Alert archive / Colorado / Flash Flood Warnings in 2012

Flash Flood Warning 26, NWS Denver/Boulder, CO

September 26, 2012Weld County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Sep 26, 2012, 5:46 PM MDT for Weld County, Colorado. It was in force for 2 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Sep 26, 2012, 5:46 PM MDT (23:46 UTC)
Expired
Sep 26, 2012, 7:46 PM MDT
In force
2 hr
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Flood severity
None

County Weld County, CO

The radar

The Denver radar (KFTG), 56 km from the middle of the area, began a volume at 23:47 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.

What was reported inside it

TimeReportWhereRemark
Sep 26, 5:55 PM MDTFLASH FLOODPlatteville, CO6 INCHES OF WATER RUNNING OVER THE ROAD. AUTOMOBILE SLID INTO A DITCH AND WAS SUBMERGED 4 FEET

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 11.8 hours before the alert went out and 141 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 12:00Z on 2012-09-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 26 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 12:00Z on 2012-09-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.1939Sfc1 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
26 J/kg
Mixed-layer CIN
-27 J/kg
Mixed-layer LCL
687 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

330 
WGUS55 KBOU 262346
FFWBOU
COC123-270245-
/O.NEW.KBOU.FF.W.0026.120926T2346Z-120927T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DENVER CO
546 PM MDT WED SEP 26 2012

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHWESTERN WELD COUNTY IN NORTHEAST COLORADO

* UNTIL 845 PM MDT

* AT 544 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM OVER PLATTEVILLE...OR 14 
  MILES SOUTH OF GREELEY. THIS STORM WAS NEARLY STATIONARY.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  PLATTEVILLE.

DOPPLER RADAR ESTIMATES THAT AROUND 2 INCHES OF RAIN HAS 
FALLEN FROM THIS STORM IN THE LAST 45 MINUTES. 

ANOTHER 1 TO 2 INCHES OF RAIN CAN BE EXPECTED BEFORE THE STORM WEAKENS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS...NORMALLY DRY WASHES AND
ARROYOS...AS WELL AS FARMLAND ALONG THE BANKS OF CREEKS AND STREAMS.

DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.  TURN AROUND...
DONT DROWN. 

&&

LAT...LON 4029 10483 4027 10475 4016 10479 4020 10487

$$



BARJENBRUCH
2 follow-up statements
582 
WGUS75 KBOU 270033
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
633 PM MDT WED SEP 26 2012

COC123-270245-
/O.CON.KBOU.FF.W.0026.000000T0000Z-120927T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WELD CO-
633 PM MDT WED SEP 26 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 845 PM MDT FOR
SOUTHWESTERN WELD COUNTY...

AT 630 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THAT THE EXTREMELY HEAVY RAIN OVER PLATTEVILLE...OR ABOUT 14
MILES SOUTH OF GREELEY....HAD ENDED. 

LOCATIONS REMAINING IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
PLATTEVILLE.

DOPPLER RADAR ESTIMATES THAT 2 TO 3 INCHES OF RAIN HAD FALLEN
FROM THE STORMS EARLIER THIS EVENING.  THE WELD COUNTY SHERIFF 
REPORTED CONSIDERABLE STREET FLOODING IN PLATTEVILLE. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS...CITY STREETS AND UNDERPASSES.
ADDITIONALLY...COUNTRY ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS
AND STREAMS AND OTHER LOW LYING AREAS ARE SUBJECT TO FLASH FLOODING.

&&

LAT...LON 4029 10483 4027 10475 4016 10479 4020 10487

$$


BARJENBRUCH
813 
WGUS75 KBOU 270146
FFSBOU

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
746 PM MDT WED SEP 26 2012

COC123-270155-
/O.CAN.KBOU.FF.W.0026.000000T0000Z-120927T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WELD CO-
746 PM MDT WED SEP 26 2012

...THE FLASH FLOOD WARNING FOR SOUTHWESTERN WELD COUNTY HAS BEEN
CANCELLED...

THE PLATTEVILLE FIRE DEPARTMENT REPORTED THAT FLOOD WATERS IN THE
PLATTEVILLE AREA HAVE SUBSIDED. FLASH FLOODING IS NO LONGER EXPECTED.

LAT...LON 4029 10483 4027 10475 4016 10479 4020 10487

$$


BARJENBRUCH

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 26, 4:33 PM MDTSevere Thunderstorm WarningBOULarimer, Weld33 min
Sep 26, 5:57 PM MDTAreal Flood AdvisoryBOUWeld93 min

Nearby

Flash Flood Warnings in Colorado, 2012Every flash flood warning in 2012

Sources

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