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FXUS07 KWBC 181231
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU MAY 18 2023
30-DAY OUTLOOK DISCUSSION FOR JUNE 2023
THE JUNE 2023 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON THE CLIMATE
FORECAST SYSTEM MODEL VERSION 2 (CFSV2), NORTH AMERICAN MULTI-MODEL ENSEMBLE
(NMME) AND COPERNICUS MODEL (C3S) SUITES FOR JUNE, THE WEEK 3-4 MODEL
SOLUTIONS, STATISTICAL TOOLS, AND SOIL MOISTURE CONDITIONS. THE MADDEN-JULIAN
OSCILLATION (MJO) REMAINS ACTIVE WITH ITS ENHANCED PHASE OVER THE WEST-CENTRAL
PACIFIC. THE MJO INFLUENCE ON THE MID-LATITUDE CIRCULATION PATTERN AND
ASSOCIATED TEMPERATURES DIMINISHES BY LATE SPRING. HOWEVER, IT CAN MODULATE
TROPICAL CYCLONE (TC) DEVELOPMENT ACROSS THE EAST PACIFIC AND ATLANTIC BASINS.
IF THE MJO CONTINUES TO PROPAGATE EASTWARD OVER THE WESTERN HEMISPHERE THROUGH
LATE MAY INTO EARLY JUNE, THAT WOULD PROVIDE A FAVORABLE LARGE-SCALE
ENVIRONMENT FOR THE GENESIS OF AN EARLY SEASON TC IN THE WESTERN CARIBBEAN SEA.
THIS WAS A FACTOR IN THE JUNE PRECIPITATION OUTLOOK FOR THE SOUTHEAST. SINCE A
TRANSITION FROM EL NIñO SOUTHERN OSCILLATION (ENSO)-NEUTRAL TO EL NIñO IS
LIKELY DURING THE NEXT COUPLE OF MONTHS, EL NIñO TEMPERATURE AND PRECIPITATION
COMPOSITES DURING MAY-JUNE-JULY WERE ALSO CONSIDERED.
A STRONG OMEGA BLOCK HAS PERSISTED OVER OR IN THE VICINITY OF NORTH AMERICA
SINCE LATE APRIL. MODEL SOLUTIONS DEPICT A WEAKENING OF THIS BLOCKING PATTERN
DURING LATE MAY WHICH LOWERS FORECAST CONFIDENCE HEADING INTO JUNE. DURING LATE
MAY AND EARLY JUNE, THE GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS) AND EUROPEAN
CENTRE FOR MEDIUM RANGE WEATHER FORECAST (ECMWF) ENSEMBLE MEANS MAINTAIN
POSITIVE 500-HPA HEIGHT ANOMALIES OVER ALASKA AND THE NORTHERN TWO-THIRDS OF
THE CONTIGUOUS U.S. (CONUS) WITH NEAR TO BELOW NORMAL HEIGHTS ACROSS THE
SOUTHERN TIER. THE PROMINENT AREA OF POSITIVE 500-HPA HEIGHT ANOMALIES AT THE
MIDDLE TO HIGH LATITUDES OF NORTH AMERICA WOULD FAVOR A WARM START TO JUNE
THROUGHOUT THE NORTHERN CONUS. THIS LIKELY WARM START TO JUNE ALONG WITH
MONTHLY DYNAMICAL AND STATISTICAL TOOLS SUPPORT INCREASED PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES FROM THE PACIFIC NORTHWEST EAST TO THE NORTHERN GREAT
PLAINS. THIS FAVORED AREA OF ABOVE-NORMAL TEMPERATURES EXTENDS SOUTHWARD TO THE
CENTRAL GREAT PLAINS AND MIDDLE MISSISSIPPI VALLEY WHERE LOW SOIL MOISTURE
CONDITIONS ARE LIKELY TO WARM SURFACE TEMPERATURES. THE WEEK 3-4 GEFS AND ECMWF
MODELS, C3S MODEL, AND RECENT DAILY CFSV2 MODEL RUNS FOR JUNE SUPPORT TO
INCREASED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ACROSS PARTS OF THE
NORTHEAST. BASED ON THE NMME, C3S, AND DECADAL TRENDS, ABOVE-NORMAL
TEMPERATURES ARE FAVORED FOR PARTS OF THE SOUTHWEST, RIO GRANDE VALLEY, GULF
COAST, AND FLORIDA. INCREASED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE
FORECAST FOR NEARLY ALL OF ALASKA, CONSISTENT WITH DYNAMICAL AND STATISTICAL
TOOLS. THE ONE EXCEPTION IS THE WESTERN COAST OF ALASKA DUE TO BELOW-NORMAL SST
ANOMALIES ACROSS THE EASTERN BERING SEA.
THE WEEK 3-4 GEFS AND ECMWF, VALID DURING EARLY TO MID-JUNE, ARE IN GOOD
AGREEMENT FOR ELEVATED PROBABILITIES OF ABOVE-NORMAL PRECIPITATION ACROSS
PORTIONS OF THE HIGH PLAINS, CENTRAL ROCKIES, AND GREAT BASIN. THIS WET SIGNAL
IS ALSO PRESENT IN THE MONTHLY NMME AND CONSISTENT AMONG DAILY CFSV2 MODEL RUNS
FOR JUNE. THEREFORE, ABOVE-NORMAL PRECIPITATION IS FAVORED FOR THOSE AREAS
DURING JUNE. THE NMME ALONG WITH AN INCREASED POTENTIAL FOR AN EARLY SEASON TC
TO EMERGE FROM THE WESTERN CARIBBEAN SEA FAVORS ABOVE-NORMAL PRECIPITATION FOR
PARTS OF THE SOUTHEAST. BASED ON THE NMME AND EL NIñO PRECIPITATION COMPOSITES,
ELEVATED PROBABILITIES FOR BELOW-NORMAL PRECIPITATION ARE FORECAST FOR
SOUTHEASTERN ALASKA AND PARTS OF THE PACIFIC NORTHWEST. A LARGE AREA OF EC WAS
NECESSARY IN THE JUNE PRECIPITATION OUTLOOK DUE TO WEAK OR CONFLICTING SIGNALS
AMONG THE GUIDANCE AND LOWER PREDICTABILITY ASSOCIATED WITH CONVECTIVE RAINFALL
DURING THE LATE SPRING AND EARLY SUMMER. THIS LARGE COVERAGE OF EC WILL BE
REEVALUATED WITH THE UPDATED JUNE OUTLOOK, RELEASED ON MAY 31.
FORECASTER: BRAD PUGH
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 JUN WILL BE ISSUED ON WED MAY 31 2023
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.
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