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Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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871 FXUS06 KWBC 201920 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Thu June 20 2024 6-10 DAY OUTLOOK FOR JUN 26 - 30 2024 During the 6-10 day outlook period, a low-amplitude flow pattern continues to be predicted over the Contiguous U.S. (CONUS) by the GEFS, ECMWF and Canadian ensemble means, with a short wave trough moving inland over the Pacific Northwest. Negative 500-hPa height anomalies are predicted over much of Canada and parts of the northern tier of the western and central CONUS. Positive 500-hPa height anomalies are forecast across most of the remainder of the CONUS by all of todays ensemble means, with +30 to +60 meter departures depicted on the manual height blend. Over time, the height anomalies over the eastern CONUS are forecast to gradually increase in amplitude, though this becomes more apparent in week-2. Weak 500-hPa height anomalies are predicted over Alaska in the manual blend, while modest negative height anomalies are indicated over Hawaii. Positive 500-hPa height anomalies and low-amplitude flow lead to likely above-normal temperatures in the forecast across most of the CONUS, except for parts of the Pacific Northwest and along the Canadian border into the central CONUS. Above-normal temperature chances exceed 60% from the Four Corners region eastward across the southern states to the Southeast Coast. Below-normal temperatures are favored for parts of the Pacific Northwest, under a predicted trough. Below-normal temperatures are favored for the Aleutians and islands in the Bering Sea, and the immediate west coast of Alaska, supported by most dynamical model forecasts and the proximity of unseasonably cold sea-surface temperatures. Near-normal temperatures are favored for the Alaska Panhandle, with a mid-level trough forecast to move across the region early in the 6-10 day period, followed by a mid-level ridge later in the period. Above-normal temperatures are favored over most of interior Mainland Alaska, supported by most of the temperature guidance. For Hawaii, the ERF CON tool favors below-normal temperatures. Above-normal precipitation is favored for the Alaska Peninsula and southwestern Mainland Alaska, in advance of a mid-level trough predicted over the Bering Sea. Near to below-normal precipitation chances are favored for Southeast Alaska, where a transition from mid-level troughing to mid-level ridging is expected. A slight tilt towards above-normal precipitation is favored for much of the CONUS, with greater chances for above-normal precipitation depicted for the Upper Midwest, the Pacific Northwest, and the Four Corners region. This is based on expected shortwaves riding up and over the anomalous ridge predicted over the east-central CONUS, a mid-level trough, and significant moisture associated with the climatological onset of the Southwest Monsoon possibly enhanced by another tropical system, respectively. Near to below-normal precipitation is favored over northern and central portions of California and Nevada, generally consistent with reforecast precipitation from the three ensemble mean models. Conflicting precipitation signals across much of the eastern CONUS warrants a broad area of favored near-normal precipitation for that region. For Hawaii, the ERF CON and automated precipitation tools favor increased odds of above-normal precipitation during the 6-10 day period. The official 6-10 day 500-hPa height blend consists of 33% of Today`s 0z GFS Ensemble Mean centered on Day 8, 34% of Today`s 0z European Ensemble Mean centered on Day 8, and 33% 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, due to good agreement among the 500-hPa height forecasts and surface temperature tools, offset by fairly weak precipitation signals for most of the country. 8-14 DAY OUTLOOK FOR JUN 28 - JUL 04, 2024 Generally, a zonal mid-level flow pattern is forecast over the CONUS in week-2, with an increase in the amplitude of positive 500-hPa height anomalies over the northeastern CONUS. A trough is predicted to deamplify across the Pacific Northwest and Northern Rockies during the period, with slightly positive height anomalies depicted on the manual height blend. Towards the end of week-2, daily height anomaly forecasts from the various dynamical models indicate a very broad area of significant positive height anomalies across most of the central and southern CONUS. Weak 500-hPa height anomalies are predicted over Alaska, while weak negative height anomalies continue to be forecast for Hawaii. Above-normal temperatures continue to be likely across most of the CONUS in week-2 (except for parts of the Pacific Northwest and northern tier as far east as the Upper Mississippi Valley), under positive 500-hPa height anomalies. Below-normal temperatures are favored for parts of the Pacific Northwest, under a predicted trough. Below-normal temperatures are favored for the coastal areas of western Alaska, the Alaska Peninsula, Kodiak Island, the Aleutians and offshore islands, in large part due to the proximity of anomalously cold sea-surface temperatures and the anticipated passage of shortwave energy across that region. Near-normal temperatures are again favored for the Alaska Panhandle, due to discrepancies between the warmer reforecast temperature tools and the cooler bias-corrected and raw temperature tools. Above-normal temperature chances are enhanced across much of Mainland Alaska, consistent with reforecast temperature tools and the automated temperature forecast. The ERF-CON and automated temperature tools for Hawaii continue to favor below-normal temperatures during week-2. The week-2 precipitation outlook is similar to the earlier 6-10 day precipitation outlook. A slight tilt in the odds for above-normal precipitation is indicated over approximately half of the Lower 48 states, with greater chances favored across the Four Corners region and Upper Midwest, as noted in the 6-10 day discussion. The odds for above-normal precipitation across the Pacific Northwest have diminished slightly relative to the 6-10 day period, due to an anticipated weakening of the mid-level trough in that region. As a result, the area of favored near to below-normal precipitation across parts of the West has increased in coverage compared to the earlier 6-10 day period. Near to slightly above-normal precipitation is depicted for Alaska, underscoring significant differences among the various precipitation inputs. The dynamical model-based precipitation tools continue to favor above-normal precipitation chances across the Hawaiian Islands. The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 0z GFS Ensemble Mean centered on Day 11, 35% 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: Average, 3 out of 5, due to good agreement among the temperature tools offset by weak and conflicting precipitation signals for large portions of the country. FORECASTER: Anthony A 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: 19840609 - 19940615 - 19570616 - 19590627 - 20050626 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: 19840609 - 19940615 - 20050609 - 19570616 - 20050627 6-10 DAY OUTLOOK TABLE Outlook for Jun 26 - 30 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF N B SRN CALIF A N IDAHO A A NEVADA A B W MONTANA N A E MONTANA A A WYOMING A A UTAH A A ARIZONA A A COLORADO A A NEW MEXICO A A N DAKOTA A A S DAKOTA A A NEBRASKA A A KANSAS A A OKLAHOMA A A N TEXAS A A S TEXAS A A W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS A A LOUISIANA A A WISCONSIN N A ILLINOIS A A MISSISSIPPI A A MICHIGAN N A INDIANA A N OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A N NEW YORK A N VERMONT A N NEW HAMP A N MAINE A A MASS A N CONN A N RHODE IS A N PENN A N NEW JERSEY A N W VIRGINIA A N MARYLAND A N DELAWARE A N VIRGINIA A N N CAROLINA A N S CAROLINA A N GEORGIA A N FL PNHDL A A FL PENIN A A AK N SLOPE A N AK ALEUTIAN B A AK WESTERN N A AK INT BSN A N AK S INT A A AK SO COAST A A AK PNHDL N N 8-14 DAY OUTLOOK TABLE Outlook for Jun 28 - Jul 04, 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B B NRN CALIF A B SRN CALIF A N IDAHO N B NEVADA A B W MONTANA B A E MONTANA N A WYOMING A N UTAH A A ARIZONA A A COLORADO A A NEW MEXICO A A N DAKOTA N A S DAKOTA A A NEBRASKA A A KANSAS A A OKLAHOMA A N N TEXAS A N S TEXAS A A W TEXAS A N MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS A N LOUISIANA A N WISCONSIN A A ILLINOIS A A MISSISSIPPI A N MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A N TENNESSEE A N ALABAMA A N NEW YORK A N VERMONT A N NEW HAMP A N MAINE A N MASS A N CONN A N RHODE IS A N PENN A N NEW JERSEY A N W VIRGINIA A N MARYLAND A N DELAWARE A N VIRGINIA A N N CAROLINA A 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 N N AK INT BSN A N AK S INT A N AK SO COAST B N 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. $$