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FXUS21 KWNC 081748
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 08 2025
SYNOPSIS: MID-LEVEL HIGH PRESSURE, INITIALLY OVER THE NORTHEAST, IS FORECAST TO
SHIFT WESTWARD TO THE NORTH-CENTRAL CONTIGUOUS U.S. (CONUS) EARLY IN WEEK-2.
ALTHOUGH 7-DAY TEMPERATURES (AUGUST 16-22) ARE FAVORED TO BE AVERAGE
ABOVE-NORMAL FOR MUCH OF THE LOWER 48 STATES, CHANCES FOR ANY WIDESPREAD MAJOR
HEAT WAVES BEGIN TO DIMINISH HEADING INTO THE LATTER HALF OF THE MONTH. AN
ENHANCED MONSOON IS EXPECTED ACROSS THE DESERT SOUTHWEST FROM AUGUST 16 TO 18.
THE TROPICS IN THE ATLANTIC BASIN ARE BECOMING MORE ACTIVE FOR TROPICAL CYCLONE
DEVELOPMENT AND WILL BE CLOSELY MONITORED IN THE WEEKS AHEAD.
HAZARDS
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE CENTRAL U.S., SAT-MON, AUG 16-18.
SLIGHT RISK OF EXTREME HEAT FOR PARTS OF THE NORTHEAST U.S., SAT-SUN, AUG 16-17.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE NORTHERN GREAT PLAINS AND
UPPER MISSISSIPPI VALLEY, SAT-SUN, AUG 16-17.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE DESERT SOUTHWEST,
SAT-MON, AUG 16-18.
DETAILED SUMMARY
FOR MONDAY AUGUST 11 - FRIDAY AUGUST 15:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY AUGUST 16 - FRIDAY AUGUST 22: THE GEFS AND ECENS ARE IN GOOD
AGREEMENT, INDICATING ANOMALOUS 500-HPA RIDGING BECOMING CENTERED OVER THE
NORTH-CENTRAL CONUS DURING WEEK-2. THESE ENSEMBLE MEANS DEPICT 500-HPA HEIGHTS
RANGING FROM 588 TO 594 DM ACROSS THE CENTRAL TO SOUTHERN GREAT PLAINS AND
MIDDLE TO LOWER MISSISSIPPI VALLEY, WHICH ELEVATES THE RISK OF EXTREME HEAT.
ALTHOUGH MODEL AGREEMENT IS NOT AS STRONG AS YESTERDAY, A SLIGHT RISK OF
EXTREME HEAT (AUGUST 16-18) REMAINS POSTED FOR PARTS OF THE GREAT PLAINS EAST
TO THE MISSISSIPPI VALLEY. THE ECMWF HAS BACKED OFF THE SEVERITY OF MAXIMUM
TEMPERATURES RELATIVE TO YESTERDAY, WHILE THE GEFS HAS BECOME MORE BULLISH,
RESULTING IN BOTH MODELS INDICATING AT LEAST A 20 PERCENT CHANCE OF HEAT INDEX
VALUES EXCEEDING 100 (105) DEGREES F FOR THE HUMID AREAS OF SOUTH DAKOTA AND
NEBRASKA (KANSAS, OKLAHOMA, ARKANSAS, AND MISSOURI) OVER THE LAST TWO DAYS.
ABOVE-NORMAL TEMPERATURES ARE FAVORED TO CONTINUE ACROSS THE NORTHEAST AND
MID-ATLANTIC THROUGHOUT WEEK-2, AND BOTH THE ECMWF AND GEFS HAVE BECOME MORE
BULLISH WITH REGARDS TO THE POTENTIAL FOR TEMPERATURES EXCEEDING HAZARDOUS
CRITERIA. TODAY’S SOLUTIONS INDICATE WIDESPREAD CHANCES OF DAYTIME TEMPERATURES
EXCEEDING 85F FOR MUCH OF THE NORTHEAST U.S. FOR DAYS 8-9 (AUG 16-17),
WARRANTING A SLIGHT RISK OF EXTREME HEAT FOR MOST OF NEW ENGLAND.
HEADING INTO WEEK-2, THE ECENS FAVORS A SHORTWAVE TROUGH PROGRESSING OVER THE
TOP THE BUILDING RIDGE ACROSS THE NORTH-CENTRAL CONUS. ALTHOUGH TIMING OF
INDIVIDUAL SHORTWAVE TROUGHS IS HIGHLY UNCERTAIN AT THIS TIME LEAD, PATTERN
RECOGNITION AND THE UNCALIBRATED ECENS PROBABILITIES FOR MORE THAN ONE INCH OF
PRECIPITATION SUPPORT A SLIGHT RISK OF HEAVY PRECIPITATION ACROSS THE EASTERN
DAKOTAS AND UPPER MISSISSIPPI VALLEY FROM AUG 16-17. GIVEN THE ANTECEDENT
WETNESS FOR MUCH OF THOSE AREAS, ANY HEAVY RAINFALL COULD LEAD TO FLASH
FLOODING.
AS THE 500-HPA RIDGE AXIS SHIFTS NORTH TOWARDS THE FOUR CORNERS REGION, AN
ENHANCED MONSOON IS EXPECTED TO RESUME ACROSS THE SOUTHWEST BY WEEK-2, WHICH IS
CONSISTENT WITH DAYS FOLLOWING A HEAT WAVE. BASED ON THE GEFS PROBABILISTIC
EXTREMES TOOL (AT LEAST A 20 PERCENT CHANCE OF 3-DAY AMOUNTS EXCEEDING THE 85TH
PERCENTILE AND 0.5 INCHES), A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR
THIS REGION FOR AUG 16-18. THIS RISK DIMINISHES QUICKLY AS RIDGING OVER THE
SOUTHWESTERN CONUS IS FAVORED TO BECOME MORE AMPLIFIED, WHICH WOULD SUPPRESS
CONVECTION. ANY HEAVY RAINFALL IN A SHORT PERIOD OF TIME COULD TRIGGER FLASH
FLOODING WITH BURN SCAR AREAS BEING THE MOST VULNERABLE.
THE NATIONAL HURRICANE CENTER IS MONITORING A TROPICAL WAVE ACROSS THE EASTERN
ATLANTIC AND STATES THAT THIS WAVE HAS A 40 PERCENT CHANCE OF TROPICAL CYCLONE
(TC) DEVELOPMENT (AS OF 2PM EDT ON AUG 8) DURING THE NEXT WEEK. MODEL CONSENSUS
FAVORS THIS POTENTIAL TC EVENTUALLY TURNING NORTH AND REMAINING WEAK. WITH THE
MADDEN-JULIAN OSCILLATION (MJO) FORECAST TO PROPAGATE EAST TO THE INDIAN OCEAN
DURING THE NEXT TWO WEEKS, THE LARGE-SCALE ENVIRONMENT IS EXPECTED TO REMAIN
FAVORABLE FOR TC GENESIS ACROSS THE MAIN DEVELOPMENT REGION (MDR) OF THE
TROPICAL ATLANTIC. THE LATEST MODEL RUNS ARE KEYING ON ANOTHER TROPICAL WAVE
ENTERING THE EASTERN ATLANTIC AND MANY GEFS AND ECENS FAVOR THIS BECOMING A TC
LATER NEXT WEEK ACROSS THE MDR. FUTURE MODEL RUNS WILL BE CLOSELY MONITORED.
FORECASTER: DANNY BARANDIARAN
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