First March snowstorm and local flooding impacts

I haven’t blogged much lately - trying to avoid thinking winter as much as I can, but with all the attention that this upcoming snowstorm is receiving, along with the flooding potential this spring, I felt it was necessary to post an entry.

First March 2011 snowstorm: About five days ago, a strong storm system was being advertised on the GFS forecast models for the March 8th-9th timeframe.  I know what you’re thinking, “That’s so far out, how can we believe it?”  Well, one of the things I picked up on was the very high preliminary snow totals, indicating the strength of the system.  At the start, the GFS was indicating over a foot of snow.  You don’t see that very often at the onset.  Yes, the totals fluctuate and tend to work DOWNWARD rather than trend upward.  The question then becomes of the storm track.  If the low pressure center tracks in a northern direction, it brings warm air with it and increases the rain/snow mix chances.  If it says south, but not too far south and miss completely, we get the cold air that wraps back around the low to produce snow.  For the last 5 days, it appeared MSP would take a direct hit from this weather system, but the latest trend is that the storm track will pass just north of St. Louis to around the Chicago area – just brushing southern Minnesota.

Here is the surface map around midnight Wednesday:

Snow totals have been reduced dramatically and now indications are that 2 – 4 inches of snow may fall:

Spring flooding: The new spring flooding outlooks have been released by that National Weather Service, and the forecast for major flooding has increased from the last forecast issued at many locations along the Minnesota and Mississippi Rivers.  Generally, many locations have a 90% chance or better at reaching major flood stage, including the Red River Valley of the Fargo-Moorhead area.  The year 1965 is being thrown out there as a comparison to the severity of the 2011 flooding will bring.  Closer to home, here are my comments that I posted on a spring weather discussion at the Shakopee Valley News website regarding the flooding situation for Shakopee (along with my old snow forecast for early next week!):

My current thinking is that there is a 50/50 chance of flooding reaching 1965 levels. I believe the NWS has the number at 40% as of 3/3/11. We may see an additional six inches of snow or more Tuesday into Wednesday. I also think we will see a sharp transition from winter to spring conditions towards the later half of March resulting in a rapid snow melt. The ground is also very saturated from last fall's precipitation with snow cover preventing deep frost penetration into the soil. Once the ground thaws, this moisture will runoff into rivers and streams.

I completely expect flooding to be of historic/epic proportions. If you have no flood insurance, you need it ASAP. This will be nothing to sneeze at.

La Nina winters have a tendency to bring more snow during early March than normal, which will not help with flooding.  I also believe we will see a quick changeover to spring-like weather towards the end of March into April as the cold air is not willing to let go coming into March. Water-snow content is a large reason why flooding is receiving the attention it is.  There is still well over a foot of snow in many parts of southwest Minnesota, and in some cases 20 inches!  This equates to roughly 10 to 20 inches of water in the snow in close proximity to the Minnesota River basin:

When melting begins this will run off into the river and flow upstream towards the Twin Cities.  Any weather impacts over southern MN will have a role in the flooding situation in and around the Twin Cities metro.  This is a situation that needs to be monitored closely.  I can’t recommend enough to purchase flood insurance, if you live near one of these rivers.  Even larger creeks such as Minnehaha and Nine Mile may see water flow above the banks, which residents need to watch.  It’s shaping up to be a historic flood event.  Stay tuned!

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RS

Red River flooding and weekend update

Well, what a beautiful week it was! A nice, sunny stretch of temperatures around 40 degrees. Just warm enough to crack open a car window to get some fresh air, or take advantage of a peaceful walk. As you have seen from looking outside, we have lost much of our snow pack. Snow lovers fret as they are now on borrowed time to get the most out of their winter activities. Dare we see some patches of dormant grass already? If not for the snow, we may have seen temperatures 10 or 15 degrees warmer this week and borderline shorts weather! Much of the sun energy this time of the year is used to melt the lowest layers of the snow.



It has been very dry month of February across Minnesota with most places seeing less than an inch of precipitation. This has aided in the decrease of widespread flooding concerns across the state.



Change in the air? It looks like our streak of dry days are about to come to an end. The GFS forecast model above is showing some rain moving into the area for Saturday. The pink line, called the "540 line" in the meteorological world, is the rain/snow line. We will stay in the warm sector, so the precip will fall as rain. Some of the roads may become slick as temps will fall below freezing as the sun sets Saturday. Take it easy out there if you must drive. Sunday looks like the better day of the two as the rain moves out of the area and sunshine returns.

The updated spring flooding outlook came out for south central Minnesota and eastern North Dakota from the North Central River Forecast Center. With the lack of precipitation over the last month, the probabilities of major flooding along the Minnesota and Mississippi rivers are low. The exception here is the Mississippi River at Hastings - there's about a 70% chance of the river reaching a flood stage of 18 feet.



That's the good news, now the bad news. Our friends that live along the Red River are still likely to experience severe flooding due significant rainfalls last fall and a greater, and heavier snow pack this winter. The city of Fargo will likely receive the brunt of the flooding as flooding will be imminent within 90 days. There's a greater than 98% chance the the river will crest to major levels at 30 feet. Last week, Fargo Mayor Dennis Walaker declared a state of emergency for the city. Citizens should already begin preparations for sandbagging and moving valuables to higher ground. If there is any positive news, the river in Fargo does not appear to reach the 2009 level of 40.84 feet. Only a 30% chance of this happening.





Next week's outlook: The weather pattern becomes more active as we will see rain chances increase Tuesday and into the middle of the week. Temperatures in the mid-40s throughout the week.