Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
037 FXUS06 KWBC 021903 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Thu May 02 2024 6-10 DAY OUTLOOK FOR MAY 08 - 12 2024 The ECENS and GEFS predicted 500-hPa heights continue to be in fairly good agreement with the Canadian ensemble mean coming into better agreement today. Negative 500-hPa height anomalies are forecast across Alaska, the western and northern contiguous U.S. (CONUS), and New England. Near- to above-normal 500-hPa heights are forecast across the southeastern CONUS. The negative mid-level height anomalies across the West are forecast to progress eastward across the northern tier during the period. Positive anomalies across the eastern Pacific may intrude into parts of the Northwest by the end of the 6-10 day period, reducing the mean heights across the Northwest relative to yesterday. Mid-level ridging across the southeastern CONUS is forecast to bring above-normal temperatures to much of the eastern CONUS during the 6-10 day period. The highest confidence for above-normal temperatures remains across the Southeast into the Mid-Atlantic ahead of any potential frontal systems associated with the negative 500-hPa height anomalies forecast to progress across the CONUS later in the period. There is reduced confidence in above-normal temperatures in parts of the western Great Lakes where the mid-level trough is forecast to influence by the end of the period. In the West, below-normal temperatures are generally favored with the highest probabilities across parts of the northern Great Basin. In Alaska, below-normal temperatures are likely across the Alaska Peninsula and southwestern Mainland. In Southeast Alaska, below-normal temperatures are slightly favored. The interior Mainland is forecast to see near-normal temperatures. In Hawaii, below-normal temperatures are favored beneath mid-level troughing. As the mid-level trough, initially along the West Coast, progresses eastward above normal precipitation is forecast beneath and just ahead of the trough. The focus of above-normal precipitation chances has shifted south relative to yesterday with a broad trough now hanging across the country. Therefore, above-normal precipitation is now forecast for the Southeast, Tennessee and Lower-Mississippi Valleys. While the GEFS precipitation reforecast tool remains weaker relative to the ECENS reforecast the spatial pattern of the anomalies is consistent, increasing confidence in above-normal across these regions. However, below-normal precipitation remains favored for Florida and the parts of the Rio Grande Valley ahead of the mean trough. Along the West Coast, below-normal precipitation chances are forecast as positive 500-hPa height anomalies build into the Pacific Northwest. In Alaska, anomalously below-normal 500-hPa heights supports above-normal precipitation across much of the state. A slight tilt towards above-normal precipitation is favored across much of Hawaii with negative 500-hPa height anomalies forecast. 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: Average, 3 out of 5, Due to good agreement among the dynamical model tools but pattern is becoming more transient reducing confidence. 8-14 DAY OUTLOOK FOR MAY 10 - 16 2024 The dynamical models have weak mean mid-level height anomalies for the week-2 period leading to increased uncertainty across much of the country. The strongest anomalies are positive across the Pacific Northwest and East Pacific. Elsewhere, near to below-normal mid-level heights are favored across much of the CONUS, Alaska, and the central Pacific. The strongest mean 500-hPa height negative anomalies are found over the Great Lakes and Northeast. Positive height anomalies are slightly stronger across parts of the Gulf of Mexico and Southern Plains relative to yesterday. Above-normal temperatures remain favored across the southeastern CONUS during the 8-14 day period. The strongest probabilities are forecast closest to the Gulf Coast and the Florida Peninsula, near the abnormally strong subtropical ridge. A weakening trough is forecast across the interior Mountain West for much of the period. This may bring unsettled weather to the region and generally cooler temperatures. As this trough progresses east it will displace warmer than normal conditions ahead of it. Therefore, near-normal temperatures are forecast for the Great Lakes and Northeast. Along the West Coast, a slight tilt towards above-normal temperatures is favored as ridging is forecast to begin building into the region during week-2. In Alaska, below-normal temperatures are favored across much of the state with the strongest chances forecast across the southern portions. In Hawaii, near-normal temperatures are forecast with near-normal heights favored over the state. Below-normal precipitation is favored for the Pacific Northwest and parts of northern California with ridging building into the region. Generally, unsettled weather is forecast across the Rockies and into the Plains through to the eastern seaboard with a broad mid-level trough forecast across the CONUS during week-2. The strongest chances for above-normal precipitation are forecast for portions of the southern Mid-Atlantic, Southeast, and Tennessee Valley as a somewhat stationary front may become established and may help to focus additional precipitation into these regions. A second area of slightly enhanced chances for above-normal precipitation is over climatologically quite dry regions of the interior West where a small amount of precipitation may bring week-2 totals above-normal. In Florida, near-normal precipitation is favored during the climatologically driest time of the year. In Alaska, above-normal precipitation is generally favored across the state with unsettled weather beneath a mid-level trough continuing. Meanwhile, above-normal precipitation is again slightly favored for Hawaii consistent with the consolidation of tools. The official 8-14 day 500-hPa height blend consists of: 5% of Today`s 0z GFS Ensemble Mean centered on Day 11, 35% 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, Good agreement in the model tools offset by the progressive pattern leading to differences in timing among the tools and low mid-level height anomalies. 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 May 16. 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: 19850423 - 19790412 - 19640503 - 20030516 - 19730419 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: 19640504 - 19850422 - 19790411 - 19990515 - 20030506 6-10 DAY OUTLOOK TABLE Outlook for May 08 - 12 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B B OREGON B B NRN CALIF B B SRN CALIF B N IDAHO B N NEVADA B N W MONTANA B A E MONTANA B A WYOMING B A UTAH B A ARIZONA B N COLORADO B A NEW MEXICO B N N DAKOTA B A S DAKOTA B A NEBRASKA B A KANSAS N N OKLAHOMA A A N TEXAS A N S TEXAS A B W TEXAS A N MINNESOTA N A IOWA N A MISSOURI A A ARKANSAS A A LOUISIANA A A WISCONSIN N A ILLINOIS A A MISSISSIPPI A A MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A A TENNESSEE A A ALABAMA A A NEW YORK A A VERMONT A A NEW HAMP A A MAINE N 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 A FL PNHDL A N FL PENIN A B AK N SLOPE N A AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A AK S INT B A AK SO COAST B A AK PNHDL B A 8-14 DAY OUTLOOK TABLE Outlook for May 10 - 16 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A B OREGON A B NRN CALIF A N SRN CALIF B A IDAHO N N NEVADA N A W MONTANA N N E MONTANA N N WYOMING B A UTAH B A ARIZONA B N COLORADO B A NEW MEXICO B A N DAKOTA N N S DAKOTA B N NEBRASKA B A KANSAS B A OKLAHOMA N A N TEXAS A A S TEXAS A A W TEXAS N A MINNESOTA N N IOWA B N MISSOURI N A ARKANSAS A A LOUISIANA A A WISCONSIN N N ILLINOIS N N MISSISSIPPI A A MICHIGAN N N INDIANA N N OHIO N A KENTUCKY N A TENNESSEE A A ALABAMA A A NEW YORK N A VERMONT N A NEW HAMP N A MAINE N A MASS N A CONN N A RHODE IS N A PENN N A NEW JERSEY N A W VIRGINIA N A MARYLAND N A DELAWARE N A VIRGINIA A A N CAROLINA A A S CAROLINA A A GEORGIA A A FL PNHDL A A FL PENIN A N AK N SLOPE N A AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A AK S INT B A AK SO COAST B A AK PNHDL B 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. $$