901
FXUS21 KWNC 091929
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 09 2025
SYNOPSIS: PERSISTENT SURFACE HIGH PRESSURE OVER THE SOUTHEASTERN QUARTER OF THE
CONTIGUOUS U.S. (CONUS) IS FAVORED TO BRING WARM MOIST AIR INTO THE GREAT
PLAINS, LEADING TO THE POTENTIAL FOR HEAVY PRECIPITATION ACROSS THE NORTHERN
TIER, AND FOR POTENTIALLY HAZARDOUS HIGH TEMPERATURES TO SEVERAL REGIONS ACROSS
THE LOWER 48. INCREASED TROPICAL MOISTURE ALSO BRINGS THE POTENTIAL FOR HEAVY
PRECIPITATION OVER SOUTHERN TEXAS.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY AS WELL AS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY,
TUE-THU, JUN 17-19.
SLIGHT RISK OF HEAVY PRECIPITATION FOR SOUTHERN TEXAS, TUE-THU, JUN 17-19.
SLIGHT RISK OF EXTREME HEAT FOR PORTIONS OF THE DESERT SOUTHWEST, TUE-WED, JUN
17-18.
SLIGHT RISK OF EXTREME HEAT FOR MUCH OF THE CENTRAL PLAINS AND MIDDLE
MISSISSIPPI VALLEY AS WELL AS WESTERN PORTIONS OF THE GREAT LAKES AND OHIO
VALLEY, TUE-FRI, JUN 17-20.
SLIGHT RISK OF EXTREME HEAT FOR THE SOUTHERN GREAT LAKES AND NORTHERN OHIO
VALLEY, THU-FRI, JUN 19-20.
SLIGHT RISK OF EXTREME HEAT FOR MUCH OF THE MID-ATLANTIC, THU-SAT, JUN 19-21.
DETAILED SUMMARY
FOR THURSDAY JUNE 12 - MONDAY JUNE 16:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JUNE 17 - MONDAY JUNE 23: THE GEFS, ECMWF, AND CMCE ARE IN
REASONABLE AGREEMENT WITH REGARD TO THE OVERALL SYNOPTIC PATTERN AS DEPICTED BY
500-HPA HEIGHT ANOMALIES DESPITE SOME SIGNIFICANT DIFFERENCES. THE MODELS AGREE
ON THE PRESENCE OF A SHORTWAVE TROUGH OVER THE WEST COAST AT THE OUTSET OF
WEEK-2, ALTHOUGH THEY SHARPLY DISAGREE WITH REGARD TO THE AMPLITUDE AND
MOVEMENT OF THIS FEATURE. ENSEMBLE SOLUTIONS ALSO ARE IN GOOD AGREEMENT WITH
RESPECT TO A STRONG BERMUDA HIGH ENABLING MOIST AIR TO MOVE OFF THE GULF AND
INTO THE MIDDLE OF THE CONUS, BUT DISAGREE WITH RESPECT TO THE LOCATION AND
INTENSITY OF ANY PRECIPITATION ASSOCIATED WITH THIS TROPICAL INFLOW. THE BEST
AGREEMENT AMONG THE MODELS IS IN FAVORING WIDESPREAD POSITIVE HEIGHT ANOMALIES
ACROSS THE SOUTHERN HALF OF THE CONUS FOR MUCH OF WEEK-2, LEADING TO THE
POTENTIAL FOR EXTREME HEAT FOR SEVERAL REGIONS ACROSS THE LOWER 48.
LATE IN WEEK-1 A MID-LEVEL RIDGE BUILDING OVER THE DESERT SOUTHWEST LEADS TO A
CHANCE OF EXTREME HEAT TO THIS REGION EARLY IN WEEK-2. THE PROBABILISTIC
EXTREMES TOOLS (PETS) FROM THE ECMWF AND GEFS INDICATE AT LEAST A 20%
PROBABILITY OF HIGH TEMPERATURES TO EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE
AND ABSOLUTE TEMPERATURES OF 95F FOR EASTERN NEW MEXICO, 100-105F FOR WESTERN
TEXAS AND SOUTHERN NEW MEXICO, AND OVER 105F FOR SOUTHERN ARIZONA. THIS EVENT
IS SHORT-LIVED AS THE WEST COAST TROUGH QUICKLY WEAKENS THE DESERT RIDGE; A
SLIGHT RISK OF EXTREME HEAT IS POSTED FOR MUCH OF NEW MEXICO AND PORTIONS OF
WESTERN TEXAS AND SOUTHERN ARIZONA FOR JUN 17-18. THE ECMWF AND GEFS ALSO
INDICATE GENERALLY BREEZY CONDITIONS OVER THESE HIGHLIGHTED AREAS. WHILE
HAZARDOUS THRESHOLDS ARE NOT EXPECTED TO BE MET, INCREASED WINDS WOULD
NONETHELESS INCREASE THE RISK FOR WILDFIRES PARTICULARLY WITH EXPECTED EXTREME
HEAT.
POSITIVE HEIGHT ANOMALIES OVER THE SOUTHEASTERN CONUS ALSO FAVOR ANOMALOUSLY
WARM TEMPERATURES ALMOST UNIVERSALLY EAST OF THE ROCKIES, AND GULF MOISTURE
STREAMING IN WITH ASSISTANCE FROM A STRONG BERMUDA HIGH IS LIKELY TO MAKE FOR
UNCOMFORTABLE AND IN SOME CASES DANGEROUS HEAT. THE GEFS AND ECMWF PETS BOTH
INDICATE AT LEAST A 20% CHANCE OF HIGH TEMPERATURES EXCEEDING THE 85TH
PERCENTILE AND AT LEAST 90F FOR A BROAD SWATH FROM THE CENTRAL PLAINS THROUGH
THE OHIO VALLEY. THE GEFS FAVORS THESE CONDITIONS THROUGHOUT THESE REGIONS FOR
THE FIRST HALF OF WEEK-2, WHILE THE ECMWF PREFERS A MORE PROGRESSIVE SOLUTION,
MOVING THE HAZARDOUS HEAT INTO THE OHIO VALLEY MORE SLOWLY AND GENERALLY
KEEPING MAXIMUM TEMPERATURES SLIGHTLY LOWER THAN THE GEFS. FOR BOTH REGIONS AND
IN BOTH MODELS THE SIGNAL BEGINS TO DROP OFF TOWARDS THE END OF WEEK-2. A
SLIGHT RISK OF EXTREME HEAT IS POSTED FOR MUCH OF THE CENTRAL PLAINS AND MIDDLE
MISSISSIPPI VALLEY FOR JUN 17-20, AND FOR THE OHIO VALLEY AND SOUTHERN GREAT
LAKES FOR JUN 19-20. ABNORMALLY WARM TEMPERATURES AND HIGH HUMIDITIES ARE ALSO
FAVORED TO SPREAD EAST INTO MUCH OF THE MID-ATLANTIC CONCURRENT WITH THE
WARM-UP IN THE OHIO VALLEY. THE PETS BROADBRUSH AT LEAST 20% CHANCES OF MAXIMUM
TEMPERATURES TO EXCEED THE 85TH PERCENTILE AND AT LEAST 90F FOR THE REGION,
THEREFORE A SLIGHT RISK OF EXTREME HEAT IS POSTED FOR JUN 19-21 FOR MOST OF THE
MID-ATLANTIC.
AT THE BEGINNING OF WEEK-2 MODELS DEPICT THE TROUGH OVER THE WEST COAST AS
POTENTIALLY PROVIDING INCREASED INSTABILITY OVER THE NORTHERN PLAINS AND
INTERACTING WITH THE ABUNDANT GULF MOISTURE IN PLACE TO PRODUCE HEAVY
PRECIPITATION. THIS IS WELL-INDICATED BY THE ECMWF PET AS WELL AS UNCALIBRATED
PROBABILITIES INDICATING AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TOTALS TO
EXCEED 1 INCH AT THE BEGINNING OF WEEK-2 ALONG THE U.S.-CANADA BORDER, AS WELL
AS FOR MUCH OF SOUTH TEXAS. THE GEFS IS LESS BULLISH WITH REGARD TO THE
POTENTIAL FOR HEAVY PRECIPITATION OVER THE NORTHERN PLAINS BUT IS IN BETTER
AGREEMENT FOR SOUTH TEXAS. DISAGREEMENT NOTWITHSTANDING, A SLIGHT RISK OF HEAVY
PRECIPITATION IS POSTED FOR BOTH REGIONS FOR JUN 17-19. DUE TO THE SHORT TIME
IN WHICH THIS PRECIPITATION IS EXPECTED TO FALL AND THE NATURE OF THE
WATERSHEDS INVOLVED THERE IS THE POTENTIAL FOR LOCALIZED FLASH FLOODING, BUT
UNCERTAINTY IS TOO HIGH TO HIGHLIGHT A PARTICULAR AREA FOR A FLOODING POSSIBLE
HAZARD.
ICE-BOUND RIVERS ARE BEGINNING TO BREAK UP IN THE NORTH SLOPE OF ALASKA. THERE
IS NO ASSOCIATED HAZARD POSTED AT THIS TIME BUT THIS SITUATION WILL BE CLOSELY
MONITORED IN THE COMING DAYS AND WEEKS AS CONDITIONS CAN QUICKLY CHANGE,
LEADING TO THE POTENTIAL FOR ICE JAMS, AUFEIS, AND ASSOCIATED FLOODING.
FORECASTER: DANNY BARANDIARAN
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