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:
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.
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