FNUS75 KRIW 240957
FWSRIW

SPOT FORECAST FOR CYGNAT FIRE...NPS YNP
NATIONAL WEATHER SERVICE RIVERTON WY
357 AM MDT FRI AUG 24 2012

FORECAST IS BASED ON REQUEST TIME OF 1940 MDT ON AUGUST 23.
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER
SERVICE.

...RED FLAG WARNING IN EFFECT FROM NOON TODAY TO 9 PM MDT SATURDAY...

.DISCUSSION...

MODERATE SOUTHWEST FLOW AHEAD OF AN APPROACHING DRY COLD FRONT WILL
PUSH SMOKY DRY AIR IN FROM UTAH AND IDAHO TODAY. A DRY COLD FRONT
WILL SWEEP ACROSS THE AREA AT AROUND 1800 WITH WINDS SHIFTING TO
THE NORTH. THE COMBINATION OF GUSTY SHIFTING WINDS...VERY LOW
HUMIDITY AND WARM TEMPERATURES WILL CREATE RED FLAG CONDITIONS
ACROSS THE AREA THIS AFTERNOON AND EVENING. WINDS WILL DECREASE
OVERNIGHT TONIGHT WITH GOOD RH RECOVERY AND MUCH LOWER TEMPERATURES.
IT WILL LIKELY BECOME BREEZY AGAIN SATURDAY WITH CONTINUED VERY
LOW HUMIDITY CREATING ANOTHER CRITICAL FIRE WEATHER DAY. HIGH
PRESSURE BUILDS IN THEREAFTER... WITH RISING TEMPERATURES THROUGH
AT LEAST MONDAY AND MINIMUM RELATIVE HUMIDITY AROUND 20
PERCENT...HOWEVER WINDS WILL BE LIGHTER UNDERNEATH THE BUILDING
RIDGE.

...THUNDERSTORMS IMPLY STRONG GUSTY AND ERRATIC WINDS...
...HAINES INDEX IS HIGH LEVEL HAINES BOTH DAY AND NIGHT...

FORECASTER...SKRBAC/ALLEN

.TODAY...
SKY/WEATHER.........MOSTLY SUNNY (0-15 PERCENT).
MAX TEMPERATURE.....70-74.
MIN HUMIDITY........11-14 PERCENT.
20 FOOT WINDS.......UPSLOPE/UPVALLEY 5-9 MPH BECOMING SOUTHWEST 11
                    TO 19 MPH WITH GUSTS TO AROUND 35 MPH AFTER 1100.
RIDGE TOP WINDS.....SOUTHWEST AROUND 15 MPH INCREASING TO 25 TO 30
                    MPH AFTER 1100.
LAL.................1.
CHC OF WETTING RAIN.ZERO PERCENT.
HAINES INDEX........4 OR LOW POTENTIAL FOR LARGE PLUME DOMINATED
                    FIRE GROWTH.
MIXING HEIGHT.......3800-4800 FT AGL INCREASING TO 8000-9000 FT AGL
                    IN THE AFTERNOON.
TRANSPORT WINDS.....SOUTHWEST 17 TO 21 MPH INCREASING TO 29 TO 31
                    AFTER 1100.
SMOKE DISPERSAL.....GOOD (92400 KNOT-FT) INCREASING TO EXCELLENT
                    (184500 KNOT-FT) IN THE AFTERNOON.

.TONIGHT...
SKY/WEATHER.........MOSTLY CLEAR (10-20 PERCENT).
MIN TEMPERATURE.....31-34.
MAX HUMIDITY........61-64 PERCENT.
20 FOOT WINDS.......NORTHWEST WINDS 9 TO 13 MPH AND GUSTY IN THE
                    EVENING BECOMING DOWNSLOPE/DOWNVALLEY 4-7 MPH.
RIDGE TOP WINDS.....NORTHWEST 20 TO 25 MPH SHIFTING TO THE
                    NORTHEAST AROUND 10 MPH AFTER MIDNIGHT.
LAL.................1.
CHC OF WETTING RAIN.ZERO PERCENT.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH...DECREASING TO 3 LATE.
MIXING HEIGHT.......5500-6500 FT AGL DECREASING TO 1000-2000 FT AGL
                    AFTER MIDNIGHT.
TRANSPORT WINDS.....NORTHWEST 22 TO 28 MPH SHIFTING TO THE
                    NORTHEAST 10 TO 14 MPH AFTER MIDNIGHT.
SMOKE DISPERSAL.....VERY GOOD (115900 KNOT-FT) DECREASING TO POOR
                    (14900 KNOT-FT) AFTER MIDNIGHT.

.SATURDAY...
SKY/WEATHER.........SUNNY (5-15 PERCENT).
MAX TEMPERATURE.....68-72.
MIN HUMIDITY........12-15 PERCENT.
20 FOOT WINDS.......UPSLOPE/UPVALLEY 5-9 MPH BECOMING SOUTHWEST 10
                    TO 15 MPH WITH GUSTS TO 25 MPH IN THE AFTERNOON.
RIDGE TOP WINDS.....SOUTHWEST 10 TO 15 MPH SHIFTING TO THE WEST
                    AROUND 25 MPH LATE IN THE AFTERNOON.
LAL.................1.
CHC OF WETTING RAIN.ZERO PERCENT.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......1900-2900 FT AGL INCREASING TO 6200-7200 FT AGL
                    IN THE AFTERNOON.
TRANSPORT WINDS.....SOUTHWEST 12 TO 20 MPH SHIFTING TO THE WEST
                    AROUND 25 MPH LATE IN THE AFTERNOON.
SMOKE DISPERSAL.....POOR (28900 KNOT-FT) INCREASING TO VERY GOOD
                    (110800 KNOT-FT) IN THE AFTERNOON.

.FORECAST DAYS 3 THROUGH 5...
.SATURDAY NIGHT...MOSTLY CLEAR. AREAS OF SMOKE. LOWS IN THE UPPER
30S. WINDS GENERALLY LESS THAN 10 MPH.
.SUNDAY...BECOMING PARTLY CLOUDY WITH A SLIGHT CHANCE OF SHOWERS
AND ISOLATED THUNDERSTORMS. LOWS AROUND 40. HIGHS IN THE LOWER 70S.
WINDS GENERALLY LESS THAN 10 MPH.
.MONDAY...PARTLY CLOUDY. LOWS IN THE LOWER 40S. HIGHS IN THE
LOWER 70S. WINDS GENERALLY LESS THAN 10 MPH.
.TUESDAY...PARTLY CLOUDY WITH SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS. LOWS IN THE MID 30S. HIGHS IN THE LOWER 70S. WINDS
GENERALLY LESS THAN 10 MPH.

$$

FORECASTER...ALLEN
REQUESTED BY...LAURA DOOLEY
REASON FOR REQUEST...WILDFIRE
.TAG 20120823.CYGNA.01/RIW