Issued by NWS Cheyenne, WY
000 FXUS65 KCYS 141937 AFDCYS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 137 PM MDT TUE OCT 14 2008 .SHORT TERM...TONIGHT THROUGH THURSDAY... THE LARGE AREA OF MID AND HIGH CLOUDS WILL CONTINUE OVER THE NEBRASKA PANHANDLE THROUGH EARLY TONIGHT BEFORE IT IS PUSHED EAST AHEAD OF AN APPROACHING SHORTWAVE TROUGH. THAT SHORTWAVE TROUGH WAS LOCATED FROM EASTERN MONTANA TO SOUTHERN IDAHO EARLY THIS AFTERNOON. AS THE FEATURE WILL CONTINUES TO MOVE EAST AND FILL THROUGH TONIGHT. AN ASSOCIATED SURFACE COLD FRONT EXTENDED FROM EASTERN MONTANA TO NORTHWEST WYOMING AT 18Z WITH STILL A 5MB 3 HOURLY SURFACE PRESSURE RISE AREA OVER NORTH CENTRAL MONTANA. THE FRONT WILL WILL MOVE ACROSS THE CWA FROM MID AFTERNOON THROUGH MID EVENING AND IS HANDLED SIMILARLY BY THE MODELS. CLOUDS 4 TO 7 THOUSAND FEET AGL WERE LOCATED BEHIND THE FRONT AND SHORTWAVE TROUGH IN MONTANA AND NORTHWEST WYOMING AT 18Z. SOME SHOWERS WERE NOTED EARLY THIS AFTERNOON IN THAT AREA. THE CLOUDS SHOULD SPREAD SOUTH AND OVER MUCH OF THE CWA THROUGH EARLY TONIGHT. AT THIS TIME WILL LEAVE ANY SHOWERS OUT OF THE CWA FOR TONIGHT...WITH LIFT...DYANMICS AND DEEPER MOISTURE SOMEWHAT LACKING. THE CLOUD AREA WILL SLOWLY MOVE EAST LATE TONIGHT AND WEDNESDAY MORNING AS WINDS TURN MORE WESTERLY. WILL PLACE PATCHY FOG OVER THE LOWER ELEVATIONS OF CARBON COUNTY LATE TONIGHT AND EARLY WEDNESDAY MORNING. THE 700 MB TEMPERATURES COOL FOR WEDNESDAY BEHIND THE FRONT AND SHORTWAVE TROUGH. RESULTING HIGHS FOR WEDNESDAY WILL BE 4 TO 8 DEGREES COOLER THAN THOSE OF TODAY. SEVERAL WEAK SHORTWAVE TROUGHS WILL MOVE ACROSS THE CWA WEDNESDAY NIGHT AND THURSDAY. MID AND UPPER LEVEL MOISTURE WILL SPREAD BACK OVER MUCH OF THE CWA DURING THAT TIME. THE ASSOCIATED SURFACE COLD FRONT MOVES ACROSS THE CWA ON THURSDAY. AT THIS TIME WILL CONTINUE TO LEAVE POPS OUT OF THE FORECAST. AHEAD OF THE FRONT THE TEMPERATURES WILL REBOUND BACK TO AROUND NORMAL VALUES FOR THURSDAY. WINDS ALOFT INCREASE WEDNESDAY NIGHT AND THE SURFACE PRESSURE GRADIENT TIGHTENS. THAT WILL PRODUCE GUSTY WINDS LATER WEDNESDAY NIGHT NEAR AND WEST OF THE LARAMIE RANGE AND THEN OVER THE ENTIRE CWA FOR THURSDAY. .LONG TERM...THU NIGHT THROUGH TUE... NORTHWEST FLOW ALOFT THU NIGHT WILL BACK FRI AS A RIDGE APPROACHES FROM THE WEST. THE RIDGE WILL PASS OVER THE FORECAST AREA FRI NIGHT AND WILL BE FOLLOWED BY QUASI ZONAL FLOW ALOFT SATURDAY AND SUNDAY. UPPER FLOW WILL BACK TO SOUTHWESTERLY MON WITH INCREASING MOISTURE AND POSITIVE VORTICITY ADVECTION THROUGH TUE. CLOSER TO THE GROUND ...SURFACE BASED LEESIDE TROUGHING IS PROGGED FROM THU NIGHT THROUGH SAT NIGHT. FRI AND SAT WILL BOTH BE DRY AND MILD. A WEAK COOL FRONT WILL PRODUCE SLIGHTLY COOLER CONDITIONS SUN INTO MON...BUT NO PRECIPITATION IS EXPECTED EITHER DAY. TUE WILL BE A BIT COOLER WITH A CHANCE OF MAINLY OROGRAPHIC RAIN/SNOW SHOWERS IN THE HIGHEST MOUNTAINS NEAR THE CO BORDER. && .AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL OVER THE CWA THROUGH THURSDAY. CLOUDS WILL SPREAD SOUTH AND OVER MUCH OF THE CWA THROUGH EARLY TONIGHT WITH CLOUD BASED BETWEEN 4 AND 7 THOUSAND FEET AGL. THOSE CLOUDS WILL GRADUALLY DECREASE FROM WEST TO EAST LATE TONIGHT AND WEDNESDAY MORNING. PATCHY FOG IS EXPECTED OVER THE LOWER ELEVATIONS OF CARBON COUNTY BETWEEN 08Z AND 14Z AND WILL AFFECT THE AIRPORTS AT KRWL AND KSAA. WESTERLY WINDS WILL INCREASE OVER THE CWA LATE WEDNESDAY NIGHT AND CONTINUE FOR THURSDAY. WIND GUSTS WILL BE BETWEEN 25 AND 35 KNOTS. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ WEILAND/JR
