790 FXUS06 KWBC 051916 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Fri September 05 2025 6-10 DAY OUTLOOK FOR SEP 11 - 15 2025 Today's numerical models depict an amplified 500-hPa flow pattern across the higher latitudes North America and surrounding areas with the most prominent features being a strong ridge over central Canada centered just to the west of Hudson Bay and and a deep trough over the Gulf of Alaska. Notably, the trough over the Gulf of Alaska has trended significantly stronger relative to yesterday which, in turn, favors a stronger downstream ridge across northwestern Canada. Farther to the south, a tough in the southern stream is predicted over California and Nevada early in the period. Troughing is also forecast over the Eastern Seaboard downstream of the Canadian ridge. A weakness in the subtropical ridge is forecast over the Southeast, stemming from the Eastern Seaboard trough. Subtropical ridging is predicted over the Southern Plains early in the period and is expected to flatten to a more zonal configuration by the end of the period. According to NHC, Hurricane Kiko, currently in the Eastern Pacific, is forecast to approach the Hawaiian Islands early to middle portion of next week. While this approach is likely to occur mostly prior to this 6 to 10 day period, interests in Hawaii should monitor updates from NHC for the latest information on Kiko. Predicted strong mid-level ridging forecast over Central Canada favors above normal temperatures across the Northern Plains with probabilities of warmer than normal conditions exceeding 60 percent for parts of the Northern High Plains. Above normal temperatures are also most likely across southeastern Alaska and the northwestern CONUS, ahead of the predicted trough over the Gulf of Alaska. Below normal temperatures are favored behind this trough, across western Alaska. Farther to the south, troughing early in the period over the southwestern CONUS favors below normal temperatures across southern California, most of Nevada and adjacent areas of the Great Basin and Southwest. Predicted subtropical ridging over the Southern Plains leads to an increased chance of above normal temperatures across the central CONUS. Below normal temperatures are more likely along the Eastern Seaboard associated with anomalous troughing. Above normal temperatures are favored for southern Florida to the south of a predicted frontal boundary. Above normal temperatures in adjacent waters also favor warmer than normal conditions for this region. Above normal temperatures are also favored for the entire state of Hawaii associated with above normal SSTs in the adjacent Pacific, especially near the western and central islands. An active pattern is favored for much of the West due, in part, to an anomalous southern stream trough predicted over the southwestern CONUS early in the period. Teleconnections from the positive height anomaly center associated with the predicted Canadian ridge also supports increased chances of above normal precipitation across most of the West, with the main exception being Southern California and parts of western Arizona. Upstream, the predicted trough over the Gulf of Alaska supports increased chances of above normal precipitation for Southeast Alaska and adjacent areas of the Mainland. Teleconnections from the predicted ridge over Canada and the trough over the Gulf of Alaska both support a weak wet signal for northwestern Mainland Alaska leading to a slight tilt toward above normal precipitation there. Below normal precipitation is more likely for the western Mainland consistent with predicted low-level offshore flow and teleconnections from the predicted Gulf of Alaska trough. Below normal precipitation is favored from the Great Lakes and Interior Northeast southward to the Ohio, Tennessee, and much of the Lower and Middle Mississippi Valleys, due to predicted mean surface high pressure. Above normal precipitation is favored for the Florida Peninsula northward to the coastal Carolinas due to predicted frontal activity associated with the Eastern Seaboard trough. A trailing frontal boundary may also clip southern Texas, leading to slightly elevated chances of above normal precipitation for the southern tip of Texas. Above normal precipitation is favored for Hawaii due, in part, to potential residual effects from Kiko (or its remnants). The greatest chances of above normal precipitation is indicated for the western islands where potential impacts may be last to depart. The official 6-10 day 500-hPa height blend consists of 30% of Today's 6z GFS Ensemble Mean centered on Day 8, 40% of Today's 0z European Ensemble Mean centered on Day 8, and 30% of Today's 0z Canadian Ensemble Mean centered on Day 8 FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 3 out of 5, due to fair agreement among todays ensemble means. 8-14 DAY OUTLOOK FOR SEP 13 - 19 2025 During week-2, an amplified pattern persists across the higher latitudes of the Western Hemisphere into the early and middle portions of the period. The most stable feature is a predicted ridge over Central Canada. This ridge is forecast to linger throughout week-2 in the ECMWF and Canadian ensemble mean solutions. The trough predicted over the Gulf of Alaska is forecast to remain until the middle of the period and then weaken. Persistent cyclonic flow is forecast near the Bering Strait throughout the period. Farther to the south, cyclonic flow is forecast across much of the West early in the period, potentially transitioning to more zonal flow as the upstream Gulf of Alaska trough weakens. A southern stream feature predicted over the southwestern CONUS during the 6 to 10 day period is forecast to significantly weaken by the beginning of week-2. There is general agreement among the models that subtropical ridging will be present across the Southern Plains. The center of this subtropical ridge is slowly forecast to drift westward near the southern High Plains by the end of week-2. Uncertainty is high across the East as a trough near the Seaboard early in the period is forecast to weaken. However, remnant weak cyclonic flow is forecast to persist near the East Coast for much of the period. Slow height rises are forecast for the Southeast, but a general weakness in subtropical ridging still persists across the region at various times during week-2, with each ensemble mean differing in the specific timing and magnitude of this weakness. An active tropical disturbance currently in the central Atlantic will also need to be monitored for any potential impacts to the overall flow pattern across the East. Across Hawaii, Kiko (or its remnant low) is generally forecast to have passed by the island chain prior to week-2. Interests in Hawaii should continue to monitor the latest updates from the NHC for any changes in forecast track or timing of this system. Persistent ridging over central Canada leads to increased chances of above normal temperatures across the Northern Plains, with probabilities of above normal temperatures exceeding 60 percent for most of North Dakota and adjacent areas of Minnesota and Montana. Weak subtropical ridging predicted over the Southern Plains favors modestly enhanced probabilities of above normal temperatures across the remainder of the central CONUS. Above normal temperatures are also favored for most of the West, as a southern stream trough forecast during the 6 to 10 day period weakens and mid-level heights begin to rise. Above normal temperatures are likely for southeastern Alaska ahead of the predicted trough over the Gulf. Near normal temperatures are more likely for most of the remainder of the state, consistent with teleconnections from predicted negative 500-hPa anomaly center associated with the Gulf of Alaska trough. Below normal temperatures are favored along much of the Eastern Seaboard associated with predicted remnant cyclonic flow. Above normal temperatures remain more likely for the southern Florida Peninsula, influenced by above normal SSTs in the adjacent Atlantic and Gulf. Above normal temperatures are also likely for Hawaii, associated with above normal SSTs in the adjacent Pacific, particularly for the western and central islands. An active pattern remains favored for southeastern Alaska and the northwestern CONUS, ahead of the predicted trough over the Gulf of Alaska. Teleconnections from this trough favor a drier than normal pattern across the western Mainland. Above normal precipitation is favored for the Northern Plains, supported by teleconnections from the positive anomaly center associated with the ridge forecast over Central Canada. Below normal precipitation is favored for most of the interior East due to predicted expansive surface high pressure. Near or above normal precipitation is more likely along much of the immediate East Coast due to predicted onshore flow to the southeast of the predicted mean surface high position and due to uncertainty regarding the Tropics. Near normal precipitation is favored for eastern Hawaii as Kiko (or its remnants) exits the picture. A slight tilt toward above normal precipitation is indicated for the western and central islands, consistent with calibrated precipitation amounts from the GEFS and ECMWF ensembles. The official 8-14 day 500-hPa height blend consists of: 30% of Today's 6z GFS Ensemble Mean centered on Day 11, 40% of Today's 0z European Ensemble Mean centered on Day 11, and 30% 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 uncertainties surrounding the evolution of the 500-hPa flow pattern across much of the forecast domain. FORECASTER: Scott H Notes: 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 September 18. 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: 19860905 - 19710918 - 19790823 - 19740831 - 19770818 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: 19860905 - 19740831 - 19890911 - 19710918 - 20040815 6-10 DAY OUTLOOK TABLE Outlook for Sep 11 - 15 2025 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A A OREGON N A NRN CALIF N A SRN CALIF B N IDAHO N A NEVADA B A W MONTANA A A E MONTANA A A WYOMING A A UTAH N A ARIZONA N A COLORADO A A NEW MEXICO A A N DAKOTA A A S DAKOTA A A NEBRASKA A A KANSAS A A OKLAHOMA A N N TEXAS A N S TEXAS A N W TEXAS A N MINNESOTA A N IOWA A N MISSOURI A B ARKANSAS N B LOUISIANA N B WISCONSIN N N ILLINOIS N B MISSISSIPPI N B MICHIGAN N B INDIANA N B OHIO N B KENTUCKY N B TENNESSEE N B ALABAMA N B NEW YORK B B VERMONT B B NEW HAMP B B MAINE B B MASS B B CONN B B RHODE IS B N PENN B B NEW JERSEY B B W VIRGINIA B B MARYLAND B B DELAWARE B N VIRGINIA B B N CAROLINA B N S CAROLINA B N GEORGIA B N FL PNHDL N N FL PENIN N A AK N SLOPE N A AK ALEUTIAN N B AK WESTERN B B AK INT BSN A N AK S INT A N AK SO COAST A A AK PNHDL A A 8-14 DAY OUTLOOK TABLE Outlook for Sep 13 - 19 2025 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A A OREGON A A NRN CALIF A A SRN CALIF N N IDAHO A A NEVADA A A W MONTANA A A E MONTANA A A WYOMING A A UTAH A N ARIZONA A N COLORADO A N NEW MEXICO A N N DAKOTA A A S DAKOTA A A NEBRASKA A A KANSAS A A OKLAHOMA A N N TEXAS A N S TEXAS A N W TEXAS A N MINNESOTA A A IOWA A A MISSOURI A N ARKANSAS A B LOUISIANA A N WISCONSIN A N ILLINOIS A B MISSISSIPPI A B MICHIGAN A B INDIANA A B OHIO N B KENTUCKY N B TENNESSEE N B ALABAMA N N NEW YORK N B VERMONT B B NEW HAMP B B MAINE N B MASS B N CONN B N RHODE IS B N PENN N B NEW JERSEY B N W VIRGINIA N B MARYLAND B N DELAWARE B N VIRGINIA B N N CAROLINA B N S CAROLINA B N GEORGIA B N FL PNHDL N N FL PENIN A A AK N SLOPE N B AK ALEUTIAN A N AK WESTERN N B AK INT BSN A B AK S INT A N AK SO COAST A A AK PNHDL A A 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. $$