275 FXUS07 KWBC 311900 PMD30D Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 300 PM EDT Thu Oct 31 2024 30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2024 The updated November 2024 temperature and precipitation outlook is adjusted by the availability of medium- and extended-range forecast model guidance within the validation period (i.e. first 2 weeks of October) and the most recent available subseasonal forecast model guidance for the latter half of November. Additionally, the latest status of ENSO and the MJO were also considered. The lagged impacts of the MJO resulted in moderated probabilities across much of the forecast domain, as it is largely out of phase with much of the dynamical model guidance later in the month. The temperature guidance for early November reflects an early month cold period across the western CONUS. The early cool period is balanced by some guidance for later in November that reflects a moderation. MJO related circulation changes, based on lagged composites from a phase 7 MJO, would favor warmer solutions across the West and cooler solutions in the eastern CONUS. The uncertainty from the disagreement results in equal chances of above-, near-, or below-normal temperatures from the West Coast to the Rockies. Across the eastern CONUS, an early warm period followed by predicted above-normal temperatures for the rest of the month are mitigated by the potential for sub-monthly variability and some short periods of cold air across the Mississippi and Ohio Valleys. Across Alaska, near shore SSTs are moderating, so probabilities are low. Trends still favor above-normal temperatures along the northern coast. La Nina related forcings would favor cooler than average conditions along southern mainland Alaska and the Alaska panhandle, though guidance early in the month shows a likely period of significant warmth that wanes, so probabilities are low along the southern coast for below-normal temperatures. The precipitation outlook reflects high probabilities of a wet start to the month from the Southern Great Plains to the Great Lakes. Forecast precipitation totals during the first week of the month would rule out below or even near-normal precipitation for a large swath of the central CONUS. This is a large change from the mid-month outlook and highly related to short-term variability. Some models continue a wetter pattern across the Great Plains through the latter half of the month, with a moderation along the Gulf Coast. A dry start to the month along the East Coast, combined with later month outlooks of near to below-normal precipitation is enough to favor below-normal precipitation from North Carolina to New England. Probabilities are low and uncertainty high, as the MJO would favor troughing across the central CONUS, potentially bringing moisture northward during the middle of November. Early month storm activity and the developing La Nina favor above-normal precipitation across the Pacific Northwest and southern portions of Alaska, including the Alaska panhandle. ***************************************************************************** ********** Previous discussion from the middle of October ************ ***************************************************************************** The November 2024 outlook considered the current and projected state of El Nio Southern Oscillation (ENSO), the Madden Julian Oscillation (MJO), trends, and recent Sea Surface Temperatures (SSTs). Tools considered are the Sea Surface Temperature Based Constructed Analog (SST-CA), Canonical Correlation Analysis (CCA), Optimal Climate Normals (OCN), ENSO-OCN blend, and the dynamical models in both the North American Multi-model Ensemble (NMME) and Copernicus Climate Change Services (C3S) suites. Of note, soil moisture was not considered due to the waning influence at this time of year. Further, precipitation measurements over Ontario Canada were deemed unreliable so they were not considered in the analysis of tools for the precipitation outlook. The temperature outlook is close to the consolidation of the statistical tools and NMME, though notably shifted toward a less certain outlook in the Pacific Northwest and Northern Great Plains. The likely progression of the MJO and associated downstream impacts, combined with some analyses showing an over-amplified trend in the many of the dynamical models, leads to less certainty in the Pacific NorthWest and Northern Great Plains. Uncertainty about the temperature outcomes along the mid-Atlantic resulted in lowered probabilities there compared to the final consolidation, as the tools indicate either near- or above-normal temperatures. The only tool indicating below-normal temperatures is a soil moisture based constructed analog, which was not considered due to the time of year. Recent SST changes toward warmer temperatures and climatologically low sea ice favor above-normal temperatures across the North Slope and northwest coast of Alaska. Slightly elevated odds for below-normal temperatures from the Kenai Peninsula to the Alaska Peninsula are consistent with La Nia though only weakly supported in the dynamical models. The precipitation outlook reflects the consistent signals among the tools and dynamical models. Favoring below-normal precipitation along most of the southern tier is related to the developing La Nia, as well as indicated in most of the tools and dynamical models. The CFS indicates some wetness across the Southern Plains, so probabilities there are lower than the Southwest and the Lower Mississippi Valley. Statistical tools also indicate above-normal precipitation in Kansas and Oklahoma but the dynamical models do not, and calibrations result in very small and uncertain areas. Across the Pacific Northwest, the forecast for above-normal precipitation is supported in the dynamical models (NMME and C3S) and aligns with the emerging La Nia. Above-normal precipitation across Northern Alaska is typically associated with warmer SSTs and lower sea ice. Almost all of the models in the NMME suite have a signal for above-normal precipitation across the north slope, which is retained in the calibrated outlooks. FORECASTER: Matthew Rosencrans 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 Dec ... will be issued on Thu Nov 21 2024 These outlooks are based on departures from the 1991-2020 base period. $$