October 31 to November 1, 1999 High Wind Event with Fires

On the evening of October 31, 1999 a strong cold front plowed through northeast Wyoming and western South Dakota. The cold front raced across the region in less than 6 hours. At 5 PM the cold front was noted on the surface map below.

11-01-99 00z Surface Map

By 10 PM, the cold front had raced through most of the area as seen below.

11-01-99 06z Surface Map

Strong pressure rises on the order of 4-8mb in 3 hours were noted across much of northeast Wyoming and western South Dakota. Our in-house rule-of-thumb is that for every millibar of pressure rise in 3 hours, you can expect a 10 knot (11 MPH) wind to occur. This has worked fairly well, and did work fairly well for this case.

The cold front was observed on 3.9u satellite imagery. A still picture of the imagery with cold front at 0415Z on the evening of Halloween is seen below.

11-01-99 3.9u Satellite Image

The black spots you see on the imagery is where the satellite picked up much warmer readings than normal. These "hot spots" showed us where fires were occurring. The black spot south of Gillette was the remnants of a fire that burned several tens of thousands of acres of mainly grassland. On the animations we have put together a few lines down, you can see the fires going ahead of the cold front and then as the cold front passes, they flare up dramatically as strong, gusty wind fans the flames.

A lot of dust was also experienced with this cold front as well as much colder temperatures. This can been seen very well on a set of satellite animations that we have put together for you.

Satellite Animations

The recorded wind gusts from this system are provided for you perusal.

 

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
705 AM MST MON NOV 01 1999
 
TIME(MST)  .....CITY LOCATION..... STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....
 
0800 PM    CAMP CROOK                SD    NON TSTM WINDS
10/31/99   HARDING                         63 MPH NON TSTM WINDS.
 
0828 PM    RAPID CITY                SD    NON TSTM WINDS
10/31/99   PENNINGTON                      71 MPH NON TSTM WINDS.
                                           REPORTED AT THE RAPID
                                           CITY NWS OFFICE.
 
0840 PM    ELLSWORTH AFB             SD    NON TSTM WINDS
10/31/99   MEADE                           62 MPH NON TSTM WINDS.
 
0900 PM    NEMO                      SD    NON TSTM WINDS
10/31/99   LAWRENCE                        52 MPH WIND GUST.
 
0922 PM    (PHP)PHILIP ARPT          SD    NON TSTM WINDS
10/31/99   HAAKON                          55 MPH WIND GUST.
 
1105 PM    BUFFALO ARPT              SD    NON TSTM WINDS
10/31/99   HARDING                         71 MPH NON TSTM WINDS.
 
1231 AM    (RAP)RAPID CITY ARPT      SD    NON TSTM WINDS
11/01/99   PENNINGTON                      64 MPH NON TSTM WINDS.
 
1245 AM    FAITH MUNI ARPT           SD    NON TSTM WINDS
11/01/99   MEADE                           60 MPH NON TSTM WINDS.
0200 AM    DEVILS TOWER              WY    NON TSTM WINDS
11/01/99   CROOK                           55 MPH WIND GUST.
 
0400 AM    10 S WALL                 SD    NON TSTM WINDS
11/01/99   PENNINGTON                      63 MPH NON TSTM WINDS.
                                           REPORTED AT PINNACLES
                                           RANGER STATION.

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