Thursday, May 4, 2023

Warm, Unsettled Summerlike Pattern Sets Up This Weekend Through Next Week

(Forecast)

Friday (High 72, Low 53): Partly to mostly cloudy with periods of scattered showers and thunderstorms possible throughout the day and night. A few of the storms in the evening/night could be strong, or even reach severe limits.

Saturday (High 79, Low 58): Partly cloudy and somewhat muggy. Widely scattered showers and thunderstorms are possible.

Sunday (High 82, Low 61): Partly cloudy. Isolated showers and thunderstorms are possible.

(Extended Outlook)

Monday (High 81, Low 63): Partly to mostly cloudy with a 40% chance of showers and thunderstorms.

Tuesday (High 84, Low 62): Partly cloudy with a 30% chance of showers and thunderstorms.

Wednesday (High 86, Low 61): Partly cloudy with a 20% chance of showers and thunderstorms.

Thursday (High 87, Low 60): Partly to mostly sunny with a 20% chance of a shower or thunderstorm.

(Tea Leaves Territory)

Friday (High 86, Low 61): Partly cloudy with a 20% chance of showers/thunderstorms.

Saturday (High 85, Low 64): Partly to mostly cloudy with a 30% chance of showers/thunderstorms.

Sunday (High 86, Low 62): Partly cloudy with a 20% chance of showers/thunderstorms.

(Notes)

There are a handful of Weather101 classes left this month. Thanks to the National Weather Service in Nashville as always for hosting those, and by the way, they are free. 

(Discussion)

At 8 PM, we have clear skies, perfect visibility, and calm winds in Cullman. The temperature is 61 degrees. The dewpoint is 48 degrees, making our relative humidity 63%. Barometric pressure is 30.03 inches and holding steady for now, was rising slowly earlier in the evening. 

Winds today tended to be light and variable, usually from the North and West. Skies were sunny in the Tennessee Valley today. The High in Cullman was 72 after a morning Low of 39. 

Jasper also started the day with a Low of 39 and then warmed to 75 degrees for the afternoon High under sunny skies. 

Haleyville also had a Low of 39 this morning and then under abundant sunshine this afternoon, warmed up to 73 degrees. 

Elsewhere around the region, Decatur had a High of 74 and a Low of 41. Huntsville had more periods of clouds there in the city limits with a High of 76 and Low of 44. Muscle Shoals saw a High of 74 and a Low of 43, sunny skies there throughout the day. Gadsden saw a High of 73 and Low of 49. Fort Payne, there at the higher elevations, saw a High of 71 after a morning Low of 37, that may end up being our cool spot of the day. But let's look across the Tennessee border, at least peek at some of the bigger cities. Nashville, like Huntsville, saw a good bit of cloud cover from time to time today. Their winds have shifted more East/Southeast already in advance of a weather pattern change we are about to have, to more unsettled summerlike weather. Their High was 73 after a morning Low of 43. Chattanooga saw a similar increase in clouds this afternoon and evening and a High of 73, Low of 43, same as Nashville. Our neighbors over in Atlanta, Georgia also saw some increase in clouds this evening and a High of 74, a Low of 50 today. It also clouded up in Birmingham later in the day, High of 76, Low of 46. Then looking back up into Tennessee, Memphis became overcast as this evening on. The southerly winds are definitely getting established in that vicinity. Their High was 77 after a morning Low of 50. So Fort Payne does win the day for our cool spot. 





Today was our last day fully under the dominance of that High pressure system that has kept us sunny, dry, and on the cool side lately. Rain and thunderstorms are ongoing with that front, mainly over Texas tonight. 



A few of those storms out West have become severe, producing damage to trees and power lines, and even a report of golfball-sized hail. Odd note, the only tornado of the day occurred this morning in Los Angeles County, California, in the Carson-Compton area. Freak events do occur from time to time, but this tornado was brief and weak, did not cause any injuries. 



Tomorrow that system from out West advances enough to the East to bring us some rain chances. About a 40% chance of rain looks reasonable for tomorrow as we kick off this unsettled pattern tomorrow into tomorrow night. 




And we do have a very low risk that a few of the thunderstorms could reach severe limits tomorrow night. If you were to get a severe thunderstorm warning, need to stay inside away from windows and electrical stuff. Ideally be in a sturdier house than a mobile home (especially if you've got trees around) and on the lowest floor. Overall though this severe thunderstorm risk is very low, and some of the very conditional parameters like the increase in helicity we might see tomorrow night might only produce some "hailers" with only a secondary threat for damaging wind gusts. Estimating a High of 72 and Low of 53 for tomorrow. 



And then that system sort of washes out and stalls as we get into Saturday. The best lift isn't even going to be around here with a clearly defined frontal boundary in our region. This is edging toward more a pattern we would see in summer where the drier and more moist air are in a standoff and we have warmth, humidity, and lower-end rain/thunderstorm chances. 

Will cut rain chances back to 30% for Saturday, and Highs may approach 80, about 77-80 range for the High, morning Low should rebound to upper 50's under abundant moisture. 



Then on Sunday will trim rain chances back to 20%. I am undercutting model guidance, model output statistics, based on my own personal experience/opinion and what I consider to be pattern recognition. Should see a High in the lower 80's, Low of about 60 or so. 



On Monday it does look like a clearer-defined frontal boundary will push South into the region. So will bring rain chances back up to 40% then. Even tomorrow/tomorrow night, it looks like most or all of the thunderstorm activity will remain elevated, which limits any threat for organized severe thunderstorms. Isolated strong thunderstorms are possible of course, but you can see them on any typical summer's day. We are not quite into summer yet, but our overall pattern is trending away from the active spring stuff and more toward the type of weather we'd see in summer, at least for now. Our severe weather season does last until the end of May, but it is common knowledge too that most years, as we get further into May, the frequency of severe weather threats tends to gradually drop off in our part of the world. It starts ramping up out in the Plains in May and June. As it is dying down around here. Again looking at lower 80's Highs/lower 60's Lows for Monday.



The front will start to stall out in our region on Tuesday, but I still think modelling is too aggressive with rain chances in this pattern, and am learning toward cutting the rain chance for Tuesday back to only 30% instead of 40%. Highs could actually edge into the mid-80's. When I said a summerlike pattern, I was not joking around.



And with these model trends, think it is safe to trim rain chances for Wednesday of next week back to 20%. So we may see mid-or-even-upper-80's for the High, Low staying in lower 60's.



Looks like a decent chance of organized storms shaping up for the Plains on Thursday of next week, but around here, pattern staying about the same, partly to mostly sunny skies with that minimal 20% rain chance like you'd see in the summertime. High may actually get in upper 80's and the Low may fall to roughly 60 degrees again. These are general estimates of nuances in a late-spring unsettled pattern.



An upper-level ridge of High pressure gives it a more summerlike feel by next Friday. And look, by the time you get out beyond seven days, it can be like people trying to read tea leaves and predict the future. In this case however, it is better than checking out the Farmer's Almanac. Because patterns like this tend to last a while once they set up, and if there is going to be any big change in them, at least one of the global models is likely to pick it up. And they are showing this pattern holding. So once again for Friday, outlooking a 20% rain chance, a few clouds but more sunshine probably, High in mid/upper 80's and Low down close to 60. 



Then on Saturday, the GFS shows a front swinging into the region. 


While the ECMWF is not sold on that idea. Even in this relatively predictable pattern, this is why I give the disclaimer that once you're trying to predict more than a week in advance, it gets into tea-leaf or Farmer's Almanac territory. It's all right to look at for fun, but don't take it seriously and bank on it being true. 

Over the years a lot of television stations and sites like Accuweather have tried to present these really long-range forecasts as though they carry more accuracy than they actually do. So in a spirit of fun, I am playing along, but letting you know the truth, which is that at this time range, it is more of a guess than it is educated. So for Saturday I'm "forecasting" an increase in rain chances but only to 30% instead of 20%. Adjust Low temperature up a degree or two, maybe take day temperature down a degree. 



Then on Sunday May 14th, the GFS shows that front washing out. 


The European model has us high and dry. It has been my personal experience that even with a recent upgrade, the American model tends to go on some wild goose chases and get too aggressive with a more active pattern. When the European model does not show the same idea, and it conflicts with a human forecaster's sense of the overall pattern and what it should do, then I think it's good to pay more attention to the model that is closer to what would reasonably be expected in the pattern, and think about climatology. So in light of that, Sunday's rain chance comes back down to 20%. May gain a degree or two during day, lose a degree or two at night due to a slight change back to drier air. But part of my trying to nail down such details at such a ridiculous time-range is just my playfully poking fun at the sources that do try to present such forecasts as serious and reliable. At best, we're looking at general trends in this long of a time-range. And my joke (that I borrowed from a lawyer) about it being more like reading tea leaves is probably more accurate. 




Average rainfall totals during this unsettled period are expected to be an inch or less. Much like the risk of any storms going severe tomorrow/tomorrow night, the threat for any flash flooding or river flooding issues is very low. If we see activity like that anywhere, it should be isolated. Please note that the rainfall estimates only go out seven days, even though I'm going a 10-Day-Forecast for this package, to be sort of tongue-in-cheek and have some harmless fun - harmless because I'm telling you what I'm doing. Similar to when the British magician Derren Brown, or the late Harry Houdini, held seances onstage. Or when you go to a haunted house or haunted water ride and know the snakes are rubber, and so on. The folks at the Weather Prediction Center have very good sense, so they do not try to predict beyond a week in advance. I do think the science has progressed to the point that our 7-Day-Forecasts are pretty good. But by Day 7, you are often still looking at general trends, more than being able to iron out details. Depending on the situation, even a 3-Day-Forecast can be quite challenging. This one is easier, earlier in the year than usual, so I decided to . . . as I said . . . have some harmless fun. Hope somebody got a kick out of it. Including anyone who might happen to read this from Accuweather. 

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