FNUS75 KBYZ 111903
FWSBYZ

SPOT FORECAST FOR GRASSY RX...USDA FOREST SERVICE GALLATIN NATIONAL FOREST
NATIONAL WEATHER SERVICE BILLINGS MT
103 PM MDT SAT MAY 11 2013

FORECAST IS BASED ON IGNITION TIME OF 1250 MDT ON MAY 11.
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER
SERVICE.

.DISCUSSION...
A WEAK DISTURBANCE WILL MOVE THROUGH THE AREA THIS AFTERNOON AND
PROVIDE ISOLATED SHOWERS AND THUNDERSTORMS. SUNDAY LOOKS MAINLY
DRY AS HIGH PRESSURE TRIES TO WORK INTO THE AREA. CAN NOT RULE OUT
AN ISOLATED AFTERNOON AND EVENING THUNDERSTORM...BUT ACTIVITY
COULD SPLIT THE SITE TO THE NORTH AND SOUTH. WARMER TEMPERATURES
ARE EXPECTED SUNDAY AND MONDAY WITH LOWERING HUMIDITIES EACH DAY.
WINDS WILL BE DRIVEN PRIMARILY BY TERRAIN TODAY AND SUNDAY. WINDS
WILL GET ERRATIC IN THE AFTERNOON AS UPSLOPE WINDS BATTLE WINDS
ALOFT WHICH WILL BE PRIMARILY OUT OF THE WEST. WINDS WILL BE
STRONGEST NEAR THE RIDGE TOPS. MONDAY WILL HAVE THE STRONGEST
WINDS AS WINDS ALOFT INCREASE FROM THE SOUTHWEST. A COLD FRONT
WILL PUSH INTO THE AREA MONDAY EVENING AND THIS WILL TRIGGER
SCATTERED SHOWERS AND THUNDERSTORMS. TWH


.THIS AFTERNOON...

SKY/WEATHER.........MOSTLY SUNNY. ISOLATED SHOWERS AND
                    THUNDERSTORMS.
CWR.................17 PERCENT.
LAL.................3...9 TO 15 STRIKES/15 MIN/CELL.
MAX TEMPERATURE.....61-66.
MIN HUMIDITY........30-35 PERCENT.
WIND (20 FT)........
 SLOPE/VALLEY.......UPSLOPE 5 TO 10 MPH IN THE AFTERNOON. WINDS
                    A LITTLE ERRATIC AT TIMES. GUSTY AND ERRATIC
                    WINDS EXPECTED NEAR THUNDERSTORMS.
 RIDGETOP...........WEST TO NORTHWEST 10 TO 20 MPH.
MIXING HEIGHT.......6200 FT AGL.
MIXING WINDS........WEST 5 TO 15 MPH.
HAINES INDEX........4.

.TONIGHT...

SKY/WEATHER.........PARTLY CLOUDY. ISOLATED SHOWERS AND
                    THUNDERSTORMS IN THE EVENING.
CWR.................13 PERCENT.
LAL.................3...9 TO 15 STRIKES/15 MIN/CELL.
MIN TEMPERATURE.....40-45.
MAX HUMIDITY........80-85 PERCENT.
WIND (20 FT)........
 SLOPE/VALLEY.......NORTHEAST WINDS 5 TO 10 MPH IN THE EARLY
                    EVENING BECOMING DOWNSLOPE BY MID EVENING.
                    GUSTY AND ERRATIC WINDS EXPECTED NEAR
                    THUNDERSTORMS.
 RIDGETOP...........WEST TO NORTHWEST 15 TO 25 MPH.
MIXING HEIGHT.......1400 FT AGL.
MIXING WINDS........WEST 10 TO 20 MPH.
HAINES INDEX........4.

.SUNDAY...

SKY/WEATHER.........MOSTLY SUNNY. ISOLATED SHOWERS AND
                    THUNDERSTORMS IN THE AFTERNOON AND EVENING.
CWR.................12 PERCENT.
LAL.................2...1 TO 8 STRIKES/15 MIN/CELL.
MAX TEMPERATURE.....70-75.
MIN HUMIDITY........24-29 PERCENT.
WIND (20 FT)........
 SLOPE/VALLEY.......DOWNSLOPE WINDS 5 TO 10 MPH IN THE EARLY MORNING
                    BECOMING UPSLOPE 5 TO 15 BY MID MORNING. WINDS
                    ERRATIC IN THE AFTERNOON WITH SOME GUSTS TO 20
                    MPH POSSIBLE NEAR THE TOP OF THE SLOPES. GUSTY
                    AND ERRATIC WINDS NEAR THUNDERSTORMS.
 RIDGETOP...........WEST 15 TO 25 MPH.
MIXING HEIGHT.......8200 FT AGL.
MIXING WINDS........WEST 15 TO 25 MPH.
HAINES INDEX........5.

.MONDAY...

SKY/WEATHER.........MOSTLY SUNNY. ISOLATED SHOWERS AND
                    THUNDERSTORMS IN THE AFTERNOON.
CWR.................12 PERCENT.
LAL.................2...1 TO 8 STRIKES/15 MIN/CELL.
MAX TEMPERATURE.....70-75.
MIN HUMIDITY........24-29 PERCENT.
WIND (20 FT)........
 SLOPE/VALLEY.......WEST TO SOUTHWEST WINDS 5 TO 15 MPH IN THE
                    MORNING. WINDS INCREASING TO 15 TO 25 MPH WITH
                    GUSTS TO 30 MPH IN THE AFTERNOON...ESPECIALLY
                    NEAR THE TOP OF THE SLOPES. GUSTY AND ERRATIC
                    WINDS EXPECTED NEAR THUNDERSTORMS.
 RIDGETOP...........SOUTHWEST 20 TO 35 MPH.
MIXING HEIGHT.......9200 FT AGL.
MIXING WINDS........WEST 15 TO 30 MPH.
HAINES INDEX........5.

$$
FORECASTER...HUMPHREY
REQUESTED BY...CRISTI HEANEY
TYPE OF REQUEST...PRESCRIBED
.TAG 20130511.GRASS.01/BYZ