Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 191010
AFDBOU

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

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 244 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 244 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 18Z SUNDAY AFTERNOON)
ISSUED AT 244 AM MDT SAT APR 19 2014

COLD FRONT IS EXPECTED TO MOVE TROUGH THE DENVER AREA FROM THE
NORTHEAST AROUND 1500Z THIS MORNING. WINDS WILL SHIFT FROM WEST-
NORTHWEST TO A NORTHEAST COMPONENT WITH ITS PASSAGE. COULD SEE A
1-2 HOUR PERIOD OF 15-20 KTS GUSTS WITH FROPA. CLOUD BASES WILL
LOWER THROUGH THE DAY WITH BASES AS LOW AS 5000-6000 FEET AGL WITH
SCATTERED SHOWERS AND ISOLATED T-STORMS THIS AFTERNOON. BEST
CHANCE FOR THESE SHOWERS IN THE DENVER AREA BETWEEN 19/2100Z AND
20/0100Z. OVERNIGHT...SHOULD SEE A GRADUAL RISE IN CLOUD BASES
WITH PARTIAL CLEARING AFTER MIDNIGHT. EXPECT EAST-NORTHEAST SFC
WINDS OF 8-15KTS IN THE AFTERNOON...SOUTHEAST WINDS OF 7-12KTS IN
THE EVENING...THEN LIGHT DRAINAGE FLOW AFTER MIDNIGHT.

&&

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

$$

SHORT TERM...BAKER
LONG TERM...ENTREKIN
AVIATION...BAKER


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