000 FXUS65 KBOU 081724 AFDBOU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 1024 AM MST WED FEB 8 2012 .UPDATE... && .SHORT TERM...TEMPERATURES SLOW TO WARM ON THE PLAINS THIS MORNING WITH CURRENT READINGS IN THE SINGLE DIGITS ABOVE ZERO ACROSS THE NORTHEAST CORNER OF THE STATE AND TEENS ELSEWHERE. MID-MORNING READINGS IN THE HIGH COUNTRY SLIGHTLY WARMER WITH TEENS AND 20S THE RULE...WARMEST UP ALONG THE CONTINENTAL DIVIDE WITH WEAK WARM AIR ADVECTION IN INCREASING WESTERLY FLOW AT MID- LEVELS. MOUNTAIN WAVE CLOUD BAND NOW LOOSING ITS GRIP ON THE FRONT RANGE...WILL EXPOSE THE PLAINS TO MORE SUNSHINE IN THE NEXT COUPLE OF HOURS WHICH SHOULD ACCELERATE THE WARMUP. WILL HOLD ONTO THE CURRENT TEMPERATURE FORECAST...WITH WARMEST READINGS LIKELY IN BREEZY AREAS ALONG THE BASE OF THE FOOTHILLS...AND COOLEST READINGS IN RIVER BOTTOM AREAS ALONG THE SOUTH PLATTE RIVER BELOW WIGGINS. THE SLIGHT WARMING AT MID-LEVELS ALSO INCREASING THE STABILITY AT MTN TOP LEVEL. THE RESULT SHOULD BE AN INCREASE IN WESTERLY WIND GUSTS TO AROUND 40KTS ON THE HIGH MTN TOPS AND UPPER EAST SLOPES OF THE FRONT RANGE IN THE NEXT FEW HOURS...THEN A GRADUAL DECREASE IN WIND SPEEDS THROUGH THE AFTERNOON AS INSTABLITY INCREASES AHEAD OF THE APPROACHING TROUGH. MEANWHILE... CLEARING DOWNWIND FROM THE FRONT RANGE THIS MORNING STILL EXPECTED TO REVERSE THIS AFTERNOON AS THE NEXT WAVE OF MID-LEVEL MOISTURE ADVECTS IN FROM UTAH. 12Z NAM AND GFS INDICATE MOSTLY CLOUDY/ OVERCAST SKIES ACROSS THE FCST REGION BY LATE THIS AFTERNOON AND EVENING...WITH ISOLATED TO SCATTERED OROGRAPHICALLY PRODUCED SNOW SHOWERS DEVELOPING ALONG AND WEST OF THE CONTINENTAL DIVIDE AFTER 23Z THIS AFTERNOON. IT MAY BE NECESSARY TO MOVE UP THE LIKELY POPS IN THE HIGH COUNTRY TO MID-EVENING SHOULD SHOWERS DEVELOP SOONER THAN EXPECTED THIS AFTERNOON. .AVIATION...IFR CEILINGS AND VISIBILITIES EXPECTED AT DENVER AREA AIRPORTS THROUGH AT LEAST 05Z THIS EVENING. AFTER 05Z THE METRO AREA COULD SEE CEILINGS LOWERING TO AROUND 5000 FT AGL AS A WEAK UPPER LEVEL LOW PRESSURE TROUGH PASSES OVER CENTRAL AND SOUTHERN COLORADO. AT THIS TIME...IT APPEARS THE CHANCE FOR PRECIPITATION/ SNOWFALL IN THE DENVER AREA OVERNIGHT IS MIMINAL WITH THE SFC TO 15000 FT AGL FLOW PREDOMINANTLY NORTHWESTLY IN DIRECTION--WHICH IS A DRYING WIND COMPONENT FOR THE METRO AREA. SKIES ARE EXPECTED TO QUICKLY CLEAR THURSDAY MORNING IN THE WAKE OF THIS UPPER LEVEL WEATHER DISTURBANCE. && .PREV DISCUSSION... /ISSUED 345 AM MST WED FEB 8 2012/ SHORT TERM...MAIN CHANGE FOR THIS FORECAST PACKAGE IS TO INCREASE THE CLOUD COVER AS PERSISTENT WAVE CLOUD WILL GIVE WAY TO A GENERAL INCREASE IN MID AND UPPER LEVEL MOISTURE LATER TODAY. WEAK LOW LEVEL SHORTWAVE MOVES ACROSS THE NORTHERN PLAINS TONIGHT WHILE MOISTURE INCREASES IN SLIGHT WARM ADVECTION ALOFT. TEMPERATURE ADVECTION IS FAIRLY WEAK SO NOT MUCH QG FORCING...BUT MOUNTAINTOP LEVEL WINDS DO INCREASE FOR A WHILE LATER TODAY BEFORE DIMINISHING EARLY THURSDAY. WITH MOISTURE INCREASING AND ENOUGH WIND...EXPECT OROGRAPHIC SNOW IN THE HIGHER MOUNTAINS AS THESE FEATURES MOVE THROUGH. LAPSE RATES REMAIN FAIRLY STABLE...SO SNOWFALL AMOUNTS SHOULD BE FAIRLY LIGHT...SNOW MODEL GAVE UP TO 4 INCHES IN SPOTS FAVORED BY WESTERLY FLOW OVERNIGHT. LOWERED HIGHS ON THE PLAINS TODAY A LITTLE DUE TO THE CLOUD COVER AND HELD ON TO LOWS WHICH ARE GENERALLY ABOVE GUIDANCE TONIGHT FOR THE SAME REASON. FINALLY...PATCHY FOG LOOKS LIMITED TO THE CREST OF THE PALMER DIVIDE AND THE FAR NORTHEAST CORNER THIS MORNING...NOT TOO THICK AS THERE IS SOME WIND AND SHOULD LIFT BY MID MORNING. LONG TERM...AN UPPER TROUGH IS PROGGED TO PUSH ACROSS THE CWA THURSDAY. FAIRLY STRONG NORTH-NORTHWESTERLY FLOW ALOFT IS PROGGED BEHIND THE TROUGH FOR LATER THURSDAY NIGHT. ON FRIDAY AND FRIDAY NIGHT...THE FLOW BECOMES NORTHWESTERLY AND SLOWLY DECREASES IN SPEED AS AN UPPER RIDGE IS EXPECTED TO MOVE ACROSS COLORADO ON SATURDAY. THERE IS WEAK UPWARD SYNOPTIC SCALE ENERGY PROGGED FOR THE CWA ON THURSDAY...THEN DOWNWARD MOTION IS EXPECTED THURSDAY NIGHT THROUGH MUCH OF FRIDAY NIGHT. THE BOUNDARY LAYER FLOW IS PROGGED TO BE DOMINATED BY NORTHWESTERLY DOWNSLOPING ON THURSDAY ..THEN NORMAL DIURNAL PATTERNS WILL PERSIST THURSDAY NIGHT AND FRIDAY. BY FRIDAY NIGHT...A SURGE OF COOLER AIR AND EASTERLY UPSLOPE IS PROGGED OVER THE EASTERN PLAINS. FOR MOISTURE...IT DECREASES RAPIDLY OVER THE CWA ON THURSDAY MORNING. THERE IS TAD PROGGED TO LINGER OVER THE HIGH MOUNTAINS. THERE IS SOME MOISTURE IN THE MID LEVELS THURSDAY EVENING...OTHERWISE IT LOOKS PRETTY DRY. FRIDAY IS DRY OVER THE PLAINS...BUT MOISTURE IS ON THE INCREASE OVER THE MOUNTAINS BY AFTERNOON FRIDAY. BY FRIDAY NIGHT...MOISTURE IS LIMITED OVER THE MOUNTAINS...BUT THE EASTERN TWO-THIRDS OF THE PLAINS HAVE PRETTY DECENT MID AND UPPER LEVEL MOISTURE IN PLACE. THERE IS A TAD OF MEASURABLE SNOW OVER THE MOUNTAINS ON QPF FIELDS THURSDAY. WILL GO WITH MINIMAL POPS IN THE MOUNTAINS ON THURSDAY... WITH THE LINGERING MOISTURE IN MIND. FOR TEMPERATURES...THURSDAY'S HIGHS LOOK CLOSE TO TODAY'S READINGS. FRIDAY'S ARE PRETTY CLOSE TOO. THE NORTHEAST CORNER...HOWEVER...IS ABOUT 5 C COLDER THAN THURSDAY. FOR THE LATER DAYS...SATURDAY THROUGH TUESDAY...MODELS BRING AN UPPER RIDGE ACROSS COLORADO SATURDAY...THEN A WEAK UPPER TROUGH ON SUNDAY. MORE RIDGING FOR MONDAY...THEN ANOTHER UPPER TROUGH/CLOSED LOW ON TUESDAY. THE LOOK OF THE PATTERN WE'VE HAD OVER US THE LAST FEW DAYS...CONTINUING INTO THE EXTENDED PERIOD... DOES NOT LOOK VERY COMMON. IT'S RATHER DIFFICULT TO BUY...BECAUSE IT JUST DOESN'T LOOK LIKE THAT/THIS VERY OFTEN. THESE 00Z MODELS SHOW THE TROUGH FOR SATURDAY NIGHT/SUNDAY TO HAVE LESS MOISTURE THAN PREVIOUS RUNS INDICATED. THE MOISTURE FOR THE TUESDAY TROUGH IS NOT VERY SIGNIFICANT EITHER. WE'LL HAVE TO SEE. TEMPERATURES DON'T APPEAR TO GET ABOVE SEASONAL NORMALS ANY OF THE FOUR DAYS. ALSO OF NOTE...THE SURGE THAT THE MODELS SHOW FOR FRIDAY NIGHT THROUGH SATURDAY THAT JUST GETS INTO THE EASTERN PLAINS WILL LIKELY MAKE INTO THE LOWER FOOTHILLS ANYWAY. AGAIN..WE'LL HAVE TO SEE. AVIATION...VFR CONDITIONS EXPECTED THROUGH TONIGHT. SOME UNCERTAINTY ABOUT WINDS THIS AFTERNOON...KDEN/KAPA SHOULD GO TO LIGHT EASTERLY WINDS BUT KBJC MAY REMAIN NW DUE TO A WEAK DENVER CYCLONE. SPEEDS SHOULD BE UNDER 8 KNOTS IN ANY EVENT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BAKER/GIMMESTAD LONG TERM....RJK AVIATION...BAKER/GIMMESTAD