Wednesday, November 27, 2024

Rain and Maybe Some Storms Late Tonight/Tomorrow Morning, Then Clearing and Turning Really Cold For a While

FORECAST:

Today (High 64): Partly cloudy. Breezy at times.

Tonight (Low 50): Rain likely as we approach midnight, and a few thunderstorms are possible. A few thunderstorms could become severe. 

Thanksgiving (High 63): Rain likely with a few thunderstorms possible through the early morning - some could become severe. Then staying breezy and turning sharply colder through the afternoon and night hours. 

Friday (High 45, Low 32): Sunny. Cold and breezy. 

EXTENDED OUTLOOK:

Saturday (High 48, Low 23): Sunny. 

Sunday (High 46, Low 26): Mostly sunny.

Monday (High 42, Low 20): Sunny.

Tuesday (High 44, Low 22): Sunny.

READING TEA LEAVES:

Wednesday December 4 (High 49, Low 25): Mostly sunny.

Thursday December 5 (High 51, Low 29): Partly cloudy. 

Friday December 6 (High 53, Low 33): Partly cloudy with a 20% chance of showers.

PRONÓSTICO:

Hoy (Máxima 64): Parcialmente nublado. Ventoso a veces.

Esta Noche (Mínima 50): Probabilidad de lluvia a medida que nos acercamos a la medianoche y algunas tormentas eléctricas son posibles. Algunas tormentas eléctricas podrían volverse severas.

Día de Acción de Gracias (Máxima 63): Probabilidad de lluvia con algunas tormentas eléctricas posibles durante la madrugada; algunas podrían volverse severas. Luego, se mantendrá ventoso y se tornará mucho más frío durante la tarde y la noche.

Viernes (Máxima 45, Mínima 32): Soleado. Frío y ventoso.

PERSPECTIVA EXTENDIDA:

Sábado (Máxima 48, Mínima 23): Soleado.

Domingo (Máxima 46, Mínima 26): Mayormente soleado.

Lunes (Máxima 42, Mínima 20): Soleado.

Martes (Máxima 44, Mínima 22): Soleado.

LEYENDO LAS HOJAS DE TÉ:

Miércoles 4 de Diciembre (Máxima 49, Mínima 25): Mayormente soleado.

Jueves 5 de Diciembre (Máxima 51, Mínima 29): Parcialmente nublado.

Viernes 6 de Diciembre (Máxima 53, Mínima 33): Parcialmente nublado con un 20 % de probabilidad de lluvias.

NOTES:

The risk for severe weather tonight/tomorrow morning is pretty low, but it still is good to make sure your severe weather safety plan is ready to go just in case. 

The National Weather Service in Nashville is still offering these free Weather 101 classes through December. If you know anybody who would like to learn more about the weather and isn't already in college for it, please consider clueing them in that these exist. They are great classes with great instructors who love to answer questions at the end. 

DISCUSSION:

At 7:30 AM skies are sunny in Cullman. The temperature is 43 degrees. The dewpoint is also 43 degrees, making the relative humidity 100%. Winds are calm. The pressure is 30.03 inches and steady. The Low temperature this morning was 36. 

Skies are fair in Jasper as well, but some residual fog is limiting the visibility to 8 miles. The temperature is 37 degrees with a dewpoint of 36 degrees, making the relative humidity 93%. For any nitpickers, technically the temperature is 37.4 degrees, with a dewpoint of 35.6. But for all the things I've forgotten from school, I do remember how to round to the nearest whole number. And that's what I do here. Because if I tell people temperatures down to a tenth of a degree, they're going to tune out right away . . . Winds are calm in Jasper, and the barometric pressure is 30.04 inches and steady. 

It is foggy in Haleyville, reducing the visibility to 6 miles. It is 33 degrees, same dewpoint, 100% relative humidity. Winds are calm. Pressure is 30.03 inches/993.2 millibars (Cullman and Jasper don't show millibars, and I don't feel like calculating it every single time) and holding fairly steady. 

It is mostly cloudy and 39 degrees in Huntsville with visibility of 9 miles. Nashville is mostly cloudy and 35 degrees, but like Cullman, they are enjoying a perfect 10 miles of visibility. 






We are in between systems in the Tennessee Valley. Tonight and tomorrow are our only shot at rain for a while and our only moderate temperatures for a while. Much of tomorrow will turn cold, certainly by afternoon. And then some serious cold over the weekend and into next week. 




It is kind of a messy setup for much of the country today when a lot of people are travelling, lots of places getting rain and even a little bit of a wintry mix. Then from Montana, the Dakotas, into Minnesota, we've got snow potential. The main problems spots look to be in Colorado where heavy snow is possible and in North Central Kansas/South Central Nebraska, where freezing rain could become a problem. 

And as the weather systems move along, they'll be clear out in Colorado by Friday, with snow moving into the Midwest. And we'll be clear and cold here again. 

Overall Thanksgiving looks all right for most people across the country, but we are in one of those zones where we do have to keep an eye on things, strong storm potential in the dark hours of tomorrow morning. 



Today is just going to be partly cloudy and breezy around here, southerly breeze, a High near 64. 


At Midnight going into tomorrow morning, the GFS shows rain moving in here, maybe some thunderstorms. We have good agreement from the NAM and ECMWF as far as the position of the surface Low pressure now. It is not in the best position for severe thunderstorms, but this is a scenario we have to keep an eye on. The Low tonight should get down to about 50. 



The GFS has come around to the other models' forecast of the rain being out of here by Noon tomorrow. So the window for rain and maybe some strong thunderstorms is between about 11 PM tonight to about 8 AM tomorrow morning. Rain will be tapering off after that, and by the afternoon hours, we'll just be feeling that shift in the weather with the cold air from the front moving in, temperatures falling through the 50's and then the 40's. 

By the way, our High tomorrow should come in the morning, one of those weird days. Technically our Low for tomorrow should be later in the night, before we hit Midnight and change over to Friday. But to avoid confusing people, going to just list the Low tomorrow as the lowest we should get overnight/in the morning. Up at the top in an official-looking forecast, people just want the bullet points in the simplest terms. So that's how we'll do it here. If you care to read down this far, you get the details. Estimating a High of 60-63 tomorrow. 



We start to get the seriously cold air on Friday, with sunny skies but a High only making it to about 45-46 degrees, the morning Low down around freezing. And it'll still be breezy, with winds having shifted back to the North/Northwest, gusts up to 10-15 mph at times. Could see some frost in the morning. 



But that's only the beginning. We'll see widespread frost or even a hard freeze Saturday morning, the Low in Cullman expected to be in the lower 20's and then only warming to the upper 40's in the afternoon despite plenty of sunshine. 

This is the day of the Alabama/Auburn game, and while I'm not going to waste time putting an official forecast for that up top (the people I used to watch football with are dead . . . the few still alive, I have no opportunity to sit and enjoy a game with anymore, and have a hard time even getting on the phone . . . so forget it . . . Nick Saban is retired, and I could not care any less what's going on with football), but it looks sunny with temperatures dropping through the 40's during the game. If it were to go into overtime, might dip into upper 30's before the game is over. I don't think hardcore fans let the weather stop them though, and everybody should know by now it's going to be cold. 



We get a weak/dry reinforcing cold front on Sunday with mostly sunny skies and a High in mid-40's, Low in mid-20's. 



And the arctic blast continues for Monday, when that reinforcing front brings us to about 20 degrees in the morning, only warming to the lower 40's in the afternoon despite plenty of sunshine. Winter is coming in with a vengeance this year apparently, despite how warm we were through a lot of the Fall months. Sunday will be the first day of December, and here Monday is the 2nd. This is the kind of weather that could turn somebody into a popsicle if they get caught out all night. 



Tuesday looks about the same, sunny skies and a Low in the lower 20's, a High in the mid-40's. 



Looks like we'll stay mostly sunny Wednesday and Thursday of next week, if you want to peek into the land of reading tea leaves, with Highs getting back to 50 or so, Lows rebounding to 30 or so. 

And then on Friday it looks like a low chance of isolated rain may come back, with a High in the lower 50's, Low down around freezing or just above. 

These really long-range forecasts are not always the most reliable, but this time, I'm going to try one, because the extended period looks quiet, mainly just trying to figure out which days are colder than others and if we see any cloud cover or just totally clear sunny skies. When the pattern is that calm, I don't mind taking a gamble. I expect readers to be smart enough to figure out that you can't take every single detail to the bank 10 days in advance. 


Rainfall totals will average about one tenth of an inch to a quarter of an inch. Tonight/tomorrow morning is really our only shot at meaningful rain for the next week or so. We are in for a stretch of clear skies and serious cold. 


If you'd like to support these weather efforts and see them more often, please consider dropping a dollar in my bucket. 

MESOSCALE DISCUSSION:

The NAM still is not showing any real chances for severe weather in North Alabama with this system. And usually it is the most aggressive model for those sorts of things. 



The SREF is showing marginal instability where CAPE might approach 500 j/kg for some of us. These graphics are valid at 3 AM tomorrow morning. And the directional wind shear is not overwhelming for this time of year, but it's also enough to respect. 

Started to show the RAP, but frankly, it is messy and doesn't really add to what the SREF is showing. At times I wonder if we're going to see any problems out of this system at all, might just be a cool rain. 



But taking all these bits of guidance together with how the pattern has looked over the last several days, and just knowing the climatology around here, we do have a marginal threat for severe thunderstorms late tonight through tomorrow morning, storms that could produce damaging winds, large hail (probably up to the size of a quarter), and also maybe an isolated tornado somewhere in this broad region - although the tornado risk does look very low with this. 



The top graphic from the SPC is through 6 AM tomorrow, and the bottom graphic is after 6 AM tomorrow. So our risk in North Alabama is from late tonight (close to midnight) through about daybreak tomorrow morning. The chance of seeing any thunderstorms become severe is low, and if that happens, the severe thunderstorms should stay isolated, with most places just getting a cool rain. But sometimes it pays to respect even these really low-end threats, since any severe storm is a significant event for whoever it hits directly. It might not make huge headlines if a tree falls on someone's home (or vehicle), but it's a big deal to the person it happens to, and especially if it happens at a holiday when families are getting together. So this is one of those deals where we might get by without any problems, but I'd rather people play it safe. 

And that means having a way to get warnings overnight. At least have Wireless Emergency Alerts enabled on a cell phone, so it can wake somebody up if need be. Ideally you'd have a NOAA Weather Radio with battery backup. You can't rely on outdoor sirens while indoors overnight. That's never a good idea. 

And it also means being able to shelter quickly in a place that is not a mobile home. Any sturdy house or apartment where you can get to the ground floor, in the center part, away from windows, will do fine. But mobile homes are very vulnerable to severe thunderstorm winds, or especially if we did have the bad luck to get a tornado somewhere in the region, you can't really risk staying in a trailer during a tornado. 

So as low-risk as this setup is, I'm choosing to take it seriously just because it is a holiday and the dark hours of the night/morning. 

Hopefully we get by with few or no problems with storms, and I wish you a good time with your family or whoever you're fortunate enough to get to share a good meal and hopefully some warmth with. 

Tuesday, November 26, 2024

Wet and Possibly Stormy Tomorrow Night into Early Thanksgiving, Then Turning Seriously Cold

FORECAST:

Wednesday (High 65, Low 36): Breezy and cool with increasing clouds. Rain is likely late at night, and thunderstorms are also possible - a few of which could become severe. 

Thanksgiving (High 63, Low 49): Rain likely, mainly in the morning. Thunderstorms are also possible and could become severe where they are able to form. 

Friday (High 46, Low 33): Sunny and cold. Beware of rabid shoppers. 

EXTENDED OUTLOOK:

Saturday (High 48, Low 23): Sunny. 

Sunday (High 45, Low 26): Mostly sunny. 

Monday (High 42, Low 20): Sunny.

Tuesday (High 44, Low 22): Sunny. 

PRONÓSTICO:

Miércoles (Máxima 65, Mínima 36): Ventoso y fresco con nubosidad creciente. Es probable que llueva a altas horas de la noche y también es posible que haya tormentas eléctricas, algunas de las cuales podrían volverse severas.

Acción de Gracias (Máxima 63, Mínima 49): Probable lluvia, principalmente por la mañana. También es posible que haya tormentas eléctricas que podrían volverse severas donde se formen.

Viernes (Máxima 46, Mínima 33): Soleado y frío. Tenga cuidado con los compradores frenéticos.

PERSPECTIVA EXTENDIDA:

Sábado (Máxima 48, Mínima 23): Soleado.

Domingo (Máxima 45, Mínima 26): Mayormente soleado.

Lunes (Máxima 42, Mínima 20): Soleado.

Martes (Máxima 44, Mínima 22): Soleado.

NOTE:

The risk for severe thunderstorms is low tomorrow night into Thursday, but if you want to be on the safe side, here is a review of severe weather safety rules

DISCUSSION:




The weather is calm today behind last night's cold front, that brought us some rain. At 2 PM it is sunny in Cullman with a temperature of 55 degrees. The dewpoint-temperature is 41 degrees, making the relative humidity 59%. Winds are variable at 6 miles per hour, with higher gusts up to 15 mph. The pressure is 30.14 inches and steady. The Low this morning was 48 degrees. 

It is sunny and 59 degrees in Jasper. The dewpoint is 41, making the relative humidity 51%. Winds are variable at 5 mph with higher gusts to 12 mph. Pressure is 30.14 inches and steady at the moment. The Low in Jasper was 52 this morning. 

It is sunny and 57 in Haleyville. The dewpoint is 36, making the relative humidity 45%. Winds are calm. The pressure is 30.17 inches/997.6 millibars and falling slowly at the moment. Earlier in the day it showed a marked rising trend. It fluctuates throughout the day up and down sometimes. The Low temperature this morning was 48. 

Huntsville is mostly sunny and 57 degrees with a dewpoint of 38, making the relative humidity 49%. Winds are from the North at 9 mph. The pressure is 30.14 inches/1020.6 millibars and falling slowly. The Low this morning was 49. 

Nashville is partly cloudy and 51 degrees. The dewpoint is 29, making the relative humidity 43%. Winds are Northeast at 5 mph. The pressure is 30.19 inches/1022.3 millibars and falling slowly. The Low this morning was 40 degrees, or technically 39.9 degrees. I round to the whole number. 




The weather pattern remains dynamic, which is normal for late November. Much of the country will be dealing with a wintry mix tomorrow/tomorrow night, and places like Montana, Wyoming, Utah, and especially Colorado are likely to see some snow. They'll also see some snow in the Dakotas and Minnesota and up around the Great Lakes into Canada. And New England may see a wintry mix into Thanksgiving Day. 

Around here in the Southeast and Tennessee River Valley, we've got another front coming at us, so will see some rain and thunderstorm chances as early as tomorrow night lasting into at least the early parts of the day on Thursday, Thanksgiving Day. So let's look at the details. 



Tomorrow should be fine, during the day, just a breezy, cool day with a mix of sun and clouds. Could see some patchy fog and/or frost in the morning, starting the day about 35-36 degrees and warming to about 64-65 degrees in the afternoon. 


The GFS has come around to showing here at Midnight going into Thursday, the surface Low associated with this front being positioned in a reasonably favorable spot for us to have some concern for severe thunderstorms. If you followed the past few days, you know the models have been all over the place and not agreeing with each other, often not agreeing with themselves from one run to the next, as to where this Low will be. 


The NAM has it centered up in Kentucky instead of Tennessee. 


And the ECMWF is reasonably in line with the NAM guidance. 

Will discuss severe thunderstorm potential below the main forecast discussion, but the main thing I'm adjusting for this forecast is timing. Definitely including rain chances for Wednesday night, could see some rain move in before Midnight. 

I'm just going to say that rain is likely. The only question is how soon it starts to move in. I think some of us, at least in Northwest Alabama and parts of Tennessee, will see some rain before Midnight, so late tomorrow night. And there could be thunderstorms in there. We do have to watch in case any of these thunderstorms try to reach severe limits tomorrow night into Thursday. 



The GFS shows plenty of rain hanging around by Noon Thursday. 


The NAM has us in the clear by then, the line of rain and thunderstorms moving a lot faster. This mesoscale model tends to do well at this time range. 


And the other global model, the ECMWF (European . . . I forget what all the other letters stand for), favors this faster clearing out of the rain. 

If we see showers hanging around at Noon or after, I think they'll be very scattered in nature. Main threat of rain and storms is Thursday morning, a lot of it during the dark hours. And that's why I'm taking the threat for severe thunderstorms seriously, even though that threat is looking low. 

Thursday/Thanksgiving is also going to be a day when the High will come in the morning hours instead of the afternoon. By afternoon, that front will be blowing some colder air in here, and we'll be falling through the 50's and 40's and then 30's by the time we get into Thursday night. 

To avoid confusion in the official forecast I'll write up top, I'm going to use the morning "Low" for Thursday, which should be about 50 degrees. At the moment, I'm inclined to forecast a High of 63 Thursday, but I'll fine-tune that estimate after looking at everything, including the chance for any severe thunderstorms. It may need to be more like 60 degrees. Rain is likely, and some thunderstorms are possible. The chance for those thunderstorms becoming severe looks low, but the potential is still there. 



On Friday, a lot of fools will be running into each other shopping, but let's stay focused on the weather part today. It is looking sunny and cold, with a Low down near the freezing mark and a High in the mid-40's. 



 And the cold, dry air behind this front is really going to be our first taste of Winter. Saturday is the last day of November, and we'll be sunny again, a High in the upper 40's and the Low all the way down in the lower 20's. I try not to give too much advice on here, but please do what you need to do to stay warm Friday night into Saturday. And the cold isn't going to let up any time soon really. 



Thanks to a reinforcing cold front, we'll only get to the mid-40's on Sunday. The morning Low should be in the upper 20's because the extra shot of arctic air won't get here by Sunday morning, will wait until Sunday night. 



Monday will be sunny and quite cold with a High in the lower 40's and the Low near 20 degrees. This is coming in suddenly this year, and this is the kind of cold that can get dangerous, reminds me more of something I'd expect in January. Glad at least the daytime temperatures are above freezing. 

Sometimes our weather does go to extremes. We have some of the most interesting weather you'll find anywhere. 



Even by Tuesday, it looks like the High will only get up to about the mid-40's and the Low will stay in the lower 20's. 


Tomorrow night into Thursday looks like our only real shot at rain for this forecast period, and amounts are likely to stay under a half-inch, probably only up to a quarter of an inch on average. 

MESOSCALE DISCUSSION:

Well, the NAM is not showing any severe signals up this way, so I guess that saves the time of looking at it in any detail. 



The SREF is showing the best timing for severe being between Midnight and 3 AM early Thursday morning, but even then, it is going to be tough to realize even the baseline of about 500 j/kg of CAPE in North Alabama. 



But the wind shear does look pretty strong, including the low-level directional wind shear, Helicity values of 200 m2/s2 or more even down at the lowest kilometer. 



So if the dewpoints can make it up into the 60's and we have that marginal instability, we'll be looking at a low risk of a few isolated thunderstorms becoming severe in the region. 



And we could even see an isolated tornado somewhere in the region. The risk of that is very low, but it is not zero either. 

This will mainly be a threat for damaging thunderstorm winds and maybe some marginally severe hail (about quarter-sized), if we have a severe weather threat out of this. 




And that's what the Storm Prediction Center is forecasting. This is a marginal situation where most places will get by without any severe weather, but a few isolated storms may go severe. And it's happening at a bad time, the overnight/early morning hours. This outlook is valid until 6 AM Thursday. 



Then after about 6 AM Thursday, the risk shifts further to the South and East. Parts of Northeast Alabama may still have to keep an eye on things. 

Let's go ahead and zoom in to a more detailed graphic that is focused on North Alabama (and Southern Middle Tennessee).




And you can clearly see that this is a marginal risk level and really is not expected to affect Tennessee counties, just North and Central Alabama. Most of it will happen during the pre-dawn hours Thursday, if we get anything severe. 

The two main points to remember for this potential event are:

* Make sure you have a reliable way to get the warning, beyond an outdoor siren. At least have Wireless Emergency Alerts enabled on a cell phone, but ideally, have a NOAA Weather Radio on alert that will wake you up if need be. These can be lifesavers in some cases. 

* Be prepared to shelter in a sturdy house or other strong building. Do not stay in a mobile home during a Tornado Warning. I'd really rather people be in a sturdier structure if they can for a Severe Thunderstorm Warning. All it takes is one tree falling the wrong way . . . plus those homes, great as they can be to live in, are just not built to withstand severe winds. If you have the bad luck to get hit with even damaging straight-line winds directly in a mobile home, you stand a good chance of being injured . . . . perhaps seriously. So try to plan ahead so that tomorrow night/Thursday morning, you can take shelter in a sturdy structure of some kind. Just in case you do need to. 

And this is a setup where any severe weather would tend to hit fast and probably not last long. And like I say, the nature of the storms would be isolated. Most of us are probably just going to get a cool rain and a good breeze from this, but some places are likely to have thunderstorms. And a few isolated places within this broad risk area may get a severe thunderstorm. So I would prepare for that and have a healthy respect while keeping in mind that the risk is low. Hopefully you won't need your severe weather safety plan. But I believe in respecting even these low-risk setups. Whoever gets that storm or two that does some damage somewhere will be glad they had a reasonably safe place to go. 

And after that, we're just in for some serious cold for a while. But some of the days will be pleasant. And if you don't mind the cold, the skies are staying clear for a while, plenty of sunshine to soak up, just not as warm as we've been used to for a while.