The past couple of weeks will not go down as banner weather producers here in the Midwest. We haven't had much in the rain bucket but we have been plagued by wind and chilly temperatures. These are the departures we've racked up over the past 2 weeks.
Throw in another 7 days and you can see how prevalent the chill has been over the central U.S. since April 13th (the past 3 weeks).
Troughs similar to the one below to start this week have seen to it that moisture is lacking leading to little if any rain around the central Midwest. The NW flow has also promoted the below normal temperatures.
The upper level flow is in the process of changing and you can watch the evolution of a pattern that will bring warmer temperatures, higher humidity, and increased chances for rain starting later this weekend. This looks far more typical of early May.
Warmer weather began to get a foothold Wednesday with highs getting back in the 60s. With more of a southerly component to the wind the next two days we'll up our game and shoot for 70s. Thursday is shaping up to be a stellar with a gentle breeze, plenty of sunshine, and highs of 70-75. Friday's highs should be similar but passing clouds and a some scattered light showers are possible. Any rain looks very light and more areas will avoid it than see it.
THE WEEKEND AHEAD...
That gets the weekend off to a pretty good start and while Saturday and Sunday remain mild, there is a chance showers and scattered thunderstorms could get into the mix Saturday night or at some time Sunday. The rain forecast is a bit ambiguous as synoptic details are still in flux. But, the general idea is that the region will be on the periphery of an upper ridge. Short wave energy is likely to come out of the southwesterly flow aloft at times well into next week generating the forcing necessary for showers and storms. As I mentioned yesterday, the position of the boundary will hold the key to where storms fire and how warm temperatures will get. It still seems as if the daytime hours of Saturday will be dry and temperatures will generally be in the low to mid 70s, perhaps pushing 80 in the far south.
The first real chance for rain comes Saturday night on the nose of the low level jet which cranks up after dark. An elevated storm cluster may form that could deposit some locally heavy rains. The EURO is the most aggressive with this potential showing the area near and south of I-80 with the best potential.
If storms do fire they should weaken and fizzle Sunday morning. After that, the amount of debris clouds will determine how warm the day gets. However, guidance is consistently pumping out highs in the low to mid 80s in all but the far north where mid to upper 70s are more likely closer to HWY 20. By then the GFS has dew points reaching 60-65. That would generate some decent instability as shown in the CAPE values it depicts late Sunday afternoon
That sets the table for another ridge riding disturbance that combined with the low level jet could again generate additional showers and storms late Sunday afternoon or night. Some models indicate an MCS (mesoscale convective complex) with the potential for heavy rains and strong storms. Again, the position of the baroclinic boundary will determine where the action sets up. Such mesoscale features won't be known until closer to the event.
Recent trends hold the storm track and baroclinic boundary across the central U.S. for much of next week. If indeed that is the case an active pattern with showers and storms could result in near daily chances for rain. That said, the best opportunities in such a pattern are typically found in the late afternoon or night allowing plenty of dry hours and warm days.
Over the 10 day period ending May 13th both the GFS and EURO indicate a wet period around the Midwest. However, there are differences regarding where the heavier rains will fall. Again, that is due to mesoscale influences tied to the timing and placement of energy ejecting out of the mean trough over the western U.S. These are the suggested 10 day rain totals off the EURO and GFS.
No matter how the rain plays out, I am thoroughly looking forward to the revival of spring temperatures that will leave me without the need of a jacket. Here is the NWS based IDSS forecast for the Quad City metro through next Tuesday. Gotta love what they are showing for highs.
Alright then, lets get out and enjoy the beautiful day ahead. We've earned it. Roll weather...TS