MESOSCALE PRECIPITATION DISCUSSION 0208...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
651 PM EDT SUN MAY 27 2018

CORRECTED FOR TYPO

AREAS AFFECTED...ERN WYOMING ...WRN SOUTH DAKOTA...FAR NWRN
NEBRASKA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 272251Z - 280451Z

SUMMARY...A DEEPENING MOISTURE POOL ALONG AN AXIS OF STRONG LOW
LEVEL CONVERGENCE AND UPSLOPE FLOW IS EXPECTED TO SUPPORT
DEVELOPING CONVECTION, WITH HEAVY AMOUNTS POSSIBLE.

DISCUSSION...AN AREA OF STRONG LOW LEVEL CONVERGENCE NEAR THE
INTERSECTION OF AN AMPLIFYING SOUTHERLY LOW LEVEL JET AND A
NORTHEAST-SOUTHWEST ORIENTED BOUNDARY EXTENDING FROM THE DAKOTAS
BACK INTO THE CENTRAL ROCKIES IS EXPECTED TO PROVIDE THE FOCUS FOR
DEEPENING MOISTURE AND DEVELOPING CONVECTION THIS EVENING INTO THE
OVERNIGHT HOURS.  WITH ANOMALOUS MOISTURE ALREADY IN PLACE,
ANOMALIES ARE EXPECTED TO INCREASE FURTHER AS SOUTHERLY LOW LEVEL
WINDS AMPLIFY OVER THE CENTRAL HIGH PLAINS THIS EVENING.  ALSO
STRENGTHENING NORTHEASTERLY WINDS NORTH OF THE FRONT WILL HELP
FURTHER FORTIFY PWS ACROSS THE REGION.  THE GFS SHOWS PWS
ANOMALIES INCREASING TO 2-3 STANDARD DEVIATIONS ABOVE NORMAL
ACROSS MUCH OF CENTRAL/EASTERN WYOMING INTO WESTERN SOUTH DAKOTA
OVERNIGHT.  MEANWHILE A CLOSED LOW REMAINS CENTERED OVER THE GREAT
BASIN, WITH A SERIES OF SHORTWAVES LIFTING AHEAD OF THE LOW
PROVIDING LARGER SCALE LIFT.  AS THE EVENING PROGRESSES, ONGOING
CONVECTION ACROSS WYOMING IS EXPECTED TO CONTINUE TO SHIFTING
NORTHEAST, WITH THE AMPLIFYING NORTHEASTERLY UPSLOPE FLOW NORTH OF
THE BOUNDARY HELPING TO ANCHOR CONVECTION ACROSS NORTHEAST WYOMING
INTO THE BIGHORNS FOR A PERIOD.  MEANWHILE, EXPECT CONVECTION TO
BEGIN SPREADING FURTHER EAST ALONG AND NORTH OF THE AFOREMENTIONED
BOUNDARY INTO THE NORTHEASTERN NEBSRASKA PANHANDLE AND WESTERN
SOUTH DAKOTA, INCLUDING THE BLACK HILLS.  THROUGH 06Z MON, LATEST
RUNS OF THE OPERATIONAL AND EXPERIMENTAL HRRR SHOWING HEAVIEST
AMOUNTS (1-2 INCHES/6 HR) CENTERING FROM EASTERN WYOMING NEAR THE
SOUTHERN POWDER RIVER COUNTRY BACK INTO THE BIG HORNS.  THE HREF
ALSO SHOWS SIGNIFICANT NEIGHBORHOOD PROBABILITIES (50 PERCENT OR
GREATER) FOR ACCUMULATIONS OF 2 INCHES OR MORE ACROSS THIS REGION.
 GIVEN THE WET ANTECEDENT CONDITIONS, THESE AMOUNTS ARE LIKELY TO
CAUSE SHORT-TERM RUNOFF CONCERNS.

PEREIRA

ATTN...WFO...ABR...BYZ...CYS...LBF...RIW...UNR...

ATTN...RFC...MBRFC...

LAT...LON   45120746 44870674 44550581 44590532 44560437
            44400304 44920155 44890086 43750141 43210230
            42630319 42110375 42090428 42170472 42330487
            42820530 42840629 43210680 43680699 44090715
            44860800