####018013261#### 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 April 08 2024 6-10 DAY OUTLOOK FOR APR 14 - 18 2024 A rapid change in the forecast height pattern over the weekend has resulted in a much different height pattern today relative to that predicted last Friday. Today's model solutions are in good agreement on the predicted amplified 500-hPa circulation pattern across North America and surrounding regions during the 6-10 day period. However, the major features across the western contiguous U.S. (CONUS) and adjacent Pacific have retrograded slightly relative to the official outlook yesterday. The manual 500-hPa height blend is based primarily on the ensemble means from the GEFS, ECENS, and Canadian models due to recent model skill. The resultant manual blend features positive 500-hPa height anomalies over Alaska down into the eastern Pacific, negative 500-hPa height anomalies over the Interior West into the Great Plains, and positive anomalies over the eastern CONUS. Near-normal heights are favored for Hawaii with negative 500-hPa height anomalies northwest of the island chain. Mid-level ridging forecast across the East brings elevated chances for above-normal temperatures across much of the country east of the Rocky Mountains. The strongest chances are forecast in the Mississippi Valley with probabilities exceeding 70% in this region. Across the West, there is greater uncertainty in the temperature forecast with many of the raw and short-term bias-corrected tools indicating increased chances for below-normal temperatures while the reforecast tools generally favor more near-to-above-normal temperatures in the region. Therefore, there is a slight tilt towards below-normal temperatures for the Northwest while near-normal temperatures are favored across the southwestern CONUS. In Alaska, below-normal temperatures are favored. Relatively strong mid-level flow is forecast to bring Siberian air into the state. The GEFS and Canadian reforecasts favor a much cooler solution while the ECENS favors more near- to even above-normal temperatures adding to the uncertainty. In Hawaii, a slight tilt towards above-normal temperatures in forecast consistent with the consolidation tool. The 6-10 day precipitation outlook is consistent with yesterday’s forecast. An area of above-normal precipitation is favored across the center of the CONUS east of a mid-level trough. The GEFS and ECENS are supportive of the potential for lee-side cyclogenesis that could bring enhanced chances for above-normal precipitation to parts of the Rockies, Plains, and Mississippi Valley. Further East, beneath strongly positive 500-hPa height anomalies and mid-level ridging, near to below-normal precipitation is favored. While behind the trough axis across the West, below-normal precipitation is also favored across most of California and much of the Pacific Northwest. In Alaska, above-normal precipitation is favored across the northern half of the Mainland with near-normal precipitation favored in the southern half and below-normal precipitation favored in the Alaska Peninsula and southern Southeast Alaska. In Hawaii, above-normal precipitation is favored for much of the state with strong chances forecast by the consolidation tools. The official 6-10 day 500-hPa height blend consists of 10% of Today's 0z GFS Ensemble Mean centered on Day 8, 25% of Today's 6z 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 agreement among the dynamical model height tools offset by differences among the sensible weather tools. 8-14 DAY OUTLOOK FOR APR 16 - 22 2024 During week-2 a strong positive 500-hPa height anomaly is forecast over the Bering Sea with positive anomalies across most of Alaska and into the eastern Pacific off the West Coast. Weakly negative anomalies are forecast across the northern Interior West with near-normal heights over the southern Four Corners region. While across the eastern CONUS, positive 500-hPa height anomalies remain forecast as in the 6-10 day period. As in the 6-10 day period, the major features across the parts of the CONUS have largely retrograded a few hundred miles relative to yesterday’s forecast. The week-2 temperature forecast is similar to the 6-10 day forecast with the strongest chances for above-normal temperatures across the eastern half of the CONUS. Above-normal temperature chances exceeding 50% are forecast for parts of the Great Lakes and New England along with portions of the Southeast. In the southwestern CONUS, above-normal temperatures are favored for the week-2 period with a weaker trough forecast reducing chances for cold air to intrude into the region. In the northwestern CONUS, near- to below-normal temperatures are forecast. There remains considerable disagreement between the ensemble dynamical tools regarding the magnitude of any below-normal temperatures in the Northwest. As a result, a broader area of near-normal temperatures is favored for the Pacific Northwest while over the Northern Rockies and Northern High Plains below-normal is favored with more agreement among the tools in this region. In Alaska, below-normal remains favored across most of the State despite a ECENS reforecast tool that is considerably warmer than its raw counterpart and the reforecasts from the GEFS and Canadian. This does introduce more uncertainty into the temperature forecast across the State. In Hawaii, near-normal temperatures are favored. The week-2 precipitation forecast is similar to the 6-10 day forecast with a large area of slightly enhanced chances for above-normal precipitation across the center of the CONUS in conjunction with the troughing across the Interior West. Behind the trough along the West Coast, below-normal precipitation is favored with positive 500-hPa heights beginning to progress into the region by the end of the period. In the East, near-normal is favored in the Northeast and along much of the Eastern Seaboard with positive anomalies remaining forecast in the region. In Alaska, above-normal precipitation remains favored across the northern half of the mainland. Near-normal is favored for the Gulf of Alaska coast. In Hawaii, a slight tilt towards above-normal precipitation is favored for much of the state, excluding the Big Island. The official 8-14 day 500-hPa height blend consists of: 10% of Today's 0z GFS Ensemble Mean centered on Day 11, 25% of Today's 6z 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, Fair agreement in the evolution of the mid-level height pattern offset less agreement in the temperature forecast across the West and Alaska. 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 April 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: 20010402 - 19870319 - 20060319 - 20070418 - 20050411 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: 19870318 - 20010402 - 19950323 - 20060319 - 20060418 6-10 DAY OUTLOOK TABLE Outlook for Apr 14 - 18 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B N OREGON B B NRN CALIF N B SRN CALIF N B IDAHO N A NEVADA N N W MONTANA N A E MONTANA A A WYOMING N A UTAH N A ARIZONA N N COLORADO A A NEW MEXICO A N 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 A A ILLINOIS A A MISSISSIPPI A A MICHIGAN A A INDIANA A A 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 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 B A AK ALEUTIAN B B AK WESTERN B A AK INT BSN B A AK S INT B N AK SO COAST B N AK PNHDL B N 8-14 DAY OUTLOOK TABLE Outlook for Apr 16 - 22 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON N B OREGON N B NRN CALIF A B SRN CALIF A B IDAHO N N NEVADA A B W MONTANA B N E MONTANA B A WYOMING B A UTAH N N ARIZONA A B COLORADO N A NEW MEXICO A A N DAKOTA N A S DAKOTA N 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 A 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 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 A S CAROLINA A A GEORGIA A A FL PNHDL A A FL PENIN A N AK N SLOPE B A AK ALEUTIAN B N AK WESTERN B A 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. $$ ####018005448#### FXUS01 KWBC 081903 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 303 PM EDT Mon Apr 08 2024 Valid 00Z Tue Apr 09 2024 - 00Z Thu Apr 11 2024 ...Heavy rain, flash flooding and severe weather threat emerging across the Southern Plains into the Lower Mississippi Valley tonight and through Tuesday & Wednesday... ...Critical fire danger shifts into Texas Big Bend by Tuesday... At the writing of this discussion, the 2024 Great American Eclipse was well underway with the culprit for reduced visibility over the southern portion of the United States from Texas to the Lower Mississippi Valley is an anomalous deep upper level low starting to dig into northern Old Mexico. This has resulted in increased low level moisture, cloud cover but will become much more dangerous evolving into a very strong Southern Plains surface low bringing a cornucopia of severe weather hazards starting this evening across much of the southern Plains eventually sliding eastward into the lower Mississippi Valley. After eclipse parties may come with unwanted crashers in the form of: fireworks, potential spinners, wind machines, water sprayers and ice makers, as much of Texas has a broad Slight Risk (2 of 5) of severe weather over much of Texas, with an Enhanced Risk (3 of 5) across much of Northwest and Northeast Texas south of the Red River. Significant hail appears to be the greatest threat, but overlapped are isolated tornadoes and severe winds. As the severe party is going, heavy rainfall potential with possible flash flooding conditions will continue to the party into the later hours of Monday evening into Tuesday morning; with the Weather Prediction Center issuing a Slight Risk (level 2 of 4) much of northeast Texas and into southern Arkansas, northern Louisiana and western Mississippi into the early morning hours of Tuesday. On the western side of the system over the mid Rio Grande Valley and Big Bend of Texas, increased fire danger will exist with very low humidity values (single digit dewpoints) and increasing winds. Today, the Storm Prediction Center (SPC) has an Elevated (level 1 of 3) risk of fire danger, but as the surface low really takes shape tomorrow (Tuesday) and winds further increase, a Critical Fire (2 of 3) is forecast over the Big Bend to Lower Pecos River. Tuesday will fair little better across the Southern Plains as the upper-level low brings cooling aloft and with continued warm, moist air off the Gulf and dry air from the Mexican Plateau in the low to mid-levels; very unstable weather conditions will exist again across much of Texas; though the axis of concern will shift ever so southward, from the Permian Basin/Edwards Plateau across to the Piney Woods of E Texas and into Louisiana. Low level wind profiles become a bit more conducive for tornadoes with similar wind and hail risks. SPC has an Enhanced Risk (3 of 5) across central Texas to west-central Louisiana which also aligns with the hatched area indicating an increased potential for strong tornadoes. Similarly, with an overlap of additional round and increased overall moisture to the area, WPC has a Moderate Risk of Excessive Rainfall (3 of 4) is up for downstream areas of far E Texas, northern half of Louisiana, southern Arkansas into western Mississippi indicating broader areal coverage for potential flash flooding conditions. By Wednesday, the surface low is deepening in earnest across southern Texas and starting to lift into the Sabine River Valley by early Wednesday; so once again, a similar environment for severe weather and flash flooding will exist but start shifting east with the core of the Enhanced Risk from SPC over the Lower Mississippi Valley of LA/MS with a Slight Risk covering much of N MS and into AL and far western FL Panhandle. A similar downstream Slight Risk of Excessive Rainfall from WPC extends a bit further north and east into Western Kentucky and eastern Georgia, as multiple days/rounds of rainfall likely have saturated the ground making them more susceptible into Wednesday. A Moderate Risk of Excessive Rainfall is located from E MS, across central AL to the Chattahoochee River and western Georgia likely for stronger thunderstorms with rates of 2-3"/hr and potential training/repeating to induce higher risk of flash flooding as well. Elsewhere, cloud cover remains across the Northern Plains into the Upper Great Lakes with the rapidly filling cyclone. The warm frontal band of clouds and weak showers are/have ruined eclipse viewing in much of New York. Weak showers will slide downstream into the Northeast later today, with a secondary surge of light rain showers for the central Great Lakes into New York for Tuesday into Wednesday. Behind the front, clear skies will allow for increased heating across the Upper Midwest with the only area of above average temperatures (about 10-15 degrees) as places reach the mid to upper 60s on Wednesday. The Pacific Northwest will see a clipping frontal zone with some moisture and high elevation light snows into the northern Cascades and eventually Rockies Tuesday, drying out for Wednesday. Gallina Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$