March 5, 1999 Snowstorm (page 1)

On March 5th, 1999 a compact, yet locally powerful storm system swept through northeast Wyoming and western South Dakota. A narrow band of moderate to heavy snow fell across the region. The map below depicts snowfalls greater than 3". The map contours have been smoothed.

On March 6th, 1999 we saved a copy of the 1km visible satellite images that shows where the snow fell in great detail. See a discussion of this image for additional information.

The contour map below could change if we receive late snowfall reports. Click here for a snowfall map with terrain on it.

March 5th, 1999 Snowfall Map

Detailed Snowfall Reports (inches)

...NORTHEAST WYOMING...
GILLETTE AIRPORT         10-12
10 N GILLETTE 6
12 S GILLETTE 4
15 SE GILLETTE 3
SUNDANCE 4-6
...AROUND THE BLACK HILLS...
LEAD                     5
DEADWOOD 4
STURGIS 10-11
TILFORD 10
PIEDMONT 10
JOHNSON SIDING 9
HILL CITY 6
MEDICINE MT 5
3E CUSTER PEAK 5
SPEARFISH 1-6
WIND CAVE 1
HOT SPRINGS 1-2
HERMOSA 9
8 W SPEARFISH 4
CEDAR PASS 6
CUSTER 6
2 N HEREFORD 5
MOUNT RUSHMORE 6
PACTOLA DAM 8
CRAZY HORSE MONUMENT 8
CHEYENNE CROSSING 6
2 WSW ROCHFORD 5.5
23 NNW EDGEMONT 3
...AROUND RAPID CITY...
WEST RAPID               14
NWS OFFICE 14
REGIONAL AIRPORT 12
ELLSWORTH AFB 10
SE RAPID CITY 15
3 SW RAPID CITY 14
...SOUTH DAKOTA PLAINS...
CROOKED OAKS/
6N WINDMILL TRUCK STOP 12
INTERIOR 9-10
BELLE FOURCHE 4-6
LONG VALLEY 5
PHILIP 5
HARRINGTON 5
KADOKA 3-4
BUFFALO GAP 1
PINE RIDGE TRACE

Weather Maps

The storm system really cranked up over north central Wyoming early Friday morning. It spread east-southeast into extreme southern South Dakota during the day. The lighter snow amounts were caused by general synoptic scale forcing ahead of and just north of the storm track. Just north of the track in a narrow band, convective snow developed. What is convective snow? Convective snow can be likened to showers in the summertime, but instead of showers you get heavy snow. The heaviest snow fell in a band where convective snow lasted most of the day. Snowfall rates of 1-2 inches per hour were noted by many observers.

Take a look at the Surface Map at 18Z, or 11:00 AM MST. The surface low wasn't all that impressive. Look at some of the observations, too, especially the "four snowflake" observations. This means heavy snow, and for those of you that drove in it yesterday, heavy snow has a new meaning. Also, check out the 1km visible image linked here. The enhanced band you see across central Pennington county was producing heavy snow. The bumpy tops strongly suggests the snow was convective as mentioned above.

Finally, we use a computer model called the RUC2. This model runs every 3 hours. We received the 18Z (11:00 AM MST) run and used it's analysis to make the following graphic. The graphic is the 18Z (11:00 AM MST) infrared (IR) satellite image overlaid with the 500mb heights and vorticity. Notice the maximum of vorticity (spin of air parcels) right southwest South Dakota. Normally, ahead of and just north of these pieces of energy is where the "active" weather occurs. On the satellite image, note the enhanced clouds tops over western South Dakota. The scale at the left of the image shows how cold the tops were. The best enhancement coincides with the "bumpy" clouds you saw in the visible image.

Sequence of Forecast Events

The National Weather Service in Rapid City, SD is responsible for issuing advisories and warnings for these types of winter storms. Here are the products we issued through Friday.

  • Thursday, March 4th
  • 3 PM and 9 PM - issued a Special Weather Statement highlighting the potential for hazardous snowfall on Friday
  • Friday, March 5th
  • 3-5 AM - issued a Snow Advisory
  • 10-11 AM - issued a Heavy Snow Warning
  • 7 PM - cancelled the Heavy Snow Warning

The best way to hear about hazardous winter weather conditions in the Black Hills is NOAA Weather Radio. Our transmitter operates on a frequency of 162.55 MHz on station WXM-63. Our broadcasts can be heard on a scanner or via dedicated weather radios. These radios are available for purchase at your local electronics store. The information you receive will assist you in planning your day and will help you cope with winter storms.

Click on the above link to see a long animation of the 1km visible images from our GOES-8 satellite. Check out the spinning clouds and note how the bumpy clouds stay over the Rapid City area the whole day giving us plenty of snow. Warning: The animation is very large.

Record Event Report

NATIONAL WEATHER SERVICE RAPID CITY SD
735 PM MST FRI MAR 5 1999

...RECORD SNOWFALL AT RAPID CITY...

THE OFFICIAL SNOWFALL FOR RAPID CITY...AT THE RAPID CITY REGIONAL AIRPORT...WAS 12.0 INCHES. THIS SETS A NEW 24 HOUR RECORD SNOWFALL FOR FOR MARCH 5. THE OLD RECORD WAS 3.1 INCHES SET IN 1964.

12.0 INCHES IS ALSO THE FOURTH LARGEST 24 HOUR SNOWFALL...MIDNIGHT TO MIDNIGHT...FOR THE MONTH OF MARCH. THE RECORD IS 15.3 INCHES SET ON 3/31/27. 14.7 INCHES FELL ON 3/16/63...AND 12.2 INCHES FELL ON 3/14/73.

OTHER SNOWALL AMOUNTS IN AND AROUND RAPID CITY RANGE FROM 12 TO 15 INCHES

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