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- 3 - Short term weather forecast (National Weather Service- Treste Huse) . National flood outlook as of march 25th shows elevated southwest Colorado flood risk, as well as Nevada, and California. This is the first spring flood risk report for this year. . A short-term weather outlook was also provided to the group. Lon2: term weather outlook (HDR En2:ineerin2:. Inc. - John Henz) John Henz explained recent research and understanding into the different hydro-climatic indicators that affect Colorado. All of these influences originate in the oceans but impact Colorado weather. ENSO (El Nino - Southern Oscillation) - Dominated by East- West changes in air temperature and pressure in tropical Pacific (MEI, SOl) PDO (Pacific Decadal Oscillation) - Primary North- South difference in sea temperature in Pacific Ocean NAO (North Atlantic Oscillation) - linked to changes in sea surface conditions in the Atlantic Ocean AMO (Atlantic Multi-Decadal Oscillation) MJO (Madden Julian Oscillation) - 2-3 month build-up of warm water in Indian Ocean during Winter/Spring. Sends pulses of energy into the sub-tropical jet stream. El Nino 04/05 features a Pacific storm track merging with the sub-tropical jet stream to bring a wet winter to SW and West. Polar jet moved west to add cold air! Result: Jan Snows in Colorado! Spring storms on the way. The sunspot cycle graphs show double high sunspot incidences during the 2000-2002 drought. Henz predicts we will find out during the next 10-15 years how the sun affects our oceans. During April storms on the Front Range and adjacent plains will give us an opportunity for the South Platte River basin to get back to average. He believes there will be short warm pockets between stormy periods that will moderate the spring snow melt runoff. The snowmelt runoff will peak later than average in late May and early June. What does it take for snowmelt related floodin2: to occur? ,The answer is above normal (SWE > 125%), snow pack between 9,000ft and 11,000ft, a period of significantly above normal temperatures for 5-10 days with night-time low temperatures greater than 32 degrees F. Rainstorms on top of runoff swollen streams can produce flooding similar to the Rifle-Government Creek floods of 1993. Due to the conditions this year there is a higher likelihood than normal that this type of event could occur. Henz believes spring storms will add 4-5" of water in South Platte basin, and it will be important to monitor the South Platte over the next five weeks. . . . . . . . . . . . gOON 600N 300N 00 300S 600S 900S a" 600E 1200E 180' 120 off 60 "ff a" SST ANOM 10/12/03-10/18/03 Base Per i Dd, 1982-96 _1-:1 1 1 I. CI=I- -4..11 -u ~.o -4.60 -!!) -H -1,t;I -Olj .60 1.0 1.60 !.(J ~ 3.0 ;!1.5 U Flood Protection . Water Project Planning and Finance. Stream and Lake Protection Water Supply Protection. Conservation Planning