© 2019 Terry Swails

FINAL FLOOD OUTLOOK A REAL EYE OPENER...

March 8, 2019

The final spring flood outlook came out Thursday and it was an eye opener, especially for those living on the Mississippi. It stresses that this year has some of the highest potential ever seen. It also indicates the the severity will be determined by how fast the thaw occurs and how much precipitation attends it. No matter what happens in that regard, the hydrologists have issued a 100% chance of the Mississippi river reaching major flood stage from Dubuque to just north of Keokuk. You can see the final NWS spring outlook by clicking HERE.

 

One thing that really stood out to me in the new report was the chance of reaching a record crest in the Quad Cities.  At lock and dam 15 there is a 1 in 2 chance (50%) of the river reaching 22.6', the current record set in 1993. The second highest crest is the 22.48' level set in 1965. (those are the two benchmark years for Mississippi River floods in my viewing area.

The big issues going forward in this scenario (as mentioned above) is temperatures and precipitation. They will dictate everything with regards to the scope of any flooding in any of our rivers. To give us an idea of coming trends here's what the latest EURO weeklies are showing. 

 

Starting with precipitation the EPS control is plenty wet, continuing a theme that's been going on for months. This is not a positive trend (roughly 200% above normal the next 46 days) and we best hope this does not verify.

Temperatures are also expected to be below normal the next 32 days over all of the central U.S. This would likely do two things. First, it would keep snow falling through much of March over the upper Midwest. Secondly, it would prevent the existing deep snow pack from significantly melting.

The longer the snow remains on the ground up north the greater the chances a rapid thaw will eventually occur later in March or April. We don't want that. We want a gradual thaw with above freezing days, below freezing nights, and minimal precipitation. The cold forecast is another problematic trend.

 

I mentioned the issue of more snow. Check out what the EPS control is showing the next 46 days. The rich get richer and whiter up north. That snow holds a lot of locked up moisture that's eventually going to be released. This is ominous.

Now, since we are talking about long range forecasts we all know they are less likely to verify as shorter ones. Therefore, it's important not to get caught up in the specifics/amounts, just the trends. I do not want to be an alarmist but I just showed you 3 very important elements that will come into play. If these do become reality, they will aggravate the situation and enhance the chances of serious flooding. If you live in an area that is prone to flooding, especially along the Mississippi, I would keep a close eye on developments and have a plan of action if this does come to fruition.

 

The next storm comes rolling in Saturday. It too will bring moderate to heavy precipitation. Much of my area will see rain but the far north could get in on a mix or late transition to snow. Here's some snowfall forecasts.

 

The GFS

The NAM

The 3k NAM

This is the liquid precipitation forecast off the GFS.

Well, that's it for now. Have a darn good weekend and roll weather...TS 

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