Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 281459
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
859 AM MDT TUE APR 28 2015

.UPDATE...
ISSUED AT 859 AM MDT TUE APR 28 2015

PATCHY FOG THAT DEVELOPED EARLY THIS MORNING IN WAKE OF PARTIAL
CLEARING HAS PRETTY MUCH BURNED OFF WITH DAYTIME HEATING. 12Z
DENVER SHOWED SHALLOW INSTABILITY IN THE MOIST LAYER UNDER A
STRONG CAPPING INVERSION NEAR 650 MB. AS A RESULT...THE DAYTIME
HEATING HAS LED TO A FAST DEVELOPMENT OF SHALLOW
CUMULUS/STRATOCUMULUS. EXPECT PARTLY CLOUDY SKIES MOST OF THE DAY
ALTHOUGH CONTINUED MIXING SHOULD EVENTUALLY BRING MORE SUNSHINE
THROUGH THE AFTERNOON. OVERALL FORECAST IS ON TRACK WITH JUST
SLIGHT ADJUSTMENTS TO CLOUD COVER.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 420 AM MDT TUE APR 28 2015

EARLY IN THE SHIFT BELIEVED FOG WOULD FORM NOT TOO LONG AFTER
MIDNIGHT AND BECOME WIDESPREAD ON THE PLAINS BY 09Z BASED ON THE
00Z NAM AND WRF...AND 06Z RAP AND HRRR SFC AND BNDRY LAYER RH
FIELDS. SAME MODELS ALSO INDICATED A SURGE OF NELY LOW-LEVEL FLOW
AROUND A SFC HIGH SLIPPING SEWRD OUT OF WY DURING THE PRE-DAWN
HOURS. STILL NOT SEEING MUCH IN THE WAY OF FOG YET...ALTHOUGH SFC
WINDS HAVE TURNED NELY IN AREAS EAST OF THE I-25 URBAN CORRIDOR
WITHIN THE PAST COUPLE OF HOURS. SO WILL HOLD ONTO THE FOG AND LOW
CLOUD FORECAST FOR THE PLAINS UNTIL AROUND 15Z THIS MORNING.
SHOULD SEE LOWEST VISIBILITIES IN LOW LYING AREAS ALONG THE SOUTH
PLATTE FROM AROUND GREELEY TO STERLING. WILL ALSO KEEP PATCHY FOG
IN THE MTN VALLEYS...PARTICULARLY SOUTH PARK WITH ITS FRESH
BLANKET OF SNOW...THROUGH EARLY THIS MORNING.

SHOULD SEE THE LAST OF THE FOG AND LOW CLOUD BURN OFF BY LATE
MORNING AS DRIER AIR FILTERS DOWN FROM WYOMING ON LIGHT NORTHERLY
WINDS. COULD SEE A BAND OF THICK CIRRUS SWINGING SOUTHWARD OVER THE
AREA LATE THIS MORNING...MARKING THE START TO WARMING ALOFT. UPPER
RIDGE BUILDING OVER THE WESTERN CONUS IS FORECAST WITH SLOWLY
MIGRATE EASTWARD OVER COLORADO NEXT 24 HOURS. AIRMASS ACCOMPANYING
THIS RIDGE IS WARMER AND MUCH DRIER. ALTHOUGH LINGERING LOW-LEVEL
MOISTURE AND DAYTIME HEATING MAY BUBBLE UP INTO A FEW SHOWERS OVER
THE MTNS AND SOUTH PARK AREA THIS AFTERNOON. SHOULD THEN SEE SKIES
CLEAR OVERNIGHT. HIGHS EXPECTED TODAY AND TONIGHT WILL HOOVER
AROUND THE SEASONAL NORMS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 420 AM MDT TUE APR 28 2015

HIGH PRESSURE RIDGE ALOFT BUILDS ACROSS COLORADO ON WEDNESDAY WITH
CONTINUED WARMING AND DRY AIRMASS. 700MB TEMPERATURES NEARING +6C
WILL RESULT IN READINGS IN THE 70S ACROSS THE PLAINS. THE RIDGE
SHIFTS EAST OF COLORADO ON THURSDAY AS A FAST MOVING UPPER LEVEL
DISTURBANCE AND ASSOCIATED COLD FRONT POISED TO MOVE OVER THE
REGION LATE THURSDAY AFTERNOON AND NIGHT WITH INCREASING MOISTURE
AND SHALLOW UPSLOPE FLOW DEVELOPING. THIS WILL BRING A RETURN TO
LATE DAY SHOWERS AND THUNDERSTORMS. STORMS MAY LINGER WELL INTO
THE NIGHT...ESPECIALLY SOUTHERN AND EASTERN SECTIONS OF THE CWA.

BEHIND THE THURSDAY TROF...THE FLOW ALOFT BECOMES MORE OF A ZONAL
WEST TO NORTHWEST FLOW WITH ENOUGH MOISTURE TO KEEP A CHANCE OF
AFTERNOON AND EVENING THUNDERSTORMS FROM FRIDAY AFTERNOON AND
CONTINUED THROUGH THE WEEKEND. STORMS MAY BECOME MORE NUMEROUS BY
LATE SUNDAY WITH ANOTHER WEAK COLD FRONT AND AN EMBEDDED
DISTURBANCE. HIGHEST POPS WILL REMAIN OVER MOUNTAINS AND PALMER
DIVIDE. TEMPERATURES THROUGH THE PERIOD WILL BE AROUND OR A BIT
HIGHER THAN SEASONAL NORMALS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z WEDNESDAY MORNING)
ISSUED AT 859 AM MDT TUE APR 28 2015

FOG THREAT HAS ENDED THIS MORNING BUT SHALLOW
CUMULUS/STRATOCUMULUSCLOUDS DEVELOPING WITH DAYTIME HEATING.
THESE MAY GO BROKEN WITH CEILINGS IN THE 2000-2500 FOOT LAYER
THROUGH ABOUT 18Z BEFORE GRADUALLY LIFTING AND SCATTERING OUT
AGAIN. ILS LANDING CONDITIONS COULD LINGER INTO EARLY AFTERNOON.
OTHERWISE VISUAL LANDINGS WILL PREVAIL WITH LIGHT AND NORMAL
DIURNAL WIND PATTERNS 10 KNOTS OR LESS.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...BARJENBRUCH
SHORT TERM...BAKER
LONG TERM...ENTREKIN
AVIATION...BARJENBRUCH


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