AS THE WEATHER WORLD TURNS
Thursday was what I would call a dark, dreary day around the region. The cool, cloudy conditions were in the backside of a weather system that brought widespread rain Wednesday and Wednesday night. You can see a distinct split in the rain totals, with a well-defined dry slot showing up over SE Iowa and WC Illinois. Either side of that, much heavier amounts were found in western Iowa and southern Indiana.
Here are some specific totals from around the state of Iowa by way of the Iowa Mesonet.
This event only added to the impressive precipitation amounts that have been racked up over the past 15 days, October 31st-November 14th. Here in Dubuque, we've measured nearly 7 inches of rain in that short period. The previous 60 days, the total was 1/4 inch. Talk about turning on the hose!
Below, you can see this year's accumulated precipitation for Cedar Rapids. Much of the year's first 5 months were above normal, with a surplus that grew as large as 6 inches to start August. Then came the driest September on record and by mid-October, totals were actually a couple inches below the norms. Now, with the recent heavy rains, Cedar Rapids is back above normal with more rainfall in the forecast next week.
The additional precipitation coming is tied to a complex interaction of energy that will be ejecting out of the SW next week. Currently, the GFS and EURO are at odds with different solutions. Both develop a strong cut-off low and associated trough over the central U.S. that brings an initial wave of low pressure into the NW tip of Iowa Monday. That brings the first round of rain.
After that, the EURO taps a secondary chunk of vorticity that rotates out of the base of the trough Wednesday, creating another wave of low pressure further east in SE Illinois. As it lifts northeast, it would bring another round of precipitation that could linger into Friday as it consolidates with the remnants of the initial disturbance.
It creates a potent storm that looks something like this at 500mb, Thursday, November 21st.
Here's what the EURO depicts with the second disturbance. A powerful 984mb surface low in Missouri. Look at the wind pattern associated with the cyclone. Is this for real? My initial reaction to this aggressive solution is probably not with cold air lacking.
Even so, precipitation between the solutions could still be substantial, especially if the EURO pans out. Here's what models suggest from next Monday through the following Saturday.
The EURO
The GFS, without the benefit of the secondary wave, is noticeably drier.
Another factor that is still in doubt is dynamic cooling that could flip rain over to snow sometime Thursday or Thursday night, November 21st. This is the wild card that could get played if the system takes a similar track and intensity to what the EURO depicts. Both the EURO and GFS have dialed the snow potential down, even so there is still a chance we will see our first snowflakes later next week. The stew is still simmering, but recent trends are suggesting less in the way of phasing, limiting the amount of cold and snow compared to 24 hours ago. I was surprised to see such a significant reduction. This is a game changer and something that needs to be addressed in fresh data Friday.
Undoubtably, we are going to see temperatures trending colder as the storm spins east of the area the middle of next week. That said, both the GFS and EURO have resorted to less in the way of cold, along with a shorter duration to it than yesterday. I suspect that idea has merit as the MJO is moving into warmer phases by the end of November. My hope is the move is short and sweet, and we get back into a colder "phase"/cycle towards mid-December, just in time for Christmas. Fingers crossed!
Meantime, we've got quiet weather to look forward to this weekend, along with moderating temperatures. Happy Friday! Roll weather...TS
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