Navigation

External Links

Style Options



Widescreen:
| 

000
FXUS65 KBOU 180953
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
353 AM MDT FRI MAY 18 2012

.SHORT TERM...UPPER LEVEL TROUGH OVER CALIFORNIA WILL RACE EASTWARD
TODAY AND BE OVER UTAH AT 00Z THIS EVENING AND BY 12Z SATURDAY
MORNING THE TROUGH WILL BE OVER CENTRAL COLORADO. SOUTHWEST FLOW
AHEAD OF THE TROUGH WILL TRANSPORT WARM AND DRY AIR INTO THE AREA.
AIRMASS WARMS ABOUT 5 DEGREES FAHRENHEIT TODAY WHICH WILL PUT HIGHS
IN THE MID 80S TO LOWER 90S ACROSS NORTHEAST COLORADO. LIFT FROM THE
APPROACHING TROUGH AND MID LEVEL INSTABILITY WILL PRODUCE SCATTERED
TO ISOLATED CONVECTION. IF ANY RAIN REACHES THE GROUND TODAY...IT
WILL BE LIGHT. DUE TO THE DRY ATMOSPHERE AND DEEP MIXING...NEARLY UP
TO 500MB...GUSTY OUTFLOW WINDS WILL OCCUR WITH NEARLY ALL THE
SHOWERS AND THUNDERSTORMS. WINDS SPEEDS WILL TOP OUT NEAR 50 MPH.

A WEAK FRONT TO MOVE THROUGH THE AREA THIS EVENING WILL CAUSE WINDS
TO TURN NORTHWESTERLY ALONG THE FRONT RANGE. STRONGER COLD FRONT
FROM THE NORTH WILL PUSH SOUTH ACROSS COLORADO AFTER MIDNIGHT. WINDS
WILL TURN NORTHERLY BEHIND THE FRONT AND GUST UP TO 40 MPH ACROSS
THE PLAINS. THERE WILL BE ENOUGH MOISTURE AND LIFT BEHIND THE FRONT
THAT LOW CLOUDS AND SCATTERED RAIN SHOWERS WILL PREVAIL BY SUNRISE
SATURDAY MORNING.

.FIRE WEATHER...UPGRADED THE FIRE WEATHER WATCH TO A RED FLAG
WARNING ACROSS THE PLAINS AND PALMER DIVIDE WHERE WINDS WILL GUST
TO AROUND 30 MPH AND RELATIVE HUMIDITIES WILL FALL TO AROUND 10
PERCENT. FOR THE AREAS FROM DENVER NORTH...APPEARS WINDS WILL STAY
BELOW THE 25 MPH FOR 3 HOURS CRITERIA. GUSTY WINDS WILL OCCUR FOR A
SHORT TIME WHEN THE OUTFLOW BOUNDARIES BLOW THROUGH. BECAUSE OF THE
DRY AIRMASS GUSTS TO 50 MPH WILL BE POSSIBLE WITH THE OUTFLOW
BOUNDARIES. SOME ISOLATED DRY LIGHTNING WILL BE POSSIBLE AS MOST OF
THE SHOWERS AND STORMS WILL AT MOST PRODUCE LIGHT RAIN.

.LONG TERM...WILL CONTINUE WITH THE COOLING AND MOISTENING ON
SATURDAY WITH THE UPPER TROUGH PASSING OVERHEAD. HOWEVER DO NOT
SEE MUCH SUPPORT FOR DEEP CONVECTION WITH ONGOING LOW-LEVEL COLD
AIR ADVECTION THROUGH THE MORNING HOURS AND WITH THE BULK OF THE
LARGE SCALE QG ASCENT SHIFTING EAST OF THE FRONT RANGE. NORTH-
NORTHWEST LOW- LEVEL FLOW EAST OF THE MTNS SATURDAY MORNING
GRADUALLY GOES ANTICYCLONIC UPSLOPE IN THE AFTERNOON WHICH SHOULD
PROVIDE THE LIFT NECESSARY FOR A BETTER CHANCE FOR SHOWERS AND
ISOLATED T-STORMS OVER AND ALONG THE FRONT RANGE. FARTHER OUT ON
THE PLAINS ATMOSPHERE NOT AS MOIST AND MORE STABLE. WILL BEGIN THE
DAY WITH LOW POPS ON THE PLAINS EXCEPT ACROSS SRN LINCOLN COUNTY
WHERE POST-FRONTAL NLY FLOW WILL BE DOWNSLOPING...I.E. DRYING THE
BNDRY LAYER IN THE AREA. MODEL QPF FIELDS INDICATE POCKETS OF 0.25
TO 0.50 INCH RAINFALL AMOUNTS OVER THE FRONT RANGE FOOTHILLS BY
EVENING. THIS SEEMS A BIT MUCH WITH THIS SETUP...BUT HIGH
SCATTERED POPS LOOK TO BE IN ORDER IN AND NEAR THE FRONT RANGE.
TEMPERATURES ON SATURDAY WITH THE CLOUD COVER AND COLD AIR
ADVECTION SOME 20-25F LOWER THAN THE DAY BEFORE. BY SATURDAY
EVENING SHOULD A STEADY REDUCTION IN THE SHOWER ACTIVITY AS THE
EAST- NORTHEASTERLY UPSLOPE FLOW TURNS SOUTH-SOUTHEASTERLY WITH
THE SFC HIGH DROPPING OUT OF EASTERN WYOMING. IN FOR A COOL NIGHT
WITH CLEARING SKIES...BUT DO NOT SEE ANY RISK FOR FROST AT LOWER
ELEVATIONS WITH UPPER LEVELS ALREADY BEGINNING TO WARM.

SUNDAY...SHORTWAVE RIDGE BUILDING OVER THE GREAT BASIN WILL SHIFT
EAST OVER UTAH AND WESTERN COLORADO DURING THE DAY CAUSING WINDS
ALOFT TO GO WEST-NORTHEASTERLY. MEANWHILE EAST OF THE MTNS...SFC
WINDS WILL REMAIN GENERALLY SOUTHEASTERLY FOR MUCH OF THE DAY.
THIS FLOW WILL TRANSPORT LOW-LEVEL MOISTURE UP INTO NORTHEAST
COLORADO ESLY UP ALONG THE FRONT RANGE...AND WITH STG SOLAR
HEATING COULD SEE ISOLATED TO WIDELY SCATTERED SHOWERS AND
T-STORMS OVER AND NEAR THE THE HIGH TERRAIN IN THE AFTERNOON.
GUSTY OUTFLOW AND LIGHTNING WILL PROBABLY BE THE MAIN PRODUCT OF
THIS CONVECTION. TEMPERATURES ON SUNDAY PROBABLY 10-15F WARMER
THAN THOSE ON SATURDAY.

LOOKING AHEAD TO NEXT WEEK...THE UPPER RIDGE MENTIONED ABOVE SHIFT
OVER COLORADO AND PRETTY MUCH REMAINS OVER THE STATE THROUGH
TUESDAY MORNING. LIGHT WINDS...AMPLE SUNSHINE AND WARMER
TEMPERATURES ARE IN STORE FOR MONDAY. UNSEASONABLY WARM
TEMPERATURES ALSO ANTICIPATED ON TUESDAY WITH THE WARMEST AIR
ALOFT PASSING OVER THE AREA. FLOW ALOFT ALSO TURNS SOUTHWESTERLY
AHEAD OF A SHORTWAVE TROUGH DROPPING IN OVER THE CENTRAL GREAT
BASIN. LOW HUMIDITY...VERY WARM TEMPERATURES AND GUSTY SOUTH-
SOUTHWEST WINDS WILL LIKELY INCREASE...POSSIBLY SIGNIFICANTLY THE
WILDLAND FIRE DANGER IN MOST AREA ON TUESDAY. BY WEDNESDAY THE GFS
SHOW A WELL FORMED TROUGH SWINGING ACROSS COLORADO ACCOMPANIED BY
A DECENT AMOUNT OF COOL AIR...MOISTURE AND LIFT. WHEREAS THE ECMWF
AND CANADIAN MODELS NOT AS OPTIMISTIC AS THEY SHOW A FLATTER
TROUGH PRETTY MUCH PASSING OVR WYOMING AND NORTHERN COLORADO.
BECAUSE OF THE UNCERTAINTY IN THE MODELS AT THIS POINT...WILL HANG
ONTO LOW POPS WEDNESDAY AND THURSDAY AND MAKE ONLY MINOR
ADJUSTMENTS TO SKY COVER AND TEMPERATURE THAT FAR OUT.

&&

.AVIATION...SOUTH TO SOUTHWEST WINDS ARE EXPECTED TO CONTINUE
THROUGH THE MORNING. A FEW GUSTS TO 25 KNOTS WILL BE POSSIBLE.
AIRMASS WILL BECOME UNSTABLE THIS AFTERNOON. BECAUSE OF THE DRY
AIRMASS...HIGH BASED SHOWERS AND STORM WILL FORM AND PRODUCE GUSTY
OUTFLOW WINDS WITH GUSTS TO 45 KNOTS. MULTIPLE OUTFLOW BOUNDARIES
WILL LIKELY MOVE THROUGH THE DENVER AREA PRODUCING GUSTY AND
ERRATIC WINDS FROM 21-01Z. AFTER 01Z...WINDS WILL TURN
NORTHWESTERLY AS A COLD FRONT NEARS. COLD FRONT WILL PUSH THROUGH
AROUND 06Z. BY 12Z SATURDAY...SCATTERED SHOWERS AND LOW CLOUDS
WILL BE AROUND.

&&

.HYDROLOGY...NO HYDROLOGY CONCERNS ARE EXPECTED TODAY OR TONIGHT.
WHAT RAIN THAT FALLS WILL BE LIGHT.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON MDT TODAY UNTIL 8 PM MDT THIS EVENING FOR
COZ244>251.

&&

$$

SHORT TERM...MEIER
LONG TERM....BAKER
AVIATION...MEIER

NWS BOU Office Area Forecast Discussion