688
FXUS07 KWBC 311900
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT THU JUL 31 2025
30-DAY OUTLOOK DISCUSSION FOR AUGUST 2025
THE AUGUST 2025 MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS ARE UPDATED
CONSIDERING INPUT FROM THE CLIMATE PREDICTION CENTER (CPC) EXTENDED RANGE AND
SUBSEASONAL OUTLOOKS. DYNAMICAL MODEL GUIDANCE FROM GEFSV12, ECMWF, AND CFSV2
FOR THE 6-10 DAY, WEEK 2, AND WEEKS 3-4 PERIODS, ALONG WITH BACKGROUND CLIMATE
STATES SUCH AS THE MADDEN JULIAN OSCILLATION (MJO) ALSO INFORM THIS FORECAST,
AS DO RECENT MONTHLY CFSV2 FORECASTS OF TEMPERATURE AND PRECIPITATION, AND
EXPERIMENTAL MONTHLY FORECASTS OF TEMPERATURE AND PRECIPITATION FROM EXTENDED
RUNS OF THE GEFS AND ECMWF MODELS. WITH EL NIñO SOUTHERN OSCILLATION (ENSO)
NEUTRAL CONDITIONS PRESENT, ENSO IS NOT EXPECTED TO IMPACT THIS FORECAST.
THE MJO HAS REMAINED COHERENT SINCE MID-JULY WITH THE ENHANCED CONVECTIVE PHASE
PROPAGATING EASTWARD. RECENT FORECASTS OF THE REALTIME MULTIVARIATE MJO (RMM)
INDEX INTO THE BEGINNING OF AUGUST FROM GEFSV12 AND ECMWF GENERALLY FAVOR A
CONTINUATION OF THIS EASTWARD PROPAGATION. HOWEVER, THE ULTIMATE STRENGTH AND
COHERENCE OF THE MJO IS UNCERTAIN DUE TO COMPETING MODES OF TROPICAL
VARIABILITY THAT MAY INTERFERE WITH THE MJO SIGNAL LATER IN AUGUST. AS SUCH,
MJO WAS CONSIDERED FOR THESE UPDATED FORECASTS, BUT WEIGHTED LESS GIVEN THE
UNCERTAINTY. BEYOND DYNAMICAL MODELS, SHORTER RANGE OUTLOOKS, AND POTENTIAL
IMPACTS FROM THE MJO, SOIL MOISTURE IS BELOW AVERAGE OVER THE WESTERN THIRD OF
THE CONTIGUOUS UNITED STATES (CONUS), WITH POCKETS OF ABOVE AVERAGE SOIL
MOISTURE OVER THE EASTERN HALF. BELOW-AVERAGE SOIL MOISTURE CAN SUPPORT
ABOVE-NORMAL TEMPERATURES AND BELOW-NORMAL PRECIPITATION, AND VICE VERSA, WHICH
HELPS REDUCE UNCERTAINTY IN SOME REGIONS. FURTHERMORE, COASTAL SEA SURFACE
TEMPERATURE ANOMALIES CAN LOCALLY IMPACT TEMPERATURES; THEY ARE CURRENTLY ABOVE
AVERAGE IN THE GULF AND ALONG THE EAST COAST, AND NEUTRAL TO MIXED BELOW AND
ABOVE AVERAGE ALONG THE WEST COAST.
SHORT TERM FORECASTS FOR THE 6-10 DAY PERIOD FAVOR A MID-LEVEL TROUGH OVER THE
EASTERN BEARING SEA AND ALEUTIANS, WEAK MID-LEVEL TROUGHING OVER NORTHWESTERN
AND PORTIONS OF THE EASTERN CONUS. POSITIVE 500 HPA ANOMALIES INCREASE TOWARD
THE GREAT LAKES AND NORTHEAST ASSOCIATED WITH A BROAD RIDGE OVER EASTERN
CANADA. THE ANOMALOUS RIDGE OVER THE SOUTHWEST IS FORECAST TO PEAK IN STRENGTH
ON AUGUST 7 WHEN THE GEFS AND ECENS DEPICT 500-HPA HEIGHTS NEAR 600 DM. IN THE
8-14 DAY PERIOD RIDGING BUILDS OVER THE WESTERN BEARING SEA, AND THERE IS A
SLIGHT EASTWARD PROGRESSION OF THE TROUGH OVER THE ALEUTIANS, AND ABOVE-NORMAL
HEIGHTS ARE FORECAST OVER MUCH OF THE CONUS. MOVING INTO THE WEEKS 3-4 PERIOD
(MID-TO- LATE AUGUST), DYNAMICAL MODEL GUIDANCE AGREES ON BROAD RIDGING OVER
THE NORTHERN CONUS, WITH NEUTRAL HEIGHTS OVER MUCH OF THE SOUTHERN TIER AND
FROM THE LOWER MISSISSIPPI VALLEY TO JUST SOUTH OF THE GREAT LAKES AND
SOUTHEAST. HEIGHT PATTERNS ARE UNCERTAIN OVER ALASKA IN WEEKS 3-4 FORECASTS,
WITH ECMWF FAVORING TROUGHING OVER MUCH OF THE STATE, WHILE CFSV2 AND GEFSV12
LEAN TOWARD RIDGING OR NEUTRAL HEIGHTS. OVERALL THIS HEIGHT PATTERN LEADS TO
MORE CERTAINTY IN ABOVE-NORMAL TEMPERATURES OVER THE WESTERN CONUS, WITH
UNCERTAINTY OVER PARTS OF THE INTERIOR EAST AND ALASKA.
THE UPDATED MONTHLY TEMPERATURE OUTLOOK HAS SOME COMPLEXITIES DUE TO
UNCERTAINTY IN THE LATER HALF OF AUGUST. ABOVE-NORMAL TEMPERATURES ARE FAVORED
OVER MUCH OF THE WESTERN CONUS, THE NORTHERN PLAINS AND GREAT LAKES, AND
SOUTHEAST AND EAST COASTS. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE
INCREASED OVER NEW ENGLAND AND FLORIDA, WHERE LOCAL SSTS ARE ABOVE AVERAGE AND
MODELS SHOW STRONG AGREEMENT. THE HIGHEST PROBABILITIES, REACHING 60 TO 70%,
ARE FOUND OVER THE SOUTHWEST DUE TO STRONG MODEL AGREEMENT, BELOW-NORMAL SOIL
MOISTURE, AND A FORECAST OF BELOW-NORMAL PRECIPITATION. THIS IS A SOUTHWARD
SHIFT IN THE AREA OF STRONGEST PROBABILITIES FROM THE INITIAL MONTHLY OUTLOOK,
DRIVEN BY THE POTENTIAL FOR BRIEF BELOW-NORMAL TEMPERATURES IN EARLY AUGUST
OVER PARTS OF THE NORTHWEST, WHICH SLIGHTLY REDUCES OVERALL CERTAINTY BUT IS
NOT EXPECTED TO PREVENT THE MONTH FROM BEING ABOVE-NORMAL. THERE IS ALSO A RISK
OF POSSIBLY SHORT LIVED BUT EXTREME HEAT OVER SOUTHWESTERN ARIZONA IN EARLY
AUGUST FURTHER SUPPORTING THE INCREASE IN ABOVE-NORMAL TEMPERATURE
PROBABILITIES (VISIT CPC’S 8-14 DAY U.S. HAZARDS OUTLOOK FOR MORE INFORMATION).
HOWEVER, SOME SHORT LIVED COOLER PERIODS MAY OCCUR LATER IN AUGUST FOR THIS
REGION IF GULF OF CALIFORNIA MOISTURE SURGES BRING UNSETTLED CONDITIONS, THOUGH
THIS IS UNLIKELY TO SHIFT THE ENTIRE MONTH AWAY FROM ABOVE-NORMAL TEMPERATURES.
OVER ALASKA, RIDGING IN THE EARLY PART OF AUGUST SUPPORTS A TILT TOWARD
ABOVE-NORMAL TEMPERATURES, HOWEVER, THE MIXED HEIGHT PATTERN FORECASTS OVER
ALASKA AS WE ENTER LATER PARTS OF THE MONTH, PARTICULARLY DUE TO THE ECMWF
WHICH FAVORS TROUGHING AND BELOW-NORMAL TEMPERATURES, ADDS TO UNCERTAINTY AND
CAUSES SOME CHANGES FROM THE MID-MONTH OUTLOOK. ONLY THE SOUTHERN AND CENTRAL
PARTS OF ALASKA ARE FAVORED TO BE ABOVE-NORMAL, WITH EQUAL CHANCES OF ABOVE-,
NEAR-, AND BELOW- NORMAL (EC) TEMPERATURES OVER THE CENTRAL PARTS OF THE STATE,
AND A WEAK TILT TOWARD BELOW-NORMAL TEMPERATURES OVER THE NORTH DUE TO LATE
AUGUST FORECASTS FROM ECMWF. EC IS ALSO INDICATED OVER THE CALIFORNIA COAST,
WHERE NEUTRAL TO COOLER THAN NORMAL SSTS AND THE POSSIBILITY OF SEABREEZES MAY
LEAD TO COOLER TEMPERATURES, AND DYNAMICAL MODEL FORECASTS FEATURE WEAKER
PROBABILITIES. A LARGE AREA OF EC IS ALSO INDICATED OVER THE MIDWEST STRETCHING
TO THE GULF COAST, WHICH IS SLIGHTLY MODIFIED COMPARED TO THE INITIAL MONTHLY
OUTLOOK. WHILE THE BEGINNING OF AUGUST MIGHT BE ABOVE-NORMAL FOR MUCH OF THIS
REGION, THERE IS CONSIDERABLE UNCERTAINTY IN THE LATTER PART OF THE MONTH GIVEN
THE WEAK HEIGHT PATTERN AND POTENTIAL FOR COOLER TEMPERATURES FROM THE MJO.
FOR THE UPDATED MONTHLY PRECIPITATION OUTLOOK, A KEY CHANGE FROM THE INITIAL
OUTLOOK IS THE SOUTHWARD SHIFT OF BELOW-NORMAL PRECIPITATION, NOW FEATURED OVER
THE SOUTHWEST AND CENTRAL GREAT BASIN. DRIER THAN AVERAGE SOILS, ABOVE-NORMAL
TEMPERATURES, AND MODEL AGREEMENT SUPPORT THIS CHANGE. EARLY AUGUST
PRECIPITATION FORECASTS FAVOR POTENTIAL FOR ABOVE-NORMAL PRECIPITATION OVER THE
NORTHERN TIER OF THE CONUS, WHICH LEADS TO A CHANGE TO EC OVER THIS REGION.
THOUGH MODELS TITLED TOWARD BELOW-NORMAL OVER SOUTHWESTERN ARIZONA, EC IS
FAVORED GIVEN THE POSSIBILITY OF AN ENHANCED MONSOON RESUMING LATER IN THE
MONTH. SIMILARLY, WHILE PRECIPITATION CLIMATOLOGY IS LOW OVER THE WEST COAST
THERE MAY BE BURSTS OF MOISTURE INTO THE REGION THAT CAN CAUSE STORMINESS AND
UNSETTLED CONDITIONS, BUT ARE LIKELY NOT ENOUGH TO TILT THE PROBABILITY TOWARD
ABOVE-NORMAL. THE FORECAST FOR ABOVE-NORMAL PRECIPITATION OVER THE SOUTHEAST
AND PARTS OF THE MID-ATLANTIC AND MID-SOUTH IS MAINTAINED FROM THE PRIOR
VERSION, WITH ONLY MINOR ADJUSTMENTS BASED ON UPDATED TOOLS, AS THE CHANCES OF
ABOVE-NORMAL PRECIPITATION REMAINED CONSISTENT ACROSS FORECASTS AND MODELS. THE
PRECIPITATION PATTERN OVER ALASKA WAS MORE UNCERTAIN IN THE INITIAL MONTHLY
OUTLOOK, WITH THE FORECAST MAINLY BASED ON ABOVE-NORMAL PRECIPITATION TRENDS
AND NMME. MODELS WERE SURPRISINGLY CONSISTENT THROUGHOUT FORECASTS FOR EARLY
AUGUST, THE WEEKS 3-4 PERIOD, AND IN MONTHLY FORECASTS OVER ALASKA DESPITE THE
UNCERTAINTY IN THE HEIGHT PATTERN MENTIONED ABOVE. GIVEN THE MODEL FORECASTS,
BELOW-NORMAL PRECIPITATION IS FAVORED OVER THE WESTERN COAST, AND ABOVE-NORMAL
PRECIPITATION OVER THE SOUTHEAST. ELSEWHERE OVER THE CONUS EC IS BROADLY
INDICATED, AS MODELS WERE MIXED OR INCONSISTENT.
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***** PREVIOUS MID-MONTH DISCUSSION BELOW *****
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EL NIñO SOUTHERN OSCILLATION (ENSO) NEUTRAL CONDITIONS ARE PRESENT WITH SEA
SURFACE TEMPERATURES (SSTS) NEAR AVERAGE ACROSS MOST OF THE EQUATORIAL PACIFIC
OCEAN. RECENT FORECASTS FROM DYNAMICAL MODELS INCLUDING GEFSV12 AND ECMWF
INDICATE THE POSSIBILITY OF A ROBUST MADDEN JULIAN OSCILLATION (MJO) EMERGING
ACROSS THE WESTERN PACIFIC IN MID-TO LATE- JULY. THE AUGUST 2025 TEMPERATURE
AND PRECIPITATION OUTLOOKS ARE BASED ON A COMBINATION OF DYNAMICAL MODELS,
INCLUDING CFSV2, THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME), THE COPERNICUS
CLIMATE SYSTEM (C3S), DYNAMICAL MODELS AND STATISTICAL TOOLS FOR THE WEEKS 3-4
PERIOD WHICH COVER THE EARLY PART OF AUGUST, AND POTENTIAL IMPACTS FROM THE
EMERGING MJO. LOCAL SSTS AND ANTECEDENT SOIL MOISTURE ANOMALIES ALSO
CONTRIBUTED TO THIS OUTLOOK WHERE APPLICABLE. MJO IMPACTS ARE WEIGHTED
COMPARATIVELY LESS AS THERE IS STILL SOME UNCERTAINTY ON HOW THE MJO MAY
PROGRESS INTO AUGUST. IMPACTS FROM THE MJO WILL BE RE-EVALUATED AT THE END OF
THE MONTH FOR THE UPDATED VERSION OF THIS OUTLOOK.
THE AUGUST 2025 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES ACROSS
MUCH OF THE CONTIGUOUS UNITED STATES (CONUS). THE REGION OF HIGHEST
PROBABILITIES (REACHING 60 TO 70%) IS LOCATED OVER THE NORTHWESTERN QUADRANT OF
THE CONUS. PROBABILITIES ARE INCREASED IN THIS REGION GIVEN HIGHER
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES IN ALMOST ALL AVAILABLE TOOLS,
INCLUDING THE NMME, THE C3S, CFSV2, POSITIVE DECADAL TEMPERATURE TRENDS, AND
BELOW-NORMAL SOIL MOISTURE. WHILE TOOLS ALSO AGREE ON PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURE OVER THE EAST COAST, PROBABILITIES ARE WEAKER
RESPECTIVELY. STRONGER POSITIVE DECADAL TEMPERATURE TRENDS OVER NEW ENGLAND AND
FLORIDA, ALONG WITH ABOVE-NORMAL SSTS, LEAD TO A WEAK TILT TOWARD ABOVE-NORMAL
(40 TO 50%) TEMPERATURES. THERE IS LESS SUPPORT FROM TRENDS OVER PORTIONS OF
THE SOUTHEAST AND MID-ATLANTIC AND PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION
THAT MAY MODERATE TEMPERATURES, THUS PROBABILITIES ARE DECREASED TO 33 TO 40%
OVER THE AREA. WEAKER BUT STILL INCREASED PROBABILITIES (33 TO 40%) FOR
ABOVE-NORMAL TEMPERATURES ARE ALSO INDICATED OVER THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY REGIONS. WHILE THIS ABOVE-NORMAL TILT IS SUPPORTED BY
DECADAL TRENDS AS WELL AS FORECAST BELOW-NORMAL PRECIPITATION, MOST TOOLS HAD
WEAKER PROBABILITIES OVER THIS REGION, LEADING TO COMPARATIVELY MORE
UNCERTAINTY. OVER ALASKA, MOST TOOLS SHOWED MIXED FORECASTS, PARTICULARLY OVER
THE CENTRAL PARTS OF THE STATE WHERE EQUAL CHANCES (EC) OF ABOVE-, NEAR-, AND
BELOW-NORMAL TEMPERATURES ARE FAVORED. POSITIVE DECADAL TEMPERATURE TRENDS,
CFSV2, AND C3S SUPPORT A WEAK TILT TOWARD ABOVE-NORMAL TEMPERATURE
PROBABILITIES OVER THE NORTHERN COAST AND EASTERN PARTS OF ALASKA, WHILE
NEAR-NORMAL PROBABILITIES ARE FAVORED OVER THE WEST, ALSO SUPPORTED BY C3S. AN
AREA OF EC IS LOCATED OVER PARTS OF THE GULF COAST, STRETCHING NORTHWARD INTO
PARTS OF THE SOUTHERN AND CENTRAL PLAINS, MIDDLE AND LOWER MISSISSIPPI VALLEY,
AND OHIO AND TENNESSEE VALLEY REGIONS. IN ADDITION TO LOWER PROBABILITIES IN
MOST MONTHLY TOOLS, THERE IS A POSSIBILITY OF COOLER TEMPERATURES OVER THIS
REGION GIVEN THE EMERGING MJO AS WELL AS THE PRESENCE OF ABOVE-NORMAL SOIL
MOISTURE WHICH MAY WORK TO MODERATE TEMPERATURES AND DECREASE CONFIDENCE. EC IS
ALSO INDICATED OVER SOUTHERN PARTS OF THE WEST COAST, WHERE COOLER THAN NORMAL
SSTS AND THE POSSIBILITY OF SEABREEZES MAY LEAD TO COOLER TEMPERATURES.
THERE IS MORE UNCERTAINTY AND DISAGREEMENT IN TOOLS SUPPORTING THE AUGUST 2025
PRECIPITATION OUTLOOK, THUS THE PRECIPITATION OUTLOOK HAS MORE EXTENSIVE AREAS
OF EC. A TILT TOWARD BELOW-NORMAL PRECIPITATION IS INDICATED FROM THE NORTHWEST
COAST TO THE UPPER MISSISSIPPI VALLEY, THOUGH PROBABILITIES ARE SOMEWHAT LOW
(33 TO 40%) FOR MUCH OF THIS REGION GIVEN SOME INCONSISTENCIES IN TOOLS.
PROBABILITIES REACH 40 TO 50% WHERE THERE WAS AGREEMENT BETWEEN THE C3S AND
NMME. TOOLS HAD BETTER AGREEMENT ON THE CHANCE OF ABOVE-NORMAL PRECIPITATION
OVER THE SOUTHEASTERN CORNER OF THE CONUS AND PARTS OF THE MID-ATLANTIC, WHICH
IS ADDITIONALLY SUPPORTED BY ABOVE-NORMAL SOIL MOISTURE (TOWARD THE WESTERN
PARTS OF THIS REGION), AND CHANCES OF STORMINESS AND UNSETTLED CONDITIONS
LEADING TO POSSIBILITY OF INCREASED PRECIPITATION. ABOVE-NORMAL PRECIPITATION
IS ALSO WEAKLY FAVORED OVER WESTERN ALASKA, OWING TO ABOVE-NORMAL PRECIPITATION
TREND, AND STRETCHING ACROSS CENTRAL ALASKA TO THE EAST COAST, WHERE NMME
MODELS HAD A MODEST TILT TOWARD ABOVE-NORMAL PRECIPITATION.
FORECASTER: JOHNNA INFANTI
THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1991 AND 2020, FOLLOWING
THE WORLD METEOROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3
COMPLETE DECADES AS THE CLIMATE REFERENCE PERIOD. THE PROBABILITY ANOMALIES
FOR TEMPERATURE AND PRECIPITATION BASED ON THESE NEW NORMALS BETTER REPRESENT
SHORTER TERM CLIMATIC ANOMALIES THAN THE FORECASTS BASED ON OLDER NORMALS.
THE NEXT MONTHLY OUTLOOK...FOR SEP ... WILL BE ISSUED ON THU AUG 21 2025
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.
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