CAN'T GET ME NO SATISFACTION...
Our week got off to a respectable start Monday with ample sunshine providing us with a bright and shiny day. However, the sun was deceiving as the overall look was far better than the feel. Morning temperatures in the NW half of my area were down in the teens, as cold as 16 in Clinton and 17 at the NWS office in Davenport. Lows like that are about 20 degrees below normal. Highs managed to reach 40 in most spots but again that's a little on the crisp side for late March.
From the looks of things, Monday was probably the best day we'll see all week as our next storm is already coming together over the SW United States. You can see the energy rounding the bend in California getting ready to eject into the Midwest for a prolonged stay Tuesday through Thursday. I can't get me no satisfaction when it comes the weather pattern the next 1-2 weeks.
As with the last two systems, this new one takes a fairly similar track, has plenty of moisture, and significant dynamics. That all leads to another wet storm that ends with wind, much colder temperatures, and perhaps snow showers. We'll ride the temperature roller coaster as well with the thermometer reaching the upper 50s to low 60s Wednesday before crashing and holding in the 30s Thursday.
The animation shows the surface and precipitation fields as the storm grinds northeast through Iowa towards northern Lake Michigan Tuesday through Thursday. If you notice the GFS is showing snow wrapping in on the back side of the deep 977mb surface low.
What you can't see is a warm front that is approaching my southern counties Tuesday morning. Clouds will be on the increase ahead of it and a few light showers or areas of drizzle will be possible. Any precipitation Tuesday looks minimal and it won't have much impact on the day (if at all). We'll see a be range of temperatures with readings in the north remaining in the upper 30s while the far south approaches 50 with the approach of the warm front.
Tuesday night temperatures will rise as the low pressure tracks towards north-central Iowa drawing the warm front through the entire area. The evening hours look quiet but after Midnight strong forcing should allow showers and thunderstorms to develop. These will be elevated and with some CAPE and shear, could reach levels that would allow some small hail in the stronger updrafts. Brief heavy downpours are also possible in spots. The Storm Prediction Center shows the greatest risk to the west.
Wednesday's weather is highly dependent on the speed of the cold front which appears to be coming through during the late morning and early afternoon. That is not optimal for strong storms with limited heating restricting instability. It may be that rain ends in the NW half of my area by afternoon as the front passes. Showers and some thunderstorms are still possible in the early to mid-afternoon hours across the southeast before the rain ends there. Here's what models are indicating for total rainfall. Notice that they all show the impacts of a dry slot near the storms path somewhere in central or eastern Iowa where amounts are lower than those to the east and west. The track of the surface low and speed of the cold front will determine where the heaviest rains and stronger storms occur Wednesday. A couple hours slower or faster could make a big difference.
The 12K NAM
The 3K NAM
Once the cold front passes the heavier precipitation ends and then we watch for a deformation band that wraps in from the west. Strong cold air advection changes the rain to snow here and it's possible some minor accumulations could occur, particularly across the north half of my area (especially HWY 30 north). Depending on the track, I could see and inch or so of accumulation roughly near and north of a line from Cedar Rapids to Dubuque, mainly on grassy and elevated surfaces. Here's what models are currently indicating for amounts late Wednesday night and early Thursday. I have low confidence in any of these solutions and remind you that what you are seeing is just raw model output, not official forecasts. This is the guidance we look at to determine trends and eventually make forecasts. We want to see consistency among the various solutions and right now the signals are pointing to the northwest for any meaningful amounts. Here you go.
The 12K NAM
The 3k NAM
Any lingering snow showers depart Thursday morning and then we get to enjoy another batch of wind and cold air. Most models depict temperatures holding in the 30s Thursday. Again as you can see in the departures below those readings are 14-16 degrees below normal.
Friday will be a dry day with clouds increasing later in the day after a sunny start. A little moderation is anticipated with highs getting back in that range of 45 to 50 from north to south.
Another disturbance could bring rain or snow back to the area Saturday before it departs by Sunday. More on that in coming days. Meantime, the weekend looks cold with 30s and 40s for temperatures. Where for art thou spring! Roll weather...TS