Alert archive / Colorado / Winter Storm Watches in 2007

Winter Storm Watch 4, NWS Denver/Boulder, CO

April 11, 200722 counties in Colorado

NWS Denver/Boulder, CO issued this winter storm watch at Apr 11, 2007, 3:00 PM MDT for 22 counties in Colorado. It took effect at Apr 13, 2007, 12:00 AM MDT. It was in force for .

The area

The counties it named.

The facts

Issued
Apr 11, 2007, 3:00 PM MDT (21:00 UTC)
In effect from
Apr 13, 2007, 12:00 AM MDT
Expired
Apr 12, 2007, 5:38 AM MDT
In force
Issued by
NWS Denver/Boulder, CO
All 22 counties

Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Clear Creek County, CO, Denver County, CO, Douglas County, CO, Elbert County, CO, Gilpin County, CO, Grand County, CO, Jackson County, CO, Jefferson County, CO, Larimer County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Park County, CO, Phillips County, CO, Sedgwick County, CO, Summit County, CO, Washington County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 21 km from the middle of the area, began a volume at 20:57 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 (KDNR), launched 12:00Z, 9.0 hours before the alert went out and 120 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 2007-04-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 12:00Z on 2007-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 56 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2088 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
56 m²/s²
0-3 km storm-relative helicity
112 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter storm 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 winter storm watch went out at Apr 11, 2:30 PM MDT, 30 minutes earlier.

Area forecast discussion, Apr 11, 2:30 PM MDT, 30 minutes before
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Hazardous weather outlook, Apr 11, 11:10 AM MDT, 3 hours 50 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER CO
1110 AM MDT WED APR 11 2007

COZ030>051-121200-
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-
1110 AM MDT WED APR 11 2007

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

.DAY ONE...TODAY AND TONIGHT

SNOW SHOWERS IN THE MOUNTAINS WILL SLOWLY DIMINISH BY LATER THIS
AFTERNOON BUT BEFORE THEN AN ADDITIONAL INCH OR TWO IS POSSIBLE
MAINLY IN AREAS CLOSER TO THE DIVIDE.  NORTHWEST WINDS OF 15 TO 30
MPH WITH GUSTS TO 40 TO 50 MPH WILL PREVAIL ABOVE TREELINE PRODUCING
AREAS OF BLOWING SNOW.  GUSTY WINDS WILL ALSO PREVAIL ALONG THE
EASTERN SLOPES AND ONTO THE PLAINS THROUGH THIS AFTERNOON.  ON THE
EASTERN PLAINS NORTHWEST WINDS OF 15 TO 25 MPH WITH GUSTS OF 35 MPH
WILL BE COMMON...ESPECIALLY EAST OF A LINE FROM GREELEY TO LIMON.  A
FEW LIGHT RAIN OR SNOW SHOWERS ARE ALSO POSSIBLE OVER THE FAR
NORTHEAST PLAIN.  CONDITIONS SHOULD QUIET DOWN OVERNIGHT EXCEPT FOR
AN INCREASE IN CLOUDINESS IN THE MOUNTAINS WITH SOME LIGHT SNOW
DEVELOPING TOWARDS DAYBREAK.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SNOWFALL WILL INCREASE IN THE HIGH COUNTRY THURSDAY AFTERNOON BEFORE
SPREADING INTO THE PLAINS AND FRONT RANGE THURSDAY EVENING. SNOW MAY
BE HEAVY AT TIME EARLY FRIDAY MORNING...PARTICULARLY FOR THE
FOOTHILLS AND ADJACENT AREAS OF THE FOOTHILLS SOUTH OF I-70. THESE
AREAS MAY SEE SEVERAL INCHES OF SNOW ACCUMULATION BEFORE SNOWFALL
ENDS FRIDAY NIGHT. COLD TEMPERATURES AND GUSTY WINDS ARE EXPECTED
WITH THE STORM.

A BRIEF WARMUP IS EXPECTED FOR THE WEEKEND BEFORE ANOTHER PACIFIC
STORM SYSTEM MOVES INTO THE AREA FOR THE FIRST PART OF NEXT WEEK.
THIS STORM WILL LIKELY BRING RAIN AND SNOW TO THE DISTRICT MONDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

Nearby

Winter Storm Watches in Colorado, 2007Every winter storm watch in 2007

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.