Prognostic Discussion for Monthly Outlook NWS Climate Prediction Center College Park MD 300 PM EDT Sun Jul 31 2022 30-DAY OUTLOOK DISCUSSION FOR AUGUST 2022 The August 2022 Temperature and Precipitation Outlooks are updated considering current active La Niña conditions, Weather Prediction Center (WPC) Outlooks for week 1, Climate Prediction Center (CPC) Extended Range and Week 3-4 Outlooks, dynamical model guidance for week 2, weeks 3-4, and the month of August, and current soil moisture conditions. The atmospheric teleconnection pattern remains consistent with that expected during August La Niña events, and recent weekly sea surface temperature (SST) departures in the Niño 3.4 region reached -0.7 degrees C. The Madden Julian Oscillation (MJO) signal weakened through mid-July due to destructive interference from La Niña, and recent Realtime Multivariate MJO (RMM) forecasts from the GEFS and ECMWF depict an inactive MJO signal. Thus, La Niña remains the primary remote influence on the August 2022 Temperature and Precipitation Outlooks. The previous mid-month August 2022 Temperature Outlook favored enhanced above normal temperature probabilities over most of the contiguous U.S. (CONUS), and a slight tilt toward above normal temperature probabilities over the North Slope of Alaska. Short term 6-10 and 8-14 day consolidated dynamical model forecasts as well as recent CFSv2 and GEFS monthly temperature forecasts now favor enhanced probabilities of cooler temperatures over the Desert Southwest under a robust monsoon signal. Forecasted ridging over the northern CONUS in the beginning of August is expected to persist through the Week 3-4 period given dynamical model forecasts of 500 hPa heights. This forecasted ridging supports enhanced probability of above normal temperatures over the northern CONUS. A weak tilt toward above normal temperature probability is favored for the Pacific Northwest, in contrast to the area of Equal-Chances (EC) of above, near, and below normal temperature previously indicated over the Pacific Northwest in the mid-month outlook. The area of EC previously indicated for parts of eastern Montana and western North Dakota in the mid-month Outlook is shifted eastward to the Upper Mississippi Valley and parts of the Northern Great Lakes following dynamical model guidance from CFSv2, as well as anomalously high soil moisture. Consolidated temperature forecasts for the beginning of August along with monthly CFSv2 forecasts support strengthening of above normal temperature probabilities over the mid-Atlantic (40 to 50 percent). Elevated probability of above normal temperature (60 to 70 percent) is maintained over parts of the Southern Plains and Lower Mississippi Valley in the updated August 2022 Outlook, but is shifted northward given monthly CFSv2 forecasts that favor weaker probabilities along the Gulf Coast. 6-10 and 8-14 day and week 3-4 dynamical model forecasts of 500 hPa heights depict troughing over Alaska and below normal temperature probabilities. Though in contrast to the most recent CFSv2 monthly temperature forecast which favors EC over Alaska, the forecasted persistent troughing supports a tilt toward below normal temperature probabilities over southern Alaska. Anomalously high sea ice off the northern coast of Alaska supports removal of the weak tilt toward positive temperatures previously indicated, and EC is now favored for the North Slope of Alaska in the updated August 2022 Outlook. The updated August 2022 Precipitation Outlook favors a broad area of below normal precipitation probabilities for parts of the northern, central, and northeastern CONUS. EC was previously indicated in the mid-month outlook for the Pacific Northwest and Northeast, but there is consistent below normal precipitation forecasted for early August and in GEFSv12 Week 3-4 forecasts, as well as elevated probability of below normal precipitation in recent CFSv2 monthly forecasts. This consistency along with the below normal CFSv2 forecast supports a tilt toward below normal precipitation over the Pacific Northwest (33 to 40 percent) and parts of the northeast (40 to 50 percent). Enhanced probability of below normal precipitation (40 to 50 percent) is favored over parts of the Southern Plains and Lower Mississippi Valley in the updated August 2022 Outlook following forecasted elevated probability of above normal temperatures, anomalously low soil moisture, and a confident forecast of below normal monthly precipitation from CFSv2. The area of EC previously indicated for parts of eastern Montana and western North Dakota in the mid-month Outlook is shifted eastward to the Upper Mississippi Valley and parts of the Northern Great Lakes following dynamical model guidance from CFSv2, as well as anomalously high soil moisture, similarly to the updated Temperature Outlook. EC is also indicated along the Gulf Coast and Florida given weak or conflicting signals from available guidance, and an area of enhanced probability of above normal precipitation is maintained in the mid-Atlantic. Short-term, subseasonal, and recent monthly guidance from CFSv2 and GEFS favor probability of above normal rainfall in a large area of the Desert Southwest related to a robust forecasted Southwest Monsoon. Enhanced precipitation may be expected in Southern California due to chance of monsoon pulses but probability remains weak (33 to 40 percent). Finally, elevated probability of above normal precipitation is maintained over eastern Alaska, but recent guidance suggests a southward shift and more coverage of the Alaska Panhandle. ****************************************************************************** ***** Previous mid-month discussion below ***** ****************************************************************************** The August 2022 Temperature and Precipitation Outlooks reflect current active La Niña conditions, the latest statistical and dynamical model guidance, impacts from decadal trends, antecedent soil moisture, and local sea surface temperature (SST) anomalies. Following a period of weakened below-average SSTs across most of the equatorial Pacific Ocean, recent negative SST anomalies in the central Pacific have strengthened. The latest weekly SST anomalies in the Niño 3.4 region reached -0.6C, and an extratropical response consistent with August La Niña events is anticipated. Impacts from La Niña on August temperature probabilities may be expected over southern Alaska and parts of the Pacific Northwest, and weak impacts may be expected on Western U.S. precipitation. Recent observations show that the Madden Julian Oscillation (MJO) has stalled over the Maritime Continent due to destructive interference from the ongoing La Niña, though dynamical model Realtime Multivariate MJO (RMM) forecasts show potential for a more coherent MJO emerging over the Western Hemisphere through the next two weeks. However, the MJO forecast is uncertain into August, thus the MJO did not play a strong role in the August 2022 Outlook. Available statistical and dynamical model guidance generally favor enhanced above normal temperature probabilities over most of the contiguous U.S. (CONUS). Monthly 200-hPa height forecasts from the North American Multi-Model Ensemble (NMME) as well as recent Week 3-4 dynamical model forecasts of 500-hPa heights favor widespread ridging over the CONUS, with stronger anomalous ridging predicted over the northern CONUS. In addition, anomalously low soil moisture in parts of the southern and central CONUS are expected to strengthen above normal temperatures. The area of highest above normal temperature probabilities are over eastern portions of the Southern Plains as well as much of the Lower Mississippi Valley (60-70 percent), where there is agreement among the Statistical Consolidation, NMME, Copernicus Climate Change Service multi-model ensemble (C3S), recent Climate System Forecast version 2 (CFSv2) temperature forecasts, and anomalously dry soil moisture conditions. Elevated probabilities of above normal temperatures (50-60 percent) are indicated for much of the central CONUS related to dry soil moisture anomalies, and considering recent CFSv2 forecasts which depict strong probabilities of above normal temperatures. Enhanced above normal temperature probabilities stretch over parts of the Great Lakes and Ohio River Valley due to forecasted stronger anomalous ridging in early August, as well as favored below normal precipitation. Elevated probabilities of above normal temperatures (50-60 percent) are also indicated for New England owing to decadal trends and anomalously warm coastal SSTs. Equal chances (EC) of above, near, and below normal temperatures are indicated for parts of eastern Montana and western North Dakota due to positive soil moisture anomalies which are expected to weaken probabilities of above normal temperatures in this region. EC is indicated for parts of the Desert Southwest due to dynamical model agreement on an active monsoon. Dynamical model guidance for the western and northernmost parts of the Pacific Northwest was uncertain or leaning toward weakly enhanced probabilities of above normal temperatures, which is at odds with the expected cooler impact from La Niña, thus, EC is favored. Weakly enhanced probabilities of above normal temperatures are favored over northern Alaska owing to impacts from La Niña, decadal trends, and consistency amongst NMME, C3S, and CFSv2 monthly temperature predictions, though probabilities are moderated due to above normal sea ice along the northern coast of Alaska. EC is favored for the remainder of Alaska due to inconsistency among monthly and Week 3-4 dynamical model predictions that favored enhanced above and below normal temperature probabilities, respectively. The August 2022 Precipitation Outlook considers statistical and dynamical models, antecedent soil moisture conditions, and La Niña impacts. Dynamical model guidance was uncertain over much of the CONUS, thus, enhanced probabilities for above or below normal precipitation relative to climatology are modest. A weak tilt toward below normal precipitation is favored over the region stretching from the Northern Rockies to the Great Lakes and Ohio River Valley, and southward to the Southern Plains, though an area of EC is indicated for parts of eastern Montana and western North Dakota due to positive soil moisture anomalies. Elevated probabilities of below normal precipitation (40-50 percent) are indicated over southern Texas due to dry soil moisture anomalies and agreement among statistical tools and the NMME. Elevated probabilities of below normal precipitation (40-50 percent) are also indicated over the Great Lakes and Ohio River Valley where NMME, C3S, and recent CFSv2 forecasts agreed on favoring below normal precipitation. Positive soil moisture anomalies along with forecasts from NMME and C3S that favored above normal precipitation supports a tilt toward above normal precipitation over the Mid-Atlantic, Southeast, and parts of the Gulf states. Dynamical models, particularly C3S and CFSv2, predict favorable odds for an enhanced monsoon and a tilt toward above normal precipitation over the Desert Southwest. Probabilities of above normal precipitation are elevated for parts of eastern Alaska given expected impacts from La Niña and decadal trend, however, EC is indicated for the remainder of the state due to uncertainty among monthly dynamical models and inconsistency with short term (Week 3-4) dynamical model forecasts. 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. The next monthly outlook...for Sep ... will be issued on Thu Aug 18 2022 These outlooks are based on departures from the 1991-2020 base period. $$