FXUS65 KBOU 142137
AFDBOU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
235 PM MST MON DEC 14 2009
.SHORT TERM...THE ARCTIC PUSH HAS MADE IT AS FAR BACK AS KEENESBURG
AND HUDSON AS OF 230 PM AND WAS STILL INCHING TOWARD THE FRONT
RANGE. HOWEVER... PRESSURE FALLS WERE BEGINNING TO DEVELOP TO THE
NORTH IN WYOMING THIS AFTERNOON...SO PROGRESSION SHOULD SLOW DOWN.
THESE SHALLOW INTRUSIONS ARE ALWAYS TRICKY...BUT AT THIS POINT IT
LOOKS LIKE THERE MAY BE A BRIEF INTRUSION INTO EASTERN AND NORTHERN
DENVER...BEFORE THE DRAINAGE WINDS ARE ABLE TO KICK IN AGAIN THIS
EVENING. THE COLDEST AIR WILL STILL HOLD NORTH AND EAST OF THE
METRO AREA. THE INTERFACE OF COLDER TEMPERATURES AND DECENT LOW
LEVEL MOISTURE TO THE NORTH AND EAST OF DENVER WILL ALLOW
REDEVELOPMENT OF PATCHY FOG FROM LATE THIS EVENING THROUGH THE EARLY
MORNING HOURS TUESDAY IN AREAS FROM LONGMONT AND FORT COLLINS
EASTWARD TO THE NEBRASKA BORDER.
IN THE MOUNTAINS...SNOW SHOWERS CONTINUED AS THE AIRMASS WAS A BIT
UNSTABLE THIS AFTERNOON. WILL KEEP AT LEAST SCATTERED SNOW SHOWERS
GOING INTO THE EVENING WITH DRY CONDITIONS OVERNIGHT AS DRIER AIR
WORKS IN. A FEW SHOWERS WERE STILL DRIFTING ACROSS THE HIGHER
FOOTHILLS SO WILL MENTION A FEW EVENING FLURRIES THERE AS WELL.
TEMPERATURES SHOULD WARM UP SEVERAL MORE DEGREES ON TUESDAY AS WARM
ADVECTION OCCURS. SHIELD OF HIGH CLOUDS FROM THE PACIFIC STORM WILL
BEGIN TO INCREASE AS THE DAY PROGRESSES...WITH SOME MOUNTAIN WAVE
ENHANCEMENT AS WELL GIVEN SUFFICIENT CROSS MOUNTAIN FLOW NEAR 30
KNOTS. BREEZY CONDITIONS WILL STILL PREVAIL IN/NEAR THE FRONT RANGE
MOUNTAINS AND FOOTHILLS.
.LONG TERM...A SURFACE TROUGH WILL CONTINUE TO BUILD INTO THE
EASTERN PLAINS AS THE SURFACE HIGH REMAINS OVER WESTERN COLORADO
TUESDAY EVENING. WITH WESTERLY FLOW THROUGHOUT THE AIR COLUMN...THE
STRONG WINDS WILL CONTINUE OVER THE MOUNTAINS AND DOWN THE
FOOTHILLS. THIS WILL KEEP THE TREND OF WARMEST TEMPERATURES OVER THE
EASTERN SLOPES OF THE FOOTHILLS AND NEARBY URBAN CORRIDOR. THE ZONAL
FLOW ALOFT WILL CONTINUE WEDNESDAY TURNING SLIGHTLY NORTHWEST
KEEPING DRY AND MILD CONDITIONS. TEMPERATURES ALOFT WILL WARM
SLIGHTLY BRINGING MAX TEMPERATURES INTO THE MID TO UPPER 50S AROUND
THE METRO AREA AND EAST TO LIMON...INTO THE 40S OVER THE
NORTHEASTERN PLAINS AND INTO THE MID 30S TO MID 40S OVER THE HIGH
COUNTRY. ON THURSDAY A WEST COAST UPPER RIDGE BEGINS TO BUILD EAST
YET A SHORTWAVE WILL PUSH DOWN THE NW FLOW ALOFT...BRINGING AN
INCREASE IN MOISTURE AND COOLER TEMPERATURES BEHIND A COLD FRONT.
MODELS STILL DIFFER WITH THE STRENGTH AND WESTWARD EXTENT OF THIS
SYSTEM. MOISTURE AND DYNAMICS REMAIN LESS THAN
IMPRESSIVE...THEREFORE HAVE KEPT THE CHANCE FOR SNOW OVER THE HIGH
COUNTRY FOR THURSDAY THROUGH FRIDAY. THE ECMWF HAS A MUCH STRONGER
SHORTWAVE THAN THE GFS...WITH UPSLOPE FLOW FRIDAY BRINGING ABOUT 0.3
INCHES OF QPF. GFS IS NOT SHOWING ANY UPSLOPE WITH LITTLE
MOISTURE...THEREFORE WILL KEEP THE SLIGHT CHANCE OF PRECIPITATION
FOR THE PLAINS THURSDAY NIGHT INTO FRIDAY.
THE MODEL SOLUTIONS CONTINUE TO SPREAD FROM THIS POINT...WITH THE EC
SHOWING MORE OF A MERIDIONAL PATTERN AND A MUCH DEEPER EASTERN US
TROUGH. THE GFS SHOWS A SLIGHTLY MORE ZONAL PATTERN BUT STILL
KEEPING CO UNDER A RIDGE OR IN THE NW FLOW AHEAD OF THE RIDGE.
THEREFORE WILL KEEP THE REST OF THE PREVIOUS FORECAST
UNTOUCHED...WHICH MEANS NEAR NORMAL TEMPERATURES AND WILL KEEP ANY
MENTION OF RAIN OR SNOW OUT OF THE FORECAST.
&&
.AVIATION...THERE IS A WEAK PUSH OF ARCTIC AIR APPROACHING THE
AIRPORT LATE THIS AFTERNOON BUT FOG ASSOCIATED WITH THIS FEATURE HAS
DISSIPATED. DESPITE THE SLOWER ADVANCEMENT...THE FRONT IS STILL
EXPECTED TO SNEAK INTO DIA 23Z-00Z. HOWEVER...DRAINAGE WINDS ARE
STILL EXPECTED TO RESUME DURING THE EVENING AND SHOULD BE ENOUGH TO
KEEP THREAT OF FOG JUST TO THE NORTH AND EAST OF DIA OVERNIGHT AND
TUESDAY MORNING. AT THIS TIME...CHANCES OF FOG AT DIA APPEAR TO BE
LESS THAN 20%.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...NONE.
$$
BARJENBRUCH/KRIEDERMAN
