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FXUS21 KWNC 092008
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JUNE 09 2026
SYNOPSIS: STRONG MID-LEVEL HIGH PRESSURE ACROSS THE WEST COAST IS ANTICIPATED
TO PEAK BY THE END OF WEEK-1, WEAKENING BUT LINGERING INTO THE ONSET OF WEEK-2
RESULTING IN A SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE WEST FOR JUNE 17.
TEMPERATURES ARE ANTICIPATED TO MODERATE AS A TRANSITION TO MID-LEVEL LOW
PRESSURE OCCURS ACROSS THE WEST. A SERIES OF SURFACE LOWS ACROSS THE WEST MAY
SUPPORT PERIODS OF HIGH WINDS FOR PARTS OF THE INTERIOR WEST WHICH COULD
ENHANCE WILDFIRE RISK IN SOME AREAS. PERIODS OF HIGH WINDS ARE ALSO POSSIBLE
FOR PARTS OF THE WEST COAST. MID-LEVEL HIGH PRESSURE IS PREDICTED TO BUILD
ACROSS THE SOUTHEASTERN CONTIGUOUS U.S. (CONUS) EXPANDING WITH TIME, SUPPORTING
INCREASED CHANCES FOR EXTREME HEAT ACROSS THE REGION. A SERIES OF SURFACE LOWS
AND FRONTS MAY BRING HEAVY PRECIPITATION TO MUCH OF THE EAST-CENTRAL AND
SOUTH-CENTRAL CONUS AT THE BEGINNING OF THE PERIOD.
HAZARDS
MODERATE RISK OF EXTREME HEAT FOR PARTS OF THE FLORIDA PENINSULA, WED-FRI, JUN
17-19.
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE FLORIDA PENINSULA, WED-TUE, JUN
17-23.
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE MID-ATLANTIC AND SOUTHEASTERN
U.S., FRI-SUN, JUN 19-21.
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE WEST COAST, NEVADA, AND SOUTHWEST,
WED, JUN 17.
SLIGHT RISK OF HIGH WINDS FOR COASTAL PARTS OF SOUTHWESTERN OREGON AND NORTHERN
CALIFORNIA, WED-FRI, JUN 17-19.
SLIGHT RISK OF HIGH WINDS FOR PARTS OF THE INTERIOR WEST AND GREAT PLAINS,
WED-FRI, JUN 17-19.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE EAST-CENTRAL AND
SOUTH-CENTRAL CONUS, WED-FRI, JUN 17-19.
DETAILED SUMMARY
FOR FRIDAY JUNE 12 - TUESDAY JUNE 16:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY JUNE 17 - TUESDAY JUNE 23: AMPLIFIED RIDGING ACROSS THE NORTHEAST
PACIFIC AND WEST COAST IS PREDICTED TO PEAK BY THE END OF WEEK-1, POSSIBLY
LINGERING BUT WEAKENING BY THE OUTSET OF WEEK-2 TRANSLATING TO POSSIBLE EXTREME
HEAT AT THE START OF THE PERIOD. THE MODERATE RISK FOR EXTREME HEAT ACROSS THE
NORTHWEST HAS BEEN DISCONTINUED TODAY DUE TO TIMING OUT BY WEEK-2. A SLIGHT
RISK (20-40% CHANCE) OF EXTREME HEAT IS MAINTAINED FOR PARTS OF THE WEST COAST,
NEVADA, AND SOUTHWEST FOR JUNE 17. THE PROBABILISTIC EXTREMES TOOLS (PETS) SHOW
INCREASED CHANCES FOR TEMPERATURES EXCEEDING THE 85TH PERCENTILE
CLIMATOLOGICALLY AND 90 DEG F ACROSS THE NORTHWEST (100 DEG F ACROSS PARTS OF
CALIFORNIA), FURTHER SUPPORTED BY UNCALIBRATED ENSEMBLES, HEAT TOOLS, AND THE
EXPERIMENTAL WPC HEATRISK TOOL INDICATING SUPPORTING SIGNALS OF MAJOR OR HIGHER
HEATRISK LEVELS.
MEANWHILE, SUBTROPICAL RIDGING IS ANTICIPATED TO STRENGTHEN INITIALLY EXPECTED
ACROSS FLORIDA AT THE BEGINNING OF WEEK-2, EXPANDING TO THE SOUTHEASTERN CONUS
AND THE MID-ATLANTIC BY THE MIDDLE OF THE PERIOD. A WARMING TREND IS PREDICTED
THUS FOR THE SOUTHEASTERN CONUS. A MODERATE RISK (40-60% CHANCE) OF EXTREME
HEAT IS POSTED FOR PARTS OF THE FLORIDA PENINSULA JUNE 17-19, PRIMARILY BASED
ON THE EXPECTED POSITIVE MID-LEVEL HEIGHT DEPARTURES, UNCALIBRATED GUIDANCE AND
HEAT TOOLS SHOWING THE POSSIBILITY OF HEAT INDEX VALUES EXCEEDING 105 DEG F IN
ADDITION TO THE EXPERIMENTAL WPC HEATRISK TOOL SHOWING AREAS HAVING AT LEAST A
40% CHANCE OF EXPERIENCING MAJOR OR GREATER HEAT RISK. A BROADER AREA OF SLIGHT
RISK IS DESIGNATED FOR THE FLORIDA PENINSULA EXTENDING THROUGHOUT WEEK-2. AS
THE SUBTROPICAL RIDGE EXPANDS SO DOES THE RISK OF EXTREME HEAT. A SLIGHT RISK
OF EXTREME HEAT DESIGNATED FOR PARTS OF THE MID-ATLANTIC AND SOUTHEASTERN U.S.
JUNE 19-21 WHERE THE PETS INDICATE AT LEAST A 20% CHANCE OF TEMPERATURES
EXCEEDING THE 85TH PERCENTILE AND 90 DEG F (95 DEG F ACROSS THE CAROLINAS AND
FURTHER SOUTH), WITH THE ECENS SHOWING SOME AREAS HAVING GREATER THAN 30%
CHANCES. HIGHER HEAT INDEX VALUES ARE ANTICIPATED WITH AT LEAST A 20% CHANCE OF
EXCEEDING 100 DEG F IN THE HIGHLIGHTED RISK AREA.
A SERIES OF SURFACE LOWS ACROSS THE WEST AT THE BEGINNING OF WEEK-2 SUPPORTS A
SLIGHT RISK OF PERIODS OF HIGH WINDS FOR THE INTERIOR WEST AND GREAT PLAINS JUN
17-19. ADJACENT SURFACE HIGH PRESSURE OVER THE NORTHEASTERN PACIFIC SUPPORTS A
SLIGHT RISK OF HIGH WINDS ALSO FOR COASTAL PARTS OF SOUTHWESTERN OREGON AND
NORTHERN CALIFORNIA FOR THE SAME PERIOD. THE PETS INDICATE AT LEAST A 20%
CHANCE FOR MANY OF THESE AREAS EXCEEDING THE 85TH PERCENTILE AND UNCALIBRATED
ECENS AND GEFS ENSEMBLES SHOWING ENHANCED PROBABILITIES OF WIND GUSTS EXCEEDING
20MPH (>34 MPH FOR PARTS OF THE WEST COAST). GUSTY WIND SPEEDS MAY ENHANCE
WILDFIRE RISK ESPECIALLY ACROSS PARTS OF THE FOUR CORNERS REGION AND THE
SOUTHWEST, WHERE THE NATIONAL INTERAGENCY FIRE CENTER INDICATES MODERATE RISK
OF SIGNIFICANT FIRE POTENTIAL BY THE END OF WEEK-1 AND WHERE THERE ARE
CURRENTLY ACTIVE FIRES.
AN AMPLIFIED 500-HPA TROUGH CONTINUES TO BE FORECAST OVER THE MIDWEST,
SUPPORTING A SERIES OF SLOW-MOVING SURFACE LOWS AND STALLED FRONTS TRACKING
ACROSS THE CENTRAL AND EASTERN CONUS. RECENT DETERMINISTIC GFS AND ECMWF RUNS
ARE HIGHLIGHTING THE POTENTIAL FOR A ROBUST LOW-PRESSURE SYSTEM TO TRACK INTO
THE GREAT LAKES REGION, WITH CENTRAL PRESSURE VALUES MODELED TO DROP NEAR 980
MB. STRONG SOUTHERLY FLOW INTO THE SOUTH-CENTRAL AND EASTERN CONUS ASSOCIATED
WITH THE AFOREMENTIONED SUBTROPICAL HIGH COULD BRING ENHANCED MOISTURE, FURTHER
SUPPORTING LOCALLY HEAVY RAINFALL, WITH CONDITIONS POSSIBLY BEING CONDUCIVE TO
STRONG THUNDERSTORMS IN SOME OF THE RISK AREAS. THE MODERATE RISK OF HEAVY
PRECIPITATION HAS TIMED OUT AND IS ANTICIPATED TO OCCUR BY THE END OF WEEK-1.
THERE IS MORE UNCERTAINTY OF WHERE THE HEAVIEST RAINFALL WILL OCCUR DURING
WEEK-2. THEREFORE A BROAD AREA IS HIGHLIGHTED WITH A SLIGHT RISK OF HEAVY
PRECIPITATION ACROSS PARTS OF THE SOUTH-CENTRAL AND EASTERN CONUS, JUNE 17-19.
STRONG ONSHORE FLOW MAY ALSO ELEVATE WATER LEVELS ALONG THE GULF COAST IN
ADDITION TO FLASH FLOODING POSSIBLE.
IN ALASKA, RIVER ICE BREAKUP SEASON IS ENDING AND EVEN THE RIVERS ACROSS THE
NORTH SLOPE ARE BEGINNING TO OPEN. RIVER BREAKUP FLOODING CAN OCCUR WITH LITTLE
OR NO NOTICE AS CONDITIONS ON FROZEN RIVERS CAN CHANGE QUICKLY, SO PLEASE CHECK
WITH THE ALASKA PACIFIC RIVER FORECAST CENTER FOR THE LATEST CONDITIONS AND
ADVISORIES.
FORECASTER: MELISSA OU
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