moving to the east. It usually starts in the Indian Ocean, moves east, and then dies out in the Atlantic, although it doesn't always make it all the way to the Atlantic. The MJO is a fairly large area of enhanced convection (stormy weather) that can help kick off tropical development. We need some kind of seed system to get tropical development started and the MJO helps with this. The MJO, and another phenomenon called a Convectively Coupled Kelvin Wave (CCKW, don't worry I really don't understand it either) are responsible for the uptick in activity to our west. This is important because when we see development start in the East Pacific it can give us an idea what may be coming our way in the Caribbean and Atlantic in a few weeks if the MJO continues to the east.

Right now a ton of dust and dry sinking air from the Sahara Desert are preventing tropical development in the Atlantic but it looks like this may subside in the coming weeks. This MJO event doesn't look like it'll be particularly strong when it moves into the Atlantic but it may be enough to kick off tropical development if the dust and dry air settle down. However, if the dust and dry air continue to stream across the Atlantic from the Sahara we probably won't see any development no matter what the MJO does.

Everything continues to point to an active season with above average activity. Several people have mentioned that the tropical wave train coming off Africa is more active than usual for this time of year. Most of the waves are a bit too far south to develop just yet but the signs are there that things could get busy soon. One of the MJO models is forecasting a very active phase of the MJO in the Atlantic for the end of July. I'm not sure how well the models do for the MJO that far out but if that holds there could be trouble in a month.

Another worrisome trend is that steering patterns are such that more storms than normal may get steered toward the US instead of out to sea if the pattern holds. There can be active seasons with an out to sea steering pattern that leads to only a few landfalls. Right now that doesn't look to be the case.

That's all I have for today. We'll just have to keep watching as we get deeper into the season.

Have a great week.

Chris

Weather Nerd Corner
I thought I'd take the opportunity to talk about teleconnections since I brought it up today. "The term "teleconnection pattern" refers to a recurring and persistent, large-scale pattern of pressure and circulation anomalies that spans vast geographical areas." See here for way too much info: https://www.cpc.ncep.noaa.gov/data/teledoc/teleintro.shtml. In much simpler words, just think of a teleconnection as a recurring pattern that we can use to predict the weather when we see that it is occurring or might occur. It is sort of the meteorological equivalent of history repeating itself. The ENSO (El Nino Southern Oscillation) is the most well known teleconnection, and one you've surely heard of.

Severe Weather Possible Tomorrow in AL

June 7, 2020

The chance for more severe weather associated with Cristobal continues tomorrow and now includes most of Alabama. The SPC has most of the state in a marginal risk area (level 1 out of 5) for severe weather with the west-central portion in a slight risk area (level 2 out of 5). Tornadoes and damaging wind are both possible. I'm not sure on timing but I think the threat will increase once daytime heating has occurred in the late morning into the afternoon and early evening.

Stay safe and have a good week.

Chris

Tornado Risk Today and Tonight

June 6, 2020

The Storm Prediction Center has placed most of Florida along the Gulf Coast in a marginal risk area for severe weather for today. This area has a 2% chance of tornadoes. For the northern Gulf Coast the greatest threat will be late this evening into early Sunday.

 
For tomorrow, the risk area shifts to the west, with only the western most portion of the Florida Panhandle and the Alabama Panhandle in the risk area.

Without going into too much detail, tornadoes spawned by tropical weather along the coast are a little different than typical supercell tornadoes. In tropical cyclones, most often in the east or northeast feeder bands, mini-supercells (short rotating storms) will form over open water sometimes producing waterspouts. When these storms come ashore the interaction with land can create a tornado very quickly, almost right as the storm crosses the coast but sometime farther inland. Keep an eye out for Special Marine Warnings (SMWs) just offshore of your location. The NWS doesn't issue tornado warnings over water, they use SMWs instead. Often the text of the warning will state that waterspouts or strong winds are present with the storm. Not all tornado producing storms over land will have SMW associated with them over the water, but I would pay special attention to any warned storms over water and be prepared when they come ashore.

Keep alert for changing weather conditions, Have a good weekend and stay safe.

Chris

TD Cristobal Update

June 5, 2020

The forecast for Cristobal has been pretty consistent for the past several days. The official NHC track is below. In their discussion, the NHC is forecasting that due to an expected asymmetric structure at landfall that the highest winds, heaviest rain, and strongest storm surge will likely be well away from and east of the center.

Even though this is expected to "just" be a tropical storm at landfall, there are still hazards to be aware of. For most of us to the east and away from the landfall point, flooding rainfall is the main hazard. The 3 and 5 day rainfall forecasts are below. Keep in mind that isolated locations may receive double this amount.

Storm surge and coastal flooding will also be a hazard. The Tallahassee NWS office is expecting moderate coastal flooding along the Big Bend region of Florida and minor coastal flooding elsewhere along the Florida Panhandle. There will also be storm surge concerns to the west. The NHC has issued a storm surge watch but I haven't been able to find a map for the watch locations. The locations are: 1) Indian Pass to Arepika Florida, 2) Grand Isle Louisiana to Ocean Springs Mississippi, and 3) Lake Borgne. Peak surge is expected to be during the day on Sunday, below is the expect peak storm surge range.

Severe weather is also a threat. The SPC is indicating a marginal risk area on Day 3 (Sunday) for the coast due to the threat of isolated tornadoes, with a 5% chance of severe weather in the dark green shaded region.

I hope you all have a good Friday and a good weekend.

Chris

Update on TS Cristobal and Severe WX Possible Tomorrow Up North

June 3, 2020

Here is the 7 a.m. CDT update from the NHC on Cristobal. A few notes on the forecast are below for those that are interested as well as a note on the possibility for severe weather tomorrow in northern AL and TN.

The NHC is showing a tropical storm impact to Louisiana early next week and that is the most likely scenario but there is still some uncertainty. The NHC cone captures the range of track possibilities well so I won't go into that. I will say that Levi Cowan (TropicalTidbits) mentioned last night that timing could vary by as much as 24 hours. Where the storm ends up in the current cone has to do with timing as well as the storm's strength and other factors that cause normal forecast variability.

Here are a few comments on what is causing the uncertainty and how that may affect the forecast. At some point tomorrow and through the weekend steering influences will start to pull weather from the southern Gulf northward. What this "weather" is depends on how far inland Cristobal goes over Mexico today and tomorrow. Some models have been consistently showing Cristobal going far enough inland to completely dissipate. What they then show is the whole monsoon gyre over southern Mexico and Central America being pulled north on Friday and Saturday potentially spawning another system over the open Gulf. If this were to happen and another full-fledged tropical cyclone were to form it would probably be named Dolly. I won't go into too much detail but both the GFS and ECMWF show this occurring to different degrees with the GFS showing complete dissipation and the Euro keeping Cristobal relatively intact. The GFS and ECMWF ensemble models (GEFS and EPS) show a range of possibilities from Cristobal staying completely offshore before being pulled north to completely dissipating over Mexico. It seems like some kind of interaction with land that will weaken the storm, but not cause dissipation, is most likely and this is what the NHC is forecasting with the official track just inland enough to weaken Cristobal to a tropical depression before it reenters the Gulf.

The degree of land interaction will influence the intensity of the storm as it moves north. Conditions are favorable for intensification right now but will become more hostile over the next few days due to increasing wind shear and dry air intrusion. If Cristobal weakens a lot over land then it won't strengthen as much when it crosses the Gulf and vice versa. So we could be looking at anything from a rainy messy system without a name to a category 1 hurricane. Right now a tropical storm looks most likely and this is what the NHC forecast shows.


Severe Weather Possibility Tomorrow

Turning to severe weather, there is a marginal chance (1 on a scale of 1 to 5) of severe weather tomorrow for northern Alabama and Tennessee. Damaging wind and hail are the main threats, with the hail threat being only in Tennessee. Timing looks to be in the afternoon

That's all I have today. I don't think we're looking at a major event from Cristobal but it's something to keep an eye on. Have a great rest of the week.

Chris

Tropical Depression Three Forms in the Gulf

June 1, 2020

Well that didn't take long... It's the first day of hurricane season and as of the 4 p.m. CDT update from the NHC the system that was Tropical Storm Amanda in the Pacific has been designated Tropical Depression Three in the Bay of Campeche in the southern Gulf. You can see the official 5 day forecast track below. This storm will like become Tropical Storm Christobal tomorrow. You'll notice that it's not really in a hurry to get anywhere. This is one of the main factors that is causing a lot of uncertainty in the forecast right now. Don't take this as a forecast, but beyond the 5 day mark a landfall somewhere from Louisiana to Texas on Sunday or Monday as a tropical storm or maybe even a hurricane looks to be the most likely scenario at this point. My guess is that it'll be the middle of the week or even Thursday or Friday before forecast confidence solidifies.

I'll keep you updated as the week progresses.

Chris