Sunday, February 25, 2024

Warm and Sunny Tomorrow, Then Clouds and Rain/Storms Return by Wednesday

Today (High 66): Sunny. Mild.

Tonight (Low 46): Clear. Cool.

Tomorrow (High 71): Mostly sunny. Warmer and becoming breezy.

Tuesday (High 75, Low 57): Partly to mostly cloudy. Warm and windy.

Wednesday (High 72, Low 61): Rainy and windy. Isolated thunderstorms are possible, and some could be strong.

Thursday (High 53, Low 32): Mostly sunny.

Friday (High 56, Low 38): Partly to mostly cloudy with a 40% chance of showers. 

Saturday (High 61, Low 43): Partly to mostly cloudy with a 30% chance of showers.

Sunday (High 65, Low 46): Partly cloudy with a 20% chance of showers.

Here at 11:30 AM latest observations show sunny skies in Cullman, as does looking out the window. The temperature is 57 degrees. The dewpoint is 28, making the relative humidity 33%. Winds are from the South at 9 miles per hour, with gusts up to 17 mph. The pressure is 30.15 inches and falling slowly.

Jasper also has sunny skies. It is 59 degrees there with a dewpoint of 34, so a relative humidity of 39%. Winds are variable at 7 mph. Whenever a specific direction was observed with consistency this morning, they were out of the Southeast. The pressure is 30.16 inches and falling slowly. Sometimes I wonder how to record such things, as a lot of times in this sort of weather pattern, the pressure waffles up and down a lot throughout a day or two. And I might should just go ahead and call it steady. But it is falling slowly for the moment. 

I forgot to mention this above, but the Low for Cullman was 30 degrees. And now the Low for Jasper was also 28. I believe I forecast 30, so we got a little colder than expected, dipping into the upper 20's. 

And Haleyville actually got down to 27 degrees this morning. They are currently sunny with 58 degrees. The dewpoint is 31, making the relative humidity 36%. Winds are South at 10 mph. The pressure is 30.16 inches/1020.6 millibars and steady. It is clearly waffling up and down to the point that I'm just going to call it steady-enough. 


The weather does have nuances though even on days that seem to be clear-cut. We have some light showers moving through Central and Eastern Tennessee right now, even though the forecast verified for North Alabama to stay dry as a bone. 


Since I can't find one particular regional radar image that shows the best view of that precipitation, we'll just look at the whole country this time. And overall rain is scarce across the great fruited plain. 



Somebody correct me on this if I have it wrong, but I think these clouds and showers are probably the result of air rising up the mountains and condensing into very light rain. Tennessee has a lot of higher elevations even before you get over into the Smoky Mountains, and I know a lot of people don't have basements up there because the ground is so rocky and tough to dig through. 


There is nothing on the synoptic scale that would make me think we'd have even residual showers form the last system, which is now centered down close to Miami. High pressure is firmly in control of our region's weather now. 

Well, looking at the movement of that front over the past 24 hours, I guess those showers could be residual moisture that lingered behind it, but I bet the elevations up there played a factor too. 




Today is a day the pattern is shifting. The high pressure is moving off to our East but staying in control. It is now looking like while our skies stay sunny, we'll only warm up to about 65-66 degrees this afternoon. 

Tomorrow as a winter storm gets ready to unfold in the Rocky Mountains and nearby, our southerly winds will bring a few clouds back and continue our warming trend. We'll start the day about 45-46 degrees and warm into about the 70-72 range. And the winds will be picking up some, it'll get sort of breezy, at least toward the evening. 

Between the GFS, NAM, and ECMWF, there is still some suggestion of isolated rain being possible on Tuesday, at least for Southern Middle Tennessee. And you see that reflected in the WPC graphics above. They may see some severe thunderstorms up in Illinois, Indiana, Eastern Missouri, on the warm side of that front bringing snow and ice to the Great Lakes region and as mentioned before, stretching back through the Rockies. We will be clouding up and warming up on Tuesday, a High near 75, mid-70's anyway, the Low in about the 56-58 range. It will get windy especially in the evening and then Tuesday night, South winds gusting easily up to 20-30 mph. 


Wednesday continues to be interesting. The Storm Prediction Center has taken us out of any severe weather risk then because of model trends making it look like the air will stay too stable and capped for much in the way of storms to get going. It is definitely going to be a rainy and windy day, and with a temperature still in the lower 70's and a continental polar airmass on the other side of this front, I am not sure I'm comfortable taking the mention of strong storm potential out of the forecast completely. But the risk of severe weather is looking very low with this system now, which frankly, I do not mind. We had enough high-impact weather with that ice storm back in January to do me a while. 



This event is now within the reach of the NAM, and it is showing what the GFS was a day or two ago, same basic theme, except that the unstable air looks even more limited. And it looks like there is a strong cap on the atmosphere preventing warm air parcels from rising. On the forecast sounding (from Southern part of Cullman County, around Bremen or Dodge City), you can see the temperature line (green) wave strongly off course to the left, and that is an inversion layer of warm air that would only be overcome if we were able to get a lot of daytime heating ahead of the rain and storms. Which it doesn't look like we can. This looks like a marginal setup for severe thunderstorms, with damaging winds being the main threat and storms likely to stay more elevated. I know that it says "weak tornado" under hazard type, but that is automatically generated. A human forecaster can notice that even with Helicity values of 200-300 or greater, the directional shear is not great as you move up through the atmosphere. The hodograph that is projected does not look like you'd want to see for any kind of organized tornado threat. If we get any thunderstorms that become severe with this, looks like that activity will stay isolated. 

For most of us, we're probably just looking at a rainy, windy day, with a few thunderstorms possible in the mix. An isolated stronger storm is possible, and we could see something go severe somewhere, but the risk is very low. 

If that isn't enough to think about, on the back side of this, some mix of snow is possible as we quickly transition to a continental polar airmass again. If that happens, it will likely be in Northeast Alabama where we have so many mountains and Southern Middle Tennessee and of course the mountains of the Cumberland Plateau up there. But the most they are expecting to see even up in the mountains of TN is a tenth of an inch accumulation and are not expecting any travel problems from it. So I wouldn't worry about it down here either. 

Mainly a rainy, windy day with some thunder and lightning involved, where we were fortunate not to get a nastier setup, considering the time of year. It is still always a good idea to be prepared in case a thunderstorm becomes severe. Try to go to a small central room or hallway on the lowest floor of a sturdy house until the potential for damaging wind has passed if you go under a warning. 


Taking the rain chances out for Thursday. The GFS and ECMWF both keep trending dry. Might see an isolated snow shower Thursday morning (or Wednesday night) as mentioned above, but not expecting any impact even if that happens. We should start the day around freezing and only warm to the lower 50's, with skies turning mostly sunny again. 


Then on Friday there is some suggestion of the moisture North of that front surging back into our region, although the ECMWF advertises this much more than the GFS. Going to reintroduce a 30-40% chance of rain here, a High in mid-to-upper-50's and a Low in the upper 30's or maybe about 40. The latest model output statistics for Cullman from the GFS shows 39. Or no, wait, that is for Haleyville. The Cullman one is not available and hasn't been for a long time. We work with what we have to.



The model madness continues into the weekend with the GFS keeping us dry and the ECMWF keeping some moisture and rain around. Best thing for now is to taper the rain chances down from 40% Friday to 30% Saturday to 20% Sunday. High should be 60 or so Saturday, Low rebounding into lower 40's. Then Sunday we might make it to about the mid-60's, Low starting the day in about the mid-40's.

And the Storm Prediction Center took us out of any severe weather outlook for Wednesday because model trends kept going against it. There are no areas of the country outlooked for severe thunderstorms on Wednesday as of right now. They might reintroduce marginal probabilities tomorrow or Tuesday if there is enough evidence to justify it. 


Our rainfall totals for this forecast period will average up to about a half-inch. 

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