Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 191611
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1011 AM MDT SAT APR 19 2014

.UPDATE...
ISSUED AT 1011 AM MDT SAT APR 19 2014

FORECAST LOOKS GOOD WITH MOSTLY CLOUDY...COOLER...AND INCREASE IN
SHOWERS THIS AFTERNOON. COLD FRONT HAD PUSHED ACROSS MOST OF THE
FORECAST AREA INCLUDING DENVER THIS MORNING. MEANWHILE...A THICK
MID/UPPER LEVEL CLOUD DECK REMAINED ACROSS THE FORECAST AREA. THIS
CLOUD DECK WAS SHOWING SOME SIGNS OF THINNING IN THE LATEST
SATELLITE PICS...SO WE SHOULD SEE A FEW BREAKS THROUGH EARLY
AFTERNOON BEFORE CONVECTIVE CLOUDINESS AND NEARLY OVERCAST SKIES
REDEVELOP LATER THIS AFTERNOON. THE MOST NUMEROUS SHOWERS ARE
EXPECTED TO DEVELOP IN THE PARK/SUMMIT COUNTY AREA STRETCHING
NORTHWARD ALONG THE FRONT RANGE FOOTHILLS WHERE BEST BUT STILL
WEAK INSTABILITY IS PROGGED. CAPES ONLY ABOUT 100-300 J/KG BUT
SHOULD STILL BE ENOUGH FOR THUNDER AND BRIEF HEAVY RAIN...SNOW IN
ELEVATIONS ABOVE 10-10.5 THOUSAND FEET. DID INCREASE
POPS...QPF...AND HIGHER ELEVATIONS SNOW AMOUNTS A BIT MORE IN
THOSE LOCATIONS. I-25 URBAN CORRIDOR ON THE EDGE OF ANY
INSTABILITY BUT SHOULD STILL SEE SCATTERED SHOWERS AND PERHAPS AN
ISOLATED STORM DRIFT OFF THE HIGHER TERRAIN. EASTERN PLAINS LOOK
TOO STABLE BEHIND WEAK FRONTAL PASSAGE FOR MUCH CONVECTION UNTIL
PERHAPS LATER IN THE AFTERNOON SO DELAYED WEATHER CHANCES
THERE...AND EVEN THOSE ARE QUITE SMALL.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 410 AM MDT SAT APR 19 2014

MID- AND HIGH-LEVEL MOISTURE CONTINUES TO FLOW IN FROM THE DESERT
SOUTHWEST IN ADVANCE OF A CLOSED LOW OVER SOUTHERN CALIFORNIA AND
UPPER LEVEL OPEN WAVE TROUGH SLOWLY PROGRESSING EASTWARD ACROSS
THE REGION. IR SAT IMAGERY HAS SHOWN A DRAMATIC INCREASE IN
MID/HIGH CLOUD COVER OVER EASTERN COLORADO IN THE PAST HOUR IN
RESPONSE TO THIS INFLUX OF MOISTURE AND WARM SECTOR ISENTROPIC
LIFT. NOT SEEING ANY PRECIP REACHING THE GROUND AS OF YET...
EXCEPT PERHAPS ON THE HIGH MTN PEAKS. MEANWHILE A SFC TROUGH IN
ERN COLORADO INTERSECTS WITH A RELATIVELY WEAK SFC COLD FRONT
ADVANCING SEWRD ACROSS NRN WYOMING AND NORTHWEST NEBRASKA AT THIS
TIME. TEMPERATURE...THICKNESS AND WIND FIELDS SHOW THIS NEBULOUS
FRONTAL BOUNDARY REACHING THE NORTHEAST CORNER OF COLORADO JUST
BEFORE 1200Z AND MOVING INTO THE DENVER METRO AREA AROUND 1500Z.
AIR ONLY SLIGHTLY COOLER AND MORE HUMID BEHIND THIS BNDRY. POCKETS
OF GUSTY NELY WINDS CAN BE SEEN JUST BEHIND THIS FRONT. WITH THE
MAIN RISE/FALL PRESSURE COUPLET REMAINING WELL EAST OF THE
CWA...MODELS SHOW POST-FRONTAL WINDS WEAKENING AS THEY MAKE THEIR
WAY TO THE FRONT RANGE. HOWEVER MAY STILL SEE A SHORT PERIOD OF
15-20KT NELY WINDS WITH FRONTAL PASSAGE. WITH POST FRONTAL UPSLOPE
FLOW IN PLACE SHOULD SEE A STEADY LOWERING OF CLOUD BASES ALONG
AND EAST OF THE FRONT RANGE AS THE BOUNDARY LAYER CONTINUES TO
MOISTEN. IN ADDITION...THE PASSAGE OF A WEAK VORT LOBE NOW
CROSSING SWRN COLORADO WILL PROVIDE ADDITIONAL LIFT AND MOISTURE
FOR FAIRLY RAPID SHOWER FORMATION IN THE CENTRAL MTNS AROUND SOUTH
PARK LATER THIS MORNING. MODELS INDICATE THIS HAPPENING AFTER
1500Z.

SHOULD SEE SYNOPTIC SCALE LIFT AND INSTABILITY INCREASE THROUGH THE
DAY OVER THE CWA WITH THE UPPER TROUGH INCHING CLOSER. WRF...NAM
AND HRRR SHOW SCATTERED CONVECTION OVER THE FRONT RANGE DRIFTING
OVER THE I-25 URBAN CORRIDOR AFTER 2000Z TODAY. MODEL
REFLECTIVITIES ARE GENERALLY OF LOW INTENSITY. ALTHOUGH THE WRF
AND NAM SHOW A BAND OF 20-35DBZ CELLS SWINGING SEWRD ACROSS THE
DENVER METRO AREA JUST PRIOR TO 20/0000Z AND THEN OVER DOUGLAS AND
WESTERN ELBERT COUNTIES BETWEEN 0000Z AND 0300Z. MODELS SHOW A
FAIRLY DEEP EASTERLY LOW-LEVEL FLOW SETTING UP ALONG THE SPINE OF
THE PALMER DIVIDE THIS AFTERNOON WHICH DRIVES A THETA-E RIDGE UP
AGAINST THE SOUTHERN FOOTHILLS. THIS IS WHERE THE POTENTIAL FOR
BRIEF HEAVY RAINFALL WILL EXIST LATE THIS AFTERNOON AND EVENING.
COULD SEE UPWARDS OF A HALF INCH OF RAIN IN A SHORT PERIOD WITH
ISOLATED STORM CELLS ALONG THIS AXIS. GUSTY OUTFLOW WINDS ALSO
POSSIBLE. NOT AS CONFIDENT WE/LL SEE ANY HAIL FROM THESE LOW-TOP
T-STORMS AS CAPES AND LAPSE RATES NOT AS IMPRESSIVE AS MODELS
INDICATED YESTERDAY. ELSEWHERE...LOW POPS WARRANTED UNDER MOSTLY
CLOUDY TO OVERCAST SKIES. TEMPERATURES TODAY AS MUCH AS 15 DEG F
COOLER THAN YESTERDAY.

SHOWER ACTIVITY APPEARS TO QUICKLY DROP OFF FROM NORTH TO SOUTH THIS
EVENING. ALTHOUGH...A SMATTERING OF WEAK SHOWERS MAY LINGER OVER THE
HIGH TERRAIN SOUTHWEST OF DENVER AND ACROSS SOUTH PARK THROUGH THE
WEE HOURS OF THE MORNING. OVERNIGHT...TEMPERATURES WILL LOW ENOUGH
FOR A RAIN/SNOW MIX IN THIS AREA. IT IS POSSIBLE THE SOUTHERN
FOOTHILLS COULD SEE AN INCH OR TWO OF WET SNOW BEFORE MIDNIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 410 AM MDT SAT APR 19 2014

ON SUNDAY...THE UPPER LEVEL TROF WILL SLOWLY SHIFT EASTWARD INTO
THE CENTRAL PLAINS WITH MOST OF THE MOISTURE AND ENERGY ACROSS
SOUTHEAST PORTION OF CWA. THIS ALREADY REFLECTED IN FORECAST WITH
LITTLE CHANGE NEEDED. DRIER FURTHER NORTH BUT ENOUGH MOISTURE AND
INSTABLITY FOR SCATTERED SHOWER COVERAGE IN THE MOUNTAINS.

HIGH PRESSURE RIDGE BUILDS IN ALOFT OVER COLORADO AS FLOW ALOFT
SHIFTS MORE NORTHWEST ON MONDAY.  A COLD FRONT PUSHES ACROSS
NORTHEAST COLORADO SUNDAY NIGHT WITH SLIGHTLY COOLER TEMPERATURES
ON MONDAY. DRY AND MORE STABLE ON THE PLAINS BEHIND THE FRONT BUT
THERE WILL BE SOME SHOWERS AND STORMS OVER MOUNTAINS AND EAST
SLOPES AS LIGHT SOUTHEAST FLOW POOLS MOISTURE OVER EAST SLOPES.

FOR TUESDAY AND EARLY WEDNESDAY NEXT TROF DEEPENS OVER THE
NORTHERN GREAT BASIN WITH INCREASING SOUTHWEST FLOW ALOFT. THIS
WILL RESULT IN BIG WARMUP OVER LOWER ELEVATIONS AS STRONG
SOUTHERLY FLOW DEVELOPS OVER THE PLAINS. COULD BE A DRY LINE SETUP
OVER THE EASTERN BORDER WITH KANSAS WITH HIGHER DEWPOINTS IN THE
40S. BEST CHANCES FOR STORMS WILL BE OVER THE FAR PLAINS WITH
BETTER LOW LEVEL MOISTURE. FURTHER WEST TOWARDS THE FRONT
RANGE...GENERALLY DRY SOUTHWEST FLOW. THE UPPER TROF LIFTS
NORTHEAST INTO THE NORTHERN ROCKY MOUNTAIN REGION AND HIGH PLAINS
LATE WEDNESDAY AND THURSDAY. THIS WILL RESULT IN DRY...COOLER AND
WINDY CONDITIONS ON THE NORTHEAST PLAINS.

HIGH PRESSURE ALOFT WILL BUILD AGAIN INTO COLORADO ON FRIDAY FOR
GENERALLY DRY CONDITIONS AND WARMER TEMPERATURES AGAIN.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z SUNDAY AFTERNOON)
ISSUED AT 1011 AM MDT SAT APR 19 2014

WEAK COLD FRONT HAS PUSHED ACROSS THE FRONT RANGE AIRPORTS WITH
WINDS BECOMING MORE EAST/NORTHEASTERLY. WINDS SPEEDS ALREADY
SLACKING OFF TO 10 KTS OR LESS BEHIND THE FRONT AND TURNING MORE
EASTERLY. EXPECT WINDS TO REMAIN THIS WAY THROUGH THE AFTERNOON
UNTIL SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MAY DEVELOP AFT
21Z WITH VARIABLE WIND GUSTS 15-25 KTS NEAR SHOWERS. CEILINGS
COULD LOWER TO AROUND 6 THOUSAND FEET FOR ILS LANDING CONDITIONS
WITH ANY PASSING SHOWERS 21Z-02Z.  OTHERWISE VISUAL LANDINGS
WILL PREVAIL. CHANCE OF ANY THUNDER IS QUITE LOW WITH CAPES LESS
THAN 100 J/KG.

&&

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

$$

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


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