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

by f2p2＠udfcd.org

Time: 1208 AM Sat June 3, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID UNTIL 2:00 AM SATURDAY Message 1’s will continue valid until 2:00 AM Saturday as moderate to brief heavy rain still lingers over southern areas of the District. A boundary pushed back to the west into the District and produced thunderstorms with moderate heavy rainfall over the past few hours. These thunderstorms have peaked in intensity and are now weak to moderate for areas S of I-70. The weakening trend and southern progression of the rain is expected to continue over the next 1-2 hours and Messages will likely be allowed to expire. Additional rain showers will likely re-develop after 2:00 AM and persist into daybreak Saturday but are expected to be light in intensity. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. A moderate to strong thunderstorm may result in rainfall rates of 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A moderate to strong stationary thunderstorm may result in up to 1.6” in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 200 AM Current TO 100 AM Jefferson County 1 Current TO 200 AM Current TO 100 AM Broomfield County 1 Current TO 200 AM Current TO 100 AM Douglas County 1 Current TO 200 AM Current TO 100 AM Adams County 1 Current TO 200 AM Current TO 100 AM Denver County 1 Current TO 200 AM Current TO 100 AM DIA 1 Current TO 200 AM Current TO 100 AM Arapahoe County 1 Current TO 200 AM Current TO 100 AM the City of Aurora 1 Current TO 200 AM Current TO 100 AM Arvada 1 Current TO 200 AM Current TO 100 AM Wheat Ridge 1 Current TO 200 AM Current TO 100 AM Lakewood 1 Current TO 200 AM Current TO 100 AM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 200 AM SAT 0.1" (40%) to 0.3" (20%) to 0.8" (10%) ISSUED Arapahoe Current TO 200 AM SAT 0.1" (90%) to 0.3" (50%) to 0.8" (20%) ISSUED Boulder Current TO 200 AM SAT 0.1" (40%) to 0.3" (20%) to 0.8" (10%) ISSUED Broomfield Current TO 200 AM SAT 0.1" (40%) to 0.3" (20%) to 0.8" (10%) ISSUED Denver Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (15%) ISSUED Douglas Current TO 200 AM SAT 0.1" (100%) to 0.3" (60%) to 0.8" (30%) ISSUED Jefferson Current TO 200 AM SAT 0.1" (90%) to 0.3" (50%) to 0.8" (20%) ISSUED Foothills above 6500ft Boulder Current TO 200 AM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (10%) ISSUED Douglas Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (15%) ISSUED Jefferson Current TO 200 AM SAT 0.1" (60%) to 0.3" (30%) to 0.8" (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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 930 PM Fri June 2, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S HAVE BEEN RE-ISSUED AND WILL BE VALID UNTIL 2:00 AM SATURDAY Message 1’s will be allowed to expire as the threat for heavy rainfall has ended at least temporarily. A boundary has pushed back to the west into the District and thunderstorms are developing at this time over parts of Jefferson County. Elevated surface moisture levels will allow storms to be able to produce heavy rain that may lead to excessive runoff. Storms will most likely be pulse-like and move very little from their initiation point. The slow moving nature of the storms may allow for extended periods of moderate to heavy rainfall. Best chances for thunderstorms will be over the next 3-4 hours then precipitation should favor light non-thunderstorm rain showers into Saturday morning. STORM RAINFALL POTENTIAL AND DURATION: Weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. A moderate to strong thunderstorm may result in rainfall rates of 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A moderate to strong stationary thunderstorm may result in up to 1.6” in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME the City of Aurora 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Arapahoe County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY DIA 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Denver County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Douglas County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Adams County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Broomfield County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Arvada 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Jefferson County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Boulder County 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Wheat Ridge 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY Lakewood 1 Current TO 200 AM SATURDAY Current TO 100 AM SATURDAY County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 200 AM SAT 0.1" (90%) to 0.3" (60%) to 0.8" (30%) ISSUED Arapahoe Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Boulder Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Broomfield Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Denver Current TO 200 AM SAT 0.1" (90%) to 0.3" (60%) to 0.8" (30%) ISSUED Douglas Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Jefferson Current TO 200 AM SAT 0.1" (90%) to 0.3" (60%) to 0.8" (30%) ISSUED Foothills above 6500ft Boulder Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Douglas Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) ISSUED Jefferson Current TO 200 AM SAT 0.1" (80%) to 0.3" (40%) to 0.8" (20%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 723 PM Fri June 2, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL BE ALLOWED TO EXPIRE AT 8:00 PM/RAIN SHOWERS EXPECTED TO BUILD IN OVERNIGHT AND A THUNDERSTORM CANNOT BE RULED OUT Message 1’s will be allowed to expire as the threat for heavy rainfall has ended at least temporarily. Conditions are expected to be generally dry this evening but if an outflow boundary from storms to the E or S of the District pushes through new storm development may occur and Message 1’s could be re-issued. Rain showers are expected to build in overnight after midnight and likely linger into Saturday morning with possibly an isolated thunderstorm. Precipitation overnight will remain light as long as thunderstorms do not develop. Rain showers and isolated to widely scattered thunderstorms are expected to increase in coverage Saturday morning as the low pressure system will be to our east and “upslope” flow will be in place along the I-25 corridor. Moisture will increase and thunderstorms will be capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. If temperatures remain too cool precipitation may favor general light to moderate rain showers versus thunderstorms. Either way a wet day is in store for Saturday and Message 1’s will likely be issued by noon or before. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3” of rain in 10-30 minutes. WORST CASE SCENARIO: Should a moderate to strong thunderstorm develop rainfall rates of 0.3-0.8” in 10-30 minutes is possible and up to 1.5” in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM Current TO 730 PM Jefferson County 1 Current TO 800 PM Current TO 730 PM Broomfield County 1 Current TO 800 PM Current TO 730 PM Douglas County 1 Current TO 800 PM Current TO 730 PM Adams County 1 Current TO 800 PM Current TO 730 PM Denver County 1 Current TO 800 PM Current TO 730 PM DIA 1 Current TO 800 PM Current TO 730 PM Arapahoe County 1 Current TO 800 PM Current TO 730 PM the City of Aurora 1 Current TO 800 PM Current TO 730 PM Arvada 1 Current TO 800 PM Current TO 730 PM Wheat Ridge 1 Current TO 800 PM Current TO 730 PM Lakewood 1 Current TO 800 PM Current TO 730 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Arapahoe Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Boulder Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Broomfield Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Denver Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Douglas Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Jefferson Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Foothills above 6500ft Boulder Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Douglas Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW Jefferson Current TO 900 AM SAT Trace (90%) to 0.1" (60%) to 0.3" (20%) LOW 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 457 PM Fri June 2, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID/HEAVY RAINFALL THREAT RAPIDLY DECREASING/ALL CLEAR MAY BE ISSUED NEXT 1-2 HOURS Message 1’s continue valid until 8:00pm but the threat for heavy rainfall is rapidly diminishing as drier air is working its way into the District. An outflow boundary from storms outside the District may push back into the District and increase moisture and supply a trigger for new storms but the threat for this situation to play out is quite low. Isolated light rain showers will be the most likely outcome for the rest of the afternoon and evening resulting in Message 4’s (All Clear) possibly being issued over the next 1-2 hours. Rain showers and isolated to widely scattered thunderstorms are expected to increase in coverage on Saturday as the low pressure system will be to our east and “upslope” flow will be in place along the I-25 corridor. Moisture will increase and thunderstorms will be capable of producing heavy rainfall. If temperatures remain too cool precipitation may favor general rain showers versus thunderstorms. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak to moderate thunderstorms will produce a trace to 0.2" of rain. Moderate thunderstorms will have the potential to produce rainfall rates of 0.2-0.5” in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm is able to develop with the potential to produce brief heavy rainfall of 0.3-0.8" in 10-30 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM Current TO 700 PM Jefferson County 1 Current TO 800 PM Current TO 700 PM Broomfield County 1 Current TO 800 PM Current TO 700 PM Douglas County 1 Current TO 800 PM Current TO 700 PM Adams County 1 Current TO 800 PM Current TO 700 PM Denver County 1 Current TO 800 PM Current TO 700 PM DIA 1 Current TO 800 PM Current TO 700 PM Arapahoe County 1 Current TO 800 PM Current TO 700 PM the City of Aurora 1 Current TO 800 PM Current TO 700 PM Arvada 1 Current TO 800 PM Current TO 700 PM Wheat Ridge 1 Current TO 800 PM Current TO 700 PM Lakewood 1 Current TO 800 PM Current TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 800 PM FRI Trace (50%) to 0.2" (20%) to 0.5" (10%) ISSUED Arapahoe Current TO 800 PM FRI Trace (50%) to 0.2" (20%) to 0.5" (10%) ISSUED Boulder Current TO 800 PM FRI Trace (50%) to 0.2" (20%) to 0.5" (10%) ISSUED Broomfield Current TO 800 PM FRI Trace (50%) to 0.2" (20%) to 0.5" (10%) ISSUED Denver Current TO 800 PM FRI Trace (50%) to 0.2" (20%) to 0.5" (10%) ISSUED Douglas Current TO 800 PM FRI Trace (65%) to 0.2" (30%) to 0.5" (10%) ISSUED Jefferson Current TO 800 PM FRI Trace (60%) to 0.2" (30%) to 0.5" (10%) ISSUED Foothills above 6500ft Boulder Current TO 800 PM FRI Trace (75%) to 0.2" (40%) to 0.5" (10%) ISSUED Douglas Current TO 800 PM FRI Trace (75%) to 0.2" (40%) to 0.5" (10%) ISSUED Jefferson Current TO 800 PM FRI Trace (75%) to 0.2" (40%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 1220 PM Fri June 2, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT Message 1’s have been issued for the entire District and will be valid until 8:00pm this evening. Once again storms have initiated along the higher terrain and are slowly moving onto the plains at this time. Temperatures have remained in the mid to upper 60’s which should help suppress stronger storm development this afternoon. Dew points are currently in the mid to upper 40’s resulting in even moderate thunderstorms to produce heavy rainfall. The best chance for showers and thunderstorms will be from NOW until 8pm with lingering rain showers possible through midnight. Storm motions today will continue from the S/SE to N/NE for the most part, with additional storms likely forming along outflow boundaries. These outflow storms will likely have the highest chance of bringing localized heavy rainfall as the storm movements will be non-existent at times. There could be multiple rounds of storms today, however the initial round should have highest chance for impactful rain showers, with additional rounds likely becoming much weaker into the evening hours. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.7” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.4” of rain in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM Current TO 700 PM Jefferson County 1 Current TO 800 PM Current TO 700 PM Broomfield County 1 Current TO 800 PM Current TO 700 PM Douglas County 1 Current TO 800 PM Current TO 700 PM Adams County 1 Current TO 800 PM Current TO 700 PM Denver County 1 Current TO 800 PM Current TO 700 PM DIA 1 Current TO 800 PM Current TO 700 PM Arapahoe County 1 Current TO 800 PM Current TO 700 PM the City of Aurora 1 Current TO 800 PM Current TO 700 PM Arvada 1 Current TO 800 PM Current TO 700 PM Wheat Ridge 1 Current TO 800 PM Current TO 700 PM Lakewood 1 Current TO 800 PM Current TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Arapahoe Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Boulder Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Broomfield Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Denver Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Douglas Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Jefferson Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Foothills above 6500ft Boulder Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Douglas Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) ISSUED Jefferson Current TO 800 PM FRI 0.1" (80%) to 0.3" (40%) to 0.7" (20%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 827 AM Fri June 2, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- MOSTLY SUNNY AND MILD CURRENTLY WITH ANOTHER CHANCE FOR AFTERNOON AND EVENING SHOWERS/THUNDERSTORMS A minimal change to the overall pattern today as an active weather pattern has stalled out of the Colorado region and will continue to do so over the next several days. A few dynamics have changed for today with slightly more sunshine this morning, with slightly lower dew points at the surface than yesterday which are currently in the mid to upper 40’s. However, the added sunshine will suggest a better chance for daytime heating leading to the possibility for stronger storms, especially along the far eastern plains. Dew points are slightly less, which could help limit heavier rainfall if they are able to drop into the low to mid 40’s this afternoon. Showers and thunderstorms are expected to initiate along the higher terrain around midday with the best chance for impactful storms in the District between 1-9pm. Storm motions will generally be south to north between 5-10mph, with erratic storm motions likely for storms formed along outflow boundaries. These outflow storms will also have the highest chance for localized heavy rainfall, with the largest threat today being a quick 0.5” in 10-15min, rather than any long-lasting heavy rainfall. However, a long-lasting heavy shower cannot be completely ruled out if a stronger storm can anchor for an extended period today. Similar to yesterday/last night, another chance for some isolated overnight rain showers with a few rumbles of thunder will be possible; however, the threat of heavy rainfall should subside later this evening. Overnight lows will drop into the upper 40’s to low 50’s on the plains with mid 40’s along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.7” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm formed along an outflow boundary may result in up to 1.4” of rain in 45-75 minutes. A LOOK AHEAD: Cooler and cloudy tomorrow will result in temperatures playing a big part in the heavy rainfall threat as temperatures are not expected to reach 70 degrees. This should help limit stronger storm development as minimal sunshine expected to enhance daytime heating. A good chance will remain for showers and an isolated thunderstorm with likely a LOW to MOD chance for Message 1’s to be issued since an abundance of moisture will be available both at the surface and aloft. These conditions remain in place Sunday with another chance for shower activity throughout the day, once again hinging on whether or not there is enough daytime heating to get stronger storms to develop. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (15%) MOD Arapahoe 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (15%) MOD Boulder 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (10%) LOW Broomfield 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (10%) LOW Denver 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (10%) LOW Douglas 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (15%) MOD Jefferson 100 PM TO 900 PM 0.1" (70%) to 0.3" (35%) to 0.7" (10%) LOW Foothills above 6500ft Douglas 100 PM TO 900 PM 0.1" (75%) to 0.3" (50%) to 0.7" (15%) MOD Jefferson 100 PM TO 900 PM 0.1" (75%) to 0.3" (50%) to 0.7" (15%) MOD Boulder 1200 PM TO 800 PM 0.1" (75%) to 0.3" (50%) to 0.7" (15%) MOD 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 815 PM Thu June 1, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL BE ALLOWED TO EXPIRE AT 9:00 PM/ADDITIONAL RAIN SHOWERS LIKELY OVERNIGHT Message 1’s will be allowed to expire at 9:00pm as the threat of heavy rainfall has ended for the day. Additional rain showers and possibly a weak thunderstorm over the foothills will continue possible into the overnight period as an upper level low pressure system churns near the 4-Corners. Thunderstorms are not expected as temperatures are cooling and the atmosphere is becoming more stable. Chances for rain showers will persist past midnight with dry conditions expected by daybreak tomorrow. More showers and thunderstorms are expected to develop on Friday with stronger storms having the potential to produce brief heavy rain and hail. Active weather pattern will continue over the upcoming weekend into early next week with below normal temperatures. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and possibly a weak thunderstorm will produce a trace to 0.3” of rain. COUNTY MESSAGE VALID TIMES PRIME TIME Adams County 1 1200 PM TO 900 PM 100 PM TO 830 PM Denver County 1 1200 PM TO 900 PM 100 PM TO 830 PM DIA 1 1200 PM TO 900 PM 100 PM TO 830 PM Arapahoe County 1 1200 PM TO 900 PM 100 PM TO 830 PM the City of Aurora 1 1200 PM TO 900 PM 100 PM TO 830 PM Arvada 1 1200 PM TO 900 PM 100 PM TO 830 PM Wheat Ridge 1 1200 PM TO 900 PM 100 PM TO 830 PM Broomfield County 1 1200 PM TO 900 PM 100 PM TO 830 PM Lakewood 1 1200 PM TO 900 PM 100 PM TO 830 PM Douglas County 1 1200 PM TO 900 PM 100 PM TO 830 PM Jefferson County 1 1200 PM TO 900 PM 100 PM TO 830 PM Boulder County 1 1200 PM TO 900 PM 100 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Arapahoe Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Boulder Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Broomfield Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Denver Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Douglas Current TO 400 AM FRI Trace (90%) to 0.1" (50%) to 0.3" (15%) ISSUED Jefferson Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Foothills above 6500ft Boulder Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) ISSUED Douglas Current TO 400 AM FRI Trace (90%) to 0.1" (60%) to 0.3" (20%) ISSUED Jefferson Current TO 400 AM FRI Trace (80%) to 0.1" (40%) to 0.3" (15%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 408 PM Thu June 1, 2023 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL CONTINUE VALID Message 1’s will continue valid until 9pm this evening. The first round of moderate to strong thunderstorms is currently exiting the District to the east with additional showers and thunderstorms expected to develop over the next few hours. Moderate to strong thunderstorms will still be capable of producing brief heavy rainfall that may lead to excessive runoff. Stronger thunderstorms may also produce hail. Storm motions are relatively slow from SW to NE at 10-15mph. The slow storm motions will allow for extended periods of moderate to heavy rain under thunderstorms. Best chances for additional storms will be through 8-9pm then drier conditions are expected to develop for the later evening and overnight period. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.6” of rain in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 1200 PM TO 900 PM 100 PM TO 830 PM Jefferson County 1 1200 PM TO 900 PM 100 PM TO 830 PM Broomfield County 1 1200 PM TO 900 PM 100 PM TO 830 PM Douglas County 1 1200 PM TO 900 PM 100 PM TO 830 PM Adams County 1 1200 PM TO 900 PM 100 PM TO 830 PM Denver County 1 1200 PM TO 900 PM 100 PM TO 830 PM DIA 1 1200 PM TO 900 PM 100 PM TO 830 PM Arapahoe County 1 1200 PM TO 900 PM 100 PM TO 830 PM the City of Aurora 1 1200 PM TO 900 PM 100 PM TO 830 PM Arvada 1 1200 PM TO 900 PM 100 PM TO 830 PM Wheat Ridge 1 1200 PM TO 900 PM 100 PM TO 830 PM Lakewood 1 1200 PM TO 900 PM 100 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Arapahoe Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Boulder Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Broomfield Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Denver Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Douglas Current TO 900 PM THU 0.1" (80%) to 0.3" (60%) to 0.8" (20%) ISSUED Jefferson Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Foothills above 6500ft Boulder Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) ISSUED Douglas Current TO 900 PM THU 0.1" (80%) to 0.3" (60%) to 0.8" (20%) ISSUED Jefferson Current TO 900 PM THU 0.1" (75%) to 0.3" (50%) to 0.8" (15%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 1129 AM Thu June 1, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT Message 1’s have been issued for the entire District and will be valid until 9:00pm this evening. Storm have initiated along the higher terrain at this time and should move into the District in the next hour or two. Currently temperatures have been fairly suppressed with upper 50’s to low 60’s across the District. These cooler temperatures could help limit storm strength heading into this afternoon, however, with this approaching disturbance, combined with dew points currently in the low 50’s, there will be a good chance for moderate to heavy rainfall this afternoon and evening even out of weak to moderate thunderstorms. The best chance for showers and thunderstorms will be from 1-9pm with lingering rain showers possible through midnight. Storm motions today will continue from the S/SW to N/NE for the most part, with additional storms likely forming along outflow boundaries. These outflow storms will likely have the highest chance of bringing localized heavy rainfall as the storm movements will be non-existent at times. There will be multiple rounds of storms possible today as well, however the initial round should have highest chance for impactful rain showers, with additional rounds likely becoming much weaker into the evening hours. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.6” of rain in 45-75 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 1200 PM TO 900 PM 100 PM TO 830 PM Jefferson County 1 1200 PM TO 900 PM 100 PM TO 830 PM Broomfield County 1 1200 PM TO 900 PM 100 PM TO 830 PM Douglas County 1 1200 PM TO 900 PM 100 PM TO 830 PM Adams County 1 1200 PM TO 900 PM 100 PM TO 830 PM Denver County 1 1200 PM TO 900 PM 100 PM TO 830 PM DIA 1 1200 PM TO 900 PM 100 PM TO 830 PM Arapahoe County 1 1200 PM TO 900 PM 100 PM TO 830 PM the City of Aurora 1 1200 PM TO 900 PM 100 PM TO 830 PM Arvada 1 1200 PM TO 900 PM 100 PM TO 830 PM Wheat Ridge 1 1200 PM TO 900 PM 100 PM TO 830 PM Lakewood 1 1200 PM TO 900 PM 100 PM TO 830 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Arapahoe 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Boulder 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Broomfield 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Denver 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Douglas 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Jefferson 1200 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) ISSUED Foothills above 6500ft Boulder 1200 PM TO 900 PM 0.1" (90%) to 0.3" (80%) to 0.8" (40%) ISSUED Douglas 1200 PM TO 900 PM 0.1" (90%) to 0.3" (80%) to 0.8" (40%) ISSUED Jefferson 1200 PM TO 900 PM 0.1" (90%) to 0.3" (80%) to 0.8" (40%) 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, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 854 AM Thu June 1, 2023 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ISOLATED SHOWERS THIS MORNING WITH THUNDERSTORMS LIKELY THIS AFTERNOON AND EVENING Cloudy and cool this morning with a few scattered showers, favoring areas north of I-70 at this time. These showers should slowly move northward through the morning before another round of afternoon thunderstorms with showers/isolated thunderstorms likely continuing into the evening. Similar to yesterday, storms will move from south to north between 5-15mph, with some erratic storm motions possible as storms form along outflow boundaries. These erratic storms will have the best opportunity for longer lasting moderate to heavy rainfall today as they generally anchor in place for an extended period of time. The best chance for impactful storms will be between 2-8pm with some lingering light to moderate showers likely through midnight. Typical weak to moderate thunderstorms this afternoon will produce light to moderate rain and gusty winds. Stronger thunderstorms will be capable of producing brief heavy rainfall and may become severe with large hail and winds in excess of 50mph. Overnight lows will drop into the upper 40’s to low 50’s on the plains with low to mid 40’s along the higher terrain and into the foothills. A few off and on light showers will be possible into daybreak Friday, however there is currently no threat for heavy rainfall through the overnight hours. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes. WORST CASE SCENARIO: A nearly stationary strong thunderstorm formed along an outflow boundary may result in up to 1.6” of rain in 45-75 minutes. A LOOK AHEAD: This active weather pattern will continue Friday bringing another decent chance for showers and thunderstorms Friday with at least a LOW chance for isolated heavy rainfall. Similar conditions remain in place on Saturday. However, daytime temperatures will dictate the storm intensities as mostly cloudy and off and on rain showers will likely impact the District throughout the day. If we do see enough sunshine during the day, chances will increase of a heavy rainfall threat. This pattern holds Sunday with another good chance for off and on rain showers throughout most of the day Sunday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Adams 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Arapahoe 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Boulder 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Broomfield 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Denver 200 PM TO 800 PM 0.1" (80%) to 0.3" (60%) to 0.8" (30%) MOD Douglas 200 PM TO 800 PM 0.1" (70%) to 0.3" (50%) to 0.8" (20%) MOD Jefferson 200 PM TO 800 PM 0.1" (70%) to 0.3" (50%) to 0.8" (20%) MOD Foothills above 6500ft Boulder 200 PM TO 800 PM 0.1" (90%) to 0.3" (80%) to 0.8" (40%) MOD Douglas 200 PM TO 800 PM 0.1" (70%) to 0.3" (60%) to 0.8" (20%) MOD Jefferson 200 PM TO 800 PM 0.1" (80%) to 0.3" (70%) to 0.8" (30%) MOD 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, 6 months

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