535 FXUS06 KWBC 311907 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Fri May 31 2024 6-10 DAY OUTLOOK FOR JUN 06 - 10 2024 While today's model solutions are in good agreement on an amplified 500-hPa circulation pattern across North America during the 6-10 day period, ensemble means from the GEFS and ECMWF are showing some differences in the evolution of the pattern and resulting surface temperature and precipitation forecasts. The manual 500-hPa height blend is based on the 0Z ensemble means from the GEFS, ECMWF, and Canadian ensemble models. At the start of the period a trough is predicted to the west of Mainland Alaska that extends southward across the Aleutians into the North Pacific by both the GEFS and ECMWF ensemble means. During the period, the center of negative 500-hPa height anomalies in the GEFS moves southeastward into the North Pacific, as mid-level heights rise over Mainland Alaska in both models. The manual blend predicts a trough and negative 500-hPa height anomalies over the Aleutians and North Pacific. A ridge and positive 500-hPa height anomalies are predicted over the western contiguous U.S. (CONUS) in the manual blend. Ensemble mean forecasts from the GEFS and ECMWF models both predict the amplification of a trough and negative 500-hPa height anomalies over the eastern CONUS during the 6-10 day period, while the trough axis in the ECMWF ensemble mean is slightly west of the trough axis in the GEFS ensemble mean. Negative 500-hPa height anomalies are predicted over the entire eastern CONUS in the 6-10 day mean manual blend, with the exception of northern Maine. Enhanced chances for above-normal temperatures are predicted over the western CONUS due to the predicted mid-level ridge and positive 500-hPa height anomalies, and supported by most dynamical model temperature forecast tools. Probabilities for above-normal temperatures exceed 70 percent and in some areas 80 percent for much of the Great Basin and Central Rockies. Above-normal temperatures are also favored for the Gulf and southern Atlantic Coasts and slightly favored for parts of the Northeast, supported by the temperature consolidation. Below-normal temperatures are favored for most remaining areas of the eastern CONUS, under the predicted trough. Probabilities for below-normal temperatures are enhanced over southern Alaska, including the Aleutians and Southeast Alaska, under the predicted trough and enhanced precipitation, while above-normal temperatures are slightly favored for northern Mainland Alaska, as a ridge pushes into the region later in the period. Near-normal temperatures are favored for Hawaii, where temperature forecast tools are in disagreement. Near- to above-normal precipitation is favored for most of Mainland Alaska and northern areas of Southeast Alaska, with southerly flow ahead of a predicted trough over the North Pacific. A predicted anomalous mid-level ridge favors below-normal precipitation from much of the Pacific Northwest across the Northern Plains into parts of the Upper Mississippi Valley. Above-normal precipitation is slightly favored from eastern New Mexico and central Texas into parts of the Southern Plains, consistent with most dynamical model precipitation forecasts. Median precipitation accumulation predictions by the consolidation tool are as little as one or two millimeters during the 6-10 day period in semi-arid regions of the Southwest. However, any precipitation in arid regions would be considered above-normal. Above-normal precipitation is also favored for the northeastern CONUS, consistent with the consolidation. Near-normal precipitation is favored for the Southeast, where dynamical model precipitation forecasts are inconsistent. Probabilities of below-normal precipitation are enhanced across Hawaii, consistent with the consolidation precipitation forecast tool. The official 6-10 day 500-hPa height blend consists of 40% of Today's 0z GFS Ensemble Mean centered on Day 8, 40% of Today's 0z European Ensemble Mean centered on Day 8, and 20% of Today's 0z Canadian Ensemble Mean centered on Day 8 FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: About average, 3 out of 5, due to good agreement among model solutions on the mean circulation pattern, offset by an evolving pattern and some differences among forecast temperature and precipitation tools. 8-14 DAY OUTLOOK FOR JUN 08 - 14 2024 While GEFS and ECMWF ensemble means for the 8-14 day period 500-hPa height forecast are consistent with the overall mid-level circulation pattern across North America and with the 6-10 day period forecast, larger differences between models are apparent in week 2, as uncertainty increases. Larger positive 500-hPa height anomalies are predicted over Mainland Alaska during the 8-14 day period by the ECMWF forecast, with the center of negative 500-hPa height anomalies shifting southward into the North Pacific. A more amplified ridge and associated positive 500-hPa height anomalies is predicted over the western half of the CONUS in the ECMWF ensemble mean than in the GEFS ensemble mean, while an amplified trough and negative 500-hPa height anomalies are predicted over the eastern CONUS during week 2 by both the ECMWF and GEFS. Below-normal temperatures continue to be favored for the southwestern coast of Mainland Alaska and the Aleutians, associated with the predicted trough over the region, while near-normal is favored for most of southern Mainland Alaska. Above normal temperatures are slightly favored for northern Mainland Alaska, consistent with most temperature tools including the consolidation. A predicted ridge over the western CONUS and positive 500-hPa height anomalies favor above-normal temperatures, with probabilities exceeding 70 percent over parts of the Northwest. Below-normal temperatures are favored over most of the eastern CONUS, under a predicted trough during the period. Above-normal temperatures continue to be likely for much of the Gulf Coast and southern Atlantic Coast, consistent with dynamical model forecast tools. Near-normal temperatures are slightly favored for New England, where temperature forecast tools are inconsistent. Near-normal temperatures continue to be favored for Hawaii, where temperature forecast tools are in disagreement. Above-normal precipitation continues to be very slightly favored for interior Mainland Alaska and southern Alaska, consistent with most dynamical model forecast tools, and under southerly flow. Below-normal precipitation is slightly favored for western Washington and the northern tier of the CONUS from Montana to the Upper Mississippi Valley, under a predicted ridge. Above normal precipitation continues to be slightly favored from northeastern New Mexico and much of Texas into parts of the Central Plains, consistent with most dynamical model precipitation forecasts. Above-normal precipitation is favored for much of the northeastern CONUS, ahead of a predicted trough. Above-normal precipitation is favored for the Florida Peninsula, consistent with most precipitation tools. Near-normal precipitation is favored across remaining areas of the CONUS, where there is greater uncertainty and precipitation tools are inconsistent. Near-normal precipitation is favored across Hawaii, as precipitation tools are inconsistent. The official 8-14 day 500-hPa height blend consists of: 40% of Today's 0z GFS Ensemble Mean centered on Day 11, 40% of Today's 0z European Ensemble Mean centered on Day 11, and 20% of Today's 0z Canadian Ensemble Mean centered on Day 11 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Below average, 2 out of 5, due to general consistency in the forecast pattern among ensemble mean model forecasts, offset by increasing differences among models and especially precipitation forecast tools. FORECASTER: D Collins Notes: Automated forecasts are issued on Saturday and Sunday. Occasionally manual intervention is necessary to address quality control and consistency issues. In these cases, forecasts are manually drawn but a full discussion is not issued. The notation for the categorical forecast indicated on the maps is the same as that in the tables: A-above N-near normal B-below The temperature map shows regions with > 33% chance of being warmer (orange, "A"), colder (blue, "B"), or close to (unshaded, "N"). Historical average values for the calendar period of the forecast (dashes, "f"). Labels on the shaded lines give the probability (> 33%) of the more likely category (B or A). Probability of N is always < 40%. The precipitation map shows regions with > 33% chance of being wetter (green, "A"), drier (tan, "B"), or close to (unshaded, "n"). Historical median values for the calendar period of the forecast (dashes, "inches"). Labels on the shaded lines give the probability (> 33%) of the more likely category (B or A). Probability of N is always < 40%. In the southwest and other climatologically dry regions - there will be a greater than 33.3% chance of no precipitation and occasionally even a normal (i.e. Median) value of zero - especially during the dry seasons. In such cases a forecast of near normal is effectively a forecast of little or no precipitation. The climate prediction center uses 1991-2020 base period means as reference in the climate outlooks. The next set of long-lead monthly and seasonal outlooks will be released on June 20. Analogs to the 5 day mean observed pattern centered 3 days ago (D-3) for the region from 20N to 70N latitude and 175E to 60W longitude include the 5 day periods centered on the following dates: 19660514 - 20030515 - 20040530 - 20010601 - 19890518 Analogs to the 7 day mean observed pattern centered 4 days ago (D-4) for the region from 20N to 70N latitude and 175E to 60W longitude include the 7 day periods centered on the following dates: 20030514 - 20040531 - 19660515 - 20010601 - 19840530 6-10 DAY OUTLOOK TABLE Outlook for Jun 06 - 10 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A B OREGON A N NRN CALIF A N SRN CALIF A N IDAHO A B NEVADA A N W MONTANA A B E MONTANA A B WYOMING A N UTAH A N ARIZONA A N COLORADO A A NEW MEXICO A N N DAKOTA A B S DAKOTA B B NEBRASKA B N KANSAS B A OKLAHOMA B A N TEXAS A A S TEXAS A N W TEXAS A A MINNESOTA B B IOWA B B MISSOURI B N ARKANSAS B N LOUISIANA A N WISCONSIN B B ILLINOIS B N MISSISSIPPI B N MICHIGAN B N INDIANA B N OHIO B N KENTUCKY B N TENNESSEE B N ALABAMA B N NEW YORK N A VERMONT A A NEW HAMP A A MAINE A A MASS N A CONN N A RHODE IS N A PENN B A NEW JERSEY N A W VIRGINIA B A MARYLAND N A DELAWARE N A VIRGINIA B A N CAROLINA A N S CAROLINA A N GEORGIA A N FL PNHDL A N FL PENIN A N AK N SLOPE A A AK ALEUTIAN B A AK WESTERN B A AK INT BSN A A AK S INT B A AK SO COAST B A AK PNHDL B N 8-14 DAY OUTLOOK TABLE Outlook for Jun 08 - 14 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A N OREGON A N NRN CALIF A N SRN CALIF A N IDAHO A N NEVADA A N W MONTANA A B E MONTANA A B WYOMING A N UTAH A N ARIZONA A N COLORADO A A NEW MEXICO A N N DAKOTA B B S DAKOTA B B NEBRASKA B N KANSAS B A OKLAHOMA B A N TEXAS A A S TEXAS A A W TEXAS A A MINNESOTA B B IOWA B N MISSOURI B N ARKANSAS B A LOUISIANA A N WISCONSIN B N ILLINOIS B N MISSISSIPPI B N MICHIGAN B N INDIANA B N OHIO B N KENTUCKY B N TENNESSEE B N ALABAMA B N NEW YORK B A VERMONT N A NEW HAMP N A MAINE N A MASS N A CONN N A RHODE IS N A PENN B N NEW JERSEY B A W VIRGINIA B N MARYLAND B N DELAWARE B N VIRGINIA B N N CAROLINA N N S CAROLINA A N GEORGIA A N FL PNHDL A N FL PENIN A A AK N SLOPE A N AK ALEUTIAN B N AK WESTERN A N AK INT BSN A N AK S INT N A AK SO COAST N A AK PNHDL N N LEGEND TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN B - BELOW B - BELOW THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE. FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS PMDMRD. $$