FNUS75 KRIW 202138
FWSRIW

SPOT FORECAST FOR BEACH...NPS YNP
NATIONAL WEATHER SERVICE RIVERTON WY
338 PM MDT TUE JUL 20 2010

FORECAST IS BASED ON REQUEST TIME OF 1518 MDT ON JULY 20.
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER
SERVICE.

.DISCUSSION...

WEAK HIGH PRESSURE ALOFT WILL BRING DRY WEATHER TO THE AREA LATE
THIS AFTERNOON AND TONIGHT WITH LIGHT...TERRAIN DRIVEN WINDS.
DEVELOPING LOW PRESSURE IN THE PACIFIC NORTHWEST WEDNESDAY WILL
ALLOW LOW AND MID LEVEL MOISTURE FROM UTAH AND COLORADO TO MOVE
NORTHWARD. MINIMUM RELATIVE HUMIDITY WEDNESDAY AFTERNOON WILL BE IN
THE LOW TO MID 20 PERCENT RANGE. THE WIND WILL BECOME SOUTH AT 10 TO
15 MPH DURING THE MORNING ON WEDNESDAY WITH GUSTS UP TO 20 MPH IN
THE AFTERNOON. ISOLATED SHOWERS AND THUNDERSTORMS ARE EXPECTED
WEDNESDAY AFTERNOON AND EVENING. WETTING RAINFALL IS UNLIKELY...AND
THE MAIN THREAT FROM THESE THUNDERSTORMS WILL BE STRONG OUTFLOW
WINDS AND LIGHTNING.

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

FORECASTER...SMITH

.REST OF TODAY...
SKY/WEATHER.........PARTLY CLOUDY (30-40 PERCENT).
MAX TEMPERATURE.....73-76.
MIN HUMIDITY........11-14 PERCENT.
WIND (20 FT)........UPSLOPE/UPVALLEY 5-9 MPH.
RIDGE TOP WINDS.....SOUTHWEST AROUND 10 MPH.
LAL.................1.
CWR.................ZERO PERCENT.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......7500 FT AGL.
TRANSPORT WINDS.....SOUTHWEST AROUND 15 MPH.
SMOKE DISPERSAL.....VERY GOOD (132000 KNOT-FT).

.TONIGHT...
SKY/WEATHER.........PARTLY CLOUDY (30-40 PERCENT).
MIN TEMPERATURE.....AROUND 40.
MAX HUMIDITY........83-86 PERCENT.
WIND (20 FT)........DOWNSLOPE/DOWNVALLEY 4-7 MPH.
RIDGE TOP WINDS.....SOUTHWEST AROUND 10 MPH SHIFTING TO THE SOUTHEAST
                    AROUND 10 MPH AFTER MIDNIGHT.
LAL.................1.
CWR.................ZERO PERCENT.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......6000-7000 FT AGL DECREASING TO 1500-2000 FT AGL
                    AFTER MIDNIGHT.
TRANSPORT WINDS.....SOUTHWEST 10 TO 15 MPH.
SMOKE DISPERSAL.....GOOD (81400 KNOT-FT) DECREASING TO POOR (19400
                    KNOT-FT) AFTER MIDNIGHT.

.WEDNESDAY...
SKY/WEATHER.........PARTLY CLOUDY (45-55 PERCENT). ISOLATED
                    SHOWERS AND THUNDERSTORMS IN THE AFTERNOON.
MAX TEMPERATURE.....67-70.
MIN HUMIDITY........22-25 PERCENT.
WIND (20 FT)........UPSLOPE/UPVALLEY 5-9 MPH BECOMING SOUTH AROUND
                    10 TO 15 MPH WITH GUSTS UP TO 20 MPH IN THE AFTERNOON.
                    GUSTY AND ERRATIC WINDS EXPECTED NEAR
                    THUNDERSTORMS IN THE AFTERNOON.
RIDGE TOP WINDS.....SOUTH 10 TO 15 MPH...INCREASING TO AROUND 20 MPH
                    LATE IN THE AFTERNOON.
LAL.................1 UNTIL 1200...THEN 2.
CWR.................5 PERCENT.
HAINES INDEX........5 OR MODERATE POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......2000-3000 FT AGL INCREASING TO 6500-7500 FT AGL
                    IN THE AFTERNOON.
TRANSPORT WINDS.....SOUTH 15 TO 20 MPH.
SMOKE DISPERSAL.....POOR (29000 KNOT-FT) INCREASING TO GOOD (85300
                    KNOT-FT) IN THE AFTERNOON.

.FORECAST DAYS 3 THROUGH 5...
.WEDNESDAY NIGHT...PARTLY CLOUDY. SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS IN THE EVENING...THEN ISOLATED SHOWERS AND
THUNDERSTORMS AFTER MIDNIGHT. LOWS IN THE UPPER 30S. WINDS
GENERALLY LESS THAN 10 MPH.
.THURSDAY...PARTLY CLOUDY. LOWS IN THE UPPER 30S. HIGHS IN THE
MID 60S. WINDS GENERALLY LESS THAN 10 MPH.
.FRIDAY...MOSTLY CLEAR. LOWS AROUND 40. HIGHS IN THE UPPER 60S.
WINDS GENERALLY LESS THAN 10 MPH.
.SATURDAY...MOSTLY CLEAR. LOWS IN THE LOWER 40S. HIGHS IN THE
LOWER 70S. WINDS GENERALLY LESS THAN 10 MPH.

$$

FORECASTER...SMITH
REQUESTED BY...EDWIN FOLTS
REASON FOR REQUEST...WILDFIRE
.TAG 20100720.BEACH.02/RIW