WORT 89.9FM Madison
Forecast For Wednesday 9 - 18 - 24
It's time now for the most comprehensive weather report on the airwaves with W-O-R-T weather expert, Rob McClure. Well, we've run a full week now with high temperatures in the upper 80s at a time of year when the average high temperature is in the low 70s. So we've got a 2-degree temperature surplus now for September after having been nearly 5 degrees below normal following that first rather cold week of the month, you might remember. High clouds cut into our high temperatures a little bit today, drifting southeastward off of showers that were going on out in the plane, so that held the thermometer down just a little over my expectations. But at least the clouds are an indication that some kind of moisture, anyway, is finally working into the air column overhead after what's been an extremely dry start to the month, we've had just a mere 200th of an inch of rain so far. That's not actually the dryest start to a September though on record in case you're wondering, we've stayed totally dry in at least the year 2009, at least up through the first 19 days of September back then. And similar to 2009, it appears that the 19th may be our lucky day, that's tomorrow, pardon me, the prospects we're getting around our showers or thunderstorms to come through during the day tomorrow, or actually probably in the evening have definitely increased since I gave the forecast back on Monday morning, though there appears just to be a fairly narrow window in the mid and late evening hours tomorrow during which sufficient column moisture will be available to produce those. Nevertheless though, there's certainly been a much greater enthusiasm on the last several runs of the high resolution forecast models for seeing showers and thunderstorms come through, so it's a fairly high expectation at this point. Part of the reason for the forecast change appears to be a slightly better east and north-easterly pushed in the upper winds that are coming around the bottom of the upper trough that's going to be ejecting northeastward out of the western plains into Canada tomorrow, so that's going to help sustain better lift along the attendant cold front that's going to be approaching with that system tomorrow evening. If you have a look at the water vapor image of the contiguous US that we have linked up at the top of the WRRT weather webpage this evening, you'll be able to see some of those features, including what is a quite vigorous upper low within that trough, spinning briskly now over northeastern Montana, the strong west south-westwardly upper winds that are ejecting from about the four corners region up through Kansas are going to help provide enough lift by later tomorrow along with that pulse of mid-level moisture coming in to break up the capping inversion that's been underneath the now departing upper ridge, that upper ridge has been over us and that capping inversion has kept us clear for several days in a row now. Pardon me. Developing thunderstorms over Iowa and Minnesota tomorrow afternoon may initially become super cellular given sufficient speed and directional shear along with the modest buoyancy, but concerns are likely to shift more towards straight line winds by the time that line of thunderstorms finally moves through here. As I mentioned, probably towards midnight or even after that on early Friday morning, even though I'm not expecting anything too concerning with that, skies are likely to clear out some then on the day Friday as a Pacific high pressure cell pushes into the area from the west, that air mass is not going to lower temperatures terribly much over what we see tomorrow, but a little bit that week surface high is going to push eastward then on Saturday as low pressure begins again to develop out on the plains to our west, and then how things commence from there is still a significant issue on the longer range forecast models. We're likely to see winds backing suddenly again in any case on Saturday, so we should still be fairly warm that day. I think in the low 80s showers may hold off until early Sunday, but I'm expecting warm air advection precipitation to set in sooner or later that day ahead of a more robust cold front. It'll be pushing through as we enter the day or get into the day Monday probably. Anyway, we should have temperatures well down in the 70s by Monday, still probably up in the mid 70s with cloud cover on Sunday. However, back at the night, though, for the details, increasing high clouds and the lights are essentially winds of three to seven miles per hour should keep temperatures falling too much past 60, I don't think, through the balance of the overnight period. Tomorrow sky conditions and their effect on temperatures are a little bit of a tough call. I think we'll get enough clearing to bump the temperatures into the mid 80s anyway. We'll likely see a couple rounds of high and mid level clouds passing overhead from shower activity out to our west. Slightly more active winds, though, tomorrow coming up to five to ten miles per hour will help with some vertical mixing, and that will also help us warm, I think, again to the mid 80s, perhaps despite the cloud cover. Showers and thunderstorms will develop over central Iowa and up into Minnesota in the late afternoon, and then advanced eastward as we get into the overnight, probably reaching Madison towards midnight, possibly after that. The precipitation band shouldn't be terribly wide, probably passing in an hour or two, but initially drier, lower atmosphere may help to produce some decent winds with those storms as they come in. Temperatures will drop to the low 60s overnight, with suddenly winds veering south-westerly, and Friday may actually start a bit humid and summer-like before the south-westerly winds veer a little more westerly with the cold frontal passage and skies start to clear. Temperatures will reach the low 80s on Friday, with the west and northwest winds up at four to eight miles per hour in the afternoon. Temperatures will drop back then into the upper 50s overnight on later northwest-westerly winds, and Saturday should be seen a fair bit of sunshine early on anyway, perhaps through a good chunk of the day even, but with high and mid-level clouds, again starting to be on the increase later in the day and in the overnight period, as light and northwest-westerly winds back subtly again. And then passing showers are possible as we go overnight, but certainly more likely on Sunday, which so again see a high temperature in the mid-70s. At the moment of the station down here on Bedford Street, the temperature is 76 degrees, the due point temperature is 58. Winds have been fairly light and variable over the past hour. A thick pall of cirrus up above the station as I looked down up at about 25,000 feet or better, and the barometers at 29.92 inches of mercury and falling slowly.
Photo by David Devereaux-Weber