696
FXUS21 KWNC 191827
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 19 2026
SYNOPSIS: FORECAST MID-LEVEL HIGH PRESSURE OVER THE SOUTHWESTERN CONTIGUOUS
U.S. (CONUS) IS EXPECTED TO PROMOTE ABOVE-NORMAL TEMPERATURES WITH POSSIBLE
EXTREME HEAT CONDITIONS ACROSS THE CALIFORNIA VALLEY EASTWARD INTO THE LOWER
FOUR CORNERS EARLY WEEK-2. ENHANCED SUBTROPICAL HIGH PRESSURE OVER THE
SOUTHEASTERN CONUS BRINGS AN INCREASED RISK OF EXTREME HEAT FROM THE FLORIDA
PENINSULA NORTHWARD INTO THE SOUTHERN AND MIDDLE ATLANTIC REGIONS THROUGHOUT
WEEK-2. MID-LEVEL HIGH PRESSURE ALSO BUILDS TOWARD THE HIGH PLAINS, INCREASING
THE RISK OF EXTREME HEAT ACROSS THE CENTRAL AND SOUTH-CENTRAL CONUS. MEANWHILE,
SURFACE LOW DEVELOPMENT IN THE LEE OF THE ROCKIES AND ENHANCED MOISTURE
TRANSPORT FROM THE SOUTH SUPPORT AN INCREASED RISK OF HEAVY PRECIPITATION
ACROSS PARTS OF THE MIDDLE AND UPPER MISSISSIPPI VALLEY AND ADJACENT AREAS
EARLY IN THE PERIOD.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF CALIFORNIA CENTRAL VALLEY, DESERT
SOUTHWEST, AND SOUTHERN HIGH PLAINS, SAT-SUN, JUN 27-28.
SLIGHT RISK OF EXTREME HEAT FOR THE CENTRAL AND SOUTHERN PLAINS AND ADJACENT
LOWER MISSISSIPPI VALLEY, SAT-FRI, JUN 27-JUL 3.
SLIGHT RISK OF EXTREME HEAT FOR THE FLORIDA PENINSULA AND PORTIONS OF THE SOUTH
ATLANTIC AND LOWER MID-ATLANTIC REGIONS, SAT-FRI, JUN 27-JUL 3.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE EAST-CENTRAL AND NORTHERN
PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEY, LOWER OHIO VALLEY, AND ADJACENT
GREAT LAKES REGION, SAT-MON, JUN 27-29.
DETAILED SUMMARY
FOR MONDAY JUNE 22 - FRIDAY JUNE 26:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JUNE 27 - FRIDAY JULY 03: MID-LEVEL HEIGHT ANOMALY FORECASTS FROM
GEFS, EUROPEAN ENSEMBLE (ECENS), AND CANADIAN ENSEMBLE (CMCE) FAVOR AN ZONAL
PATTERN EARLY IN WEEK-2 WITH WEAK MID-LEVEL RIDGING NEAR THE WEST COAST AND
FROM THE SUBTROPICS INTO FLORIDA, WITH A WEAK TROUGH CENTERED NEAR SOUTHWESTERN
ALASKA. THE PATTERN MODESTLY AMPLIFIES AS THE PERIOD PROGRESSES, AND MODELS
GENERALLY AGREE THAT MID-LEVEL HIGH PRESSURE WILL RETROGRADE INTO THE CENTRAL
NORTH PACIFIC AS WEAK MID-LEVEL TROUGHING DROPS FROM NEAR ALASKA TOWARD THE
WESTERN CONUS. MEANWHILE, THE SUBTROPICAL RIDGING EXTENDING INTO FLORIDA BUILDS
NORTHWESTWARD INTO THE CENTRAL CONUS AND EASTERN ROCKIES WHILE A WEAK TROUGH
MEANDERS NEAR THE NORTHEAST. BY THE END OF WEEK-2, NEAR TO ABOVE-NORMAL 500-HPA
HEIGHTS WILL ENCOMPASS NORTH AMERICA AND ADJACENT AREAS, INCLUDING AREAS OF
MID-LEVEL TROUGHING WHICH ARE MORE DEFINED BY UPSTREAM AND DOWNSTREAM RIDGING
AND NOT MARKEDLY BELOW-NORMAL 500-HPA HEIGHTS.
ANALYSIS OF ECMWF AND GEFS 500-HPA HEIGHT ANOMALIES IN STANDARDIZED SPACE
CONTINUES SHOWS A FAIRLY STRONG HEIGHT MAXIMA CENTERED JUST WEST OF THE CONUS
EARLY IN THE PERIOD, SUPPORTIVE OF EXTREME HEAT RISK. PROBABILISTIC EXTREME
TOOLS (PETS) FROM THE GEFS AND TO A LESSER EXTENT THE CMCE INDICATE AT LEAST
20% CHANCES OF DAYTIME TEMPERATURES EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE IN THE LOWER ELEVATIONS OF THE SOUTHWEST AND THROUGH THE CALIFORNIA
VALLEYS, SUPPORTING A SLIGHT RISK OF MARGINALLY-EXTREME HEAT EARLY WEEK-2
BEFORE THE RIDGE CENTER RETROGRADES INTO THE NORTH PACIFIC AND WEAK MID-LEVEL
TROUGHING DROPS TOWARD THE REGION FROM NEAR ALASKA. WITHIN THE HAZARD AREA, RAW
TEMPERATURE TOOLS CONTINUE TO DEPICT INCREASED CHANCES FOR MAXIMUM TEMPERATURES
EXCEEDING 105 DEG F OVER PARTS OF THE CALIFORNIA VALLEY, AND 110 DEG F OVER THE
LOWER ELEVATIONS OF THE DESERT SOUTHWEST, ALTHOUGH THE PREPONDERANCE OF TOOLS
SHOWS SLIGHTLY LOWER ODDS THAN YESTERDAY..
THE SUBTROPICAL MID-LEVEL RIDGING THAT EXTENDS INTO FLORIDA ESTABLISHES A
SLIGHT RISK OF EXTREME HEAT ACROSS THE FLORIDA PENINSULA AT THE OUTSET OF
WEEK-2. AS MID-LEVEL HIGH PRESSURE BUILDS NORTHWARD AND NORTHWESTWARD,
TEMPERATURES ARE EXPECTED TO RISE QUICKLY IN THE SOUTH-CENTRAL AND CENTRAL
CONUS AND ALSO ALONG THE EASTERN SEABOARD, BRINGING A SLIGHT RISK OF EXTREME
HEAT TO THESE REGIONS STARTING EARLY WEEK-2 AND LASTING THROUGH THE PERIOD. ALL
THREE PETS GENERALLY KEEP AT LEAST 20 PERCENT CHANCES FOR DAYTIME HIGHS
EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE THROUGHOUT WEEK-2 OVER THE FLORIDA
PENINSULA, BUT ARE LESS ROBUST FARTHER NORTH AND NORTHWEST. THE GEFS AND ECENS
PETS SHOW AT LEAST 20 PERCENT CHANCES FOR HIGHS IN THE 85TH CLIMATOLOGICAL
PERCENTILE ACROSS PARTS OF THE SOUTHERN AND MIDDLE ATLANTIC REGIONS THROUGH
MOST OF WEEK-2, RISING ABOVE 30 PERCENT ON THE ECENS PET ON JUNE 30. ACROSS THE
CENTRAL AND SOUTH-CENTRAL CONUS, THE PETS ARE EVEN LESS REMARKABLE, SHOWING A
MINORITY OF THE REGION WITH AT LEAST A 20 PERCENT CHANCE FOR HIGH TEMPERATURES
EXCEEDING THE 85TH PERCENTILE EACH DAY. HOWEVER, INTERNAL HEAT TOOLS INDICATE
ENHANCED CHANCES FOR HEAT INDEXES TO RISE ABOVE 105 DEG F AT TIMES THROUGHOUT
THE SOUTHERN AND LOWER MID-ATLANTIC REGIONS, AND ACROSS THE CENTRAL AND
SOUTH-CENTRAL PLAINS AND ADJACENT LOWER MISSISSIPPI VALLEY, ALONG WITH
INCREASED ODDS FOR TEMPERATURES AND/OR HEAT INDEXES TO EXCEED THE 90TH
CLIMATOLOGICAL PERCENTILE AT TIMES. IN ADDITION, THE MID-LEVEL HIGH PRESSURE
SLOWLY BUILDING INTO THE CENTRAL CONUS SEEMS MORE LIKELY TO BRING EXTREME HEAT
INTO THE REGION THAN THE PETS INDICATE, WITH HIGH HUMIDITY LIKELY INCREASING
THE ODDS FOR UNUSUALLY HIGH HEAT INDEXES DESPITE ONLY NOMINALLY HIGH
TEMPERATURES. THESE FACTORS SUPPORT A SLIGHT RISK OF EXTREME HEAT THROUGHOUT
WEEK-2 ACROSS THE CENTRAL AND SOUTH-CENTRAL CONUS, AND ALONG PARTS OF THE
MIDDLE AND SOUTHERN ATLANTIC REGION, INCLUDING THE ENTIRE FLORIDA PENINSULA. AT
THIS TIME, THE RISK DOES NOT APPEAR TO SYSTEMICALLY RELENT DURING WEEK-2, THE
THREAT IS MARGINAL, AND OPPRESSIVE HEAT MAY NOT OCCUR EVERY DAY.
FOR PRECIPITATION, MODELS CONTINUE TO POINT TO POTENTIAL SURFACE LOW
DEVELOPMENT IN THE LEE OF ROCKIES EARLY IN WEEK-2, HOWEVER ENSEMBLE SOLUTIONS
REMAIN DIFFUSE IN REGARDS TO THE LOCATION OF DEVELOPMENT AND THE EVENTUAL TRACK
OF ANY SURFACE LOW. DESPITE THIS, THE COMBINATION OF LOWER SURFACE PRESSURES
AND THE ROBUST ADVECTION OF TROPICAL MOISTURE INTO PARTS OF THE CENTRAL AND
NORTH-CENTRAL CONUS ENHANCES THE PROBABILITY OF HEAVY PRECIPITATION ACROSS THE
MIDDLE AND UPPER MISSISSIPPI VALLEY AND ADJACENT SECTIONS OF THE GREAT LAKES,
EASTERN GREAT PLAINS, AND LOWER OHIO VALLEY. THE ECENS PET DEPICTS A 20 TO 40
PERCENT CHANCE FOR 3-DAY PRECIPITATION AMOUNTS TO EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND ONE INCH TOTAL DURING THE FIRST 3 DAYS OF WEEK-2
(JUN 27-29) WHILE THE GEFS AND CMCE PETS SHOW 20 TO 30 PERCENT CHANCES FOR SUCH
CONDITIONS OVER AT LEAST PART OF THESE AREAS. RAW ENSEMBLE SOLUTIONS HAVE NOT
BEEN CONSISTENT IN HIGHLIGHTING EITHER WHICH AREAS IN THE HEAVY PRECIPITATION
HAZARD ARE AT GREATEST RISK, NOR IN FORECASTING THE HIGHEST AMOUNTS, SO NOTHING
BEYOND A SLIGHT RISK OF HEAVY PRECIPITATION IS SUPPORTED. DUE TO THE SLIGHT
RISK FOR EXCESSIVE RAINFALL FORECAST DURING WEEK-1 ACROSS PARTS OF LOWER
MISSOURI RIVER AND OHIO RIVER BASINS, ANY HEAVY PRECIPITATION REALIZED MAY
TRIGGER SCATTERED FLOODING DURING WEEK-2, BUT CHANCES ARE NOT HIGH ENOUGH TO
JUSTIFY A SPECIFIC AREA AT RISK OF BROADSCALE FLOODING..
NO HAZARDS ARE POSTED OVER ALASKA. BUT THERE IS THE POTENTIAL FOR INCREASED
THUNDERSTORM ACTIVITY THAT COULD TRIGGER WILDFIRES.
FORECASTER: RICH TINKER
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