615
FXUS21 KWNC 121903
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 12 2025
SYNOPSIS: MULTIPLE MODELS INDICATE MID-LEVEL HIGH PRESSURE OVER THE INTERIOR
WESTERN CONTIGUOUS U.S. (CONUS) DURING WEEK-2. THIS PATTERN SUPPORTS INCREASED
CHANCES FOR EXTREME HEAT ACROSS THIS BROAD REGION. THERMAL LOW PRESSURE NEAR
THE ARIZONA-CALIFORNIA BORDER COMBINED WITH SURFACE HIGH PRESSURE OFF THE WEST
COAST MAY LEAD TO A TIGHT PRESSURE GRADIENT ACROSS COASTAL CALIFORNIA RESULTING
IN INCREASED CHANCES FOR HIGH WINDS ACROSS THE REGION. TROPICAL STORM ERIN,
CURRENTLY (AUG 12) LOCATED OVER THE CENTRAL LOW-LATITUDE ATLANTIC, IS PREDICTED
TO MOVE WEST AND IS FORECAST BY THE NATIONAL HURRICANE CENTER TO BE NORTH OF
THE LESSER ANTILLES JUST PRIOR TO THE START OF WEEK-2. SOME MODEL GUIDANCE
INDICATES THAT ERIN MAY APPROACH THE EASTERN SEABOARD AND COULD BRING HAZARDOUS
WIND AND PRECIPITATION TO THE REGION. HOWEVER, UNCERTAINTY REMAINS HIGH WITH
THE EVENTUAL TRACK OF THIS TROPICAL SYSTEM.
HAZARDS
MODERATE RISK OF EXTREME HEAT FOR PARTS OF THE GREAT BASIN, SOUTHWEST, AND
CENTRAL AND SOUTHERN ROCKIES, WED-THU, AUG 20-21.
SLIGHT RISK OF EXTREME HEAT FOR MANY PARTS OF THE INTERIOR WEST, WED-TUE, AUG
20-26.
SLIGHT RISK OF EXTREME HEAT FOR THE CALIFORNIA CENTRAL VALLEY, THU-MON, AUG
21-25.
SLIGHT RISK OF HEAVY PRECIPITATION NEAR THE CAROLINA COAST, WED-SAT, AUG 20-23.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR COASTAL PORTIONS OF MOST OF THE EAST
COAST, WED-SAT, AUG 20-23.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR COASTAL PORTIONS OF CALIFORNIA, WED-SAT,
AUG 20-23.
DETAILED SUMMARY
FOR FRIDAY AUGUST 15 - TUESDAY AUGUST 19:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY AUGUST 20 - TUESDAY AUGUST 26: THE 0Z GEFS, ECENS, AND CANADIAN
ENSEMBLE MEANS PREDICT AMPLIFIED MID-LEVEL RIDGING OVER THE WEST-CENTRAL CONUS
AT THE BEGINNING OF WEEK-2, WITH MAXIMUM 500-HPA HEIGHTS NEAR 595 DM CENTERED
NEAR THE FOUR CORNERS. THIS PATTERN SUPPORTS THE INCREASED LIKELIHOOD OF
EXTREME HEAT OVER THE INTERIOR WEST. A MODERATE RISK (40-60% CHANCE) OF EXTREME
HEAT IS POSTED FOR PARTS OF THE GREAT BASIN, SOUTHWEST, AND CENTRAL AND
SOUTHERN ROCKIES, AUG 20-21. MULTIPLE PROBABILISTIC EXTREMES TOOLS (PETS) SHOW
AT LEAST A 40% CHANCE OF TEMPERATURES EXCEEDING THE 85TH PERCENTILE
CLIMATOLOGICALLY, WITH VALUES EXCEEDING 95 DEG F ACROSS THE DESIGNATED RISK
AREA (GREATER THAN 110 DEG F ACROSS THE DESERT SOUTHWEST). A BROADER AREA IS
HIGHLIGHTED WITH A SLIGHT RISK FOR MUCH OF THE INTERIOR WEST THROUGHOUT WEEK-2.
A SLIGHT RISK OF EXTREME HEAT IS ALSO INDICATED OVER THE CALIFORNIA CENTRAL
VALLEY (RANGING FROM ABOUT 100 DEG F IN THE NORTH TO 105+ DEG F IN THE SOUTH),
FROM AUG 21-25. THOUGH THESE TEMPERATURES ACROSS THE WEST WILL BE HOT, THE
NATIONAL BLEND OF MODELS (NBM) DOES NOT INDICATE ANY RECORD BREAKING DAYTIME
TEMPERATURES, BUT A FEW OVERNIGHT RECORDS MAY BE APPROACHED OR BROKEN.
ANTICIPATED DRY, HOT CONDITIONS AND POTENTIALLY GUSTY WINDS MAY SUPPORT
INCREASED WILDFIRE RISK. THE NATIONAL INTERAGENCY FIRE CENTER (NIFC) INDICATES
MODERATE RISK FOR SIGNIFICANT FIRE POTENTIAL AT THE END OF WEEK-1 AND THERE ARE
CURRENTLY ACTIVE WILDFIRES ACROSS THE INTERIOR WEST
(HTTPS://FSAPPS.NWCG.GOV/PSP/NPSG/FORECAST/HOME/STATICMAPS).
AS OF 2PM EDT, THE NATIONAL HURRICANE CENTER SHOWS TROPICAL STORM ERIN OVER THE
LOW-LATITUDES OF THE CENTRAL ATLANTIC. MULTIPLE MODEL ENSEMBLES FORECAST THIS
STORM TO CONTINUE TRACKING WESTWARD, REACHING THE VICINITY OF THE BAHAMAS BY
THE END OF WEEK-1. BY THEN, UNCERTAINTY REGARDING THE FUTURE TRACK AND
INTENSITY OF ERIN BECOMES RATHER LARGE, WITH A MID-LEVEL TROUGH PREDICTED NEAR
THE MID-ATLANTIC COAST AND A SECONDARY SHORTWAVE TROUGH EXPECTED TO DIG
SOUTHWARD ON ITS WESTERN SIDE. SOME AMPLIFICATION OF THE MID-ATLANTIC TROUGH IS
PREDICTED, WHICH WOULD HELP TO KEEP THE BULK OF ERIN’S ENHANCED WIND AND
PRECIPITATION FIELDS OFFSHORE. HOWEVER, EVEN IF THIS DOES OCCUR, THE CAROLINAS
CAN STILL EXPECT TO SEE AN EXTENDED PERIOD OF CLOUDINESS, PRECIPITATION, GUSTY
WINDS, HIGH SURF, AND DANGEROUS RIP CURRENTS. FOR NOW, THERE IS A SLIGHT RISK
OF HEAVY PRECIPITATION, MODEL GUIDANCE CURRENTLY INDICATES AROUND AN INCH OF
PRECIPITATION, POSTED ALONG THE CAROLINA COAST FROM AUG 20-23, AND A SLIGHT
RISK OF HIGH WINDS (25 MPH+) POSTED FOR MOST OF THE ATLANTIC COAST DURING THE
SAME PERIOD. RESIDENTS LIVING NEAR THE ATLANTIC COAST ARE ENCOURAGED TO KEEP
UPDATED WITH THE LATEST INFORMATION COMING FROM THE NATIONAL HURRICANE CENTER
AND LOCAL FORECAST OFFICES.
THERMAL LOW PRESSURE NEAR THE CALIFORNIA-ARIZONA BORDER COMBINED WITH SURFACE
HIGH PRESSURE OFF THE WEST COAST MAY LEAD TO A TIGHT PRESSURE GRADIENT OVER THE
COAST OF CALIFORNIA. THIS PATTERN SUPPORTS A SLIGHT RISK OF PERIODIC HIGH WINDS
FOR PORTIONS OF COASTAL CALIFORNIA, AUG 20-23. THE ECENS AND GEFS PETS INDICATE
AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND 25 MPH.
POSITIVE MID-LEVEL HEIGHT DEPARTURES ARE ANTICIPATED FOR THE MEAN WEEK-2
PATTERN FOR ALASKA, FAVORING ABOVE NORMAL TEMPERATURES ACROSS MOST AREAS SOUTH
OF THE BROOKS RANGE. NO HAZARDS ARE ANTICIPATED FOR ALASKA AT THIS TIME.
FORECASTER: ANTHONY ARTUSA
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