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Old 02-17-2011, 10:51 AM
 
Location: E ND & NW MN
4,818 posts, read 10,963,353 times
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Quote:
Originally Posted by dutchinnd View Post
DaninEGF--
Once again looking to you for an answer:
From this morning's flood outlook:
The Red River in Fargo has a 20 percent chance of reaching 41.2 feet, up from last month’s prediction of 40.7 feet.

If the current amount of melting has no impact on lessening the flood levels, where is all that water currently going? Of course, the local media isn't expalining it terribly well.
Are we looking at Feb/March moisture replacing all that current runoff and then some?
Tough one to answer as I am not a hydrologist and dont know the ends and outs of river flows, etc. I know more about weather systems, etc...river routing is not by strong suit. But from what I have been told and from my experience....the snow melt that did occur does run off into the ditches and culverts where mostly of those remain plugged with snow. Now, I asked our hydrologist about today's outlook and really it isnt a technical increase per se but a tightening of the probability range... when you raise up the lower end but keep the very high end (the 2-5 pct chances) most percentages will increase a bit. More of a statistician thing.

Part of what goes into the river outlooks is the long range outlooks from the Climate Prediction Center and also our local thoughts. The long range outlooks remain bullish for a stormier and colder than average period in March and April. Of course the devil is in the details and it is those details that is just unknown at this time. Stormier for the area....does that mean the southern valley gets a lot more snow or does it hit just south or north of us.... those things and how it trend weatherwise is more of a within a 2 wk knowledge period.

Best I could explain it.... A lot of statistics and engineering routing/hydrology river routing curves goes into these outlooks and thus anytime you are trying to model something you are prone to some degree of error. Forecasting in the long range such as rivers and in weather period has gotten better but a long ways to go. Thus we do a probablistic percentage thing instead of trying to throw a dart and guess a final crest number which was previously done back in the 90s.

--Dan
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Old 02-18-2011, 09:41 AM
 
Location: E ND & NW MN
4,818 posts, read 10,963,353 times
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Hi again

I spoke with our hydrologist at the office who speaks with the River Forecaster Center in Chanhassen frequently.... there was some minor up ticks along some of the tributaries (smaller rivers) that feed into the Red in the southern basin over the past week. So indeed some melting water did get into a few of the smaller rivers (likely by flowing on top of the ice). Gage along the Ottertail River near Doran Minnesota went up about a foot and the gage along the Wild Rice near Mantador went up about a foot too. But that water never made it to the mainstem Red as many of the channels are just too plugged up. Grand Forks proper has escaped a lot of the snow this winter whereas the southern basin has been hit harder. Upcoming storm for this weekend looks to hit the far southern basin as well with over 1 inch liquid.

So in answer to the question....there was some effect of the melt to raise a few of the local tribs up a bit...but no impact on the mainstem Red

--Dan
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Old 02-18-2011, 10:43 AM
 
Location: Fargo, ND
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Thank you so much for the update! Thinking I'll spend my President's Day off at Sandbag Central . . .
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Old 02-18-2011, 12:27 PM
 
Location: E ND & NW MN
4,818 posts, read 10,963,353 times
Reputation: 3631
Quote:
Originally Posted by dutchinnd View Post
Thank you so much for the update! Thinking I'll spend my President's Day off at Sandbag Central . . .
Your welcome...there is a lot that goes into forecasting far out for a river that is still frozen.

One thing I wish we (meteorologist-hydrologists) could scream out to the media is that this is an outlook probablity wise and not a "forecast" per se. A deterministic forecast (one with specific numbers for a crest) is not done til about 7-10 days before the crest. But when I see in the paper....forecast for xx point goes up in regards to the latest release it make me cringe as they are using the 50 pct line. That is not our number prediction. Our prediction covers the whole probablistic range. Past years spring precip is thrown into the river models based on current modeled conditions to come with different scenerios. I.E if 4 inches of rain fell like in 1979, then that produces a forecast of xx feet. If 2 inches of precip fell it produces xx feet.
The whole history of different spring precip is included and then probabilities are then done.... the outliers or 2 or 5 pct are the higher precip years....where are all clustered together that is a more confident idea.

So much depends on March-early April. The Ottertail river is very fast flowing that is different than 09. In March if we get a storm like 09 or a melt like it when it came pretty fast then probably can make the case crest will be worse than 09. That is a possibility, not a certainity. If we have weather like 2010 and it was dry then certainly it would probably be blo 40 ft.

The percentage outlooks were done in response to the 97 flood when most people focused on one number that was given as a possible crest for Grand Forks way back before the melt began. Thus little preparation was done for higher than that. In todays prob fcsts....the decision makers have all the data and scenerios and each city can make their own decisions based on more information. Sometimes the more info there is the more confusion there is and that can be the case with media. However, most city and county Emergency Mangers and city officials have taken a lot training and communicate internally with the RFC and NWS and understand our info more than we think.

My brief rant on this stuff....

Be safe

Will be watching the storms coming up. The one Sunday appears to brush the far southern valley with very tight snowfall gradient. Mostly 6-8 Lake Traverse with much less over Fargo due to high pressure north of us. Next psbl event around 24-26th.

--Dan
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Old 02-18-2011, 01:44 PM
 
Location: Fargo, ND
419 posts, read 1,391,941 times
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Yeah, glad that I'm not the one in the decision-making-seat on situations like these. The City gets accused of crying wolf or being woefully unprepared--take your pick. If I remember correctly from an interview with someone from the NWS on MPR last year, there are something like 30-40 different models that produce a range of projected crest levels.
And then "King Denny" goes out driving in Richland County and consults w/ his own "Team Red" of "experts." Yeah, right . . .
Completely understand the frustration w/ the media. The print media has laid off so many of their employees--and it seems like the dimmer ones are the ones left--who don't understand nuance, no matter what the field or subject.
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