Thursday, February 15, 2024

A Little Rain Tomorrow Night/Turning Cold Again With Clearing Skies This Weekend

FORECAST:

Friday (High 65, Low 44): Becoming breezy with increasing clouds during the day. Showers are likely at night, with gusty winds at times. 

Saturday (High 44, Low 33): Variably cloudy. Turning cold and staying breezy.

Sunday (High 50, Low 23): Sunny. Cold. 

EXTENDED OUTLOOK:

President's Day (High 56, Low 24): Sunny. 

Tuesday (High 61, Low 32): Mostly sunny.

Wednesday (High 67, Low 37): Mostly sunny.

Thursday (High 69, Low 50): Increasing clouds with a 40% chance of rain/thunderstorms. 

PRONÓSTICO:

Viernes (Máxima 65, Mínima 44): Se volverá ventoso y aumentarán las nubes durante el día. Es probable que haya lluvias por la noche, con ráfagas de viento en ocasiones.

Sábado (Máxima 44, Mínima 33): Variablemente nublado. Pasar frío y mantenerse ventoso.

Domingo (Máxima 50, Mínima 23): Soleado. Frío.

PERSPECTIVA EXTENDIDA:

Día del Presidente (Máxima 56, Mínima 24): Soleado.

Martes (Máxima 61, Mínima 32): Mayormente soleado.

Miércoles (Máxima 67, Mínima 37): Mayormente soleado.

Jueves (Máxima 69, Mínima 50): Nubes en aumento con un 40 % de probabilidad de lluvia/tormentas eléctricas.

NOTES:

The National Weather Service in Birmingham has scheduled SKYWARN classes for the Spring season. Whether the class is in-person or online, these are free, and you don't have to know anything about the weather going in; that's the whole point of the class, to educate people so they know what they're looking at when it comes to storms. If you've never taken one of these, I strongly recommend it. 

A favorite radio station of mine to catch weather forecasts (when I'm not online as much) and to hear good music recently suffered a bizarre and petty theft. If you would like to help them get back on the air, here is where you can drop a dollar in their bucket, or simply stop by to offer some encouraging words. 

And I decided to try a Spanish version of the forecast one more time just for the hell of it, since I'm not planning on being here for at least another week. 

DISCUSSION:






At 1 PM, latest observations (though granted they were about half an hour ago) show fair, sunny skies in Cullman. The temperature is 64 degrees. The dewpoint-temperature is 39 degrees, making the relative humidity 40%. Winds are from the West at 8 miles per hour. The pressure is 30.15 inches and falling slowly.

The Jasper observations are from only about five minutes ago. Skies are also fair there. The temperature id 66 degrees with a dewpoint of 43 degrees. That makes for a relative humidity of 43%. Winds are out of the West at 9 miles per hour. The pressure is 30.15 inches and falling. 

Haleyville is sunny and 63 degrees, with a dewpoint of 40, making the relative humidity 43%. It is more blustery there, winds from the Southwest sustained at 10 miles per hour, with higher gusts up to 18 mph. The pressure is 30.19 inches/1021.5 millibars and falling. By the way, millibars are what they use on the weather maps. (See Figure 4. Not the leglock, but a 4-dimensional view of the weather above.)

Notice the isobars connecting lines of Low pressure up around the Great Lakes. For Slow Joe in the back of the room, that's what the L stands for. (Or for people who have never been taught any of this stuff.) Here in the Southeast, that H stands for the higher pressure that we have around here. If you see a local observation of 30.19 inches/1021.5 millibars nearby, it is a safe bet that a weather map will have an H for a high pressure system somewhere close to you. 

Anyway let's look at some other observations around the area: Fort Payne is sunny and 64 with winds gusting up to 17 from the Southwest. Decatur is sunny and 66 with winds gusting up to 20 mph, out of the West there. Huntsville is mostly sunny and 67, Southwest winds gusting up to 16 mph, sustained at 9. Muscle Shoals has sunny skies and 67, West wind at 14 mph. Tupelo is sunny and 67, not as breezy, Southwest winds at 8 mph. Memphis not very breezy either, mostly sunny and 62. Nashville is mostly cloudy and 65 degrees, West winds there at 8 mph but with gusts all the way up to 24 miles per hour. So I guess up there, it's a good day to walk around and find a good honky-tonk to stop your hair from blowing around. But is there really a bad day to go in somewhere for a bite to eat and to enjoy the music up there . . . ?




Sometimes the weekend takes forever to get here, but for some reason, this week feels like it flew by, and here we are with another weekend looming. And we have another cold front going to pass through the region this weekend. This front is causing some mixed winter mischief in mainly the Ohio Valley and Great Lakes region but actually some in the mountains of far Eastern Tennessee as well. Arkansas and Missouri also having a wintry mix today. As you get up into Canada and New England, this system is producing a lot of snow. And this front has a long reach; we also have snow in the Midwest, places like Iowa, stretching all the way back into the Rocky Mountains and into Montana, parts of the Pacific Northwest. And then as you get down toward Northern California, Las Vegas, into Utah, odds are you'll see more of a wintry mix than just snow. 



Tomorrow during the day, or at least most of the rain, I think rain chances around here will be slim to none. Looking at raw model guidance here, the GFS. It should be a day of increasing clouds, overall maybe slightly more clouds than sunshine. The High should be in the mid-60's, about 65. The Low should rebound to at least the lower 40's but maybe more toward mid-40's, so about 43-44. I forgot to check the Low for Cullman above when I was looking at observations, so I went and checked now. It was 34 degrees this morning. So this will be a jump of about ten degrees as we have less radiational cooling and more moisture tonight, meaning Thursday night. Today's High should get up to about 67 over the next few hours before we lose the daylight and things start to cool. 


Model guidance has trended strongly in favor of the rain being an overnight thing. Here we are at midnight between Friday and Saturday. Rain is likely during the overnight hours. Should not be the heavier rains like we had last weekend (or the weekend before). These are generally going to be light rain showers in the night hours as Friday becomes Saturday. 



We are in for a shot of cold air as that front pushes down to the Gulf Coast by midday Saturday. It's going to be variably cloudy with a clearing trend, but the clearing may be slow to happen, where the clouds come and go throughout the day. And by the way, tomorrow night and Saturday do look breezy, typical when we have a low pressure system and cold front coming through. We'll start Saturday down in the lower 30's, maybe not quite to freezing because of the leftover moisture in the air, but then we will struggle to even get to about 45 for the afternoon High, probably only make it into the lower 40's. So a cold, blustery day Saturday, with a lot of clouds hanging around but likely several peeks of sunshine for most of us too. 



After that, the high pressure system parked out in Texas will bring us clear skies and cold temperatures. For Sunday, we will start out in the lower 20's at daybreak, and then only warm up to about 50 degrees in the afternoon. And there may not be a cloud in the sky. So as mentioned in previous blog posts, we will continue to have cold snaps at times before Spring gets established next month and into April. Even if you see some model guidance or climate guidance saying temperatures could go below average, it doesn't have to be anything drastic like we saw in the middle of January. This is a routine cold snap like we get at some point just about every year. But do be aware that Saturday night and Sunday morning is going to be very cold. 



That high pressure gets moving through our region on Monday. Which is George Washington's birthday, so a national holiday. We'll see sunny skies again and a High rebounding to the upper 50's under that abundant sunshine. Still great radiational cooling overnight, and we'll see mid-20's for the Low temperature. 



If you pay attention to the forecast upper-air map above and the surface map below it, you can see where there is a weak shortwave trough producing some precipitation mainly over the Ohio Valley on Tuesday. At this point, see no reason to reintroduce rain chances in the Tennessee Valley, North Alabama or Southern Middle Tennessee. Our rain chances should stay about 10% or less. Which is just not worth including in a forecast. Will mention a slight increase in cloud cover, but overall a mostly sunny day, High in the lower 60's, Low in the lower 30's. 



On Wednesday the high pressure system moves to around the Florida Bend. Our skies will stay mostly sunny with a High rebounding to the upper 60's and the Low to about 40, but perhaps just upper 30's. 



On Thursday of next week we have another cold front knocking on our door via the GFS. 


As is often the case, the ECMWF has a slower, more conservative approach to bringing the next front in there. 


The Weather Prediction Center has a pretty good general illustration of how it may play out. A 30% chance of rain seems reasonable here, and the High may approach 70, the Low near 50. So we could see some thunderstorms in the mix. 

And this time, I'm going to take a look at days 8-10, although I may not include them in the official forecast up top. Depends on how clear the forecast is for that tea leaves period. 

And you know what, before I even show any graphics. I'm just going to drop it. There are differences in timing and coverage of rain between the GFS and ECMWF this next Thursday night and Friday. And I just don't think it's worth the effort trying to make a forecast that is probably going to be no good anyway. Sometimes you can do a 10-Day-Outlook, I've decided, but even at best, you are looking at general trends, can't rely on specific High/Low temperatures at that range, and definitely have to fall back on probabilities. Like if I said rain was likely next Thursday night, I would be wrong for that, pretending a level of certainty and confidence in the long-range which simply does not exist with the current state of the science. But hey, there was a time people thought there would never be accurate 7-Day Forecasts. A lot of progress has been made. 

A lot of people forget that during the big 2011 tornado outbreak, in April, we didn't have dual-polarization radar, except for the ARMOR radar in Huntsville. So things have come a long way over even the last decade. For now, I don't feel right about doing 10-Day Forecasts all that often. People make plans based on forecasts. 


Rainfall amounts for this forecast period are expected to remain light, only up to about a quarter-inch for North Alabama and up to about a half-inch for Southern Middle Tennessee. 

By the way, yes, much of Tennessee could see a wintry mix of sleet and snowflakes tomorrow night as the cold front blows through and there is still precipitation falling. However, even along the Cumberland Plateau, the really high elevations, not much more than a dusting is expected. So no winter weather advisories or warnings are expected even up across the Tennessee state line. It is always wise to look out for any slick spots on the roads after you've had a lot of rain and then some temperatures around freezing. But as far as any significant travel problems, no, not expected. 

None of the weather for this forecast period looks high-impact. 

And I'm going to take a long break from this blog. It's not like I get paid for it, but lately I did get a few notes from people who said they appreciated it, enjoyed reading. So I may keep it up as time allows when we get into severe weather season next couple months. 


And I modified the forecast slightly up top from what I discussed beforehand. I take my time and use some intuition before the final product. The discussion is really my way of talking it out before committing to a forecast. 

3:39 pm Editing discussion for some typos I made in a hurry.

I meant to say not expecting any significant travel issues in Tennessee tomorrow night but somehow wrote "many." Also got the days mixed up when explaining that a 10 Day outlook looked like it would be junk here. 

Not fixing this one, but I also made a slight mistake by saying I was showing a four-dimensional look at the current weather. Usually I do: Radar, satellite, surface map, upper-air map. But since the only precipitation in the region was light rain in South Texas, I skipped it and replaced radar this time with a regional view of the visible satellite imagery from the Storm Prediction Center's mesoanalysis page.

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