063
FXUS07 KWBC 201231
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU JUL 20 2023
30-DAY OUTLOOK DISCUSSION FOR AUGUST 2023
THE MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS ARE MADE UNDER STRENGTHENING
EL NIñO CLIMATE CONDITIONS. THE RECENT WEEK NIñO 3.4 SEA SURFACE TEMPERATURE
(SST) ANOMALY IS GREATER THAN +1.2 DEGREES CELSIUS. SSTS ACROSS THE CENTRAL AND
EASTERN EQUATORIAL PACIFIC OCEAN HAVE INCREASED SIGNIFICANTLY OVER THE LAST
MONTH. LOWER LEVEL WINDS AT 850 HPA ARE NEAR AVERAGE ACROSS MUCH OF THE
EQUATORIAL PACIFIC OCEAN, EXCEPT FOR WEAK EASTERLY ANOMALIES OVER PARTS OF THE
EAST-CENTRAL PACIFIC OCEAN. NEGATIVE OUTGOING LONGWAVE RADIATION (OLR)
ANOMALIES ARE PRESENT JUST WEST OF THE DATE LINE, INDICATING ANOMALOUSLY
ENHANCED CONVECTION. THESE OCEAN AND ATMOSPHERE CONDITIONS INDICATE THAT THE
ONGOING EL NIñO IS STRENGTHENING. WHILE IT IS EXPECTED THAT TELECONNECTIONS
BETWEEN THE TROPICS AND THE CLIMATE OVER NORTH AMERICA WILL TAKE TIME TO BE
ESTABLISHED, EL NIñO MAY IMPACT TEMPERATURE AND PRECIPITATION PATTERNS IN THE
NEAR FUTURE AND PLAYS A ROLE IN THE AUGUST TEMPERATURE AND PRECIPITATION
OUTLOOKS. THE MADDEN JULIAN OSCILLATION (MJO) WAS DISORGANIZED DURING THE LAST
MONTH, THOUGH DYNAMICAL MODELS INDICATE THAT THE MJO MAY BECOME ACTIVE OVER THE
MARITIME CONTINENT AND PROPAGATE ACROSS THE WESTERN PACIFIC IN THE NEXT FEW
WEEKS. HOWEVER, THE MJO FORECAST APPEARS SOMEWHAT UNCERTAIN AT THIS TIME AND
WAS NOT USED AS A SIGNIFICANT FACTOR IN THE AUGUST MONTHLY OUTLOOK.
THE AUGUST TEMPERATURE AND PRECIPITATION OUTLOOKS WERE PRIMARILY BASED ON A
SKILL-WEIGHTED CONSOLIDATION OF STATISTICAL AND DYNAMICAL FORECAST TOOLS. THE
FULL CONSOLIDATION INCLUDES A CONSOLIDATION OF RECENT DYNAMICAL MODEL FORECASTS
FROM THE NORTH AMERICA MULTIMODEL ENSEMBLE (NMME) FOR THE MONTH OF AUGUST. IN
ADDITION, THE FULL CONSOLIDATION INCLUDES A CONSOLIDATION OF THE CANONICAL
CORRELATION ANALYSIS (CCA), THE CONSTRUCTED ANALOG (CA), AND AN ENSO OCN TOOL,
THAT COMBINES THE IMPACT OF ENSO, BASED ON THE FORECASTS OF NIñO 3.4 SST
ANOMALY, WITH THE OPTIMUM CLIMATE NORMAL (OCN) REPRESENTATION OF DECADAL
TRENDS. DAILY INITIALIZED FORECASTS FROM THE NCEP CFSV2 DYNAMICAL MODEL, THE
MOST RECENT CPC WEEK 3-4 OUTLOOK THAT OVERLAPS THE BEGINNING OF THE MONTH OF
AUGUST, AND A STATISTICAL MULTIVARIATE LINEAR REGRESSION (MLR) FORECAST FOR THE
FIRST HALF OF AUGUST USING THE CURRENT NIñO 3.4 AND MJO INDICES AS PREDICTORS,
WERE ALSO CONSIDERED. RECENT BOUNDARY CONDITIONS, INCLUDING NEAR COASTAL SSTS
AND SOIL MOISTURE ANOMALIES, WERE ADDITIONAL FACTORS CONSIDERED.
THE AUGUST TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES OVER MUCH OF
ALASKA, CONSISTENT WITH DYNAMICAL MODEL GUIDANCE AND THE MONTHLY TEMPERATURE
CONSOLIDATION. FORECASTS OF EQUAL CHANCES (EC) OF ABOVE, NEAR AND BELOW NORMAL
TEMPERATURES ARE INDICATED FOR THE WEST COAST OF ALASKA, WHERE BELOW AVERAGE
SSTS SHOULD MODERATE AIR TEMPERATURES. EQUAL CHANCES (EC) IS ALSO FORECAST FOR
THE NORTHEAST MAINLAND, WHERE TOOLS ARE INCONSISTENT. WIDESPREAD ABOVE NORMAL
TEMPERATURES ARE FAVORED OVER MUCH OF THE CONTIGUOUS U.S. (CONUS), SUPPORTED BY
THE CONSOLIDATION OF STATISTICAL AND DYNAMICAL FORECAST TOOLS. PROBABILITIES
FOR ABOVE NORMAL TEMPERATURES EXCEED 60 PERCENT OVER THE PACIFIC NORTHWEST, DUE
TO DYNAMICAL MODEL FORECASTS AND DRY SOIL MOISTURE ANOMALIES. BELOW NORMAL
TEMPERATURES ARE FAVORED FOR PARTS OF THE EASTERN NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY. EL NIñO IMPACTS FAVOR POTENTIAL TROUGHING OVER THE EASTERN
CENTRAL CONUS WITH NORTHERLY FLOW INTO THIS REGION. STATISTICAL FORECASTS BASED
ON THE CURRENT STATE OF ENSO PREDICT A LARGER AREA OF FAVORED BELOW NORMAL
TEMPERATURES, RESULTING IN A REDUCTION IN PROBABILITIES OF ABOVE NORMAL
TEMPERATURES FOR MUCH OF THE EAST-CENTRAL CONUS. ABOVE AVERAGE SST ANOMALIES
ALONG THE GULF AND EAST COASTS INCREASE THE PROBABILITY OF ABOVE NORMAL
TEMPERATURES IN THESE REGIONS.
THE AUGUST PRECIPITATION OUTLOOK FAVORS BELOW NORMAL PRECIPITATION NEAR THE
COAST OF THE SOUTHWESTERN ALASKA MAINLAND, SUPPORTED PRIMARILY BY DYNAMICAL
MODEL FORECASTS FROM THE NMME AND THE CONSOLIDATION OF PRECIPITATION FORECAST
TOOLS. THOUGH ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED IN SOUTHWESTERN
ARIZONA AT THE START OF THE MONTH BY THE WEEK 3-4 OUTLOOK, EL NIñO IMPACTS AND
STATISTICAL FORECAST TOOLS FAVOR A SUPPRESSED MONSOON FOR THE FULL MONTH OF
AUGUST. BELOW NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE SOUTHWEST MONSOON
REGION FROM WEST TEXAS TO NORTHEASTERN ARIZONA AND NORTHWARD ACROSS THE
INTERMOUNTAIN WEST INTO PARTS OF EASTERN OREGON AND SOUTHERN IDAHO. ABOVE
NORMAL PRECIPITATION IS FAVORED FROM EASTERN AREAS OF THE CENTRAL PLAINS ACROSS
THE CENTRAL MISSISSIPPI VALLEY TO THE ATLANTIC COAST, ALONG A PREFERRED
POTENTIAL STORM TRACK AND SUPPORTED BY THE CONSOLIDATION OF PRECIPITATION
FORECAST TOOLS. ABOVE NORMAL PRECIPITATION IS FAVORED FROM NORTHEASTERN FLORIDA
ALONG THE ATLANTIC COAST INTO SOUTHERN NEW ENGLAND, SUPPORTED BY THE
CONSOLIDATION.
FORECASTER: DAN COLLINS
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 AUG WILL BE ISSUED ON MON JULY 31 2023
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.
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