RECAP - Snow Returns Wednesday
By Justin Poublon
April 17, 2018 - 12:00 PM CST | 30 0
Here are a few things we learned during this event that we will consider next time:
- Heavy snow band (strong forcing) regardless of time of year (but most significant in fall and spring) will have higher-than-forecast snow ratios. Sun angle, time of day, month of the year, moon phase, day of the week, odd or even year; it doesn't matter. Heavy snow will accumulate.
- April moisture availability.
- Surface temperatures were colder than forecast. When the snow started flying temperatures were at or below freezing in the southwest. Amounts were lower in the southeast were some melting did occur.
- Tight, compact system with a tendency to linger will lead to higher snow amounts.
- The forecast models are not that bad at forecasting snow. Especially following the historic blizzard last weekend. The GFS has been performing very well lately
- BUFKIT would have helped. Strong signaling for heavy snow on the reanalysis.
We didn't post another forecast on Wednesday morning. If we had perhaps we wouldn't have been too far off. After reanalyzing bufkit soundings it was pretty clear that snow would be heavy. Not sure if BUFKIT would have saved us but I'd like to think it would have. Either way, no excuses. We will get it next time!
24Hr storm Loop
ORIGINAL POST April 17, 2018 - On Wednesday 4/18/2018, a storm system will move through Wisconsin bringing accumulating snow to southern Wisconsin. The storm will be focused on the afternoon hours with best chance for snow between 10am Wednesday and 7PM Wednesday, decreasing in coverage & intensity Wednesday night.
SNOW - 2-5" of snow is expected in southern Wisconsin with lower amounts along the WI/IL border and to the north. Locally higher amounts to 6" are possible depending on where the main snow band sets up. Snow may be heavy at times having the biggest impact on the evening commute. Sleet will mix with snow along the WI/IL border. It's also possible that some of the snow will melt on contact and have adjusted the forecast down slightly to account for that.
The National Weather Service has issued a Winter Storm Watch in the southwest and Winter Weather Advisory in the southeast (see warnings map below).
Notes: Seeing lots of 2, 3, 4" in our calculations and majority of models. Decided to lean lower and mention locally higher amounts. Some locations will exceed 5", most will not. This is supported by April climatology, time of day, urban heating, temps in lower 30's, etc etc. This looks like an advisory level event in my opinion but I can understand the idea of a warning due to afternoon timing. I'd say start with an advisory and upgrade when/if confidence/qpf increases.
Simulated Radar Loop
Here is the NAM simulated radar loop for Friday through Monday morning. Time is in UTC(CST +5hr).
For the latest radar, click here
For the latest warnings & storm reports, click here
For storm chaser video of the storm, click here
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