000 FXUS65 KCYS 050941 AFDCYS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 341 AM MDT SUN JUL 5 2009 .SHORT TERM...TODAY THROUGH MONDAY NIGHT... WIDELY SCATTERED SHOWERS CONTINUE EARLY THIS MORNING OVER SOUTH CENTRAL WYOMING. THE ACTIVITY IS MOVING SOUTHEAST AND WEAKENING AHEAD OF A SHORTWAVE TROUGH. MODELS...ESPECIALLY THE NAM HAS BEEN DEVELOPING QPF OVER THE ENTIRE SOUTHERN PART OF THE CWA THROUGH 15Z. THE OTHER CONCERN THROUGH MID MORNING WILL BE FOG. THE BOUNDARY LAYER IS NEARLY SATURATED AT 09Z WITH FOG ALREADY OBSERVED AT KCYS AND KLAR. EXPECT THE FOG AND LOW CLOUDS TO DEVELOP OVER MUCH OF THE REST OF THE CWA BY SUNRISE AND THEN CONTINUE UNTIL 15Z. ANOTHER ROUND OF AFTERNOON AND EVENING THUNDERSTORMS IS ON TAP FOR MUCH OF THE CWA LATER TODAY. THE ATMOSPHERE WILL BE MOIST AND UNSTABLE ESPECIALLY TO THE EAST OF THE LARAMIE RANGE. ANOTHER SHORTWAVE TROUGH WAS MOVING INTO SOUTHWEST WYOMING AND EASTERN UTAH EARLY THIS MORNING FROM SATELLITE IMAGERY. THAT FEATURE MAY MOVE EAST OF THE CWA BY EARLY AFTERNOON. HOWEVER...MODELS INDICATE VORTICITY MOVING INTO THE CWA AT 250 MB BY 00Z AND WAS NEAR THE OREGON AND NORTHERN CALIFORNIA COAST AT 06Z. IN ADDITION...SURFACE CONVERGENCE ALONG THE MOUNTAINS...ESPECIALLY THE LARAMIE RANGE...SHOULD AID IN THE STORM INITIATION. THERE WILL ALSO BE BETTER 0-6KM SHEAR OVER THE CWA LATER TODAY AND SHOULD ENABLE STORMS TO BE STRONGER THAN THOSE OF SATURDAY. FREEZING LEVEL WILL STILL BE HIGH AND MAY HINDER LARGE HAIL DEVELOPMENT. HAVE INCREASED POPS OVER THE CWA THIS AFTERNOON AND EVENING AND ADDED THE MENTION OF POSSIBLE SEVERE STORMS EAST OF THE LARAMIE RANGE AND MAINLY IN WYOMING. THE LOW CLOUD COVER WILL HINDER SURFACE HEATING TODAY WITH HIGHS REACHED LATE IN MANY PLACES AND MAY PRODUCE MAXIMUM TEMPERATURES A BIT COOLER THAN EARLIER THOUGHT. HEIGHT ALOFT THEN CONTINUE TO RISE THROUGH 12Z TUESDAY AND WITH THE ATMOSPHERE SLOWLY DRYING FROM WEST TO EAST. LATE DAY THUNDERSTORMS WILL AGAIN BE SCATTERED OVER AREAS ALONG AND EAST OF THE LARAMIE RANGE ON MONDAY. STRONGER STORMS WILL BE POSSIBLE OVER THE PANHANDLE WHERE THERE WILL BE MORE LOW LEVEL MOISTURE PRESENT. MONDAY WILL ALSO BE WARMER OVER THE CWA. DRIER AIR SPREAD OVER THE ENTIRE CWA IN ERNEST MONDAY NIGHT WITH PRECIPITABLE WATER VALUES DOWN TO ABOUT ONE HALF INCH BY 12Z TUESDAY. .LONG TERM...TUESDAY THROUGH SATURDAY DRY CONDITIONS WILL PREVAIL OVER THE CWA TUES AND WED. AN UPPER RIDGE WILL MOVE ACROSS THE FORECAST AREA TUES...WITH DOWNSLOPE WINDS AT THE SURFACE IN THE DRY AIR MASS. THE FLOW ALOFT WILL BECOME SW ON WED AS AN UPPER LOW MOVES FROM THE PAC NW INTO SOUTHERN CANADA. MID LEVEL MOISTURE WILL INCREASE OVER THE AREA ON THUR WITH WEST FLOW ALOFT. A FEW WEAK DISTURBANCES WILL MOVE ACROSS THE CWA AT THIS TIME. A WEAK COLD FRONT WILL ALSO MOVE ACROSS THE FORECAST AREA. THIS WILL RESULT IN A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS...MAINLY EAST OF THE LARAMIE RANGE. FOR FRI AND SAT...THE UPPER RIDGE WILL BEGIN TO BUILD OVER THE ROCKIES WITH A FEW THUNDERSTORMS IN THE MOUNTAINS. DIURNAL THUNDERSTORMS WILL OCCUR ACROSS THE AREA ON SAT WITH AMPLE MID LEVEL MOISTURE AND SURFACE BASED INSTABILITY. HIGH TEMPERATURES WILL BE FROM 5 TO 10 DEGREES ABOVE NORMAL EACH DAY. && .AVIATION...WIDESPREAD IFR CEILINGS AND VISIBILITIES IN FOG WILL DEVELOP OVER MUCH OF THE CWA BY SUNRISE AND THEN CONTINUE THROUGH MID MORNING. A SCATTERED COVERAGE OF AFTERNOON AND EVENING STORMS WILL AGAIN AFFECT MUCH OF THE CWA LATER TODAY. THE STRONGER STORMS WILL HAVE MVFR CEILINGS AND VISIBILITIES ASSOCIATED. LOW CEILINGS AND VISIBILITIES IN FOG ARE AGAIN POSSIBLE LATE TONIGHT THROUGH MID MORNING MONDAY OVER THE NEBRASKA PANHANDLE. SOME AFTERNOON AND EVENING THUNDERSTORMS WILL DEEVLOP AGAIN ON MONDAY...ESPECIALLY OVER THE NEBRASKA PANHANDLE. && .FIRE WEATHER...WARMER AND DRIER AIR WILL RETURN TO THE CWA STARTING ON MONDAY AND CONTINUING THROUGH MOST OF THIS WEEK. MINIMUM RELATIVE HUMIDITIES WILL BE BETWEEN 10 AND 20 PERCENT ON MANY OF THE AFTERNOONS...WITH THE LOWEST VALUES TO THE WEST OF THE LARAMIE RANGE. IN THOSE SAME AREAS...DAYTIME SOUTHWEST WINDS WILL GUST AS HIGH AS 25 TO 30 MPH. DRYING OF THE FUELS WILL PICK UP THIS WEEK AND FIRE WEATHER CONCERNS WILL ALSO INCREASE. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ WEILAND/KMD