165
FXUS21 KWNC 191924
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 19 2023
SYNOPSIS: MID-LEVEL HIGH PRESSURE PERSISTS OVER THE SOUTHERN CONTIGUOUS U.S.
(CONUS) DURING WEEK-2, LEADING TO THE POTENTIAL FOR EXCESSIVE HEAT FOR THE
SOUTHERN AND CENTRAL PLAINS. MID-LEVEL LOW PRESSURE OVER THE WEST COAST BRINGS
A CHANCE FOR HEAVY PRECIP FOR PORTIONS OF THE NORTHWESTERN CONUS, WHILE A
CUT–OFF LOW OVER THE GREAT LAKES COMBINED WITH ABUNDANT TROPICAL MOISTURE
BRINGS THE RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE NORTHEASTERN CONUS.
SNOWMELT SEASON CONTINUES FOR PORTIONS OF THE WEST AFTER EXCEPTIONAL WINTER
ACCUMULATIONS, LEADING TO THE CONTINUED POTENTIAL FOR FLOODING, WHILE
ABNORMALLY DRY CONDITIONS OVER PORTIONS OF WISCONSIN AND LOUISIANA RESULT IN
THE POTENTIAL FOR RAPID ONSET DROUGHT (ROD).
HAZARDS
MODERATE RISK FOR EXCESSIVE HEAT FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY, TUE-FRI, JUN 27-30.
MODERATE RISK FOR EXCESSIVE HEAT FOR PORTIONS OF THE CENTRAL PLAINS AND MIDDLE
MISSISSIPPI VALLEY, THU-FRI, JUN 29-30.
SLIGHT RISK FOR EXCESSIVE HEAT FOR THE CENTRAL AND SOUTHERN PLAINS, LOWER AND
MIDDLE MISSISSIPPI VALLEY, AND PORTIONS OF THE OHIO AND TENNESSEE VALLEYS,
SOUTHEASTERN U.S., SOUTHERN ROCKIES, AND DESERT SOUTHWEST, TUE-SAT, JUN 27-JUL
1.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE NORTHERN GREAT BASIN,
NORTHERN ROCKIES, AND NORTHERN PLAINS, TUE-THU, JUN 27-29.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE OHIO VALLEY,
MID-ATLANTIC, AND NORTHEASTERN U.S., TUE-SAT, JUN 27-JUL 1.
POSSIBLE FLOODING FOR PORTIONS OF CALIFORNIA, NEVADA, UTAH, WYOMING, AND IDAHO.
POSSIBLE FLOODING ALONG PORTIONS OF THE JAMES RIVER IN SOUTH DAKOTA.
RAPID ONSET DROUGHT RISK ACROSS PORTIONS OF NORTHERN WISCONSIN AND CENTRAL
LOUISIANA.
DETAILED SUMMARY
FOR THURSDAY JUNE 22 - MONDAY JUNE 26:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JUNE 27 - MONDAY JULY 03: ENSEMBLE MODEL SOLUTIONS FROM THE GEFS,
ECMWF, AND CMCE ALL DEPICT POSITIVE 500-HPA HEIGHT ANOMALIES PERSISTING OVER
THE SOUTHERN CONUS THROUGHOUT THE FORECAST PERIOD. THIS FAVORS INCREASING
TEMPERATURES ACROSS THE SOUTHERN AND CENTRAL CONUS, LEADING TO THE POTENTIAL
FOR EXCESSIVE HEAT. REFORECAST-BASED EXTREMES FORECAST TOOLS FROM ALL THREE
ENSEMBLES LISTED ABOVE INDICATE AT LEAST A 40% PROBABILITY OF MAXIMUM
TEMPERATURES EXCEEDING THE 85TH PERCENTILE AND AT LEAST 95 DEGF FOR MUCH OF THE
SOUTHERN AND CENTRAL PLAINS, AND THE MIDDLE AND LOWER MISSISSIPPI VALLEY, WITH
HIGH TEMPERATURES OVER 100 DEGF FOR MUCH OF TEXAS AND OKLAHOMA. THIS RISK
EXTENDS FROM JUN 27-30 FOR THE SOUTHERN PLAINS ROUGHLY TO THE TEXAS/OKLAHOMA
BORDER, WITH A NORTHWARD EXTENSION OF THIS EXCESSIVE HEAT DEPICTED BY THE
REFORECAST TOOLS AS FAR AS KANSAS CITY FOR JUN 29-30, THEREFORE A MODERATE RISK
FOR EXCESSIVE HEAT IS POSTED FOR THOSE RESPECTIVE REGIONS AND TIME PERIODS.
ADDITIONALLY, THE REFORECAST TOOLS INDICATE AT 20% PROBABILITY OF EXCEEDING THE
85TH PERCENTILE FOR PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS, LOWER AND
MIDDLE MISSISSIPPI VALLEY, AND PORTIONS OF THE OHIO AND TENNESSEE VALLEYS,
SOUTHEASTERN U.S., SOUTHERN ROCKIES, AND DESERT SOUTHWEST, THEREFORE A SLIGHT
RISK FOR EXCESSIVE HEAT IS POSTED FOR THESE REGIONS FOR JUN 27-JUL 1.
AT THE BEGINNING OF WEEK-2 MODEL SOLUTIONS CONTINUE TO DEPICT TROUGHING OVER
THE WEST COAST AND THE GREAT LAKES, LEADING TO ENHANCED PRECIPITATION FOR THE
NORTHEAST AND NORTHWEST CONUS. REFORECAST TOOLS FROM THE GEFS AND ECMWF BOTH
INDICATE AT LEAST A 20% PROBABILITY OF 3-DAY PRECIPITATION ACCUMULATIONS TO
EXCEED THE 85TH PERCENTILE AND AT LEAST A HALF INCH FOR PORTIONS OF THE
NORTHERN GREAT BASIN, NORTHERN ROCKIES, AND NORTHERN PLAINS FOR JUN 27-29. AS
THE FORECAST PERIOD PROGRESSES THIS TROUGH IS FAVORED TO DECREASE IN AMPLITUDE,
REDUCING THE POTENTIAL FOR HEAVY PRECIPITATION FOR THE NORTHWESTERN CONUS.
MEANWHILE, CONTINUED WEAK TROUGHING AND ABUNDANT MOISTURE FROM THE TROPICAL
ATLANTIC FAVORS THE POTENTIAL FOR PERIODS OF HEAVY PRECIPITATION FOR A LONGER
PERIOD, WITH THE REFORECAST TOOLS INDICATING A 20% PROBABILITY OF 3-DAY
PRECIPITATION ACCUMULATIONS TO EXCEED THE 85TH PERCENTILE AND AT LEAST A HALF
INCH FOR PORTIONS OF THE OHIO VALLEY, MID-ATLANTIC, AND NORTHEASTERN U.S. FOR
JUN 27-JUL 1. THEREFORE, A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR
THE REGIONS AND TIME PERIODS INDICATED.
DROUGHT CONCERNS ARE FORECAST TO INCREASE ACROSS PARTS OF THE MIDWEST AS THE
HEAT OF SUMMER BUILDS AND A PERSISTENCE OF BELOW-NORMAL PRECIPITATION FORECAST
FOR THE REGION. THE POTENTIAL FOR ROD CONTINUES FOR MUCH OF NORTHERN WISCONSIN
IN TODAY’S OUTLOOK. SIGNIFICANT PRECIPITATION DEFICITS HAVE BROUGHT THE
POTENTIAL FOR ROD TO CENTRAL LOUISIANA AS WELL, AND WAS INITIALLY HIGHLIGHTED
LAST THURSDAY. THERE HAS BEEN SOME RECENT HEAVY RAINFALL ALONG THE NORTHERN
LOUISIANA BORDER, SO TODAY’S OUTLOOK INCLUDES A SLIGHT RETREAT FOR THE NORTHERN
EXTENT OF THIS AREA AT RISK FOR ROD.
SNOWMELT SEASON CONTINUES ACROSS THE WESTERN CONUS AFTER ACCUMULATING A VERY
LARGE AND IN SOME CASES RECORD-BREAKING SNOWPACK, INDUCING RIVER FLOODING
ESPECIALLY ACROSS HIGHER ELEVATIONS FOR SOME AREAS IN THE WEST, WHERE A FEW
SITES STILL REPORT OVER 40 INCHES OF SNOW WATER CONTENT. AS SNOWMELT CONTINUES
IN PARTS OF THE SIERRA NEVADA, GREAT BASIN, AND NORTHERN ROCKIES, FLOODING MAY
CONTINUE TO OCCUR ALONG SOME RIVERS, AND IN AREAS ADJACENT TO THE HIGHER
ELEVATIONS. FLOODING IS ALSO EXPECTED TO CONTINUE ALONG THE JAMES RIVER IN
SOUTH DAKOTA AS RIVER LEVELS HAVE BEEN VERY SLOW TO RECEDE DUE TO SATURATED
GROUND CONDITIONS AND RELATIVELY FLAT TOPOGRAPHY.
FORECASTER: DANNY BARANDIARAN
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