799
FXUS21 KWNC 301812
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MAY 30 2025
SYNOPSIS: MID-LEVEL LOW PRESSURE IS FORECAST ACROSS WESTERN AND CENTRAL CANADA
DURING THE FIRST HALF OF THE PERIOD. WHILE MODELS DIFFER IN THE AMPLITUDE OF
THIS FEATURE, IT IS LIKELY THAT AN ASSOCIATED FRONTAL BOUNDARY WILL EXIST
ACROSS THE CENTRAL AND EAST-CENTRAL CONTIGUOUS U.S. (CONUS) SERVING AS A FOCUS
FOR EPISODES OF HEAVY, CONVECTIVE PRECIPITATION, ALTHOUGH CONFIDENCE IS LOW
REGARDING THE EXACT AREAS THAT RECEIVE HEAVY PRECIPITATION. THERE ARE ALSO
CONTINUED SIGNALS FOR INCREASING TROPICAL MOISTURE ACROSS FLORIDA AND THE
SOUTHEAST, PARTICULARLY IN THE MIDDLE AND LATER PARTS OF WEEK-2. AS THE
AFOREMENTIONED MID-LEVEL LOW SHIFTS EASTWARD, MID-LEVEL HIGH PRESSURE IS
FORECAST TO EXPAND ACROSS THE NORTHEASTERN PACIFIC INTO THE NORTHWESTERN CONUS
WHICH COULD RENEW HEAT CONCERNS ACROSS PORTIONS OF THE WEST.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS
(EXCLUDING PORTIONS OF THE NORTHEAST, NORTHERN MID-ATLANTIC, AND UPPER
MIDWEST), SAT-FRI, JUN 7-13.
DETAILED SUMMARY
FOR MONDAY JUNE 02 - FRIDAY JUNE 06:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JUNE 07 - FRIDAY JUNE 13: EARLY IN WEEK-2, TROUGHING IS FORECAST
ACROSS WESTERN AND CENTRAL CANADA, WITH THE 0Z ECENS AND 0Z CMCE BEING MORE
AMPLIFIED WITH THIS FEATURE COMPARED TO THE 0Z GEFS. THE TROUGH FAVORS A
FRONTAL ZONE SETTING UP ACROSS THE CENTRAL AND EAST-CENTRAL CONUS, WITH
POTENTIALLY MULTIPLE EPISODES OF HEAVY PRECIPITATION TIED TO ENHANCED
CONVECTIVE ACTIVITY. THE ECENS PROBABILISTIC EXTREMES TOOL (PET) DEPICTS AT
LEAST A 20 PERCENT CHANCE 3-DAY PRECIPITATION TOTALS EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH EXTENDING AS FAR NORTH AS THE UPPER
MISSISSIPPI VALLEY AT THE START OF THE PERIOD, LIKELY DUE TO THE STRONGER
UPSTREAM TROUGHING. THE GEFS PET CONFINES THESE ELEVATED PROBABILITIES TO THE
CENTRAL AND SOUTHERN PLAINS EASTWARD TO THE LOWER MISSISSIPPI AND TENNESSEE
VALLEYS. THE UNCALIBRATED 0Z ECENS DEPICTS A BROAD REGION EXTENDING FROM THE
EASTERN PLAINS TO THE OHIO AND TENNESSEE VALLEYS AND SOUTHEAST WITH A 20-40
PERCENT CHANCE WEEK-2 TOTAL PRECIPITATION EXCEEDS 2-INCHES, WITH LOCALIZED HIGH
DAILY TOTALS DEPICTED IN THE RECENT ECMWF AND GFS DETERMINISTIC GUIDANCE.
WHILE CONFIDENCE IS FAIRLY HIGH REGARDING HEAVY PRECIPITATION SOMEWHERE WITHIN
THE EASTERN HALF OF THE CONUS, CONFIDENCE IS MUCH LOWER REGARDING THE EXACT
LOCATION DUE TO THE CONVECTIVE NATURE OF THE PRECIPITATION AND UNCERTAINTY
REGARDING THE STRENGTH OF THE TROUGH. FURTHER COMPLICATING THE FORECAST IS THE
ADDED POTENTIAL FOR TROPICAL MOISTURE TO MOVE INTO FLORIDA OR THE SOUTHEAST BY
THE SECOND HALF OF THE PERIOD. THIS IS MORE EVIDENT IN THE 0Z GEFS AND 0Z CMCE
SOLUTIONS, BUT NOT AS ROBUST IN THE 0Z ECENS. IT SHOULD ALSO BE CONSIDERED THAT
THE MADDEN JULIAN OSCILLATION (MJO) IS FORECAST TO REACH PHASE 8 WHICH CAN
CORRELATE WITH A MORE ACTIVE TROPICAL ACTIVITY ACROSS THE GULF. ALL THINGS
CONSIDERED, A LARGE SLIGHT RISK FOR HEAVY PRECIPITATION IS DESIGNATED ACROSS
MOST OF THE CENTRAL AND EASTERN CONUS, EXCLUDING THE NORTHERN GREAT LAKES,
NORTHEAST, AND NORTHERN MID-ATLANTIC FOR ALL OF WEEK-2 (JUN 7-13). LOCALIZED
FLOODING IS A CONCERN FOR ANY AREAS THAT DO RECEIVE HEAVY RAINFALL.
RIDGING IS FORECAST ACROSS THE NORTHEASTERN PACIFIC, AND ASSOCIATED POSITIVE
HEIGHT ANOMALIES ARE PREDICTED TO EXPAND INTO THE WESTERN CONUS AS THE
DOWNSTREAM TROUGHING SHIFTS FURTHER EAST AND WEAKENS. THIS FAVORS A GRADUAL
INCREASE IN TEMPERATURES, AND IS BORDERLINE FOR AN EXTREME HEAT RISK OVER SOME
AREAS. AT THE START OF THE PERIOD, THE LARGEST POSITIVE TEMPERATURE ANOMALIES
ARE FAVORED FURTHER TO THE SOUTH, WITH THE UNCALIBRATED 0Z ECENS AND 0Z GEFS
DEPICTING DAILY MAXIMUM TEMPERATURES IN THE UPPER 90S DEG F TO LOW 100S DEG F
OVER THE CALIFORNIA CENTRAL VALLEY. CLOSER TO NORMAL OR EVEN SLIGHTLY
BELOW-NORMAL TEMPERATURES ARE POSSIBLE ACROSS THE NORTHWEST AT THE START OF THE
PERIOD DUE TO INFLUENCE FROM THE TROUGH, BUT HEAT SIGNALS IN THE PETS INCREASE
BY DAY-10 (JUN 9), WITH PROBABILITIES FOR MAXIMUM TEMPERATURES EXCEEDING THE
85TH CLIMATOLOGICAL PERCENTILE RISING ABOVE 40 PERCENT IN THE ECENS PET AND AT
LEAST A 20 PERCENT CHANCE HIGH TEMPERATURES IN LOW ELEVATION AREAS REACH THE
90S DEG F. DESPITE THESE WARM TEMPERATURES ACROSS THE NORTHWEST AND CALIFORNIA
CENTRAL VALLEY, AN EXTREME HEAT RISK IS NOT POSTED DUE TO INCREASING HEAT
HAZARD THRESHOLDS DURING THE MONTH OF JUNE, AND THE HEAT NOT PREDICTED TO PEAK
UNTIL THE MIDDLE OF WEEK-2. THESE AREAS WILL CONTINUE TO BE CLOSELY MONITORED
FOR A POSSIBLE HEAT RISK DESIGNATION IN FUTURE OUTLOOKS.
WEAK TROUGHING IS PREDICTED ACROSS THE BERING SEA AND WESTERN ALASKA DURING
WEEK-2. THIS GENERALLY FAVORS ENHANCED PROBABILITIES OF BELOW-NORMAL
TEMPERATURES ACROSS ALASKA, AND SOME INCREASED POTENTIAL FOR HEAVY
PRECIPITATION OVER SOUTHEASTERN ALASKA EARLY IN THE PERIOD TIED TO ENHANCED
ONSHORE FLOW. HOWEVER, PRECIPITATION AMOUNTS ARE PREDICTED TO REMAIN BELOW
HAZARDS CRITERIA. INCREASING MID-LEVEL HEIGHTS LATER IN THE PERIOD TIED TO
EXPANDING RIDGING OVER THE NORTHEASTERN PACIFIC FAVOR A DRYING TREND OVER
SOUTHERN ALASKA.
FORECASTER: THOMAS COLLOW
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