Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 221510
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
910 AM MDT WED APR 22 2015

.UPDATE...
ISSUED AT 853 AM MDT WED APR 22 2015

ONLY MINOR CHANGES PLANNED ON THIS UPDATE. WEAK RIDGE AXIS ALOFT
WILL SHIFT OVER COLORADO WITH ONLY NEUTRAL TO WEAK ASCENT NOTED IN
VERTICAL VELOCITY FIELDS THROUGH THIS EVENING. SOUTHEAST SURFACE
WINDS ALREADY INCREASING ON THE FAR PLAINS THIS MORNING AND THIS
WILL SET UP A WEAK DENVER CYCLONE CONVERGENCE ZONE LATER THIS AM
AND AFTERNOON. SHORT RANGE HIGH RESOLUTION MODELS SHOWING THIS
BOUNDARY TO SET UP MAINLY SOUTH AND EAST OF DENVER WITH BEST FOCUS
FOR STORMS ACROSS ELBERT...LINCOLN AND WASHINGTON COUNTIES.
SURFACED BASED CAPES ONLY UP TO AROUND 700J/KG AS SURFACE
DEWPOINTS WILL REMAIN IN THE 30S DESPITE SOUTHEAST FLOW.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 306 AM MDT WED APR 22 2015

A WEAK UPPER LEVEL RIDGE WILL BUILD INTO THE AREA TODAY THRU TONIGHT
WITH MAINLY WLY FLOW ALOFT.  AT THE SFC LOW PRES WILL WILL INTENSIFY
OVER WESTERN COLORADO ALLOWING FOR INCREASING SSE LOW LVL FLOW
ACROSS NERN CO THRU THE AFTN HOURS.  MAY SEE A DENVER CYCLONE DVLP
THIS AFTN WITH A CONVERGENCE ZONE SETTING UP MAINLY TO THE SOUTH AND
EAST OF DENVER. PRECIPITABLE WATER VALUES ARE FCST TO BE SIMILAR
TO YESTERDAY OVER THE MTNS AND FOOTHILLS WITH SLIGHTLY HIGHER
VALUES DEVELOPING OVER THE PLAINS LATER THIS AFTN AND EVENING. SFC
BASED CAPES WILL GENERALLY BE 500 J/KG OR LESS EXCEPT ACROSS PARK
COUNTY AND OVER THE PALMER DIVIDE WHERE VALUES MAY BE SLIGHTLY
HIGHER.

AT THIS TIME WILL KEEP IN A CHC OF SHOWERS AND A FEW TSTMS OVER THE
HIGHER TERRAIN FOR THIS AFTN AND EVENING WITH BETTER COVERAGE
EXPECTED ALONG AND SOUTH OF I-70.  AT LOWER ELEVATIONS APPEARS BEST
CHC FOR INITIAL SHOWER AND TSTM DEVELOPMENT WILL BE ALONG THE DENVER
CONVERGENCE TO THE S AND E OF DENVER SO WILL HAVE CHC POPS ACROSS
THE PALMER DIVIDE EXTENDING TOWARDS LIMON. TO THE NORTH AND NE OF
DENVER PCPN CHANCES LOOK LOWER AT THIS TIME EXTENDING INTO THE FAR
NORTHEAST CORNER. AS FOR HIGHS THIS AFTN 850-700 MB READINGS ARE
FCST TO RISE A FEW MORE DEGREES SO WILL HAVE READINGS IN THE MID
60S TO LOWER 70S OVER NERN CO.

FOR TONIGHT EXPECT LINGERING SHOWERS AND A FEW TSTMS THRU THE EARLY
EVENING HOURS HOWEVER MOST ACTIVITY SHOULD GRADUALLY END BETWEEN 03Z
AND 06Z.  A FEW SHOWERS MAY LINGER OVER THE ERN PLAINS AFTER
MIDNIGHT SO WILL KEEP IN SOME LOW POPS IN THESE AREAS BETWEEN 06Z
AND 12Z.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 306 AM MDT WED APR 22 2015

ON THURSDAY...THE UPPER RIDGE AXIS WILL BE LOCATED TO THE EAST OF
COLORADO. THE FLOW ALOFT WILL BECOME SOUTHWESTERLY WITH WEAK MID
LEVEL QG ASCENT DEVELOPING. THE MDLS MAINTAIN A SURFACE TROUGH
ALONG THE FRONT RANGE. THE FORECAST SOUNDINGS FROM THE NAM12
INDICATE DECENT MOISTURE...SHEAR AND INSTABILITY IN THE AFTN FOR A
CHANCE OF SEVERE WEATHER. FORECAST CAPES AT DENVER 1800-1900 J/KG
AT AKRON...FAVORABLE SHEAR PROFILE AS WELL WITH LOW LVL SELY WINDS
TRANSITIONING TO WSWLY IN THE MID LEVELS. WITH THE LOW LEVEL SELY
WIND COMPONENT...LOOKS LIKE FAVORABLE DEVELOPMENT FOR A DENVER
CYCLONE. BEST POTENTIAL FOR SEVERE STORMS NEAR DENVER WILL BE
ALONG THIS CONVERGENCE LINE. THURSDAY NIGHT AND FRIDAY...THE MDLS
MOVE THE UPPER LOW OVER BAJA AND MOVE IT ACROSS COLORADO IN THE
12-18Z TIME FRAME. MDT QG ASCENT ASSOCIATED WITH THE TROUGH OVER
SRN AND ERN COLORADO FRIDAY MORNING. WL KEEP CHANCE OF SHOWERS
GOING IN THE MOUNTAINS THURSDAY NIGHT. WINDS ALOFT TRANSITION FM
SWLY TO NWLY FRIDAY WITH THE PASSAGE OF THE UPPER TROF AXIS.
COOLER TEMPERATURES WITH THE POTENTIAL OF SOME LIGHT SNOW IN THE
MOUNTAINS...MAYBE 1-4 INCHES IN THE 06Z TO 18Z TIME FRAME ON
FRIDAY. ACROSS THE NORTHEAST PLAINS...FAVORABLE INSTABILITY IN
SPITE OF THE COOLER TEMPERATURES. CAPES FRI AFTN COULD BE IN THE
800-1200 J/KG RANGE. THE AMS DOES STABILIZE UNDER THE INFLUENCE OF
A SHORT WAVE RIDGE ON SATURDAY. IT WILL REMAIN UNSETTLED HOWEVER
WITH THE CHC OF SHOWERS AND MAYBE AN EMBEDDED TSTM SATURDAY AFTN.
THE NEXT DEVELOPING SYSTEM IS PROGGED IMPACT COLORADO LATE
SATURDAY AND POSSIBLY INTO EARLY MONDAY. THE ECMWF...CANADIAN AND
GFS MDLS MOVE THIS TROUGH FROM THE PACIFIC NORTHWEST TO NEAR THE
FOUR CORNERS REGION BY 18Z SUNDAY THEN EAST TOWARDS THE TX
PANHANDLE BY 12Z MONDAY. AS A RESULT...THE POTENTIAL FOR ANOTHER
PERIOD OF WIDESPREAD MOUNTAIN SNOW FOR THE FRONT RANGE...WITH A
MIX OF PCPN OVER THE NORTHEAST PLAINS/PALMER DIVIDE DOES EXIST
THROUGH MONDAY MORNING. PLENTY OF UNCERTAINTY AS THE MDLS DO
DIFFER IN TIMING/TRACK ONCE THIS SYSTEM LEAVES THE FOUR CORNERS
AND MAKES ITS WAY ACROSS NEW MX. THE AMOUNT OF PCPN AGAIN
DEPENDENT ON THE TRACK OF THE TROUGH. HIGH PRESSURE AT THE SFC AND
ALOFT WILL BUILD INTO COLORADO FM THE WEST BY TUESDAY OF NEXT
WEEK.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 853 AM MDT WED APR 22 2015

GENERALLY LIGHT WEST-NORTHWEST WINDS AT DEN/BJC THIS AM AND
EXPECTED TO SHIFT MORE NORTHERLY ON BACK SIDE OF SURFACE
LOW/DENVER CYCLONE THIS AFTERNOON. EXPECT MOST OF THE STORMS TO
DEVELOP WELL EAST OF THE TERMINALS BUT OUTFLOW BOUNDARIES MAY
SPARK ADDITIONAL STORMS LATER IN THE AFTERNOON. TEMPO GROUP MAY BE
OVERDONE...ESPECIALLY AT BJC BUT RELUCTANT TO TAKE IT OUT JUST YET
IN CASE BOUNDARY SETS UP FURTHER WEST TOWARDS AIRPORT. CONFIDENCE
ON THE LOWER SIDE ON TS DEVELOPING AT TERMINALS TODAY.

&&

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

$$

UPDATE...ENTREKIN
SHORT TERM...RPK
LONG TERM...COOPER
AVIATION...ENTREKIN



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