FXUS65 KBOU 260501 AAA
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
955 PM MST FRI DEC 25 2009

.UPDATE TO HILITES AND AVIATION DISCUSSION AT THE BOTTOM FOR BLOWING 
SNOW AND LIGHT SNOW ACCUMLATIONS. 

.SHORT TERM...BIG STORM SYSTEM OVER CENTRAL PLAINS CONTINUES TO HAVE 
AFFECT ON MOST OF CWA. STRONG WINDS ALONG WITH LIGHT SNOWFALL 
CURRENTLY OCCURRING OVER NORTHEAST CORNER OF COLORADO...MAINLY EAST 
OF A CHEYENNE TO LIMON LINE. NOT ALOT OF SNOW FALLING...BUT MAIN 
FEATURE IS THE WIND...WITH GUSTS OF 40-45 KTS COMMON IN THIS REGION. 
AKRON RECENTLY REPORTED A COUPLE OF GUSTS OF 50 AND 53 KTS...WHICH 
IS HIGH WIND CRITERIA. THESE GUSTS APPEAR TO BE LOCALIZED AND NOT 
WIDESPREAD ENOUGH FOR HIGH WIND WARNING. MODELS KEEP TIGHT GRADIENT 
GOING FOR MOST OF THE NIGHT. CURRENT WINTER WEATHER ADVISORY FOR 
BLOWING SNOW STILL LOOKING GOOD THERE THROUGH 12Z SATURDAY. ACROSS 
MOUNTAINS...LIGHT SNOW CONTINUES TO FALL...BASED ON WEB CAMS AND 
RADAR LOOPS. WITH DECENT OROGRAPHS WITH NORTHWEST FLOW ALOFT AND 
GOOD MOISTURE PROGGED OVERNIGHT...WILL KEEP THE LIKELY POPS GOING
ALONG WITH SOME BLOWING SNOW. FORECAST A BIT TRICKY ALONG FRONT 
RANGE-URBAN CORRIDOR. WINDS FINALLY HAVE INCREASED...SHOULD PERSIST 
THROUGH THE EVENING WITH A DECREASE AFTER MIDNIGHT. SATELLITE 
SHOWING MOISTURE MOVING ACROSS AREA...BUT LITTLE IF ANY SNOWFALL 
BEING REPORTED. WILL MAINTAIN THE LOW POPS AS MODELS KEEP THE 
PRECIPITATION OVER THE EASTERN PLAINS. ON SATURDAY...MODELS SHOW THE 
LARGE STORM SYSTEM MOVING TOWARD THE GREAT LAKES REGION...WITH A 
GRADUAL WEAKENING PRESSURE GRADIENT ACROSS THE AREA. CONTEMPLATED 
EXTENDING THE PLAINS ADVISORY TO 18Z...BUT LATEST NAM INDICATES 
SURFACE WINDS DECREASING TO 20-30KTS. THERE MAY STILL BE SOME 
BLOWING SNOW ISSUES...BUT OVERALL THINGS SHOULD BE IMPROVING DURING 
THE MORNING. LATEST NAM SHOWS ANOTHER BATCH OF MOISTURE MOVING 
ACROSS REGION DURING THE AFTERNOON ASSOCIATED WITH A WEAK 
DISTURBANCE. MOST OF THE MOISTURE STAYS ACROSS EASTERN PLAINS AWAY 
FROM DENVER. WITH THE PERSISTANT NORTHWEST FLOW...MAY NOT SEE ANY 
SNOWFALL ALONG URBAN CORRIDOR. BEST CHANCE FOR SNOW TO BE FURTHER 
EAST. CURRENT POPS/WEATHER ALREADY SHOW THIS TREND...SEE NOT REASON 
TO MAKE ANY CHANGES AT THIS POINT. ACROSS  MOUNTAINS... OROGRAPHS 
REMAIN FAVORABLE THROUGH THE MORNING...THEN MOISTURE DEPTH AND WINDS 
DECREASE. LIKELY POPS LOOK REASONABLE FOR THE MORNING. SNOW AMOUNTS 
SHOULD BE ON THE LIGHT SIDE GIVEN THE LOW LAPSE RATES. OVERALL... 
TEMPERATURES TO CHANGE LITTLE FROM TODAY'S READINGS DUE TO 
PERSISTANT CLOUD COVER AND MINIMAL CHANGE IN THICKNESS 
VALUES.           

.LONG TERM...THE STRONG WINTER STORM WILL BE CENTERED OVER THE GREAT 
LAKES REGION COME SATURDAY NIGHT. ANY LINGERING SNOW OR GUSTY WINDS 
WILL COME TO AN END SATURDAY NIGHT. FLOW ALOFT WILL BE VERY WEAK 
BEHIND THE STORM SYSTEM SUNDAY AND MONDAY. 

FROM MONDAY NIGHT ON...MODELS HAVE A TOUGH TIME DEPICTING THE WEAK 
WAVES EMBEDDED IN THE FLOW ALOFT. ONE FEATURE THEY AGREE ON IS A 
STRONGER SHORT WAVE MOVING ACROSS NORTHERN MEXICO AND INTO TEXAS. 
THIS WILL CAUSE FLOW ALOFT TO SHIFT NORTHWESTERLY LATE TUESDAY. THIS 
NORTHWEST FLOW WILL LINGER THROUGH THE REST OF THE WEEK AND KEEP 
TEMPERATURES NEAR NORMAL TO SLIGHTLY BELOW NORMAL. MODELS SHOW THAT 
THERE WILL BE MOISTURE OVER THE MOUNTAINS AT TIMES MONDAY NIGHT 
THROUGH FRIDAY. WILL BROADBRUSH LOW POPS IN THE MOUNTAINS FOR THIS. 
IT WILL NOT SNOW THE ENTIRE TIME...BUT TOO DIFFICULT TO PICK OUT THE 
TIMING OF THE WAVES. SINCE THESE SYSTEMS ARE WEAK...EXPECTING ANY 
SNOW THAT FALLS WILL BE LIGHT. ALSO HAVE LOW POPS FOR THE LOWER 
ELEVATIONS THURSDAY FOR A WAVE THAT THE GFS HAS BEEN HINTING AT THE 
PAST FEW DAYS. STILL DON'T HAVE MUCH CONFIDENCE IN IT BUT CAN'T 
TOTALLY RULE IT EITHER. 

&&

.AVIATION...BANDS OF VERY LIGHT SNOW WILL CONTINUE TO ROTATE BACK 
INTO MUCH OF NORTHEAST COLORADO THRU THE NIGHT. MODELS ARE SHOWING 
SOME LIGHT ACCUM SO MAYBE UP TO AN INCH AT APA...BUT KDEN SHOULD 
HAVE ONLY A TRACE TO MAYBE A .10" OF AN INCH OF SNOW AT THE MOST. 
WIND SPEEDS AT LOCAL AIRPORTS HAVE DIMINISHED TO UNDER 10KT WITH AN 
SUBSTANTIAL NW WINDS WILL BE NORTH AND WELL EAST OF LOCAL AIRPORTS 
SO BLOWING SNOW SHOULD NOT BE A PROBLEM. 

&&

.BOU WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY FOR THE   
      NORTHEAST COLORADO PLAINS FROM 5 AM MST TODAY THROUGH 5 AM     
      MST SATURDAY...ZONES 42..44..45..46..48..49..50..51.

$$

ENTREKIN/D-L/MEIER