093
AWUS01 KWNH 302300
FFGMPD
KSZ000-NEZ000-COZ000-WYZ000-310330-
MESOSCALE PRECIPITATION DISCUSSION 0281
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
659 PM EDT SAT MAY 30 2026
AREAS AFFECTED...NORTHEAST COLORADO...SOUTHEAST WYOMING...WESTERN
NEBRASKA PANHANDLE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 302259Z - 310330Z
SUMMARY...A NORTH-SOUTH AXIS OF LOCALLY TRAINING THUNDERSTORMS
ALONG THE INTERSECTION OF THE WY/CO/NE BORDERS WILL CONTINUE TO
PRODUCE RAINFALL RATES OF 1 TO 1.5 IN/HR THIS EVENING. LOCALIZED
TOTALS OF 2 TO 3+ INCHES ARE POSSIBLE, WHICH MAY LEAD TO ISOLATED
FLASH FLOODING.
DISCUSSION...REAL-TIME SATELLITE AND RADAR OBSERVATIONS DEPICT A
HIGHLY ORGANIZED, NORTH-SOUTH ORIENTED AXIS OF CONVECTION SLOWLY
ADVANCING NORTHEASTWARD ACROSS THE WESTERN HIGH PLAINS. GOES-E IR
IMAGERY SHOWS A STEADY EXPANSION OF COOLING CONVECTIVE TOPS,
INDICATIVE OF ROBUST, SUSTAINED UPDRAFTS. THIS ACTIVITY IS BEING
POORLY HANDLED BY NEARLY ALL NUMERICAL MODEL GUIDANCE BUT IS
WELL-SUPPORTED BY OBSERVATIONAL TRENDS. WATER VAPOR IMAGERY SHOWS
STRONG MID-LEVEL FORCING AND ASCENT ASSOCIATED WITH AN UPPER-LEVEL
LOW SPINNING OVER WYOMING AND A SOUTHWARD EXTENSION OF SHORTWAVE
ENERGY EJECTING OUT NEAR THE BASE OF IT.
AT THE SURFACE, AN ENHANCED LEESIDE TROUGH IS INTERACTING WITH A
STRONG INSTABILITY GRADIENT. LOW-LEVEL EASTERLY FLOW IS ACTIVELY
ADVECTING MOIST AND UNSTABLE AIR WESTWARD INTO AN INVERTED TROUGH
SITUATED JUST NORTH OF A SURFACE LOW OVER FAR NORTHEAST COLORADO.
THIS FOCUSED LOW-LEVEL CONVERGENCE IS ALLOWING CELLS TO
CONTINUOUSLY REGENERATE AND LOCALLY TRAIN ALONG THE BOUNDARY. WITH
HIGH MOISTURE EFFICIENCY, THESE CELLS ARE PRODUCING
RADAR-ESTIMATED RAINFALL RATES OF 1 TO 1.5 IN/HR.
ANTECEDENT CONDITIONS ACROSS THIS PORTION OF THE HIGH PLAINS ARE
NOTABLY DRY, WHICH WILL ACT AS A SIGNIFICANT MITIGATING FACTOR
AGAINST FLASH FLOODING. HOWEVER, GIVEN THE PERSISTENCE OF THE
CONVECTION AND ORIENTATION RELATIVE TO THE STEERING FLOW,
LOCALIZED RAINFALL TOTALS OF 2 TO 3+ INCHES ARE ACHIEVABLE THROUGH
MID-EVENING. WHERE THESE HIGH RATES PERSIST OVER COMPLEX TERRAIN
FEATURES OR LOCALIZED URBAN FOOTPRINTS, RAPID RUNOFF AND ISOLATED
FLASH FLOODING WILL REMAIN POSSIBLE.
ORRISON
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...BOU...CYS...GLD...LBF...
ATTN...RFC...KRF...TUA...NWC...
LAT...LON 42880372 42680296 41900206 41160164 40330156
39740193 39320269 39160364 39350419 39750451
40650488 41200505 42040513 42630478 42860425
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