Alert archive / Colorado / Flash Flood Watches in 2015

Flash Flood Watch 1, NWS Denver/Boulder, CO

May 5, 201510 counties in Colorado

NWS Denver/Boulder, CO issued this flash flood watch at May 5, 2015, 4:21 AM MDT for 10 counties in Colorado. It took effect at May 5, 2015, 12:00 PM MDT. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued
May 5, 2015, 4:21 AM MDT (10:21 UTC)
In effect from
May 5, 2015, 12:00 PM MDT
Expired
May 5, 2015, 5:31 PM MDT
In force
6 hr
Issued by
NWS Denver/Boulder, CO
Flood severity
None

Counties Arapahoe County, CO, Boulder County, CO, Clear Creek County, CO, Douglas County, CO, Elbert County, CO, Gilpin County, CO, Jefferson County, CO, Larimer County, CO, Lincoln County, CO, Park County, CO

The radar

The Denver radar (KFTG), 42 km from the middle of the area, began a volume at 10:28 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Denver, CO (KDEN), launched 00:00Z, 10.4 hours before the alert went out and 153 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2015-05-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 76 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2015-05-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 89 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
76 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
960 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
89 m²/s²
0-3 km storm-relative helicity
189 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Denver/Boulder, CO wrote its last area forecast discussion before this flash flood watch went out at May 5, 2:59 AM MDT, 1 hour 22 minutes earlier.

Area forecast discussion, May 5, 2:59 AM MDT, 1 hour 22 minutes before
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Hazardous weather outlook, May 4, 10:02 AM MDT, 18 hours 19 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1002 AM MDT MON MAY 4 2015

COZ030>051-051615-
JACKSON COUNTY BELOW 9000 FEET-
WEST JACKSON AND WEST GRAND COUNTIES ABOVE 9000 FEET-
GRAND AND SUMMIT COUNTIES BELOW 9000 FEET-
SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-
SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/
GILPIN/CLEAR CREEK/SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE
9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-
JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR
CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET-
CENTRAL AND SOUTHEAST PARK COUNTY-
LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-
BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD
COUNTY-
NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND
ARAPAHOE COUNTIES/EAST BROOMFIELD COUNTY-
ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-
NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD COUNTY-MORGAN COUNTY-
CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-
SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN COUNTY-
LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS COUNTY-
1002 AM MDT MON MAY 4 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...TODAY AND TONIGHT

COOL AND MOIST UPSLOPE FLOW IS IN PLACE TODAY...AND SOME SHOWERS
CONTINUE THIS MORNING TO DRIFT NORTH WITH SOUTHERLY FLOW ALOFT.
WE EXPECT THUNDERSTORMS TO ERUPT ACROSS THE MOUNTAINS AROUND
MIDDAY...THEN SPREAD ACROSS THE PALMER DIVIDE...URBAN CORRIDOR AND
FOOTHILLS THIS AFTERNOON. NEAR RECORD PRECIPITABLE WATER VALUES
WILL ALLOW FOR LOCALLY HEAVY RAINFALL FROM THE SHOWERS AND
STORMS...ESPECIALLY LATE AFTERNOON INTO THE EVENING. SNOW LEVELS
WILL BE AROUND 10 THOUSAND FEET WITH A FEW INCHES OF WET SNOW
POSSIBLE THROUGH TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS WITH LOCALLY HEAVY
RAINFALL WILL REMAIN IN THE FORECAST ON TUESDAY. AT THIS
TIME...THE MAIN THREAT FOR LOCALLY HEAVY RAINFALL WILL OCCUR FROM
THE FOOTHILLS AND I-25 CORRIDOR EASTWARD ACROSS THE PLAINS LATE
TUESDAY MORNING THROUGH THE AFTERNOON HOURS. THE HEAVY RAIN THREAT
WILL DECREASE TUESDAY EVENING AS AN UPPER LEVEL DISTURBANCE MOVES
NORTHEAST OF THE STATE. AT THIS TIME...IT APPEARS THAT MAINLY BURN
SCARS WOULD BE MORE SUSCEPTIBLE TO ANY POTENTIAL FLOODING ISSUES.

WHILE THE OVERALL THREAT OF SEVERE WEATHER WILL BE LIMITED BY
MARGINAL INSTABILITY IN THE ATMOSPHERE...A BRIEF TORNADO WOULD BE
POSSIBLE TUESDAY AS WIND SHEAR INCREASES.

IN THE HIGHER MOUNTAINS...THE SNOW LEVEL IS EXPECTED TO LOWER INTO
THE 9500-10500 FOOT RANGE TUESDAY NIGHT INTO WEDNESDAY MORNING.
THE MORE SIGNIFICANT SNOW TOTALS SHOULD STILL BE LIMITED TO THE
HIGHER MOUNTAIN PEAKS ABOVE 11 THOUSAND TO 12 THOUSAND
FEET...WHERE SEVERAL INCHES TO OVER A FOOT OF SNOW WILL BE
POSSIBLE THROUGH WEDNESDAY.

UNSETTLED WEATHER WILL REMAIN IN THE FORECAST THROUGH NEXT WEEKEND
WITH A CHANCE OF SHOWERS AND STORMS NEARLY EACH AND EVERY DAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 4, 6:59 PM MDTFlash Flood WarningBOUElbert6 hr
May 4, 7:09 PM MDTAreal Flood AdvisoryBOUAdams, Denver111 min
May 4, 10:34 PM MDTAreal Flood AdvisoryBOUBoulder3 hr
May 5, 1:02 AM MDTAreal Flood WarningBOUElbert4 hr
May 5, 8:28 AM MDTDense Fog AdvisoryBOUBoulder, Elbert, Larimer, Lincoln, Logan, Morgan and 4 more4 hr

Nearby

Flash Flood Watches in Colorado, 2015Every flash flood watch in 2015

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.