Flash Flood Warning 16, NWS Denver/Boulder, CO

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
230 PM MDT TUE AUG 17 1999

SHT WV TO BRING MORE SHWRS/TSTMS THIS EVE THEN MONSOON MSTR INFLUX
TO BE SHUT OFF FOR AWHILE.  WEAK PRESSURE SURGE AT SFC AND OUTFLOW
WILL CREATE WEAK UPSLP FLOW WHICH COMBINED WITH DYNMCS FROM SHT WV
AND THERMAL INSTBY FROM DIURNAL HEATG SHUD PROVIDE ALL INGREDIENTS
NEEDED FOR HI POPS E OF DEN WHERE DWPTS IN UPPER 50S AND 60S.  SHT
WV TO BE PAST FTHLS BY EVE SO LOWER POPS FROM I-25 W TNGT.  MODELS
ALL SHOW THAT BROAD UPPER HI OVER SRN U.S. TO RETROGRESS TO NM AND
REBUILD RDG N THRU WY AND MT WED.  THIS HI WILL REMAIN OVER NM FOR
REST OF WEEK AND THRU WEEKEND IF MRF ON TRACK.  RDG WILL BE SHOVED
TO DAKS AND MN SAT BY SHT WV MVG ACRS CANADA BUT THEN REBOUND BACK
TO MT ON SUN.  ALTHO MODELS ALL AGREE WRT H5 PTRN THRU 48 HRS THEY
HAVE DFRNCS WITH SFC AND RH PROGS.  AVN NEVER SHOWS UPSLP HERE TIL
WED AFTN WHILE NGM AND ETA INDCT UPSLP IN PLACE TIL RETURN SLY FLO
DVLPS WED AFTN/EVE.  AS FOR RH PROGS THEY SHOW THEIR USUAL BIASES
WITH NGM WETTEST AS USUAL WHILE ETA DRIES OUT ERN CO MORE THAN AVN
WHICH KEEPS A LAYER OF MSTR NEAR H5 THRU 72 HOURS.  BLV AVN RH MAY
BE BEST ALTHO PROBLY NOT ENUF LOW LVL MSTR TMW ESPCLY IF ANY HEAVY
RAIN OCCURS LATE THIS AFTN/EVE AS ANTICIPATED WHICH MEANS FAN POPS
PROBLY TOO LOW THRU PERIOD.  DESPITE INFLUX MONSOON MSTR BEING CUT
OFF FROM OUR CWA SHUD KEEP ENUF MSTR OVER AREA THRU THURS FOR SOME
POPS AS NO MECHANISM TO SWEEP ANY RESIDUAL MSTR AWAY AS SUBSIDENCE
ASSOCD WITH UPPER HI PREVAILS AND WEAKER FLOW ALF.  WILL KEEP WDLY
SCT THRU THURS.  WILL TRIM POPS IN PLAINS TO ISOLD FOR FRI AND SAT
WITH DWNSLP FLOW.  SFC HI PRES IN SRN CAN MAY PUSH SWD SAT NGT/SUN
MAY CAUSE ANOTHER UPSLP EPISODE SUN SO WILL GO CHC POPS FOR PLAINS
THEN.  MTNS TO HAVE 20-30 PRCNT POPS THRU NEXT 5 DAYS.  ONCE AGAIN
FAN TOO WARM HWVR BLV NGM TOO COOL SNC IT HAS TOO MUCH RH IN PROG.
GCF

.DEN...NONE.

COZ030-032>050-180600-

SIGNIFICANT WEATHER OUTLOOK FOR NORTHEAST AND NORTH CENTRAL COLORADO
NATIONAL WEATHER SERVICE DENVER CO
1120 AM MDT TUE AUG 17 1999

THIS OUTLOOK PERTAINS TO THE FOLLOWING COLORADO COUNTIES

ADAMS     ARAPAHOE     BOULDER   CLEAR CREEK   DENVER       DOUGLAS
ELBERT    GILPIN       GRAND     JACKSON       JEFFERSON    LARIMER
LINCOLN   LOGAN        MORGAN    PARK          PHILLIPS     SEDGWICK
SUMMIT    WASHINGTON   WELD

SYNOPSIS...THE FLOW OF MONSOONAL MOISTURE HAS INCREASED OVER THE
STATE SINCE YESTERDAY WHILE AN UPPER LEVEL WEATHER DISTURBANCE IS
LOCATED OVER WESTERN COLORADO LATE THIS MORNING.  WEAK SOUTHWESTERLY
FLOW ACROSS THE FOOTHILLS OVERNIGHT BROUGHT SOME DRYING TO THE
AIRMASS ALONG THE FOOTHILLS...BUT MORE ABUNDANT LOW LEVEL MOISTURE
REMAINS ON THE NORTHEAST COLORADO PLAINS....EAST OF A LINE BETWEEN
FORT MORGAN AND LIMON.  THE UPPER LEVEL DISTURBANCE OVER WESTERN
COLORADO LATE THIS MORNING WILL MOVE OVER NORTHEAST COLORADO LATE
THIS AFTERNOON AND EVENING...CAUSING SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY FROM THE FOOTHILLS EASTWARD.  AS THE UPPER
LEVEL SYSTEM MOVES OVER THE DEEPER MOISTURE ON THE EASTERN PLAINS
THIS EVENING...STORMS WILL STRENGTHEN AND BEGIN PRODUCING LOCALLY
HEAVY RAINFALL.

SEVERE WEATHER WITH LARGE HAIL OR DAMAGING WINDS IS NOT EXPECTED
FROM THE AFTERNOON AND EVENING STORMS...BUT HEAVY RAINS WILL BE THE
MAIN THREAT...PRIMARILY DURING THE EVENING AND EAST OF THE FORT
MORGAN TO LIMON LINE.  RAINFALL AMOUNTS IN AND NEAR THE FOOTHILLS
MAY BE UP TO ONE INCH IN 30 MINUTES.  ON THE EASTERN PLAINS THIS
EVENING...RAINFALL RATES OF TWO TO TWO AND A HALF INCHES IN 45
MINUTES WILL BE POSSIBLE.  SOME FLOODING OF FIELDS...SMALL STREAMS
AND NORMALLY DRY WASHES OR CREEKBEDS MAY OCCUR IN WASHINGTON...
LOGAN...SEDGWICK AND PHILLIPS COUNTIES TONIGHT.

SPOTTER ACTIVATION IS NOT ANTICIPATED BUT REPORTS OF HEAVY
RAINFALL...MORE THAN ONE INCH IN* 30 MINUTES OR LESS...SHOULD BE
RELAYED TO THE NATIONAL WEATHER SERVICE.

DANKERS