828
AWUS01 KWNH 120336
FFGMPD
NEZ000-SDZ000-120934-
MESOSCALE PRECIPITATION DISCUSSION 1017
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1135 PM EDT TUE AUG 11 2026
AREAS AFFECTED...PORTIONS OF SD & NE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 120334Z - 120934Z
SUMMARY...A CONVECTIVE COMPLEX IS EXPECTED TO GROW IN SCALE
SOMEWHAT OVERNIGHT. HOURLY RAIN AMOUNTS TO 2.5" WITH LOCAL TOTALS
TO 4" ARE POSSIBLE, WHICH COULD LEAD TO FLASH FLOODING.
DISCUSSION...A SMALL CLUSTER OF ELEVATED CONVECTION IS MOVING
SOUTHEAST THROUGH SOUTHWESTERN SD AT THE PRESENT TIME, WHERE 700
HPA TEMPERATURES ARE 12-15C, NEAR THE EDGE OF MORE SIGNIFICANT
MID-LEVEL CAPPING. WHILE THERE HAS BEEN SOME HAIL CONTAMINATION,
ONCE THE VALUES ARE ADJUSTED SOMEWHAT DOWNWARD, HOURLY RAIN
AMOUNTS APPEAR TO HAVE PEAKED IN THE 1.5-2" RANGE AS OF LATE.
PRECIPITABLE WATER VALUES ARE TOWARDS 2". EFFECTIVE BULK SHEAR IS
60 KTS. THE THUNDERSTORMS ARE MOVING THROUGH AN ENVIRONMENT OF
3000 J/KG OF MU CAPE.
THE 00Z GFS GALVEZ-DAVISON INDEX IMPLIES THAT THE CONVECTIVE
COMPLEX COULD GROW IN SCALE UNTIL 06Z OR SO, AND THERE COULD BE
SOME OCCASIONAL REDEVELOPMENT AS IT MOVES NEAR THE EDGE OF THE
MID-LEVEL CAPPING INVERSION. WHILE THE GUIDANCE HAS A GOOD SIGNAL
FOR HEAVY RAINFALL SOMEWHERE IN THIS REGION, MUCH OF THE GUIDANCE
IS TOO FAR NORTH TO NORTHEAST. THE 18Z HREF PATTERN APPEARS
CLOSEST, WHICH IS WITHIN THE SOUTHERN EDGE OF THE 00Z HREF SIGNAL.
THE EXPECTATION IS FOR THE CONVECTIVE COMPLEX TO START TURNING
SOMEWHAT TO THE LEFT WHICH WOULD BE MORE ALIGNED WITH THE MU CAPE
GRADIENT AND TRY TO ORIENT CLOSER TO THE 12C 700 HPA ISOTHERM AND
REMAIN CLOSE TO THE 850 HPA CONFLUENCE AXIS AS THE COMPLEX MOVES
INCREASINGLY EAST-SOUTHEAST. GIVEN THE INGREDIENTS AVAILABLE,
HOURLY RAIN AMOUNTS TO 2.5" WITH LOCAL TOTALS TO 4" ARE POSSIBLE.
HEAVY RAIN COULD OCCUR WITHIN SHORT PERIODS OF CELL TRAINING,
POSSIBLE CELL MERGERS SHOULD ANY CONVECTIVE FORM AT THE LEADING
EDGE OF THE COMPLEX, OR DUE TO EMBEDDED MESOCYCLONES. THIS DEGREE
OF RAINFALL WOULD BE MOST PROBLEMATIC IN URBAN AREAS AND OUTSIDE
OF THE SAND HILLS OF NE.
ROTH
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ABR...FSD...LBF...OAX...UNR...
ATTN...RFC...KRF...NWC...
LAT...LON 44590141 44229885 43209667 42179660 41909810
42210073 42980249 43620273
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