677
FXUS21 KWNC 061756
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 06 2023
SYNOPSIS: MID-LEVEL HIGH PRESSURE IS PREDICTED TO BUILD OVER THE SOUTH-CENTRAL
AND SOUTHEASTERN CONTIGUOUS U.S. (CONUS) DURING WEEK-2, LEADING TO INCREASED
POTENTIAL FOR EXCESSIVE HEAT ACROSS THESE REGIONS THROUGHOUT THE PERIOD. EARLY
IN WEEK-2 MID-LEVEL LOW PRESSURE OVER THE WEST COAST BRINGS THE CONTINUED
POTENTIAL FOR UNSEASONABLY WET CONDITIONS FOR PORTIONS OF THE WESTERN 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 THE OHIO VALLEY AND MIDWEST RESULT IN THE
POTENTIAL FOR RAPID ONSET DROUGHT (ROD).
HAZARDS
MODERATE RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY, WED-FRI, JUN 14-16.
SLIGHT RISK OF EXCESSIVE HEAT ACROSS PARTS OF THE SOUTH-CENTRAL AND
SOUTHEASTERN CONUS, WED-TUE, JUNE 14-20.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE GREAT BASIN, NORTHERN
AND CENTRAL ROCKIES, AND SIERRA NEVADA, WED-THU, JUN 14-15.
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 THE GREAT LAKES, THE MIDDLE AND
UPPER MISSISSIPPI AND OHIO VALLEYS.
DETAILED SUMMARY
FOR FRIDAY JUNE 09 - TUESDAY JUNE 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JUNE 14 - TUESDAY JUNE 20: THE GEFS AND ECMWF ENSEMBLE MEANS ARE
IN RELATIVELY GOOD AGREEMENT, GENERALLY SHOWING GREATER NEGATIVE 500-HPA HEIGHT
DEPARTURES ACROSS THE WEST AND NORTHEAST FOR WEEK-2 COMPARED TO YESTERDAY.
ACROSS THE SOUTH, THE POSITIVE 500-HPA HEIGHT ANOMALIES ARE SLIGHTLY LESS
EXPANSIVE IN THE ECMWF ENSEMBLE MEAN, RELATIVE TO YESTERDAY. THE GEFS ALSO
SHOWS SOMEWHAT WEAKER ANOMALOUS MID-LEVEL HEIGHTS ACROSS THE SOUTH-CENTRAL
CONUS AT THE BEGINNING OF THE PERIOD BUT IS STRONGER BY THE MIDDLE OF THE
PERIOD. DESPITE THE SOMEWHAT WEAKER HEIGHT ANOMALIES, THE MID-LEVEL RIDGE IS
ACTUALLY BROADER, EXTENDING FURTHER WEST AND EAST. THIS DIFFERENCE TRANSLATES
TO MODEL GUIDANCE AND TOOLS INITIATING THE ENHANCED HEAT POTENTIAL EARLIER,
THUS FOR A LONGER DURATION. THE SLIGHT RISK OF EXCESSIVE HEAT IS EXPANDED IN
TODAY'S OUTLOOK, COVERING MORE AREAS OF THE SOUTH-CENTRAL AND SOUTHEASTERN
CONUS THAN YESTERDAY, THROUGHOUT WEEK-2. THIS HEAT SIGNAL STARTS INITIALLY
ACROSS THE SOUTHERN PLAINS, EXPANDING NORTHWARD AND EASTWARD, REACHING THE
SOUTHEAST BY DAY 10 (JUNE 16). AN AREA OF MODERATE RISK OF EXCESSIVE HEAT IS
ADDED IN TODAY'S OUTLOOK FOR THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER
VALLEY, JUN 14 TO 16, BASED ON THE ECMWF REFORECAST TOOL NOW SHOWING AT LEAST A
40% CHANCE OF MAXIMUM TEMPERATURES EXCEEDING THE 85TH PERCENTILE (PRIMARILY FOR
TEXAS), AS WELL AS INCREASING PROBABILITIES IN THE HEAT INDEX TOOLS AND THE
NATIONAL BLENDED MODELS (NBM) WHICH INDICATE THE POTENTIAL FOR NEAR RECORD
TEMPERATURES IN THE HIGHLIGHTED REGION. TEMPERATURES IN THE MODERATE RISK AREA
MAY REACH THE UPPER 90S TO OVER 100 DEG F.
EARLY IN WEEK-2, 500-HPA HEIGHT ANOMALY ENSEMBLE SOLUTIONS CONTINUE TO DEPICT
AN AMPLIFIED ANOMALOUS TROUGH OVER THE WEST COAST. A SLIGHT RISK OF HEAVY
PRECIPITATION CONTINUES TO BE POSTED ACROSS PARTS OF THE WEST, JUN 14-15, AND
IS EXPANDED FURTHER WEST TO THE SIERRA NEVADA AND WITH LESS COVERAGE OVER THE
FOUR CORNERS BASED ON TODAY'S MODEL GUIDANCE AND TOOLS. THE REFORECAST TOOLS
FROM THE ECMWF AND GEFS, AND TO A SLIGHTLY LESSER EXTENT THE CMCE INDICATE THE
POTENTIAL FOR 3-DAY PRECIPITATION TOTALS TO EXCEED THE 85TH PERCENTILE AND AT
LEAST A HALF INCH OVER THE DESIGNATED HEAVY PRECIPITATION AREA, ACROSS PORTIONS
OF THE GREAT BASIN, NORTHERN AND CENTRAL ROCKIES, AND SIERRA NEVADA.
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 INITIALLY HIGHLIGHTED OVER PARTS OF THE
EASTERN CORN BELT HAS BEEN SPREADING EASTWARD AND NORTHWARD, WITH INCREASED
COVERAGE FOR PORTIONS OF MICHIGAN AND PENNSYLVANIA INCLUDED IN TODAY’S OUTLOOK.
SOIL MOISTURE CONTINUES TO DECLINE IN THE REGION AND ONLY NEAR NORMAL
PRECIPITATION IS FAVORED DURING WEEK-2.
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 MANY RIVERS, AND IN AREAS ADJACENT TO THE HIGHER
ELEVATIONS. THE POSSIBLE FLOOD SHAPE HAS BEEN SLIGHTLY REDUCED IN COVERAGE
TODAY, DUE TO RIVER GAUGES IN THE SOUTHERN PORTIONS OF YESTERDAY'S POSSIBLE
FLOOD RISK AREA SHOWING IMPROVEMENT IN CONDITIONS. POSSIBLE FLOODING REMAINS
ACROSS NORTHERN PARTS OF THE JAMES RIVER IN SOUTH DAKOTA AS RIVER LEVELS ARE
RECEDING SLOWER DUE TO SATURATED GROUND CONDITIONS AND RELATIVELY FLAT
TOPOGRAPHY.
MID-LEVEL TROUGHING IS FAVORED FOR THE ALEUTIANS AND ALASKA MAINLAND, RESULTING
IN INCREASED CHANCES FOR NEAR TO BELOW NORMAL TEMPERATURES AND SLIGHTLY
ABOVE-NORMAL PRECIPITATION ACROSS MUCH OF THE STATE. A RELATIVELY QUIET WEATHER
PATTERN IS ANTICIPATED FOR ALASKA, THUS NO HAZARDS ARE POSTED FOR THE STATE AT
THIS TIME.
FORECASTER: MELISSA OU
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