FNUS75 KRIW 201838 FWSRIW SPOT FORECAST FOR WIGGINS FORKUNITS4-5...USFS SHF NATIONAL WEATHER SERVICE RIVERTON WY 1238 PM MDT TUE APR 20 2010 FORECAST IS BASED ON IGNITION TIME OF 1100 MDT ON APRIL 21. IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER SERVICE. .DISCUSSION... ATMOSPHERIC INSTABILITY WILL BE SUFFICIENT TO SUPPORT ISOLATED RAIN SHOWERS THIS AFTERNOON AND EVENING. A RIDGE OF HIGH PRESSURE OVER THE REGION TODAY WILL GRADUALLY WEAKEN AS LOW PRESSURE MOVES ONSHORE OVER CALIFORNIA. THE LOW PRESSURE WILL TRACK INTO SOUTHERN NEVADA BY WEDNESDAY AFTERNOON. MOIST SOUTHERLY FLOW AHEAD OF THIS SYSTEM WILL GENERATE MORE SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING. EXPECT COOLER AND WETTER CONDITIONS THURSDAY AND FRIDAY AS THE LOW PRESSURE PUSHES EAST ACROSS THE ROCKIES. ...THUNDERSTORMS IMPLY STRONG GUSTY AND ERRATIC WINDS... ...HAINES INDEX IS HIGH LEVEL HAINES BOTH DAY AND NIGHT... FORECASTER...JONES .THIS AFTERNOON... SKY/WEATHER.........PARTLY CLOUDY (50-60 PERCENT) WITH WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. MAX TEMPERATURE.....57-60. MIN HUMIDITY........17-21 PERCENT. WIND (20 FT)........SOUTH TO SOUTHWEST 9 TO 14 MPH WITH GUSTS TO 22 MPH. GUSTY AND ERRATIC WIND TO AROUND 30 MPH WITH SHOWERS AND THUNDERSTORMS. RIDGE TOP WINDS.....SOUTH 10 TO 15 MPH. HAINES INDEX........3 OR VERY LOW POTENTIAL FOR LARGE PLUME DOMINATED FIRE GROWTH. MIXING HEIGHT.......RISING TO AROUND 8000 FT AGL BY 1400. TRANSPORT WINDS.....SOUTHWEST 10 TO 15 MPH. SMOKE DISPERSAL.....GOOD. .TONIGHT... SKY/WEATHER.........PARTLY CLOUDY (55-65 PERCENT) WITH ISOLATED SHOWERS AND THUNDERSTORMS UNTIL 2100. THEN... ISOLATED RAIN AND SNOW SHOWERS THROUGH THE NIGHT. MIN TEMPERATURE.....35-38. MAX HUMIDITY........82-85 PERCENT. WIND (20 FT)........BECOMING DOWNSLOPE/DOWNVALLEY 6 TO 10 MPH BETWEEN 1900 AND 2000. BECOMING LIGHT AND VARIABLE LESS THAN 5 MPH AFTER MIDNIGHT. GUSTY AND ERRATIC WINDS EXPECTED NEAR THUNDERSTORMS UNTIL 2100. RIDGE TOP WINDS.....SOUTH 10 TO 15 MPH. HAINES INDEX........3 OR VERY LOW POTENTIAL FOR LARGE PLUME DOMINATED FIRE GROWTH. MIXING HEIGHT.......DECREASING TO LESS THAN 2500 FT AGL BY 2000. TRANSPORT WINDS.....BECOMING DOWNSLOPE/DOWNVALLEY 7 TO 12 MPH BY 2000. SMOKE DISPERSAL.....BECOMING POOR BY 2000. .WEDNESDAY... SKY/WEATHER.........MOSTLY CLOUDY (70-80 PERCENT). ISOLATED RAIN SHOWERS IN THE MORNING...THEN SCATTERED RAIN SHOWERS AND ISOLATED THUNDERSTORMS IN THE AFTERNOON. MAX TEMPERATURE.....53-56. MIN HUMIDITY........31-34 PERCENT. WIND (20 FT)........LIGHT AND VARIABLE LESS THAN 5 MPH UNTIL 0900. BETWEEN 1000 AND 1200 WINDS WILL BECOME SOUTH TO SOUTHEAST 12 TO 16 MPH WITH GUSTS AROUND 25 MPH. GUSTY AND ERRATIC WINDS EXPECTED NEAR THUNDERSTORMS IN THE AFTERNOON. RIDGE TOP WINDS.....SOUTHEAST 14 TO 22 MPH. HAINES INDEX........3 OR VERY LOW POTENTIAL FOR LARGE PLUME DOMINATED FIRE GROWTH. MIXING HEIGHT.......LESS THAN 2500 FT AGL UNTIL 0900...THEN GRADUALLY INCREASING TO 6500 FT AGL BY 1400. TRANSPORT WINDS.....DOWNSLOPE/DOWNVALLEY 4 TO 8 MPH UNTIL 0900... THEN BECOMING SOUTHEAST 14 TO 22 MPH BY 1200. SMOKE DISPERSAL.....POOR UNTIL 1000...THEN BECOMING VERY GOOD BY 1400. .FORECAST DAYS 3 THROUGH 5... .WEDNESDAY NIGHT...CLOUDY. SCATTERED SHOWERS IN THE EVENING... THEN SCATTERED RAIN SHOWERS AND SNOW SHOWERS AFTER MIDNIGHT. LOWS IN THE MID 30S. WINDS GENERALLY LESS THAN 10 MPH. .THURSDAY...SNOW SHOWERS LIKELY....POSSIBLY MIXED WITH RAIN AT TIMES LOWS IN THE UPPER 20S. HIGHS IN THE MID 40S. WINDS GENERALLY LESS THAN 10 MPH. .FRIDAY...COLDER. CLOUDY WITH SNOW LIKELY. LOWS IN THE LOWER TO MID 20S. HIGHS IN THE MID 30S. WINDS GENERALLY LESS THAN 10 MPH. .SATURDAY...PARTLY CLOUDY WITH A SLIGHT CHANCE OF RAIN AND SNOW SHOWERS. LOWS IN THE LOWER 20S. HIGHS IN THE LOWER 40S. WINDS GENERALLY LESS THAN 10 MPH. $$ FORECASTER...JONES REQUESTED BY...SLAGOWSKI REASON FOR REQUEST...PRESCRIBED .TAG 20100421.WIGGI.01/RIW