997
FXUS21 KWNC 241831
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 24 2025
SYNOPSIS: MID-LEVEL HIGH PRESSURE FAVORED OVER SOUTHWESTERN CANADA IS EXPECTED
TO BRING ABOVE-NORMAL SUMMERTIME TEMPERATURES WITH POSSIBLE EXTREME HEAT
CONDITIONS FOR PORTIONS OF THE NORTHWESTERN AND NORTHCENTRAL CONTIGUOUS U.S.
(CONUS) EARLY IN WEEK-2. TIED TO AN ACTIVE NORTH AMERICAN MONSOON CIRCULATION
HEADING INTO JULY, THERE IS BETTER MODEL SUPPORT OF HEAVY PRECIPITATION ACROSS
THE LOWER FOUR CORNERS WHICH MAY TRIGGER LOCALIZED FLOODING AND EXACERBATE
SATURATED GROUND CONDITIONS FOLLOWING A WET WEEK-1 FORECAST IN THE REGION.
STALLED FRONTAL ACTIVITY NEAR THE SOUTHEASTERN U.S. MAY LEAD TO LOCALLY HEAVY
PRECIPITATION FROM THE EASTERN GULF TO THE COASTAL CAROLINAS.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE DESERT SOUTHWEST,
WED-FRI, JUL 2-4.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE DESERT SOUTHWEST, ROCKIES,
AND GREAT BASIN, WED-SUN, JUL 2-6.
SLIGHT RISK OF EXTREME HEAT OVER PORTIONS OF THE PACIFIC NORTHWEST, NORTHERN
INTERMOUNTAIN, GREAT BASIN, NORTHERN PLAINS, AND UPPER MISSISSIPPI VALLEY,
WED-FRI, JUL 2-4.
SLIGHT RISK OF HEAVY PRECIPITATION IN PARTS OF THE EASTERN GULF COAST REGION,
AND LOWER EASTERN SEABOARD, WED-SAT, JUL 2-5.
SLIGHT RISK OF HIGH WINDS ALONG MOST OF THE IMMEDIATE WEST COAST, WED-SUN, JUL
2-6.
FLOODING POSSIBLE OVER PORTIONS OF EASTERN ARIZONA AND NEW MEXICO.
DETAILED SUMMARY
FOR FRIDAY JUNE 27 - TUESDAY JULY 01:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JULY 02 - TUESDAY JULY 08: THERE CONTINUES TO BE FAIRLY GOOD
AGREEMENT BETWEEN THE GEFS AND ECWMF ENSEMBLE MEAN 500-HPA HEIGHT FORECASTS
DEPICTING AN ANOMALOUS RIDGE CENTER ACROSS SOUTHWESTERN CANADA, WITH WEAK
TROUGHING DOWNSTREAM TOWARDS THE MIDDLE OF NEXT WEEK. IN RESPONSE TO THIS
MID-LEVEL PATTERN, WARMING SUMMERTIME TEMPERATURES LOOK TO BECOME ESTABLISHED
OVER MUCH OF THE PACIFIC NORTHWEST, INTERMOUNTAIN WEST, GREAT BASIN, AND THE
NORTHERN PLAINS LATE IN WEEK-1, WHEREAS THE THREAT OF EXTREME HEAT CONDITIONS
IMPACTING MANY PARTS OF THE EASTERN CONUS DURING WEEK-1 IS EXPECTED TO EASE BY
THE OUTSET OF WEEK-2. BASED ON THE LATEST TEMPERATURE GUIDANCE, THE GREATEST
RISK FOR EXTREME HEAT IS FAVORED OVER THE LOWER ELEVATIONS OF THE NORTHERN
INTERMOUNTAIN AND NORTHERN HIGH PLAINS, WITH THIS RISK POTENTIALLY SHIFTING
EASTWARD LATER IN THE PERIOD. THIS IS REFLECTED IN THE PROBABILISTIC EXTREME
TOOLS (PETS), WHICH INDICATE AT LEAST 20% CHANCES FOR MAXIMUM DAYTIME
TEMPERATURES EXCEEDING THE 85TH PERCENTILE, FOCUSED INITIALLY OVER THE
INTERMOUNTAIN WEST, WITH THESE HEAT SIGNALS EXPANDING INTO THE MIDWEST BY THE
MIDDLE OF WEEK-2. WHILE THE GEFS IS A BIT MORE AGGRESSIVE WITH THE EXPANSION OF
HEAT POTENTIAL, THERE REMAINS A GOOD DEAL OF UNCERTAINTY WITH THE EVOLUTION OF
THE MID-LEVEL RIDGE CENTER DURING THE FIRST WEEK IN JULY. THEREFORE, A SLIGHT
RISK OF EXTREME HEAT REMAINS POSTED AND IS EXPANDED TO INCLUDE PARTS OF THE
UPPER MISSISSIPPI VALLEY WHERE THERE IS GREATEST AGREEMENT IN THE TOOLS, VALID
THROUGH DAY 10 (JUL 4). WHILE TEMPERATURES ARE FAVORED TO REMAIN NEAR- TO
ABOVE-NORMAL ACROSS THE EASTERN U.S., THE SLIGHT RISK FOR EXTREME HEAT IS
DISCONTINUED IN THE UPDATED OUTLOOK DUE TO A LACK OF SUPPORT IN THE TOOLS.
UNDERNEATH THE ANOMALOUS RIDGE CENTER, BOTH THE GEFS AND ECWMF ENSEMBLES FAVOR
HEIGHT WEAKNESSES IN THE 500-HPA SUBTROPICAL HEIGHT FIELDS WITH 700-HPA
INVERTED TROUGHING OVER THE SOUTHERN PLAINS AND NORTHERN MEXICO EARLY IN
WEEK-2. THESE FEATURES ARE CHARACTERISTIC OF AN ACTIVE NORTH AMERICAN MONSOON
CIRCULATION, WHERE THERE IS GROWING MODEL SUPPORT FOR ABOVE-NORMAL AND
POTENTIALLY HEAVY PRECIPITATION AFFECTING MANY PARTS OF THE SOUTHWESTERN CONUS.
IN ADDITION, ENHANCED PRECIPITATION STEMMING FROM PACIFIC TROPICAL MOISTURE MAY
ALSO BE A PLAYER IN THE OUTLOOK. THE NATIONAL HURRICANE CENTER (NHC) IS
MONITORING AN AREA TO THE SOUTH OF MEXICO WITH 70% CHANCES FOR TROPICAL CYCLONE
DEVELOPMENT DURING WEEK-1, WITH SEVERAL ENSEMBLE MEMBER SOLUTIONS TRACKING THE
LOW NEAR BAJA CALIFORNIA HEADING INTO WEEK-2. ALTHOUGH RAW ENSEMBLE TOTALS
REMAIN RATHER LIMITED IN THEIR RAW TOTALS, THERE ARE STRONGER SIGNALS IN
PROBABILISTIC AND PERCENTILE SPACE (AT LEAST 40% CHANCES FOR EXCEEDING THE 85TH
PERCENTILE) AMONG THE GEFS AND ECMWF BASED TOOLS TO SUPPORT THE ADDITION OF A
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE DESERT SOUTHWEST, VALID
FOR JUL 2-4. A SLIGHT RISK OF HEAVY PRECIPITATION REMAINS ISSUED AND IS
EXTENDED THROUGH DAY 12 (JUL 6) AND BROADENED TO INCLUDE ADDITIONAL AREAS OF
THE FOUR CORNERS AND ROCKIES WHERE THERE ARE ELEVATED CHANCES FOR 3-DAY AMOUNTS
EXCEEDING THE 85TH PERCENTILE. DUE TO LOCALLY HEAVY PRECIPITATION AND FLOODING
EXPECTED DURING WEEK-1 OVER THE LOWER FOUR CORNERS, A FLOODING POSSIBLE HAZARD
ALSO REMAINS ISSUED AS ANY HEAVY PRECIPITATION REALIZED IS LIKELY TO EXACERBATE
GROUND CONDITIONS IN THE HIGHLIGHTED AREA.
ACROSS THE SOUTHEASTERN CONUS, MODELS DEPICT THE PASSAGE OF A FRONTAL BOUNDARY
LATE IN WEEK-1 THAT LOOKS TO POTENTIALLY STALL BY EARLY WEEK-2 AND BECOME A
FOCAL POINT FOR ENHANCED PRECIPITATION. BOTH RAW AND CALIBRATED TOOLS SHOW THE
HIGHEST AMOUNTS REMAINING OFFSHORE, THOUGH THERE IS BETTER SUPPORT IN THE ECMWF
FOR 3-DAY AMOUNTS EXCEEDING AN INCH ACROSS PARTS OF THE COASTAL SOUTHEASTERN
U.S THROUGH THE MIDDLE OF WEEK-2, AND A SLIGHT RISK OF HEAVY PRECIPITATION IS
HIGHLIGHTED FROM THE EASTERN GULF COAST TO THE COASTAL CAROLINAS (JUL 2-5).
NOTABLY, THERE ARE A NUMBER OF MEMBERS IN THE ECMWF ENSEMBLE, AS WELL AS THE 0Z
DETERMINISTIC SOLUTION, DEVELOPING A SURFACE LOW AT THE TAIL OF THE FRONT LATER
NEXT WEEK THAT BEARS MONITORING FOR TROPICAL CYCLONE POTENTIAL.
SURFACE HIGH PRESSURE OVER THE NORTHEASTERN PACIFIC ADJACENT TO MEAN SURFACE
LOW PRESSURE OVER THE INTERIOR WEST MAY LEAD TO TIGHT PRESSURE GRADIENTS ALONG
MUCH OF THE WEST COAST. THIS MAY BE ENHANCED BY THE AFOREMENTIONED HEAT
POTENTIAL FAVORED EARLY IN THE PERIOD, WHICH WOULD LIKELY LOWER SURFACE
PRESSURE. AS A RESULT, A SLIGHT RISK OF HIGH WINDS REMAINS POSTED ALONG MOST OF
THE IMMEDIATE WEST COAST WHERE PETS ALSO INDICATE INCREASED CHANCES FOR WIND
SPEEDS EXCEEDING THE 85TH PERCENTILE.
NUMEROUS WILDFIRES HAVE DEVELOPED ACROSS ALASKA DURING THE PAST FEW DAYS, AND
ROBUST FIRE ACTIVITY IS EXPECTED TO CONTINUE FOR AT LEAST A FEW MORE DAYS. THE
SMOKE GENERATED BY THESE FIRES IS FORECAST TO MEANDER AROUND THE STATE DURING
WEEK-2, FOLLOWING LOW-LEVEL WIND CURRENTS. AS A RESULT, PERIODS OF VERY POOR
AIR QUALITY AND LOW VISIBILITY MAY OCCUR.
FORECASTER: NICK NOVELLA
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