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Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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961 FXUS06 KWBC 081902 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Mon July 08 2024 6-10 DAY OUTLOOK FOR JUL 14 - 18 2024 There is some disagreement in the dynamical models forecast of the mid-level height pattern across the contiguous U.S. (CONUS) with the GEFS and Canadian (CMCE) forecasting a broad ridge centered across the Plains with weak mid-level troughing along the East and West Coasts resulting from reduced positive anomalies. The ECENS maintains a stronger ridge across the western CONUS with near-normal heights across the East, leading to weak troughing. However, generally all the dynamical model tools forecast positive 500-hPa height anomalies for much of the CONUS during the 6-10 day period. In Alaska, there is good agreement for negative 500-hPa height anomalies and troughing to continue through the period. Hawaii is forecast to see near to slightly above-normal 500-hPa heights. Above-normal temperatures are favored for nearly the entire CONUS and Hawaii during the 6-10 day period. The strongest chances for above-normal temperatures are in the Mid-Atlantic and southern Atlantic States with strong agreement among the reforecast and raw ensemble guidance. A second maximum continues to be forecast across the Northern Interior West into the Central Plains with continued mid-level ridging the most likely solution during the period. There is a weakness in above-normal temperature chances across parts of the Great Lakes, where the ECENS introduces chances for near-normal temperatures during the period and in the Desert Southwest where monsoon moisture may limit diurnal heating reducing chances for above-normal temperatures. Along the West Coast, chances are diminished. Strong heating in the interior west may help to increase chances for onshore winds reducing chances for above-normal temperatures along the Coast. In Alaska, below-normal temperatures continue to be forecast with deep mid-level troughing persisting into the period. In Hawaii, above-normal temperatures are forecast consistent with dynamical tools. Above-normal precipitation is slightly favored across portions of the eastern CONUS during the 6-10 day period. The ECENS reforecast has stronger chances for above-normal precipitation relative to the GEFS, likely due to the placement of the strongest positive mid-level height anomalies. A broad area of near-normal is favored across the Plains and Lower-Mississippi Valley with generally weak and mixed signals from the dynamical tools. A slight tilt towards below-normal is favored in parts of the Great Basin, Northern Rockies, and the northern High Plains. Meanwhile, the best signals for above-normal precipitation are favored in the Four-Corners region with continued monsoon moisture in the region. In Alaska, above-normal is favored across much of the state with mid-level troughing helping to induce unsettled weather. Near-normal precipitation is favored in Hawaii, due to weak and opposite signals among the tools. The official 6-10 day 500-hPa height blend consists of 10% of Today`s 0z GFS Ensemble Mean centered on Day 8, 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 20% of Today`s 0z Canadian Ensemble Mean centered on Day 8 FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above-Average, 4 out of 5. Fair agreement among the dynamical height and temperature tools is offset by a weak summer precipitation pattern. 8-14 DAY OUTLOOK FOR JUL 16 - 22 2024 As in the 6-10 day period, there remains some disagreement between the strength and location of a broad mid-level ridge across the CONUS. The ECENS maintains the stronger ridge across the western CONUS while the GEFS and CMCE are building the strongest anomalies across the Upper-Midwest and northern Plains. Despite these differences, generally broad ridging is forecast across the CONUS with weakly positive anomalies forecast across the southern tier and stronger anomalies across the northern CONUS. In Alaska, a very different pattern is being forecast relative to the 6-10 day period with near-normal heights now favored across much of the state. The CMCE is even bringing in weak positive anomalies to the Aleutian Islands and Alaska Peninsula. In Hawaii, near to slight positive 500-hPa heights are again forecast. Above-normal temperatures continued to be favored across most of the CONUS during week-2. The strongest chances remain forecast for the Northern Rockies and northern High Plains beneath positive 500-hPa height anomalies. A secondary maximum is forecast across parts of the Florida Peninsula and southeastern CONUS. As in the 6-10 day period, there continues to be some disagreement among the reforecast tools from the ECENS, forecasting near-normal temperature chances, and the GEFS, maintaining strong above-normal temperature chances, regarding the temperature forecast across the eastern CONUS. However, the ECENS raw forecast continues to favor slight chances for above-normal temperatures in the region. Therefore, probabilities for above-normal temperatures are reduced but still lean above-normal where there are the largest disagreements. In the Southwest, chances for above-normal temperatures are again reduced relative to areas further north, as monsoon moisture continues to be favored across the region, thus limiting diurnal heating potential. In Alaska, below-normal temperatures remain forecast consistent with guidance and near-normal mid-level heights forecast. In Hawaii, above-normal temperatures are slightly favored. The precipitation signals in the guidance continue to be weak and mixed across many portions of the country. The strongest chances for above-normal precipitation are in portions of the Desert Southwest with continued monsoon moisture flowing into the region. A second area of slightly enhanced precipitation is forecast for portions of the Carolinas and Georgia where raw model tools are in agreement for a stalled front to help promote additional precipitation. Elsewhere across the southern and eastern CONUS, a slight tilt towards above-normal precipitation is generally favored. The precipitation type is most likely to be daily summer-time thunderstorms and some of the precipitation may be more localized. In the north-central CONUS, near to slightly below-normal precipitation is favored beneath the stronger positive 500-hPa height anomalies. In Alaska, above-normal precipitation is generally forecast consistent with raw model guidance and near-normal mid-level heights. In Hawaii, above-normal precipitation is favored. The official 8-14 day 500-hPa height blend consists of: 10% of Today`s 0z GFS Ensemble Mean centered on Day 11, 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 20% of Today`s 0z Canadian Ensemble Mean centered on Day 11 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Average, 3 out of 5. Some disagreement in the mid-level height pattern between the ECENS and GEFS reduces confidence offset by continued warm conditions across much of the CONUS. FORECASTER: Ryan Bolt 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 July 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: 19860721 - 19790717 - 20060623 - 19670701 - 20000626 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: 20060623 - 20060628 - 19860721 - 19670630 - 19790716 6-10 DAY OUTLOOK TABLE Outlook for Jul 14 - 18 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 A UTAH A A ARIZONA A A COLORADO A A NEW MEXICO A A N DAKOTA A N S DAKOTA A N NEBRASKA A N KANSAS A N OKLAHOMA A N N TEXAS A N S TEXAS A N W TEXAS A A MINNESOTA A N IOWA A N MISSOURI A N ARKANSAS A N LOUISIANA A N WISCONSIN A N ILLINOIS A N MISSISSIPPI A N MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A A TENNESSEE A N ALABAMA A N NEW YORK A A VERMONT A A NEW HAMP A A MAINE A A MASS A A CONN A A RHODE IS A A PENN A A NEW JERSEY A A W VIRGINIA A A MARYLAND A A DELAWARE A A VIRGINIA A A N CAROLINA A A S CAROLINA A A GEORGIA A N FL PNHDL A A FL PENIN A A AK N SLOPE B A AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A AK S INT B A AK SO COAST B A AK PNHDL B A 8-14 DAY OUTLOOK TABLE Outlook for Jul 16 - 22 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 N E MONTANA A B WYOMING A N UTAH A A ARIZONA A A COLORADO A A NEW MEXICO A A N DAKOTA A N S DAKOTA A N NEBRASKA A N KANSAS A N OKLAHOMA A A N TEXAS A A S TEXAS A A W TEXAS A A MINNESOTA A N IOWA A N MISSOURI A A ARKANSAS A A LOUISIANA A A WISCONSIN A N ILLINOIS A A MISSISSIPPI A A MICHIGAN A N INDIANA A A OHIO A A KENTUCKY A A TENNESSEE A A ALABAMA A A NEW YORK A A VERMONT A N NEW HAMP A N MAINE A N MASS A N CONN A N RHODE IS A N PENN A A NEW JERSEY A A W VIRGINIA A A MARYLAND A A DELAWARE A A VIRGINIA A A N CAROLINA A A S CAROLINA A A GEORGIA A A FL PNHDL A A FL PENIN A A AK N SLOPE B A AK ALEUTIAN B N AK WESTERN B N AK INT BSN B A AK S INT B N AK SO COAST B N AK PNHDL B 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. $$