August 2023 - hpo-ims - Udfcd-Lists.Org

by f2p2＠udfcd.org

Time: 928 AM Wed August 2, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ANOTHER CHANCE FOR MODERATE TO HEAVY AFTERNOON & EVENING SHOWERS/THUNDERSTORMS A minimal change to the overall pattern as westerly flow aloft continues to dominate over the region. Dew points have remained in the 50’s and will likely hold through the rest of the day. The best chance for storm development within the District will be between 2-10pm. Storm motions will once again be W to E between 10-20mph, effectively limiting any point rainfall amounts. However, a few storms could produce gust fronts, with additional storms forming along these gust fronts inside the District. These storms will have the potential to produce longer lasting heavy rainfall as they will likely stall out over an area for an extended period. Training of thunderstorm cells is another potential culprit for longer duration moderate to heavy rainfall that may lead to excessive runoff and flash flooding. Strong thunderstorms may also contain gusty winds and large hail. Multiple rounds of showers and thunderstorms will move across the District through the afternoon and evening, with the strongest storms likely during the first round with storms decreasing in intensity as the evening progresses. Skies will clear late this evening with overnight lows in the upper 50’s to low 60’s on the plains with low to mid 50’s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical showers/weak thunderstorms will produce a 0.05-0.25” total, in 10-30 minutes. A moderate shower/isolated thunderstorm will produce 0.25-0.75” total in 10-30 minutes. Strong thunderstorms will produce 0.75-1.25” total in 10-30 minutes. WORST CASE SCENARIO: A stronger, stalled out thunderstorm is able to develop and will have the potential to produce up to 2.40” total, in 45-60 minutes. A LOOK AHEAD: A slight decrease in overall moisture in the area tomorrow will slightly decrease the heavy rainfall threat. Storm chances will be similar to today, between 2-10pm with west to east storm movements between 15-25mph which once again should help limit point rainfall amounts. At least a low chance will likely remain for Message 1’s to be issued. Less chances for afternoon/eve showers/thunderstorms Friday with slightly warmer high temperatures around 90 degrees. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 200 PM TO 1000 PM 0.25" (65%) to 0.75" (35%) to 1.25" (15%) MOD Arapahoe 200 PM TO 1000 PM 0.25" (60%) to 0.75" (30%) to 1.25" (10%) MOD Boulder 200 PM TO 1000 PM 0.25" (70%) to 0.75" (40%) to 1.25" (20%) HIGH Broomfield 200 PM TO 1000 PM 0.25" (65%) to 0.75" (35%) to 1.25" (15%) MOD Denver 200 PM TO 1000 PM 0.25" (60%) to 0.75" (30%) to 1.25" (10%) MOD Douglas 200 PM TO 1000 PM 0.25" (60%) to 0.75" (30%) to 1.25" (10%) MOD Jefferson 200 PM TO 1000 PM 0.25" (65%) to 0.75" (35%) to 1.25" (15%) MOD Foothills above 6500ft Douglas 200 PM TO 1000 PM 0.25" (60%) to 0.75" (30%) to 1.25" (10%) MOD Jefferson 200 PM TO 1000 PM 0.25" (70%) to 0.75" (40%) to 1.25" (15%) HIGH Boulder 100 PM TO 900 PM 0.25" (75%) to 0.75" (50%) to 1.25" (20%) HIGH MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 953 PM Tue August 1, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2’S HAVE BEEN RESCNIDED/MESSAGE 4'S (ALL CLEAR) ISSUED The NWS has cancelled the Flood Watch as the threat of heavy rainfall has come to an end. A few lingering sprinkles/light rain persists over northern portions of the District and will be tapering off over the next hour or two. No additional showers are expected through the overnight. STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce a TR-0.2" total in 10-30 minutes. WORST CASE SCENARIO: A weak thunderstorm has the potential to produce 0.2-0.4" total in 10-30 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 1159 PM TUE Trace (30%) to 0.2" (15%) to 0.4" (5%) NONE Arapahoe Current TO 1159 PM TUE Trace (20%) to 0.2" (10%) to 0.4" (5%) NONE Boulder Current TO 1159 PM TUE Trace (30%) to 0.2" (15%) to 0.4" (5%) NONE Broomfield Current TO 1159 PM TUE Trace (30%) to 0.2" (15%) to 0.4" (5%) NONE Denver Current TO 1159 PM TUE Trace (25%) to 0.2" (15%) to 0.4" (5%) NONE Douglas Current TO 1159 PM TUE Trace (20%) to 0.2" (10%) to 0.4" (5%) NONE Jefferson Current TO 1159 PM TUE Trace (20%) to 0.2" (10%) to 0.4" (5%) NONE Foothills above 6500ft Boulder Current TO 1159 PM TUE Trace (30%) to 0.2" (15%) to 0.4" (5%) NONE Douglas Current TO 1159 PM TUE Trace (20%) to 0.2" (10%) to 0.4" (5%) NONE Jefferson Current TO 1159 PM TUE Trace (20%) to 0.2" (10%) to 0.4" (5%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 647 PM Tue August 1, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2’S CONTINUE VALID UNTIL MIDNIGHT Message 2’s will remain valid until midnight, although the strongest storm development has moved well east of the District at this time. A few showers persist towards the northwestern portions of the District and will continue to slowly progress eastward over the next few hours. Rainfall rates have decreased, however elevated surface dew points suggest even moderate showers can produce brief heavy rainfall. Storms should gradually weaken through the rest of the evening, with off and on light showers possible through the overnight. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers, weak thunderstorms will produce a 0.05-0.25” total in 10-30 minute. A moderate to strong thunderstorm will produce 0.25-1.00” total in 10-30 minutes. WORST CASE SCENARIO: A strong, anchored thunderstorm will have the potential to produce 2.00” in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Lakewood 2 Current TO 1159 PM Current TO 1159 PM Wheat Ridge 2 Current TO 1159 PM Current TO 1159 PM Arvada 2 Current TO 1159 PM Current TO 1159 PM the City of Aurora 2 Current TO 1159 PM Current TO 1159 PM Arapahoe County 2 Current TO 1159 PM Current TO 1159 PM DIA 2 Current TO 1159 PM Current TO 1159 PM Denver County 2 Current TO 1159 PM Current TO 1159 PM Adams County 2 Current TO 1159 PM Current TO 1159 PM Douglas County 2 Current TO 1159 PM Current TO 1159 PM Broomfield County 2 Current TO 1159 PM Current TO 1159 PM Jefferson County 2 Current TO 1159 PM Current TO 1159 PM Boulder County 2 Current TO 1159 PM Current TO 1159 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Arapahoe Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Boulder Current TO 1159 PM TUE 0.05" (60%) to 0.25" (30%) to 1" (15%) ISSUED Broomfield Current TO 1159 PM TUE 0.05" (60%) to 0.25" (30%) to 1" (15%) ISSUED Denver Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Douglas Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Jefferson Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Foothills above 6500ft Boulder Current TO 1159 PM TUE 0.05" (60%) to 0.25" (30%) to 1" (15%) ISSUED Douglas Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED Jefferson Current TO 1159 PM TUE 0.05" (50%) to 0.25" (25%) to 1" (10%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 1217 PM Tue August 1, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2'S HAVE BEEN ISSUED FOR THE ENTIRE DISTRICT AND WILL BE VALID UNTIL MIDNIGHT Message 2’s (NWS Flood/Flash Flood Watch) have been issued for the entire District and will be valid until midnight tonight. Cool temperatures with readings in the upper 70’s to lower 80’s currently is holding back the initiation of thunderstorms due to cloud cover this morning slowing daytime heating. Clouds have dissipated and good warming is underway, and thunderstorms are expected to develop over the next 1-3 hours and begin to impact the District later this afternoon and continue well into the evening with multiple rounds of showers and thunderstorms possible. Thunderstorms that develop later this afternoon and evening have ample moisture to work with and will be very capable of producing heavy rainfall that may lead to excessive runoff and flash flooding within the District. Storms will be faster moving today as upper level winds have increased with typical storm motions of around 20mph from SW to NE. Slower moving large thunderstorms or training of thunderstorm cells are the likely culprits for extended periods of heavy rainfall. Due to all of the rain yesterday it may not take as much rain today to produce excessive runoff and flash flooding. Heavy rainfall will be the primary threat from thunderstorms today, but large hail and gusty winds are also possible from stronger storms. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce rainfall rates of 0.2-0.8” in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.8-2.0” of rain in 10-30 minutes. WORST CASE SCENARIO: A slow moving strong thunderstorm or training of thunderstorm cells may result in up to 3.5” of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Lakewood 2 Current TO 1159 PM 300 PM TO 1000 PM Wheat Ridge 2 Current TO 1159 PM 300 PM TO 1000 PM Arvada 2 Current TO 1159 PM 300 PM TO 1000 PM the City of Aurora 2 Current TO 1159 PM 300 PM TO 1000 PM Arapahoe County 2 Current TO 1159 PM 300 PM TO 1000 PM DIA 2 Current TO 1159 PM 300 PM TO 1000 PM Denver County 2 Current TO 1159 PM 300 PM TO 1000 PM Adams County 2 Current TO 1159 PM 300 PM TO 1000 PM Douglas County 2 Current TO 1159 PM 200 PM TO 1000 PM Broomfield County 2 Current TO 1159 PM 300 PM TO 1000 PM Jefferson County 2 Current TO 1159 PM 200 PM TO 1000 PM Boulder County 2 Current TO 1159 PM 200 PM TO 1000 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 300 PM TO 1159 PM 0.5" (75%) to 1" (50%) to 2" (25%) ISSUED Arapahoe 300 PM TO 1159 PM 0.5" (80%) to 1" (50%) to 2" (30%) ISSUED Boulder 300 PM TO 1159 PM 0.5" (75%) to 1" (50%) to 2" (25%) ISSUED Broomfield 300 PM TO 1159 PM 0.5" (75%) to 1" (50%) to 2" (25%) ISSUED Denver 200 PM TO 1159 PM 0.5" (75%) to 1" (50%) to 2" (25%) ISSUED Douglas 200 PM TO 1159 PM 0.5" (80%) to 1" (50%) to 2" (30%) ISSUED Jefferson 200 PM TO 1159 PM 0.5" (75%) to 1" (50%) to 2" (25%) ISSUED Foothills above 6500ft Boulder 100 PM TO 1159 PM 0.5" (80%) to 1" (50%) to 2" (25%) ISSUED Douglas 100 PM TO 1159 PM 0.5" (80%) to 1" (50%) to 2" (25%) ISSUED Jefferson 100 PM TO 1159 PM 0.5" (80%) to 1" (50%) to 2" (25%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 932 AM Tue August 1, 2023 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HEAVY RAINFALL PRODUCING THUNDERSTRMS TO IMPACT THE DISTRICT AGAIN THIS AFTERNOON AND EVENING/MESSAGE 2'S WILL BE ISSUED AROUND NOON Heavy rainfall producing thunderstorms impacted the District yesterday and a repeat performance is expected today. The high risk of heavy rainfall has resulted in the NWS issuing a Flood/Flash Flood Watch for the entire District from noon to midnight. Message 2’s will be issued by noon and will be valid until midnight but the best chance for thunderstorms looks to be through about 10:00 PM this evening. Thunderstorms will first develop over the mountains and foothills between 11:00 AM and 1:00 PM. Upper level steering winds from the SW will push storms onto the plains between 1:00-3:00 PM. Prime time for thunderstorms will be between 2:00-10:00 PM with multiple rounds of thunderstorms possible. After 10:00 PM the threat for stronger thunderstorms will diminish with additional weaker thunderstorms and light rain showers possible beyond midnight. The upper level steering winds are stronger than yesterday at 20-25mph and the storms should be faster moving but strong thunderstorms may move more slowly or against the grain and produce extended periods of heavy rain. Training of thunderstorm cells is another potential culprit for longer duration heavy rainfall that may lead to excessive runoff and flash flooding. Strong thunderstorms may also contain gusty winds and large hail. Temperatures will be a little cooler today with afternoon highs in the mid to possibly upper 80’s over the plains. The cooler temperatures may hinder storm strength slightly but widespread to numerous thunderstorms are expected regardless of temperature. Due to all of the rainfall yesterday it may not take as much rain today to produce excessive runoff and flooding. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce rainfall rates of 0.2-0.8” in 10-30 minutes. Strong thunderstorms will have the potential to produce 0.8-2.0” of heavy rain in 10-30 minutes. WORST CASE SCENARIO: A slow moving large thunderstorm or training of strong thunderstorm cells may result in up to 3.5” of rain in 60-90 minutes. A LOOK AHEAD: Another high risk day for heavy rainfall producing thunderstorms on Wednesday but storms will likely be less numerous. The storms that do form will have attributes similar to the storms that form today. A decrease in thunderstorm coverage and intensity is expected Thursday and Friday but there will still be modest chances for afternoon thunderstorms and stronger storms will still have the potential to produce heavy rain. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 200 PM TO 1000 PM 0.5" (75%) to 1" (50%) to 2" (25%) HIGH Arapahoe 200 PM TO 1000 PM 0.5" (80%) to 1" (60%) to 2" (30%) HIGH Broomfield 200 PM TO 1000 PM 0.5" (75%) to 1" (50%) to 2" (25%) HIGH Denver 200 PM TO 1000 PM 0.5" (75%) to 1" (50%) to 2" (25%) HIGH Boulder 100 PM TO 1000 PM 0.5" (75%) to 1" (50%) to 2" (25%) HIGH Douglas 100 PM TO 1000 PM 0.5" (80%) to 1" (60%) to 2" (30%) HIGH Jefferson 100 PM TO 1000 PM 0.5" (75%) to 1" (50%) to 2" (25%) HIGH Foothills above 6500ft Boulder 1200 PM TO 1000 PM 0.5" (80%) to 1" (60%) to 2" (25%) HIGH Douglas 1200 PM TO 1000 PM 0.5" (80%) to 1" (60%) to 2" (25%) HIGH Jefferson 1200 PM TO 1000 PM 0.5" (80%) to 1" (60%) to 2" (25%) HIGH MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 1119 PM Mon July 31, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2’S WILL BE ALLOWED TO EXPIRE AT 11:59 PM Message 2’s will be allowed to expire at 11:59pm as the threat of heavy rainfall has come to an end. A few lingering showers/isolated thunderstorms surround the District currently, however, storm strengths have diminished at this time and should continue to weaken through the rest of the overnight. The best chance for additional showers/isolated thunderstorms will be from now through 4am. A few lingering showers will be possible through daybreak tomorrow, generally areas east of the District and onto the eastern plains. Lots of moisture hanging around the surface from today’s rainfall will bring a chance for patchy fog tomorrow morning. Skies should clear through the morning with another good chance for heavy rainfall tomorrow from noon to midnight as another Flood Watch will be in effect. Overnight lows will dip into the upper 50’s to low 60’s. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers/isolated thunderstorms will produce a TR-0.25” total in 10-30 minutes. A moderate thunderstorm could produce 0.25-0.50” total in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm, or training of moderate thunderstorms has the potential to produce 0.5-1.0” in 45-60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 2 Current TO 1159 PM Current TO 1159 PM Jefferson County 2 Current TO 1159 PM Current TO 1159 PM Broomfield County 2 Current TO 1159 PM Current TO 1159 PM Douglas County 2 Current TO 1159 PM Current TO 1159 PM Adams County 2 Current TO 1159 PM Current TO 1159 PM Denver County 2 Current TO 1159 PM Current TO 1159 PM DIA 2 Current TO 1159 PM Current TO 1159 PM Arapahoe County 2 Current TO 1159 PM Current TO 1159 PM the City of Aurora 2 Current TO 1159 PM Current TO 1159 PM Arvada 2 Current TO 1159 PM Current TO 1159 PM Wheat Ridge 2 Current TO 1159 PM Current TO 1159 PM Lakewood 2 Current TO 1159 PM Current TO 1159 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Arapahoe Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Boulder Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Broomfield Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Denver Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Douglas Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Jefferson Current TO 600 AM TUE Trace (60%) to 0.25" (30%) to 0.5" (15%) ISSUED Foothills above 6500ft Boulder Current TO 600 AM TUE Trace (50%) to 0.25" (25%) to 0.5" (10%) ISSUED Douglas Current TO 600 AM TUE Trace (50%) to 0.25" (25%) to 0.5" (10%) ISSUED Jefferson Current TO 600 AM TUE Trace (50%) to 0.25" (25%) to 0.5" (10%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

1 year, 4 months

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