Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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000 FXUS65 KBOU 230945 AFDBOU AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 345 AM MDT SAT MAY 23 2015 .SHORT TERM...
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(TODAY THROUGH TONIGHT ) ISSUED AT 342 AM MDT SAT MAY 23 2015 AN UPPER LEVEL LOW OVER EASTERN UTAH WILL MOVE VERY SLOWLY EASTWARD THRU TONIGHT. QG FIELDS SHOW MID LVL ASCENT THRU THE DAY INTO THE EARLY EVENING HOURS. MEANWHILE AT THE SFC LOW PRES WILL EXTEND FM THE CNTRL MTNS INTO SERN CO WITH MAINLY SELY LOW LVL FLOW ACROSS THE PLAINS. WITH SELY LOW LVL FLOW A DENVER CYCLONE WILL PROBABLY DVLP BY EARLY AFTN WITH A CONVERGENCE ZN OVER DENVER OR JUST TO THE EAST. SHOULD SEE A GRADUAL INCREASE IN SHOWER AND TSTM DEVELOPMENT ACROSS MUCH OF THE AREA BY MIDDAY WHICH WILL LINGER INTO THE EARLY EVENING HOURS. AS FAR AS SVR POTENTIAL IT APPEARS HIGHS OVER NERN CO MAY STAY MAINLY IN THE UPPER 50S TO LOWER 60S WITH CAPES AROUND 1000 J/KG EXCEPT POSSIBLY OVER LINCOLN COUNTY WHERE THEY MAY REACH AROUND 1500 J/KG. THERE WILL BE DECENT SHEAR SO EXPECT A FEW SVR STORMS OVER THE PLAINS WITH MARGINAL LARGE HAIL AND A FEW TORNADOES DUE TO LOW LCLS. MEANWHILE THERE WILL BE SOME POTENTIAL FOR HEAVY RAIN ACROSS THE PLAINS SO WILL ISSUE A FLASH FLOOD WATCH DUE TO SATURATED SOILS AS A FEW LOCATIONS COULD SEE A FEW INCHES OF RAIN IN LESS THAN AN HOUR. FOR TONIGHT THE UPPER LEVEL TROUGH WILL BE CENTERED OVER WESTERN COLORADO HOWEVER THE MID LVL ASCENT WILL GRADUALLY LIFT NORTH OF THE AREA THIS EVENING WITH PCPN CHANCES DECREASING BY MIDNIGHT FM SW TO NE. MAY SEE SOME FOG DVLP AFTER MIDNIGHT ACROSS THE PLAINS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 342 AM MDT SAT MAY 23 2015 M.O.T.S...MUCH OF THE SAME BEST DESCRIBES THE DAILY WEATHER CYCLE ANTICIPATED DURING THE UPCOMING WEEK. LET`S START WITH THE LARGE SCALE FLOW PATTERN. MODELS SHOW UPPER TROUGHS REPEATEDLY FORMING OVER THE INTERMOUNTAIN WEST...AND A CONTINUOUS FEED OF SUBTROPICAL AIR UP INTO THE DESERT SOUTHWEST OR ONSHORE IN SRN CALIFORNIA THROUGH THE PERIOD. THE FIRST OF THESE TROUGHS IS FORECAST TO TRACK OVER THE CENTRAL ROCKY MTN REGION ON SUNDAY BRINGING COOLER TEMPERATURES...SCATTERED SHOWERS...ISOLATED T-STORMS AND LIGHTER WINDS TO THE FORECAST AREA. PROGGED 6-HR PRECIP AMOUNTS ON THE ORDER OF 1/10TH TO 3/10TH INCH BY EVENING. SHEAR AND INSTABILITY NOT AS GREAT AS THE DAY BEFORE DUE TO WEAKER FLOW AND COOLER TEMPS. SO SEVERE WEATHER RISK WILL BE MUCH LOWER. MODELS LIFT THIS TROUGH NEWRD OVER THE NRN GREAT PLAINS BY MONDAY MORNING WHICH POSITIONS NERN COLORADO IN A SOMEWHAT DRIER AND WARMER NWLY FLOW TO START THE DAY. BUT BY AFTERNOON MOISTURE AND INSTABILITY RETURN WITH A PASSING MID-LEVEL DISTURBANCE...RESULTING IN ANOTHER ROUND OF SCATTERED SHOWERS AND ISOLATED T-STORMS MAINLY OVER AND NEAR THE MTNS THROUGH THE EARLY EVENING HRS. ON TUESDAY MODELS SHOW EVEN DRIER AND WARMER CONDITIONS WITH A PASSING SHORTWAVE RIDGE. STILL STG DAYTIME HEATING AND RESIDUAL MOISTURE SHOULD BE ADEQUATE TO PRODUCE SCATTERED AFTERNOON/EVENING SHOWERS/T-STORM IN THE HIGH COUNTRY AND ISOLATED T-STORMS ON THE NEARBY PLAINS. NOTHING SEVERE AND RAIN AMOUNTS SHOULD BE ON THE LIGHT SIDE. BY WEDNESDAY...THE NEXT UPPER TROUGH SETTLES IN OVER THE GREAT BASIN. AS IT DOES SO...STRENGTHENING SWLY FLOW OUT AHEAD OF IT PUMPS MOIST AND UNSTABLE AIR UP FROM THE DESERT SOUTHWEST POTENTIALLY RESULTING IN ANOTHER ROUND OF SOAKING SHOWERS AND THUNDERSTORMS FOR PORTIONS OF NORTH-CENTRAL AND NORTHEAST COLORADO DURING THE AFTERNOON AND EVENING HRS. SHOWER COVERAGE SHOULD BE MORE THAN THE DAY BEFORE AND WITH MEAN LAYER SPECIFIC HUMIDITY ON THE INCREASE...ODDS INCREASE FOR LOCALLY HEAVY RAINFALL OVER SWRN PORTIONS OF THE CWA. THURSDAY AND BEYOND...MODELS DIFFER SOME ON WHEN THE WESTERN TROUGH SHIFTS EAST AND THE DEGREE OF IMPACT IT`LL HAVE ON THE FORECAST AREA. MOST MODELS SHOW A COLD FRONT SLIPPING INTO NERN COLORADO ERLY ON THURSDAY AND A FAIRLY MOIST UPSLOPE FLOW ON THE PLAINS THROUGHOUT THE DAY. FOR NOW WILL HOLD OFF ON GOING HOG WILD WITH PRECIP THURSDAY BUT WILL STILL HOLD ONTO A CHANCE OF SHOWERS/T-STORMS FOR MOST AREAS...TOGETHER WITH SLIGHTLY COOLER TEMPS. FRIDAY COULD POSSIBLY BE WETTER AND COOLER YET IF THE MEDIUM RANGE MODELS ARE CORRECT...THE PRODUCT OF DEEP MOISTURE WRAPPING AROUND A CLOSED LOW SPINNING OVER E-CNTRL COLORADO. M.O.T.S.
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&& .AVIATION...
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(FOR THE TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 342 AM MDT SAT MAY 23 2015 A WK DENVER CYCLONE WAS OVER DENVER WHICH HAS KEPT THE BRUNT OF LOW CLOUDS AND FOG TO THE NORTH OF DIA. THE HRRR AND RAP STILL SHOW THAT SOME BRIEF DENSE FOG MAY DVLP FOR A FEW HOURS IN THE 10Z-14Z TIME PERIOD SO WILL KEEP IN A TEMPO GROUP FOR LIFR. OTHERWISE CEILINGS/VSBY WILL BE MVFR THRU 16Z. SHOULD BEGIN TO SEE SHOWER/TSTM DEVELOPMENT BY 18Z WITH ACTIVITY GRADUALLY ENDING BY 23Z IF HRRR/RAP CAN BE BELIEVED. MAY SEE SOME SMALL HAIL AND GUSTY WINDS WITH VSBY DOWN TO 3-5 MILES IN THE STRONGER STORMS. WINDS WILL BE LIGHT AND VARIABLE EARLY THIS MORNING AND THEN MORE ENE BY EARLY AFTN. FOR TONIGHT THE SHOWER/TSTM THREAT SHOULD END BY 02Z WITH WINDS BRIEFLY NWLY FOR A FEW HOURS BEFORE BECOMING LIGHT DRAINAGE BEFORE MIDNIGHT. THERE COULD BE SOME FOG AND LOW CLOUDS LATE TONIGHT INTO SUN MORNING.
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&& .HYDROLOGY...
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ISSUED AT 342 AM MDT SAT MAY 23 2015 MAY SEE FROM 1 TO 2 INCHES OF RAIN ACROSS PORTIONS OF THE PLAINS THIS AFTN INTO THE EARLY EVENING HOURS WITH SOME POTENTIAL FOR FLASH FLOODING DUE TO SATURATED SOILS. IN THE MTNS AND FOOTHILLS AMOUNTS WILL AVERAGE FROM ONE QUARTER TO ONE HALF INCH WITH ISOLATED AMOUNTS UP TO AN INCH IN A FEW LOCATIONS. THE CACHE LA POUDRE AND SOUTH PLATTE RIVERS REMAIN ABOVE FLOOD STAGE IN WELD COUNTY AND ACROSS WESTERN PORTIONS OF MORGAN COUNTY...AND WILL STAY THAT WAY FOR ANOTHER DAY OR SO.
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&& .BOU WATCHES/WARNINGS/ADVISORIES...
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FLASH FLOOD WATCH FROM NOON MDT TODAY THROUGH THIS EVENING FOR COZ042-044>046-048>051.
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&& $$ SHORT TERM...RPK LONG TERM...BAKER AVIATION...RPK HYDROLOGY...RPK

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