The following is the entire spring melt outlook released by the National Weather Service in Grand Forks. An outlook was issued Thursday, but has been updated Friday
This is an update to the Spring melt outlook - technical meteorological discussion update #1 issued just yesterday. Changes may start occurring faster than originally anticipated. These changes would be due to a change in the expected storm track over this weekend.
Synopsis:
The blocking pattern is breaking down rapidly, and a strong storm system moving into the Pacific northwest is partly responsible. Latest forecast data suggests the storm will be moving farther north than expected, and this change, should it materialize, will have significant impacts on the initiation of widespread flooding. As of this writing snow is forecast across the northern half of the Red River Valley, with rain or rain and snow across the south. There is also a slight chance for heavier rain showers near the Dakotas/Minnesota border.
Near term outlook: April 2 - 7
Refer to NWS Grand Forks forecast products for updates. A potent storm system will move across the plains this weekend. With the potential for a more northern track, rain is looking more likely over the southern Red River Valley. There is even the threat for isolated heavier rain-showers. Based on reports from the far southern Valley, the snow pack has been ripening and water is moving into the river systems at a slowly increasing pace. If significant rain does fall, this will enhance and accelerate the melt process. Significant rain is considered one half inch or more in a 24 hour period.
Beyond this storm another system may impact the the northern plains late next week. Between the first storm and potential late next-week storm, temperatures will be warm enough to continue, if not accelerate, the melt and runoff process.
8 to 14 day Outlook: April 9 - 15
No significant changes are presented from yesterdays outlook: During the first two weeks of April, there remains the threat for increased storminess. The pattern change continues to evolve, and this pattern is expected to lend to a gradual increase in temperatures as well as the increased risk of above normal precipitation. A broad trough of low pressure in the upper atmosphere is expected to form in the western half of the United States and the eastern Pacific, as high pressure develops over the southeast US. This will gradually make the upper level flow turn more west-southwest over the plains. This favors increased storminess over the region, which is becoming more apparent in the short term.
Flood Risk Assessment
As a result of this storm system coming in farther north, rivers could start rising more rapidly than currently forecast by the middle of next week. The forecasts on the AHPS web page reflect precipitation expected the next 24 hours. Since the impact from this storm is still beyond 24 hours, the forecasts posted on the web do not yet reflect the potential impact of the storm. As indicated above, should the system develop as is now forecast, more significant river responses are possible within the next 5 to 7 days. After the storm impacts the region, the NWS will assess the precipitation patterns and update river forecasts as needed.
See the AHPS web page for details.
http://water.weather.gov//ahps2/index.php?wfo=fgf
It is important to stress we will not be able to make significant changes to the river forecasts until an assessment of the precipitation is accomplished. This will likely occur late Sunday April 3rd or Monday, April 4th.
At this time we cannot produce Quantitative Precipitation Forecasts beyond about day 5, therefore we refer to the three categories of below, near normal or above to describe the longer term precipitation threat. The overall weather pattern should continue to favor above normal precipitation into the second week of April as described above. It is important to remember that April is a transition period, when weather systems can develop and intensity rapidly. Due to the technological limitations, the NWS in Grand Forks can only relay trends of major storm systems beyond the 7 to 10 day period.
Mark Ewens
Climate Services Focal Point
NWS Grand Forks
Tags: national weather service, flood prediction, news, flood, updates
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