From FB:
55m ·
From our state hydrologist as of 5:30am this morning re: Upper Yellowstone. We still have above average snow pack.
Rain forecast:
• Over the next six hours the National Weather Service (NWS) is forecasting 0.03 to 0.16 inches throughout the Upper Yellowstone with 0.16 inches expected in the National Park. Not much more is anticipated after that. Keep in mind this is only a NWS forecast.
Temperature:
• The National Park and Paradise Valley are expected to remain colder today (highs of 38 and 55 respectively). Then a warm wave will roll in starting with slightly increased highs Wednesday and significantly warmer conditions Thursday thru Saturday.
Snowpack:
• Rain on snow played a significant role in the current flooding. Between June 7 and June 13, 5.5 inches of snow water equivalent (SWE) was melted and subsequently became runoff. This was due to the 2 to 3 inches of rainfall rapidly increasing snowmelt rates. This is tremendous amount of snowpack to lose in a short period of time. That being said, the current SWE for the Upper Yellowstone is 11.8 inches. The median for this day is 7.7 inches. So significant snowpack still remains in the mountains.
Streamflow:
• Both of Corwin Springs and Gardiner River gages show a peak yesterday and decline since then.
What this all means:
• The next couple days flows will likely recede due to the lack of significant precipitation and cooler temperatures.
• Given no significant precipitation Thursday through Saturday, the warmer temperatures should not produce as much of an increase in runoff as the rain on snow event we just saw.
• Any significant rain events after Thursday will result in significant runoff (none is currently forecasted until Sunday)
• There is still a significant amount of snowpack remaining so keep an eye on rain forecasts over the next couple days and weeks.
Keep in mind weather forecasts are simply forecasts so focus most on the next two days rather than a week ahead. I will send these updates when conditions or forecasts change significantly.
