May 2021 - hpo-ims - Udfcd-Lists.Org

by f2p2＠udfcd.org

Time: 920 AM Mon May 3, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- COOLER TODAY WITH WIDESPREAD RAIN/MIX THIS MORNING WITH A CHANCE FOR SCATTERED RAIN SHOWERS THIS AFTERNOON/EVENING - A low-pressure system continues to churn over the region bringing widespread rain showers and mix/snow between 5,500-6,000ft with generally snow above 6,000ft at this time. As temperatures increase through the morning into the 40's lower elevations, the snow line will rise and most areas below 7,000ft will experience rain by noon. Typical rainfall amounts or melted snow equivalent is between a 0.04-0.20". - The best chance for accumulating precipitation will be until 4pm with a chance for lingering isolated rain showers after 4pm until about midnight before precipitation chances come to and end. As the evening progresses, the snow line will lower again to around 6,000ft between 8pm and midnight, although precipitation chances will be minimal at that time. After midnight skies will gradually clear with dry conditions expected into Tuesday morning. - If we get some peeks of sunshine afternoon an isolated thunderstorm cannot be completely ruled out and would have the potential to produce 0.2-0.6" in 10-30minutes. Between 0.75-2.00" of moisture has fallen over the District over the past 24 hours with isolated higher and lower amounts. Smaller creeks and streams will be running highs today as the ground is becoming saturated and additional moisture will easily produce runoff. Flash flooding is not expected. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and possibly a weak thunderstorm this afternoon will produce TR-0.20" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.20-0.40" in 30-60 minutes. WORST CASE SCENARIO: A thunderstorm is able to develop this afternoon and would be capable of producing 0.20-0.60" in 10-30 minutes. A LOOK AHEAD: An active pattern will persist over the next few days resulting in a chance for afternoon and early evening thunderstorms on Tuesday and Wednesday. High-pressure returns Thursday bringing dry conditions across the region into the weekend. LOCATION PRIME TIME 60-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Arapahoe Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Boulder Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Broomfield Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Denver Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Douglas Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Jefferson Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Foothills above 6500ft Â Â Â Boulder Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Douglas Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE Jefferson Current TO 600 PM MON Trace (100%) to 0.2" (60%) to 0.4" (10%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 751 PM Sun May 2, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S WILL BE ALLOWED TO EXPIRE, RAIN SHOWERS TO CONTINUE OVERNIGHT WITH ACCUMULATING SNOW IN THE FOOTHILLS - Message 1's will be allowed to expire at 8pm as the heavy rainfall threat from thunderstorms has ended with a long duration, light to moderate rainfall event expected to unfold overnight into the the day on Monday. - Now that temperatures have cooled into the 40's most areas, thunderstorm activity is diminishing and a widespread rain will develop over the District. A steady rain will fill in this evening and continue through the overnight with some lulls at times early on. Rain will generally fall at rates of 0.1-0.3"/hr into Monday morning. Additional rainfall on top of what has already occurred today expected to range from 0.5-1.5" through noon Monday, favoring areas W of I-25 and S of I-70 for higher end totals. - The snow line will be lowering this evening to around 8,000-9,000ft between 10pm and midnight and between 7,000-8,000ft between midnight and 2am Monday. By daybreak Monday the snow line may be as low as 6,000' briefly before slowly rising as the morning progresses. Best chances for widespread rain/snow pending elevation will be through noon then become more isolated into the afternoon before drying out in the evening. STORM RAINFALL POTENTIAL AND DURATION: Steady rain and weak thunderstorms will have the potential to produce 0.1-0.3" of rain in 60 minutes. WORST CASE SCENARIO: Moderate to heavy non-thunderstorm rain may result in up to 1.0" of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM Current TO 800 PM Jefferson County 1 Current TO 800 PM Current TO 800 PM Broomfield County 1 Current TO 800 PM Current TO 800 PM Douglas County 1 Current TO 800 PM Current TO 800 PM Adams County 1 Current TO 800 PM Current TO 800 PM Denver County 1 Current TO 800 PM Current TO 800 PM DIA 1 Current TO 800 PM Current TO 800 PM Arapahoe County 1 Current TO 800 PM Current TO 800 PM the City of Aurora 1 Current TO 800 PM Current TO 800 PM Arvada 1 Current TO 800 PM Current TO 800 PM Wheat Ridge 1 Current TO 800 PM Current TO 800 PM Lakewood 1 Current TO 800 PM Current TO 800 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 60-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Arapahoe Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Boulder Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Broomfield Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Denver Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Douglas Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Jefferson Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Foothills above 6500ft Â Â Â Boulder Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Douglas Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE Jefferson Current TO 1200 PM MON 0.1" (100%) to 0.2" (85%) to 0.6" (30%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 247 PM Sun May 2, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S CONTINUE VALID FOR THE DISTRICT - Message 1's will continue valid for the District until 8:00pm and may need to be extended to 10pm... - A round of showers and thunderstorms moved through the District earlier with just a few isolated/weak rain showers currently. Another round or two of showers and thunderstorms are likely through the afternoon/early evening with stronger storms still capable of producing brief heavy rainfall and hail. - A widespread "wetting" rain is still expected to fill in this evening sometime between 7-10pm. If the front end of these showers are moderate to heavy in intensity then messages may need to be extended until 10pm for the threat of 1.00"/hour or more rainfall rates. Most likely these showers will result in rain rates of 0.10-0.60"/hr. As the evening progresses rainfall rates will lessen into the 0.05-0.20"/hr rate range overnight with rain changing over to snow in the Front Range foothills. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: Training of moderate/strong thunderstorm cells may result in up to 1.4" of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 800 PM 1100 AM TO 700 PM Jefferson County 1 Current TO 800 PM 1100 AM TO 700 PM Broomfield County 1 Current TO 800 PM 1100 AM TO 700 PM Douglas County 1 Current TO 800 PM 1100 AM TO 700 PM Adams County 1 Current TO 800 PM 1100 AM TO 700 PM Denver County 1 Current TO 800 PM 1100 AM TO 700 PM DIA 1 Current TO 800 PM 1100 AM TO 700 PM Arapahoe County 1 Current TO 800 PM 1100 AM TO 700 PM the City of Aurora 1 Current TO 800 PM 1100 AM TO 700 PM Arvada 1 Current TO 800 PM 1100 AM TO 700 PM Wheat Ridge 1 Current TO 800 PM 1100 AM TO 700 PM Lakewood 1 Current TO 800 PM 1100 AM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Arapahoe 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Boulder 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Broomfield 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Denver 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Douglas 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Jefferson 1100 AM TO 800 PM Trace (95%) to 0.3" (65%) to 0.8" (15%) ISSUED Foothills above 6500ft Â Â Â Boulder 1100 AM TO 800 PM Trace (100%) to 0.3" (65%) to 0.8" (15%) ISSUED Douglas 1100 AM TO 800 PM Trace (100%) to 0.3" (65%) to 0.8" (15%) ISSUED Jefferson 1100 AM TO 800 PM Trace (100%) to 0.3" (65%) to 0.8" (15%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 1016 AM Sun May 2, 2021 Forecaster: Brad Simmons ------------------------- 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 are currently valid until 8:00pm this evening. - Shower and thunderstorm activity is already blossoming over W/NW Boulder County and will fill in over the District through noon. 2-3 rounds of showers and thunderstorms are likely into the evening with stronger storms capable of producing brief heavy rainfall that may lead to excessive runoff. Relatively fast storm motions from SW to NE at 20-25mph will help to keep heavier rainfall brief with training of thunderstorm cells having the greatest threat for a prolonged period of heavy rainfall. - Strong thunderstorms may also become severe, producing large hail/accumulating hail, gusty winds and frequent cloud-to-ground lightning. Thunderstorm activity is expected to diminish as temperatures cool this evening with a widespread rain forecast to fill in with lighter rainfall rates overnight into Monday morning. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Training of moderate/strong thunderstorm cells may result in up to 1.6" of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Broomfield County 1 Current TO 800 PM 1100 AM TO 700 PM Jefferson County 1 Current TO 800 PM 1100 AM TO 700 PM Boulder County 1 Current TO 800 PM 1100 AM TO 700 PM Douglas County 1 Current TO 800 PM 1100 AM TO 700 PM Adams County 1 Current TO 800 PM 1100 AM TO 700 PM Denver County 1 Current TO 800 PM 1100 AM TO 700 PM DIA 1 Current TO 800 PM 1100 AM TO 700 PM Arapahoe County 1 Current TO 800 PM 1100 AM TO 700 PM the City of Aurora 1 Current TO 800 PM 1100 AM TO 700 PM Arvada 1 Current TO 800 PM 1100 AM TO 700 PM Wheat Ridge 1 Current TO 800 PM 1100 AM TO 700 PM Lakewood 1 Current TO 800 PM 1100 AM TO 700 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Arapahoe 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Broomfield 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Denver 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Jefferson 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Boulder Current TO 800 PM SUN 0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED Foothills above 6500ft Â Â Â Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED Jefferson 1100 AM TO 800 PM 0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED Boulder Current TO 800 PM SUN 0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 922 AM Sun May 2, 2021 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON TRANSITIONING TO A SOAKING RAIN OVERNIGHT INTO MONDAY MORNING - An approaching upper level low pressure system is already producing showers and thunderstorms over the mountains and its just a matter of time until the District will be impacted... Precipitation will be convective through the afternoon with thunderstorms having the potential to become strong to severe producing brief heavy rainfall, hail, gusty winds and frequent lightning. - 2-3 rounds of showers and thunderstorms is likely through the afternoon before precipitation becomes more stratiform and an "upslope" rain/snow event develops this evening and continues overnight into the first half of the day on Monday. The threat for heavy rainfall with the potential for excessive runoff will be limited to thunderstorm activity this afternoon and evening then rainfall rates will become lighter in the 0.05-0.20"/hr rate. Total rainfall amounts from noon today until noon Tuesday is expected to range from 0.5-1.5" with the higher end of the range likely in and adjacent to the foothills. - As temperatures drop this evening the snow line will lower to 8,000-9,000ft between 10pm and midnight and between 7,000-8,000ft between midnight and 2am Tuesday. By daybreak Tuesday the snow line may be as low as 6,000' briefly before slowly rising as the morning progresses. Best chances for widespread rain/snow pending elevation will be through noon then become more isolated into the afternoon before drying out. STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes. WORST CASE SCENARIO: Training of moderate/strong thunderstorm cells may result in up to 1.6" of rain in 60-90 minutes. A LOOK AHEAD: A widespread light rain is expected Tuesday morning lower elevations with snow for the higher terrain continuing through about noon. In the afternoon shower activity will slowly diminish with dry conditions developing. Heavy rainfall is not expected. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (20%) MOD Arapahoe 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (20%) MOD Broomfield 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD Denver 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (20%) MOD Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (20%) MOD Jefferson 1030 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD Boulder 1000 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD Foothills above 6500ft Â Â Â Douglas 1100 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD Jefferson 1030 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD Boulder 1000 AM TO 800 PM 0.1" (100%) to 0.3" (75%) to 0.9" (15%) MOD MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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Flash Flood Prediction Program

by f2p2＠udfcd.org

Time: 909 AM Sat May 1, 2021 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- UNSEASONABLY WARM TODAY AHEAD OF A WET PERIOD SETTING UP SUNDAY THROUGH THE MIDDLE PART OF NEXT WEEK - Ahead of an approaching Pacific storm system SW flow aloft will usher in unseasonably warm air with high temperatures well into the 80's over the plains with 60's and 70's in the Front Range foothills. Normal high for Denver today is 66 degrees. There will be a build up of clouds this afternoon, especially over the higher terrain as high-based showers and possibly a weak thunderstorm develop. - Due to dry lower levels of the atmosphere any showers or weak thunderstorms that develop late this afternoon and evening will generally only produce a few sprinkles and gusty winds. Best chances to see any measurable moisture will be over the foothills between 4pm and midnight with the lower elevations expected to remain on the drier side. STORM RAINFALL POTENTIAL AND DURATION: A high-based rain shower or weak thunderstorm will have the potential to produce a trace to 0.1" of rain. A LOOK AHEAD: Sunday will begin dry with a chance for rain showers and thunderstorms starting by around noon and becoming likely by 3-4pm. Shower and thunderstorm activity increases through the late afternoon with chances for thunderstorms diminishing in the evening as a soaking rain develops overnight into Monday morning with the snow line dropping to around 6,000â. Some storms Sunday afternoon could produce brief heavy rainfall and become strong to severe with hail being the primary severe weather threat. Lingering rain/snow pending elevation into Monday morning looks to be persistent until noon, breaking up in the afternoon and becoming more showery. Significant snow is likely for the Front Range foothills with 1-2" of total precipitation over the District from Sunday afternoon into Monday afternoon. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains Â Â Â Adams 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Arapahoe 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Boulder 400 PM TO 1159 PM Trace (20%) to 0.1" (10%) NONE Broomfield 400 PM TO 1159 PM Trace (15%) to 0.1" (5%) NONE Denver 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Douglas 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Jefferson 400 PM TO 1159 PM Trace (20%) to 0.1" (10%) NONE Foothills above 6500ft Â Â Â Boulder 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) NONE Douglas 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) NONE Jefferson 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789 Â Â Â F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]

3 years, 6 months

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