FNUS75 KCYS 221756
FWSCYS

SPOT FORECAST FOR COTTONWOOD FIRE...HARRISON FIRE DEPT
NATIONAL WEATHER SERVICE CHEYENNE WY
1156 AM MDT FRI JUN 22 2012

FORECAST IS BASED ON REQUEST TIME OF 1127 MDT ON JUNE 22.
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER
SERVICE.

...FIRE WEATHER WATCH IN EFFECT FROM SATURDAY MORNING THROUGH
SATURDAY EVENING...

.DISCUSSION...
AN UPPER LEVEL DISTURBANCE WILL MOVE OVER THE FIRE SITE THIS
AFTERNOON AND EARLY EVENING. THIS WILL BRING A SIGNIFICANT WIND
SHIFT TO THE AREA BY EARLY THIS EVENING. BEFORE THEN...STRONG
SOUTH/SOUTHEAST WINDS WILL PERSIST THROUGH MID-AFTERNOON...KEEPING
RELATIVE HUMIDITIES IN THE 30S THROUGH MUCH OF THE AFTERNOON. THE
WIND SHIFT AND APPROACH OF THE UPPER-LEVEL DISTURBANCE WILL
PRODUCE SCATTERED THUNDERSTORMS UPSTREAM OF THE BURN SITE BY 4 OR
5 PM. THESE THUNDERSTORMS AND STRONG WIND SHIFT WILL PUSH THROUGH
THE BURN SITE BETWEEN 5 AND 8 PM. WINDS WILL TURN WEST/SOUTHWEST
AND THE AIR MASS WILL BECOME MUCH DRIER. MINIMUM RELATIVE
HUMIDITIES WILL LIKELY NOT BE REACHED UNTIL EARLY THIS EVENING.
ADDITIONALLY...A FEW OF THE THUNDERSTORMS MAY BECOME STRONG
CONTAINING LARGE HAIL AND DAMAGING WINDS. ANY THUNDERSTORM
ACTIVITY WILL DISSIPATE BY AROUND 9 OR 10 PM. THE VERY DRY AIR
MASS WILL REMAIN OVER THE AREA FOR THE REST OF TONIGHT AND DURING
THE DAY ON SATURDAY. WEST WINDS WILL INCREASE ON SATURDAY
AFTERNOON AS WELL...WITH GUSTS THAT WILL APPROACH 25 MPH.

.TODAY...

SKY/WEATHER.........PARTLY CLOUDY (40-50 PERCENT). SCATTERED SHOWERS
                    AND THUNDERSTORMS DEVELOPING AFTER 1600.
MAX TEMPERATURE.....91-94.
MIN HUMIDITY........14 TO 18 PERCENT...BUT NOT UNTIL EARLY EVENING.
WIND (20 FT)........SOUTHEAST WINDS 12 TO 17 MPH WITH HIGHER GUSTS.
CWR.................0 PERCENT INCREASING TO 25 PERCENT AFTER 1600.
LAL.................3 AFTER 1600.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......3900-5600 FT AGL.
TRANSPORT WINDS.....SOUTH AROUND 20 MPH.
SMOKE DISPERSAL.....EXCELLENT (50300-128000 KNOT-FT).

.TONIGHT...

SKY/WEATHER.........PARTLY CLOUDY (30-40 PERCENT) UNTIL 2100...THEN
                    CLEAR (0-10 PERCENT). SCATTERED SHOWERS AND
                    THUNDERSTORMS UNTIL 2000.
MIN TEMPERATURE.....57-60.
MAX HUMIDITY........30 TTO 40 PERCENT.
WIND (20 FT)........SOUTH/SOUTHEAST WINDS AT 12 TO 17 MPH WITH GUSTS
                    TO 25 MPH UNTIL 1900...THEN BECOMING SOUTHWEST
                    AT 15 TO 25 MPH WITH GUSTS TO 30 MPH. DECREASING
                    AFTER MIDNIGHT.
CWR.................25 PERCENT UNTIL 2100...THEN ZERO.
LAL.................3 UNTIL 2200.
HAINES INDEX........6 OR HIGH POTENTIAL FOR LARGE PLUME DOMINATED
                    FIRE GROWTH.
MIXING HEIGHT.......2300 FT AGL DECREASING TO 200 FT AGL AFTER
                    MIDNIGHT.
TRANSPORT WINDS.....SOUTH UNTIL 1900...THEN WEST/SOUTHWEST AT 15 TO
                    25 MPH WITH GUSTS TO 30 MPH. DECREASING AFTER
                    MIDNIGHT.
SMOKE DISPERSAL.....GOOD BECOMING POOR AFTER MIDNIGHT. (1000-54200 KNOT-FT).

.SATURDAY...

SKY/WEATHER.........MOSTLY SUNNY (5-15 PERCENT).
MAX TEMPERATURE.....AROUND 100.
MIN HUMIDITY........9 TO 13 PERCENT.
WIND (20 FT)........LIGHT AND VARIABLE OF LESS THAN 8 MPH UNTIL 1000...
                    THEN BECOMING WEST/SOUTHWEST AT 8 TO 12 MPH WITH GUSTS
                    AS HIGH AS 25 MPH.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......7300 FT AGL INCREASING TO 13300 FT AGL IN THE
                    AFTERNOON.
TRANSPORT WINDS.....WEST/SOUTHWEST AT 10 TO 15 MPH.
SMOKE DISPERSAL.....EXCELLENT (63700-156400 KNOT-FT).

$$
FORECASTER...HAHN
REQUESTED BY...JW GEISER  CHIEF
TYPE OF REQUEST...WILDFIRE
.TAG 20120622.COTTO.01/CYS