Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 250022
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
622 PM MDT SUN MAY 24 2015

.UPDATE...
ISSUED AT 622 PM MDT SUN MAY 24 2015

MAIN UPPER LEVEL LOW IS LOCATED OVER NORTHWEST COLORADO AND SOUTH
CENTRAL WYOMING. IT WILL SLOWLY MOVE EAST ACROSS NORTHERN COLORADO
TONIGHT AND MONDAY. MAIN LINE OF THUNDERSTORMS HAS SHIFTED EAST OF
THE AREA. WITH THIS...THE THREAT FOR FLASH FLOODING OVER THE
NORTHEAST PLAINS HAS ENDED AND WILL CANCEL THE FLASH FLOOD WATCH.
WILL ALSO LOWER POPS FOR THE REST OF THE EVENING.

A SURFACE LOW WILL LIFT INTO WESTERN NEBRASKA TONIGHT. THIS WILL
PRODUCE A NORTHERLY SURGE OVER EASTERN COLORADO THIS EVENING.
WINDS OVER SOUTHEAST WYOMING HAVE TURNED NORTHERLY. THIS COMBINED
WITH THE UPPER LEVEL LOW MOVING ACROSS THE AREA WILL KEEP THE
CHANCE FOR SHOWERS GOING THROUGH THE NIGHT. WILL KEEP POPS MAINLY
IN THE 30-50 PERCENT RANGE FOR THIS EVENING AND TONIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 309 PM MDT SUN MAY 24 2015

THE SATELLITE AND RADAR PICTURES HAVE THE CENTER OF THE UPPER LOW
SILL OVER SOUTHERN CENTRAL WYOMING RIGHT NOW. THERE HAS A PRETTY
DECENT LINE/AREA OF SHOWERS AND THUNDERSTORMS WITH HAIL MOVING
NORTH-NORTHEASTWARD OVER THE CENTRAL PLAINS RIGHT NOW. THEN THERE
ARE SOME STORMS MOVING MORE EAST-NORTHEASTWARD OFF THE FOOTHILLS
PRESENTLY MAKING IT INTO THE URBAN CORRIDOR. THERE IS A LOT OF
MODERATE AND HEAVY RAINFALL. OVERALL IT IS A PRETTY STATIC PATTERN
AS FAR AS THE FORECAST GOES THIS EVENING/TONIGHT...MORE OF THE
SAME. MODELS ACTUALLY SHOW THE CENTER OF THE UPPER CLOSED LOW TO
BE RIGHT OVER THE NORTHEAST CORNER OF COLORADO AT 18Z MONDAY. BY
00Z MONDAY AFTERNOON THERE IS WEAK ZONAL FLOW OVER THE CWA. THERE
IS VERY WEAK SYNOPTIC SCALE ENERGY PROGGED ON THE QG VERTICAL
VELOCITY FIELDS...UPWARD TONIGHT INTO MONDAY MORNING...THEN
DOWNWARD BY AFTERNOON MONDAY. THE BOUNDARY LAYER WINDS CONTINUE TO
BE LIGHT WITH A WEAK LOW LEVEL PRESSURE GRADIENT IN PLACE. MODELS
CONTINUE TO SHOW A LOT OF MOISTURE AROUND TONIGHT AND MONDAY. DEW
POINTS ARE PROGGED IN THE MID 40S TO LOWER 50S F TONIGHT AND
MONDAY. THERE IS MEASURABLE PRECIPITATION ON THE QPF FIELDS
TONIGHT AND MONDAY FOR ALL THE CWA. WILL KEEP DECENT POPS GOING
THIS EVENING...THEN DECREASE THEM INTO MID DAY MONDAY...THEN
INCREASE THEM AGAIN WITH POPS...BUT NOT QUITE AS HIGH AS THIS
EVENING`S CHANCES. FOR TEMPERATURES...MONDAY`S HIGHS COULD BE 1-2
C HIGHER THEN THIS AFTERNOON`S.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 309 PM MDT SUN MAY 24 2015

COOL...MOIST AND SOMEWHAT UNSETTLED WEATHER LOOKS LIKE IT WILL
CONTINUE THROUGH MUCH OF THE WEEK. RAINFALL ON THE PLAINS HAS BEEN
PLENTIFUL ENOUGH OVER THE PAST COUPLE WEEKS THAT WE ARE STUCK IN A
POSITIVE FEEDBACK LOOP WHERE PRECIPITATION ON ONE DAY FEEDS INTO
ADDITIONAL THUNDERSTORM DEVELOPMENT THE NEXT DAY. UNTIL WE GET
STRONG SUBSIDENCE AND DRYING OF THE AIRMASS...THE DIURNAL HEATING
OF EACH DAY WILL BE SUFFICIENT TO PRODUCE SHOWER ACTIVITY DURING
AFTERNOON AND EVENING HOURS. TUESDAY MAY SEE A MINOR DECREASE IN
THE AMOUNT OF SHOWER COVERAGE DUE TO A WEAK UPPER RIDGE PASSING
OVER THE STATE...BUT THUNDERSTORMS CAN NOT BE RULED OUT. BY
WEDNESDAY...ANOTHER LOW PRESSURE AREA DEVELOPS OVER EASTERN
COLORADO WHICH WILL HELP KEEP LOW LEVEL MOISTURE IN PLACE ON THE
PLAINS. DAYTIME HEATING WILL AGAIN PRODUCE AFTERNOON SHOWER AND
THUNDERSTORM ACTIVITY. A SURFACE COLD FRONT IS EXPECTED TO MOVE IN
ABOUT FRIDAY WHICH WILL ENHANCE CONVERGENCE AND LOW LEVEL UPSLOPE
WINDS TO ONCE AGAIN PRODUCE SHOWERS AND THUNDERSTORMS. STRONGER
UPPER RIDGING IS POSSIBLE NEXT WEEKEND...BUT MODEL MOISTURE FIELDS
INDICATE THAT THE AIRMASS WILL STILL BE MOIST...RATHER THAN DRY.
FARMERS AND TOWNS OUT ON THE EASTERN PLAINS ARE FINDING IT A BIT
HARD TO CATCH A BREAK AS THIS PROLONGED WET SPELL CONTINUES ACROSS
THE EASTERN HALF OF THE STATE.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 622 PM MDT SUN MAY 24 2015

WINDS ARE EXPECT TO SHIFT NORTHERLY AROUND 03Z AS A SURFACE LOW
MOVES FROM EASTERN COLORADO INTO WESTERN NEBRASKA. AIRMASS WILL
REMAIN MOIST WHICH WILL KEEP SKIES CLOUDY. CEILINGS ARE EXPECTED
TO FALL TO 3000 TO 6000 FEET BY 06Z. THERE IS CHANCE FOR FOG WITH
VISIBILITY FALLING BELOW 2SM. FOR MONDAY...WINDS WILL BE ON THE
LIGHT SIDE. THERE WILL BE ENOUGH MOISTURE AND INSTABILITY FOR A
CHANCE OF THUNDERSTORMS AFTER 18Z.

&&

.HYDROLOGY...
ISSUED AT 622 PM MDT SUN MAY 24 2015

MAIN LINE OF THUNDERSTORMS HAS SHIFTED EAST OF THE AREA. THE
THREAT FOR HEAVY RAIN AND POTENTIAL FOR FLASH FLOODING HAS ENDED
SO WILL CANCEL THE FLASH FLOOD WATCH.

FLOOD WARNINGS CONTINUE ALONG THE CACHE LA POUDRE AND SOUTH
PLATTE RIVERS AT LEAST THROUGH TUESDAY. THE SOUTH PLATTE RIVER
CONTINUES TO RISE FROM YESTERDAY AND TODAY`S RAINS. FURTHER WEST
AT DENVER AND HENDERSON WILL STILL NEED TO MONITOR FOR POSSIBLE
FLOODING IN THE NEXT SEVERAL DAYS ESPECIALLY IF STRONGER STORMS
SEND LEVELS RISING AGAIN.

&&

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

$$

UPDATE...MEIER
SHORT TERM...RJK
LONG TERM...DANKERS
AVIATION...MEIER
HYDROLOGY...MEIER/RJK



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