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FXUS07 KWBC 191231
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU OCT 19 2023
30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2023
EL NIñO CONDITIONS ARE CURRENTLY OBSERVED, AND EQUATORIAL SEA SURFACE
TEMPERATURES (SSTS) ARE ABOVE AVERAGE ACROSS THE CENTRAL AND EASTERN EQUATORIAL
PACIFIC OCEAN. THE TROPICAL PACIFIC ATMOSPHERE IS CONSISTENT WITH EL NIñO, AND
AS SUCH WE EXPECT EL NIñO TO BE THE DOMINANT TELECONNECTION FOR NOVEMBER,
THOUGH IMPACTS ARE GENERALLY WEAKER THAN DURING WINTER AND EARLY SPRING. WHILE
THE MADDEN JULIAN OSCILLATION (MJO) SHOWED SOME RENEWED ACTIVITY RECENTLY, AN
INCOHERENT MJO IS FAVORED IN FORECASTS OF THE REALTIME MULTIVARIATE MJO (RMM)
INDEX GIVEN DESTRUCTIVE INTERFERENCE FROM THE ONGOING EL NIñO AND AN EMERGING
POSITIVE INDIAN OCEAN DIPOLE (+IOD) EVENT. THUS, THE MJO WAS NOT SIGNIFICANTLY
CONSIDERED FOR THE NOVEMBER OUTLOOK. HOWEVER, GIVEN CLIMATOLOGY AND A
BROAD-SCALE ENVIRONMENT PREDICTED IN THE MODELS THAT IS CONSISTENT WITH A
CENTRAL AMERICAN GYRE (CAG) FORMATION OVER THE TROPICAL AMERICAS, CONDITIONS
ARE FAVORABLE FOR TROPICAL CYCLONE (TC) DEVELOPMENT OVER A BROAD AREA FROM THE
SOUTH OF MEXICO TO THE WESTERN ATLANTIC DURING EARLY PARTS OF NOVEMBER AS
FORECAST IN THE LATEST CPC GLOBAL TROPICS HAZARDS OUTLOOK (GTH). IN ADDITION TO
THESE INFLUENCING FACTORS, THE NOVEMBER TEMPERATURE AND PRECIPITATION OUTLOOKS
CONSIDER LOCAL SST ANOMALIES, DYNAMICAL MODEL GUIDANCE FROM THE NORTH AMERICAN
MULTI-MODEL ENSEMBLE (NMME), COPERNICUS MODEL SUITE (C3S), AND THE CLIMATE
FORECAST SYSTEM VERSION 2 (CFSV2), AS WELL AS STATISTICAL MODELS THAT INCLUDE
THE INFLUENCE OF TREND AND ENSO. WEEK 3-4 FORECASTS FROM CFSV2, ECMWF, AND
GEFSV12 FOR THE EARLY PART OF NOVEMBER WERE ALSO CONSIDERED, AS WAS THE
EXPECTED EVOLUTION FROM THE WEEK 2 FORECAST PERIOD.
THE NOVEMBER 2023 TEMPERATURE OUTLOOK FAVORS A BROAD AREA OF ABOVE NORMAL
TEMPERATURES FOR THE WESTERN CONTIGUOUS UNITED STATES (CONUS) STRETCHING INTO
THE SOUTHERN AND CENTRAL PLAINS, THE LOWER HALF OF THE MISSISSIPPI VALLEY, THE
TENNESSEE VALLEY, PARTS OF THE OHIO VALLEY, AND THE SOUTHEAST. WEEK 2
TEMPERATURE OUTLOOKS FEATURE A TILT TOWARD BELOW NORMAL TEMPERATURES OVER MUCH
OF THE WESTERN CONUS FOR THE PERIOD OF OCTOBER 25 THROUGH OCTOBER 1, THAT
SHIFTS EASTWARD TOWARD THE CENTRAL CONUS FOR OCTOBER 26 THROUGH NOVEMBER 1. IN
CONTRAST, CFSV2, GEFSV12, AND ECMWF PREDICTIONS OF WEEK 3 AND 4 TEMPERATURES
THROUGH MID-NOVEMBER BROADLY FAVOR WARMING OVER CONUS, INCLUDING THE WESTERN
AND CENTRAL PARTS OF THE COUNTRY. THIS SUGGESTS THAT ANY POTENTIAL COOLER START
TO NOVEMBER, PARTICULARLY OVER THE WESTERN CONUS, WILL BE A TRANSIENT FEATURE
WITH UNCERTAINTY ON HOW LONG IT MAY PERSIST. WHILE RECENT FORECASTS FROM CFSV2
FAVOR STRONG PROBABILITIES FOR ABOVE NORMAL TEMPERATURES OVER THE WESTERN THIRD
OF THE CONUS, PROBABILITIES IN THE NOVEMBER TEMPERATURE OUTLOOK ARE
COMPARATIVELY DAMPED (40 TO 50 PERCENT) TO REFLECT THIS UNCERTAINTY. HIGHER
PROBABILITIES (40 TO 50 PERCENT) OF ABOVE NORMAL TEMPERATURES ARE INDICATED
OVER THE SOUTHWEST WHERE DYNAMICAL MODELS AGREE. THE TILT TOWARD ABOVE NORMAL
TEMPERATURES OVER THE WEST IS ALSO SUPPORTED BY THE TYPICAL EL NIñO
TELECONNECTION, WHICH FAVORS ABOVE NORMAL OR MILDER TEMPERATURES OVER THE
WESTERN HALF OF THE CONUS. IN CONTRAST, BELOW NORMAL TEMPERATURES ARE MORE
TYPICAL OVER OVER THE EASTERN HALF OF CONUS DURING EL NIñO, HOWEVER, THIS IS AT
ODDS WITH CFSV2 PREDICTIONS THAT FAVOR (RELATIVELY) STRONG PROBABILITIES FOR
ABOVE NORMAL TEMPERATURES OVER PARTS OF THE MISSISSIPPI, OHIO, AND TENNESSEE
VALLEYS AND THE SOUTHEAST, AND WITH NMME AND C3S PREDICTIONS THAT ALSO SLIGHTLY
TILT ABOVE NORMAL. A WEAK TILT TOWARD ABOVE NORMAL IS MAINTAINED OVER PARTS OF
THE SOUTHEASTERN CONUS (33 TO 40 PERCENT), WITH HIGHER PROBABILITIES (40 TO 50
PERCENT) OVER PARTS OF THE GULF STATES AND FLORIDA PENINSULA WHERE THERE IS
STRONGER MODEL AGREEMENT, AND COINCIDENT WITH ABOVE AVERAGE SST ANOMALIES.
EQUAL CHANCES (EC) OF ABOVE, BELOW, AND NEAR NORMAL TEMPERATURES ARE INDICATED
FOR THE NORTHERN PLAINS, GREAT LAKES, PARTS OF THE MID-ATLANTIC AND NEW ENGLAND
WHERE STATISTICAL TOOLS AND DYNAMICAL MODELS SHOWED WEAK OR CONFLICTING
SIGNALS. MIXED POSITIVE AND NEGATIVE SST ANOMALIES OFF THE COAST OF NEW ENGLAND
ADDS TO UNCERTAINTY. FINALLY, A GRADIENT OF ABOVE NORMAL TEMPERATURE
PROBABILITIES TO EC IS FAVORED FOR NORTHERN ALASKA TO SOUTHERN ALASKA, WITH THE
STRONGEST PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOUND OVER THE
NORTHERNMOST PART OF THE STATE WHERE THERE WAS STRONG MODEL AGREEMENT AND
ANOMALOUSLY WARM SSTS.
MORE UNCERTAINTY IS APPARENT IN THE NOVEMBER 2023 PRECIPITATION OUTLOOK, WITH
EC INDICATED FOR A LARGE PART OF THE CONUS GIVEN WEAK AND INCONSISTENT MODEL
RESULTS, AND SIGNIFICANT DAY TO DAY DIFFERENCES IN RECENT CFSV2 PREDICTIONS. A
REGION OF FAVORED ABOVE NORMAL PRECIPITATION IS INDICATED FROM PARTS OF TEXAS
EASTWARD ACROSS THE SOUTHEAST AND UP THE EAST COAST OF THE CONUS. THIS REGION
OF ELEVATED ABOVE NORMAL PRECIPITATION PROBABILITIES IS SUPPORTED BY THE NMME
AND C3S, AND AGREES WITH THE EXPECTED EL NIñO TELECONNECTION AND THE POTENTIAL
FOR INCREASED PRECIPITATION THAT MAY BE ASSOCIATED WITH ELEVATED TC
DEVELOPMENT. HOWEVER, PROBABILITIES ARE DAMPED GIVEN CFSV2 GUIDANCE THAT FAVORS
A TILT TOWARD BELOW NORMAL PRECIPITATION PROBABILITIES. A SLIGHT TILT TOWARD
BELOW NORMAL PRECIPITATION IS DEPICTED OVER THE WESTERN GREAT LAKES WHERE NMME,
C3S, CFSV2, AND EXPECTED EL NIñO TELECONNECTIONS ALL SUPPORT BELOW NORMAL. BOTH
STATISTICAL AND DYNAMICAL MODELS SUPPORT ENHANCED PROBABILITIES OF ABOVE NORMAL
OVER NORTHERN ALASKA. GUIDANCE IS MIXED FOR THE SOUTHERN COAST, BUT RECENT
CFSV2 FORECASTS CONSISTENTLY FAVOR STRONGER PROBABILITIES OF BELOW NORMAL
PRECIPITATION, ADDITIONALLY SUPPORTED BY A SUBSET NMME AND C3S MODELS, AND THUS
BELOW NORMAL PRECIPITATION PROBABILITIES ARE ELEVATED OVER COASTAL REGIONS.
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.
AN UPDATED MONTHLY OUTLOOK... FOR NOV WILL BE ISSUED ON TUE OCTOBER 31 2023
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.
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