895
FXUS21 KWNC 071933
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 07 2025
SYNOPSIS: A STRONG MID-LEVEL RIDGE OF HIGH PRESSURE PREDICTED OVER THE WESTERN
CONTIGUOUS U.S. (CONUS) FAVORS AN INCREASED RISK OF EXTREME HEAT OVER MUCH OF
THE INTERIOR WEST DURING THE FIRST FEW DAYS OF THE WEEK-2 PERIOD. CONCURRENTLY,
EXTREME HEAT IS ALSO POSSIBLE OVER THE NORTHEAST, EXACERBATED BY HIGH HUMIDITY
LEVELS FAVORED. WITH THE SUBTROPICAL HIGH PRESSURE PREDICTED TO BE CENTERED
NEAR FOUR CORNERS, SHOWER AND THUNDERSTORM ACTIVITY IS LIKELY TO RAMP UP ACROSS
THE DESERT SOUTHWEST DURING THE MIDDLE AND LATTER PORTIONS OF THE FORECAST
PERIOD.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION OVER THE LOWER FOUR CORNERS REGION,
FRI-MON, JUL 18-21.
SLIGHT RISK OF HEAVY PRECIPITATION OVER SOUTHERN AND WESTERN ARIZONA, AND
SOUTHERN NEW MEXICO, AND WESTERN TEXAS THU-MON, JUL 17-21.
SLIGHT RISK OF EXTREME HEAT FOR CALIFORNIA’S CENTRAL VALLEY AND MUCH OF THE
INTERIOR WEST, TUE-THU, JUL 15-17.
SLIGHT RISK OF EXTREME HEAT FOR THE NORTHEAST COASTAL PLAIN, TUE-THU, JUL 15-17.
DETAILED SUMMARY
FOR THURSDAY JULY 10 - MONDAY JULY 14:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JULY 15 - MONDAY JULY 21: A STRONG MID-LEVEL RIDGE ACCOMPANIED BY
MAXIMUM MID-TROPOSPHERIC HEIGHTS NEAR 595 DM AND POSITIVE HEIGHT DEPARTURES IS
FORECAST ACROSS THE WESTERN CONUS EARLY IN WEEK-2 BY THE GEFS, ECENS AND CMCE
ENSEMBLE MODELS. AS A RESULT, A SLIGHT RISK OF EXTREME HEAT IS POSTED FOR MUCH
OF THE INTERIOR WEST, INCLUDING THE CENTRAL VALLEY OF CALIFORNIA, FROM JULY
15-17. ACTUAL AIR TEMPERATURES ARE PREDICTED TO RANGE FROM THE MID 90’S FOR
MOST OF THIS AREA TO NEAR 110 DEG F IN THE DESERT SOUTHWEST. ANOTHER MID-LEVEL
RIDGE IS FORECAST OVER THE NORTHEAST, AND THIS FEATURE SUPPORTS A SLIGHT RISK
OF EXTREME HEAT OVER THE COASTAL PLAIN FROM JULY 15-17. DETERMINISTIC RUNS OF
THE GFS (6Z) AND ECMWF (0Z) PREDICT AIR TEMPERATURES IN THE LOW TO MID 90’S
THROUGHOUT THIS CORRIDOR FROM NEAR PHILADELPHIA NORTHEASTWARD THROUGH EASTERN
MAINE. UNCALIBRATED ECENS DEWPOINT TEMPERATURES OF AT LEAST 70 DEG F ELEVATE
THE HEAT INDEX VALUES INTO THE MID AND UPPER 90’S FOR AT LEAST 2 DAYS, WHICH
SATISFIES THE CRITERIA FOR EXTREME HEAT IN THIS AREA.
IN THE SOUTHWEST, THE CENTER OF THE SUBTROPICAL RIDGE IS FORECAST TO SHIFT
EASTWARD FROM NEAR THE SOUTHERN CALIFORNIA COAST EARLY IN WEEK-2 TO THE FOUR
CORNERS AREA BY THE MIDDLE OF THE PERIOD. THIS PUTS THE RIDGE CENTER IN A
FAVORABLE POSITION FOR INCREASED SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED
WITH THE SUMMER MONSOON. THIS SCENARIO IS CONSISTENT WITH THE EVOLUTION OF THE
WEEK-2 GEFS AND ECENS PRECIPITATION PROBABILISTIC EXTREMES TOOLS (PETS). THE
ECENS IS MORE ROBUST WITH THE MONSOONAL PRECIPITATION THAN THE GEFS IS, WITH
THE ECENS FAVORING A MODERATE RISK OF HEAVY PRECIPITATION OVER WESTERN AND
SOUTHERN ARIZONA, AND SOUTHWESTERN NEW MEXICO, AND FAR WESTERN TEXAS FROM JULY
18-21. THE GEFS SUPPORTS ONLY A SLIGHT RISK, THOUGH BOTH MODELS SHOW INCREASED
CHANCES FOR AT LEAST A HALF-INCH OF PRECIPITATION FOR THE DURATION OF THE
EVENT. IN VIEW OF BOTH MODELS, A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED
FOR A SOMEWHAT BROADER AREA THAN WHAT IS COVERED BY THE MODERATE RISK, JULY
17-21. THE EXPECTED INCREASE IN MONSOON PRECIPITATION ACROSS THE DESERT
SOUTHWEST IS ALSO IN LINE WITH WEEK-2 PRECIPITATION STATISTICAL ANALOGS BASED
ON TODAY'S 500-HPA MANUAL HEIGHT BLEND FOR THE WEEK-2 PERIOD.
WITH 1.5-4.0 INCHES OF RAIN PREDICTED BY WPC IN THE WEEK-1 PERIOD OVER THE
MID-ATLANTIC (RELATED TO POST-TROPICAL CYCLONE CHANTAL), ANY ADDITIONAL
RAINFALL RECEIVED DURING WEEK-2 MAY RESULT IN RENEWED FLOODING. THE POTENTIAL
FOR RENEWED FLOODING WILL ALSO NEED TO BE MONITORED IN TEXAS.
FORECASTER: ANTHONY ARTUSA
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