310
FXUS07 KWBC 201231
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU AUG 20 2026
30-DAY OUTLOOK DISCUSSION FOR SEP 2026
EL NIñO CONDITIONS IN BOTH THE OCEAN AND ATMOSPHERE HAVE CONTINUED TO
STRENGTHEN ENTERING MID-AUGUST 2026. SEA SURFACE TEMPERATURES (SSTS) ARE NEAR
OR GREATER THAN +3 DEGREES C IN THE EQUATORIAL EASTERN PACIFIC AND THE LATEST
WEEKLY NINO3.4 SST INDEX VALUE IS +1.8 DEGREES C. A VAST RESERVOIR OF
ABOVE-NORMAL OCEAN TEMPERATURES EXISTS ALONG THE EQUATOR FROM THE DATE LINE
EASTWARD TO THE SOUTH AMERICA COAST TO A DEPTH OF 200 METERS. THE ATMOSPHERIC
RESPONSE TO THESE OCEAN CHARACTERISTICS HAS BEEN QUITE STRONG, NAMELY ENHANCED
CONVECTION OVER THE CENTRAL AND EASTERN PACIFIC, STRONGLY REDUCED TRADE WINDS
AND UPPER-LEVEL ANTICYCLONIC CIRCULATIONS SYMMETRIC ABOUT THE EQUATOR.
RESPONSE TO THE EL NIñO CONDITIONS IS THE PRIMARY DRIVER OF ANOMALOUS
UPPER-LEVEL DIVERGENCE, CONVECTION AND WINDS IN THE GLOBAL TROPICS. ANY
MADDEN-JULIAN OSCILLATION (MJO) RELATED FORCING IS MINOR IN THIS CONTEXT AND
GIVEN THE TIME OF THE YEAR. BELOW-NORMAL SURFACE MOISTURE CONDITIONS ENCOMPASS
MUCH OF THE CONTIGUOUS UNITED STATES (CONUS) WITH SEVERE, EXTREME AND
EXCEPTIONAL DROUGHT CONDITIONS AS DEFINED BY THE U.S. DROUGHT MONITOR COVERING
MANY AREAS ACROSS THE WESTERN U.S., GREAT PLAINS AND COASTAL SOUTHEAST.
THE SEPTEMBER TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL MONTHLY MEAN TEMPERATURES
FOR THE WESTERN CONUS, THE SOUTHERN PLAINS, THE SOUTHEAST, AND SOUTHEAST
MAINLAND ALASKA AND SOUTHEAST ALASKA (I.E., PANHANDLE). EQUAL-CHANCES (EC) FOR
ABOVE-, NEAR- AND BELOW-NORMAL TEMPERATURES ARE FORECAST FOR THE NORTHERN
PLAINS, MIDWEST, NORTHEAST AND PARTS OF THE OHIO VALLEY AND MID-ATLANTIC. THE
GREATEST PROBABILITIES FOR WARMER THAN NORMAL TEMPERATURES ARE FORECAST FOR THE
NORTH-CENTRAL ROCKIES AND INTERMOUNTAIN WEST. DRY SURFACE CONDITIONS, DYNAMICAL
AND HYBRID MODEL GUIDANCE FROM THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME)
AND COPERNICUS CLIMATE CHANGE SERVICE (C3S) SUITES, THE SEASONAL FORECAST
SYSTEM (SFS)-BETA AND VERY STRONG POSITIVE (WARMER) LONG-TERM TEMPERATURE
TRENDS STRONGLY SUPPORT THE FORECAST FOR ABOVE-NORMAL TEMPERATURES.
THE ABOVE OUTLINED FACTORS AND MODEL GUIDANCE ALSO SUPPORT THE SOUTHERN PLAINS
AND SOUTHEAST FORECAST FOR ABOVE-NORMAL TEMPERATURES. POTENTIAL EL NIñO
INFLUENCE (I.E., SLIGHT TILT TOWARD COOLER THAN NORMAL TEMPERATURES), CLOSER TO
NORMAL SURFACE CONDITIONS AND CONSIDERABLE SPREAD IN FORECAST GUIDANCE
INCLUDING THAT TARGETING THE WEEK 3-4 PERIOD, PARTICULARLY FROM THE EUROPEAN
CENTRE FOR MEDIUM-RANGE WEATHER FORECASTS (ECMWF) MODEL, IS THE REASON FOR THE
EC FORECAST AREA. THROUGHOUT THE SUMMER MONTHS, FREQUENT TROUGHING AND COOLER
TEMPERATURES HAS IMPACTED THIS AREA. THE FORECAST IN THIS REGION WILL BE
REFINED WITH THE UPDATED MONTHLY OUTLOOK LATER THIS MONTH.
BELOW-NORMAL SSTS OFF THE COAST OF THE PACIFIC NORTHWEST LOWER THE ODDS FOR
ABOVE-NORMAL TEMPERATURES FOR NEAR COAST AREAS IN THIS REGION. POTENTIAL FOR
ABOVE-NORMAL PRECIPITATION OVER THE SOUTHWEST U.S. AND SOUTHERN ROCKIES LOWERS
THE LIKELIHOOD FOR ABOVE-NORMAL TEMPERATURES IN THIS AREA. FOR ALASKA, EL NIñO
CONDITIONS, ABOVE-NORMAL SSTS IN THE GULF OF ALASKA AND THE MAJORITY OF MODEL
GUIDANCE SUPPORT THE ABOVE-NORMAL TEMPERATURES DEPICTED FOR MUCH OF THE STATE.
EC IS FORECAST FOR REMAINING AREAS DUE TO CONSIDERABLE FORECAST GUIDANCE
SPREAD.
ONGOING EL NIñO CONDITIONS, STATISTICAL, DYNAMICAL AND HYBRID MODEL GUIDANCE
AND POSITIVE (WETTER) LONG-TERM PRECIPITATION TRENDS SUPPORT THE FAVORED WETTER
THAN NORMAL CONDITIONS ACROSS THE WESTERN CONUS. NMME, C3S AND SFS-BETA MODEL
GUIDANCE IS UTILIZED FOR THE FORECAST IN INTERIOR ALASKA AND ELEVATED ODDS FOR
BELOW-NORMAL PRECIPITATION IN THE PACIFIC NORTHWEST AND WESTERN GREAT LAKES.
THE SIGNALS FROM THE MODEL GUIDANCE NOTED HERE ARE QUITE WEAK AND MARGINALLY
LINKED TO POTENTIAL EL NIñO IMPACTS.
THE SLIGHTLY ELEVATED LIKELIHOOD FOR ABOVE-NORMAL PRECIPITATION OVER THE OHIO
VALLEY, CENTRAL PLAINS AND CENTRAL MISSISSIPPI VALLEY IS PRIMARILY BASED ON
GENERAL PERSISTENCE FROM WHAT WE HAVE OBSERVED MUCH OF THE RECENT COUPLE OF
MONTHS. SUBTROPICAL RIDGING ACROSS THE SOUTHERN TIER OF THE U.S. HAS BEEN
OVERALL QUITE PERSISTENT WHILE SHIFTING ZONALLY. IN ASSOCIATION WITH THIS
RIDGING, ENHANCED RAINFALL HAS OCCURRED ON THE NORTHERN PERIPHERY OF THE RIDGE
DUE TO RESIDUAL SURFACE BOUNDARIES AND MESOSCALE CONVECTIVE SYSTEM (MCS)
ACTIVITY.
FORECASTER: JON GOTTSCHALCK
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.
AN UPDATED MONTHLY OUTLOOK... FOR SEP WILL BE ISSUED ON MON AUGUST 31 2026
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.
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