This post is going to focus solely on the weather from Wednesday through Friday night.
Models and intuition in fair agreement with the upcoming weather events in the region. In short summary, what we're going to see is some above temperatures with the possibility of some rain, and then we're going to see some below normal temperatures with a good chance for snow across the region. All this due in part to an active jet stream which will effect the region with two low pressures.
Wednesday, a closed off upper level low with its associated surface low pressure will be down in the southern states. A mid-Atlantic high pressure will be exiting the area, but it will still be pushing up some warmer air into the region. The closed low is going to feed off some of this moisture as it heads through the Ozarks and into the Tennessee area. This is going to allow for some decent ridging in the upper levels to occur, and again we might get into the 50's for a high on Wednesday in the region. This isn't going to last very long at all. On Wednesday, we'll also be focusing on another system that is going to really impact the region with some temperatures changes. A high pressure will slipped into the Rockies at this time, bending the upper levels into a steep trough with a good sized low pressure developing and traveling across the northern Plains during the day on Wednesday. This low will have a trailing cold front with it, but it will be way out in the Plains during this time. With the southern low moving the way it is, it will mearly provide only a glancing blow into the region. I am hesitating to keep the chances for rain showers in the western half of the region at this ploint as the low pressure from the south might have a hard time pushing it westward. The eastern half of the region nonetheless will see some rain with this system, and possbily temperatures above 50° yet again during the afternoon. Clouds will be on the increase regardless of the precip as the low pressure continues its North-northeast course.
Wednesday night, this when the forecast becomes a bit more tricky in terms of precip chances. The region is going to be sitting at this point between two weather systems: one to the north and the one to the southeast. The southern low will make an aburt turn, going to a more NE course rather than a NNE course. This low pressure will however is going to bring in the bulk of the rain during this period however as this is when the low will be the closest. Continuing to focus on the west during this time, that upper level trough really gets going into the northern Plains, as its own surface low (the northern one) continues to gradually deepen, pushing the cold front across the Plains and past the Mississippi River overnight. Our southern low wants to stay ahead of this, so that is why it will make that NE turn. As to how much lingering precip will be in the west, that is still a little bit debatable, so obviously that will be one of the top priorites when revising the forecasts this morning. At this point, the two main models still agree to an extent on the existance of the system, but they start to falter a bit with the timing. I am still leaning a bit more towards the ECMWF rather than the GFS as the ECMWF has been more consistant lately. I will keep a chance for rain showers in the west, as the low pressure will be a bit closer than earlier in the evening, but nonetheless I will still keep the chances generally low. Overnight temperatures in the region will be above average yet again, hanging around the mid 30's with the southernly advection still taking place. I am thinking that winds could start to increase a little bit with this steep pulling of the southern air, but for now, I haven't really mentioned them in the forecasts quite yet, though I will keep an eye on it.
Thursday, this is when the weather gets even more interesting in the region as the low pressure centre from the south all but pulls the majority of the moisture out of the region. The northern low will still be to the north of the region with its cold front, but at this time we'll start to see the cold front enter the region. Timing with the cold front has been a little annoying these past couple of days, but generally I am expecting that it will pass through the western half of the region in the morning, and the eastern half of the region during the afternoon. Because of this, I am going to mention that highs will probably occur in the morning in the western half of the region and then drop throughout the afternoon. The low pressure's cold front will start to move over the lake and this will begin to produce snow showers - along with some left over moisture from the southern low. The snow showers at this point that do form in the western half of the region are going to be light and fairly scattered and this isn't going to accumulate a whole lot. The eastern half of the region will still be seeing some spotty rain showers here and there, however some of those as well could mix with snow showers in the late afternoon. Upper level trough begins to enter the region, turning the flow from the W to the SW allowing for some additional moisture to be present in the region.
Thursday night, with the initial push of cool air from the cold front, there is going to be a gradual drop of temperatures. However the big question remains at this point as to how quickly that cool air will filter in. For now, I did drop temps down in 20's, but I am still holding onto some semi-mild temps for the east. As this northern low drops down into Michigan, it might start to undergo a little bit of occlusion, though this basically means that cooler air will be filtering father into the region.
Friday, lake effect snow showers might start to develop with the passage of the cold front, and at this point we might even see the upper level trough push into the region, keeping spotty snow showers and cooler temperatures into the region. As to how much accumulation will come with this lake effect snow is still a little bit debatable right now, although I am thinking that it might be a modest amount. Upper level flow will turn from the SW to the NW which will help for those lake effect snow showers to develop. However, at this point, the models really begin to differ with the position of the low pressure in the afternoon, though for now, I am still leaning more with the ECMWF.
Friday night, I went ahead and dropped temperatures further in response to the upper level trough and the cool air filling in from the west. Temperatures will be by far the coolest of the season, though I am not putting single digits into the forecasts at this point, I am unsure if the air will be that forceful.
I'll keep you updated as always, but for now, I am Timmy Albertson and that's the weather! My next update will be around 11.00 a.m. this morning, so make sure that you check back for that.
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