069 FXUS06 KWBC 051902 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Mon June 05 2023 6-10 DAY OUTLOOK FOR JUN 11 - 15 2023 Model solutions are in good agreement with a pair of anomalous 500-hPa troughs over the eastern and southwestern CONUS. The ensemble means depict negative 500-hPa height anomalies of more than 60 meters across southern California and the Desert Southwest where large probabilities of below-normal temperatures are forecast. The favored cooler-than-normal temperatures extend north to include much of California and the Great Basin, consistent with anomalous troughing and reforecast tools. Below-normal temperatures are also slightly favored for the Central to Southern High Plains, due in part to wet topsoil. Despite good model agreement on the amplified trough over the eastern CONUS, reforecast tools differ with the GEFS and Canadian favoring below-normal temperatures across the Ohio Valley, Southeast, and Mid-Atlantic and the ECMWF having near to above-normal temperature probabilities. Given these model differences and an expectation that any cooler-than-normal temperatures time off around day 9, below-normal temperatures are only slightly favored for the Ohio and Tennessee Valleys. The longwave pattern and temperature tools support increased above-normal temperature probabilities for the Pacific Northwest, Northern Rockies, Northern Great Plains, Upper Mississippi Valley, along with much of Texas, the Gulf Coast, and Florida. On days 6 and 7 (June 11-12), a cold front is forecast to shift southeastward across the east-central CONUS which favors near to above-normal precipitation across the Northeast, Mid-Atlantic, and Ohio to Tennessee Valleys. Elevated probabilities of above-normal precipitation are also forecast for parts of the Middle to Lower Mississippi Valley and Central to Southern Great Plains as the front is expected to become stationary and provide a focus for daily convection. In the wake of the cold front, below-normal precipitation is more likely across the Northern Great Plains and Upper Mississippi Valley. The amplified 500-hPa trough favors above-normal precipitation throughout much of the West. Probabilities are large (above 60 percent) across parts of California and the Great Basin which are relatively dry at this time of year. A strengthening subtropical ridge elevates probabilities for below-normal precipitation across parts of the Gulf Coast, Texas, southern New Mexico, and southeast Arizona. Model guidance is in excellent agreement with an amplified, broad 500-hPa trough over the Bering Sea and western Alaska. This trough enhances probabilities for above-normal precipitation for Alaska. Consistent with this wet pattern along with negative 500-hPa height anomalies, below-normal temperatures are favored for much of Alaska as well. The official 6-10 day 500-hPa height blend consists of 35% of Today's 0z GFS Ensemble Mean centered on Day 8, 35% 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: Average, 3 out of 5, due to good model agreement on the 500-hPa height pattern offset by differences in the temperature tools across the East and uncertainty in the precipitation outlook related to convective rainfall. 8-14 DAY OUTLOOK FOR JUN 13 - 19 2023 The pair of troughs, over the eastern and southwestern CONUS, are forecast to deamplify during week-2, while a 500-hPa ridge strengthens over the south-central CONUS. The ECMWF ensemble mean is most bullish with the amplitude of this ridge with mean 500-hPa heights increasing to 588-dm as far north as Arkansas and Oklahoma with heights peaking near 594-dm across south Texas. A significant increase in 500-hPa heights along with mean 7-day southerly surface flow results in a much warmer outcome from the Great Plains to the East Coast for week-2, compared to the 6-10 day period. In addition, a two-category change in yesterday's temperature outlook was necessary for parts of the east-central CONUS due to the predicted longwave pattern transition and good agreement among the temperature tools. Below-normal temperatures remain favored across the Southwest, Great Basin, and much of California, associated with the anomalous 500-hPa trough. Along and downstream of a 500-hPa trough axis over the western CONUS, elevated probabilities for above-normal precipitation are forecast throughout much of the West and the central Great Plains. The drier climatology results in the largest probabilities to be located across the Great Basin. A broad trough aloft and increasing low-level moisture is expected to support diurnal convection, with varying coverage across the Corn Belt, Northeast, and Mid-Atlantic where near normal precipitation is most likely. The strengthening subtropical ridge is likely to suppress sea breeze convection and the mid-latitude storm track is likely to shift well northward during the latter half of June. Therefore, increased probabilities for below-normal precipitation are forecast for much of the south-central and southeastern CONUS. Ensemble means maintain the anomalous 500-hPa trough across the Bering Sea and western Alaska through week-2, which continues to favor near to below-normal temperatures across Alaska. The precipitation outlook slightly leans toward above-normal precipitation over Mainland Alaska, consistent with the trough aloft and precipitation tools. 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 a predicted longwave pattern transition over the central and eastern CONUS. FORECASTER: Brad Pugh 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 15. 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: 19910605 - 19820516 - 19620608 - 19940518 - 19720526 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: 19910605 - 19620608 - 19820515 - 19720525 - 19940517 6-10 DAY OUTLOOK TABLE Outlook for Jun 11 - 15 2023 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A A OREGON A A NRN CALIF B A SRN CALIF B A IDAHO A A NEVADA B A W MONTANA A A E MONTANA A A WYOMING B A UTAH B A ARIZONA B A COLORADO B A NEW MEXICO B A N DAKOTA A B S DAKOTA A N NEBRASKA B A KANSAS B A OKLAHOMA B A N TEXAS A N S TEXAS A B W TEXAS B A MINNESOTA A B IOWA N N MISSOURI B A ARKANSAS B A LOUISIANA A N WISCONSIN N B ILLINOIS N N MISSISSIPPI A N MICHIGAN N N INDIANA N N OHIO N N KENTUCKY B A TENNESSEE B A ALABAMA N N NEW YORK N A VERMONT N N NEW HAMP N N MAINE N N MASS N A CONN N A RHODE IS N A PENN N A NEW JERSEY N A W VIRGINIA B A MARYLAND N A DELAWARE N A VIRGINIA N A N CAROLINA N N S CAROLINA N N GEORGIA N N FL PNHDL N N FL PENIN A B AK N SLOPE N 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 Jun 13 - 19 2023 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A N OREGON B A NRN CALIF B A SRN CALIF B A IDAHO B A NEVADA B A W MONTANA B A E MONTANA B A WYOMING B A UTAH B A ARIZONA B N COLORADO B A NEW MEXICO B B N DAKOTA A N S DAKOTA A A NEBRASKA A A KANSAS A N OKLAHOMA A B N TEXAS A B S TEXAS A B W TEXAS A B MINNESOTA A N IOWA A N MISSOURI A N ARKANSAS A B LOUISIANA A B WISCONSIN A N ILLINOIS A N MISSISSIPPI A B MICHIGAN A N INDIANA A N OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A B 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 B GEORGIA A B FL PNHDL A B FL PENIN A B AK N SLOPE N 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 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. $$