Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 221747
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1147 AM MDT FRI APR 22 2016

.UPDATE...
ISSUED AT 1145 AM MDT FRI APR 22 2016

NO CHANGES NEEDED AT THIS TIME. STILL EXPECTING ENOUGH INSTABILITY
FOR SOME WEAK SHOWERS OVER THE EAST SLOPES OF THE FRONT RANGE AND
AROUND SOUTH PARK LATER THIS AFTERNOON.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM MDT FRI APR 22 2016

ANOTHER FINE SPRING DAY IS IN STORE ACROSS NORTH CENTRAL AND
NORTHEAST COLORADO AS AN UPPER LEVEL RIDGE REMAINS IN PLACE OVER
THE STATE. THE AIRMASS IS DRY AND STABLE AND WILL BE ABOUT 10
DEGREES WARMER THAN YESTERDAY. HIGH TEMPERATURES SHOULD REACH THE
70S ACROSS THE PLAINS THIS AFTERNOON. ALTHOUGH THE RIDGE IS IN
PLACE OVER THE STATE...QUASI-GEOSTROPHIC ANALYSIS SHOWS THAT
VERTICAL FORCING OVER THE STATE IS SLIGHTLY UPWARD RATHER THAN
SUBSIDENT. THIS IS GOING TO ALLOW THE DIURNAL HEATING OVER THE
ELEVATED MOUNTAIN TERRAIN TO CAUSE THE AFTERNOON AIRMASS TO BECOME
SLIGHTLY UNSTABLE. THEREFORE...AM CONTINUING THE SLIGHT CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS OVER PARTS OF PARK AND SUMMIT
COUNTIES. THE SHOWERS SHOULD ONLY PRODUCE BRIEF RAIN AND POSSIBLY
SOME SMALL HAIL. THE SHOWERS WILL THEN RAPIDLY DISSIPATE AS THE
SUN GOES DOWN AND SKIES WILL RETURN TO MOSTLY CLEAR OVERNIGHT.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 409 AM MDT FRI APR 22 2016

AN UPPER LEVEL STORM SYSTEM OVER THE NRN GREAT BASIN EARLY SAT
WILL MOVE EASTWARD INTO ERN WYOMING BY 12Z SUN.  AHEAD OF THIS
SYSTEM BRISK SWLY FLOW WILL BE OVER NRN CO AS SFC LOW PRES
INTENSIFIES FM SERN WY INTO NERN CO.  OVERALL THERE WILL BE A QUICK
SHOT OF MID LVL ASCENT LATE SAT AFTN INTO SAT EVENING ACROSS NRN CO
WHICH WILL PRODUCE SCT SHOWERS AND A FEW TSTMS OVER THE HIGHER WHICH
WILL THEN MOVE ACROSS NERN CO SAT EVENING.  AS FOR HIGHS READINGS
OVER THE PLAINS WILL RISE INTO THE MID 70S TO LOWER 80S.

FOR LATE SAT NIGHT INTO SUN THE UPPER LEVEL WILL MOVE FM ERN WYOMING
INTO NCNTRL NEBRASKA BY LATE SUN AFTN.  CROSS-SECTIONS SHOW SOME
MOISTURE WILL AFFECT THE MTNS MAINLY NEAR THE WY-CO BORDER THRU SUN
AFTN WITH FAVORABLE OROGRAPHICS.  ZN 31 COULD CERTAINLY SEE ADVISORY
TYPE AMOUNTS LATE SAT NIGHT THRU MIDDAY SUN.  MEANWHILE THERE ALSO
COULD BE A FEW AFTN SHOWERS OVER THE PLAINS NR THE WY-NE BORDER
AREA.  MEANWHILE WITH A TIGHT SFC GRADIENT AND RATHER STG
SUSBSIDENCE OVER NRN CO LATE SAT NIGHT INTO SUN THERE COULD BE SOME
THREAT FOR HIGH WINDS IN THE NRN FOOTHILLS AND AT LOWER ELEVATIONS
NR THE WY BORDER.  AS FOR HIGHS ON SUN READINGS WILL DROP BACK INTO
THE 60S ACROSS THE PLAINS.

ON MON ANOTHER STG UPPER LEVEL TROUGH WILL MOVE INTO THE GREAT BASIN
WITH SW FLOW ALOFT REDEVELOPING OVER THE AREA.  MEANWHILE SFC LOW
PRES WILL INTENSIFY OVER THE MTNS WITH INCREASING SELY LOW LVL FLOW
ACROSS THE PLAINS.  MOISTURE WILL INCREASE IN THE MTNS BY AFTN AND
WITH DECENT LAPSE RATES THERE WILL BE A CHC OF SHOWERS AND A FEW
TSTMS.  ACROSS NERN CO IT WILL BE DRY THRU THE AFTN EXCEPT ALONG THE
FRONT RANGE WHERE THERE WILL BE A SLIGHT CHC OF TSTMS. HIGHS ON MON
WILL BE IN THE 65 TO 70 DEGREE RANGE ACROSS THE PLAINS.

FOR MON NIGHT THRU TUE SUBSTANTIAL DIFFERENCES EXIST BETWEEN THE
ECMWF AND GFS WITH THE MOVEMENT OF THE UPPER LEVEL STORM SYSTEM
OVER THE GREAT BASIN. THE ECMWF MOVES THE UPPER LEVEL LOW EASTWARD
TO NR DENVER BY 12Z TUE AND THEN INTO FAR NERN CO BY LATE TUE
AFTN. MEANWHILE THE GFS LIFTS THE SYSTEM ENE WITH THE CENTER OF
THE LOW OVER SCNTRL WYOMING BY LATE TUE AFTN. FINALLY THE CANADIAN
MODEL IS MORE IN LINE WITH THE ECMWF WHILE EVEN SOME OF THE GFS
ENSEMBLE MEMBERS SUGGEST THE LOW MAY TAKE A MORE SRN PATH. THUS
THIS MAY END UP BEING ANOTHER TRICKY SYSTEM TO DEAL WITH FM MON
NIGHT THRU TUE AS SOME PARTS OF NRN CO COULD RECEIVE SIGNIFICANT
PCPN. TEMP FIELDS SUGGEST PCPN WOULD STAY MOSTLY RAIN AT LOWER
ELEVATIONS BELOW 6000 FT. HIGHS ON TUE WILL BE COOLER WITH
READINGS IN THE 50S ACROSS THE PLAINS.

BY WED THE ECMWF MOVES THE UPPER LEVEL LOW INTO CNTRL AND ERN
NEBRASKA WHILE THE GFS MOVES THE SYSTEM INTO ERN SOUTH DAKOTA. COULD
SEE SOME LINGERING PCPN OVER THE FAR NERN PLAINS EARLY WED BASED ON
THE ECMWF SOLUTION.  BY AFTN ENOUGH INSTABILITY WILL EXIST FOR A
SLIGHT CHC OF SHOWERS OVER THE HIGHER TERRAIN AND POSSIBLY ALONG THE
FRONT RANGE. AS FOR HIGHS WILL KEEP READINGS IN THE 50S ACROSS
NERN CO.

FOR THU ANOTHER STORM SYSTEM WILL MOVE INTO THE WRN US WITH SWLY
FLOW ALOFT REDEVELOPING ACROSS THE AREA.  THE ECMWF HAS A COLD FNT
MOVING INTO NERN CO ON THU WHILE THE GFS KEEPS THIS FNT OVER THE
CNTRL PLAINS.  THE ECMWF HAS HIGHS IN THE MID 40S TO LOWER 50S
ACROSS NERN CO WHILE THE GFS HAS READINGS IN THE LOWER TO MID 60S.
FOR NOW WILL GO WITH A BLENDED APPROACH.  AS FOR PCPN THERE IS
QUITE A BIT OF MOISTURE EMBEDDED IN THE SWLY FLOW ALOFT SO WILL
KEEP IN A CHC OF SHOWERS IN THE MTNS WITH A SLIGHT CHC ACROSS THE
PLAINS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1145 AM MDT FRI APR 22 2016

VFR THROUGH TONIGHT.

&&

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

$$

UPDATE...GIMMESTAD
SHORT TERM...DANKERS
LONG TERM...RPK
AVIATION...GIMMESTAD



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