Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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713 FXUS06 KWBC 072001 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EST Thu November 07 2024 6-10 DAY OUTLOOK FOR NOV 13 - 17 2024 The GEFS, ECENS, and CMCE remain consistent that a 500-hPa trough amplifies over the western contiguous U.S. (CONUS) during the period. A transient shortwave trough is forecast to shift offshore of the East Coast on day 8 with a building ridge across the east-central CONUS. The amplifying 500-hPa trough with negative 500-hPa height departures support increased chances for below-normal temperatures across California, the Great Basin, and Desert Southwest. The GEFS and ECENS reforecast tools are in better agreement today with near to above-normal temperatures favored for the Pacific Northwest and Northern Intermountain West. From the Great Plains to the East Coast, predicted mean southerly flow during this 5-day period favors above-normal temperatures. A blocking ridge over the North Atlantic may lead to a strengthening low pressure system near southeastern New England on day 8. Although ensemble spread is large on the strength and location of this low pressure system, there could be a brief period of cold air advection and only a slight lean towards above or near normal temperatures are forecast for New England. Multi-model ensemble solutions are in good agreement and consistent that a low pressure system and trailing front progress eastward from the Mississippi Valley to the East Coast on days 6 and 7. Near to above-normal precipitation is favored for the Great Lakes, Ohio Valley, and Northeast. The ECENS continues to back off on its heavier precipitation amounts with this frontal passage east of the Appalachians, especially south of the 40th parallel. Given this consistent model trend the past few days which better aligns with the preferred GEFS reforecast tool and NAEFS, the precipitation outlook leans towards below-normal precipitation for most of the Mid-Atlantic and Southeast. A two-category change from yesterday with a slight lean towards above shifting to below-normal precipitation is warranted for the Southeast as precipitation times off by day 6. The amplifying trough over the western CONUS supports increased above-normal precipitation probabilities for this region along with the Great Plains and Middle to Upper Mississippi Valley. Westerly flow slightly favors above-normal temperatures across the Aleutians and coastal southwestern Alaska, while anomalous cold through day 8 tilts the outlook towards below-normal temperatures for portions of southeastern Alaska. A strong low pressure system is expected to track from the Bering Sea to southeastern Alaska which favors above-normal precipitation throughout Alaska. Based on the GEFS and ECENS, above-normal temperatures and above-normal precipitation are favored for Hawaii. The official 6-10 day 500-hPa height blend consists of 35% 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: Above average, 4 out of 5, due to good model agreement on the evolving longwave pattern and improved agreement on the precipitation outlook for the eastern CONUS. 8-14 DAY OUTLOOK FOR NOV 15 - 21 2024 The GEFS, ECENS, and CMCE are in good agreement on the 500-hPa longwave pattern forecast that features a ridge over the North Pacific, a full-latitude trough over western North America, and a subtropical ridge centered across the Gulf of Mexico. Temperature tools are in excellent agreement for the lower 48 states, due to the stable and amplified longwave pattern. The full-latitude trough with negative 500-hPa height anomalies favor below-normal temperatures for nearly all of the western CONUS. A strengthening subtropical ridge over the Gulf of Mexico along with a predicted storm across the north-central CONUS favors above-normal temperatures from the Great Plains to the East Coast. Probabilities are slightly lower today across the Northeast as this region could have a brief period of cold air advection at the beginning of week-2. The amplified longwave trough along with good agreement among the reforecast tools and uncalibrated output support an increased chance of above-normal precipitation throughout the western CONUS, Great Plains, and Midwest. The largest above-normal precipitation probabilities are forecast from the Four Corners Region eastward to the Great Plains where model guidance is beginning to converge on a low pressure track. Similar to the 6-10 day period, the drier GEFS reforecast tool and NAEFS are preferred with a slight lean towards below-normal precipitation across the Mid-Atlantic and Southeast. This is also supported by the uncalibrated 7-day GEFS and ECENS which have less than 0.5 inch of precipitation. For the second consecutive day, temperature tools offer conflicting signals across western and northern Mainland Alaska. Therefore, the week-2 outlook leaned towards the consolidation tool (skill-weighted combination of GEFS and ECENS) with near normal temperature favored for a majority of Alaska. Elevated above-normal temperature probabilities are forecast for the North Slope along with the Aleutians and coastal southwestern Alaska. An upstream trough over the Bering Sea and southwesterly flow favor above-normal precipitation throughout Alaska. Early in week-2, a majority of ensemble members from the GEFS and ECENS depict a strong low pressure system tracking from the Bering Sea to southeastern Alaska. Based on the GEFS and ECENS, increased chances of above-normal temperatures and above-normal precipitation are forecast for Hawaii. The official 8-14 day 500-hPa height blend consists of: 35% 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: Above average, 4 out of 5, due to a predicted amplified longwave pattern and good agreement among the temperature and precipitation tools. 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 November 21. 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: 19531119 - 19611114 - 19611104 - 19561117 - 19711117 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: 19561117 - 19611104 - 19611114 - 19531119 - 19711116 6-10 DAY OUTLOOK TABLE Outlook for Nov 13 - 17 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON N A OREGON B A NRN CALIF B A SRN CALIF B A IDAHO B A NEVADA B A W MONTANA N A E MONTANA A A WYOMING N A UTAH B A ARIZONA B A COLORADO N 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 N W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS A A LOUISIANA A N WISCONSIN A A ILLINOIS A A MISSISSIPPI A N MICHIGAN A A INDIANA A A OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A B NEW YORK A N VERMONT A N NEW HAMP A N MAINE N N MASS A N CONN A N RHODE IS A N PENN A N NEW JERSEY A N W VIRGINIA A B MARYLAND A B DELAWARE A B VIRGINIA A B N CAROLINA A B S CAROLINA A B GEORGIA A B FL PNHDL A B FL PENIN A B AK N SLOPE N A AK ALEUTIAN A A AK WESTERN N A AK INT BSN N A AK S INT N A AK SO COAST N A AK PNHDL B A 8-14 DAY OUTLOOK TABLE Outlook for Nov 15 - 21 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF B A SRN CALIF B A IDAHO B A NEVADA B A W MONTANA B A E MONTANA A A WYOMING B A UTAH B A ARIZONA B 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 N WISCONSIN A A ILLINOIS A A MISSISSIPPI A N MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A A 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 B W VIRGINIA A N MARYLAND A B DELAWARE A B VIRGINIA A B N CAROLINA A B S CAROLINA A B GEORGIA A B FL PNHDL A B FL PENIN A B AK N SLOPE N A AK ALEUTIAN A A AK WESTERN N A AK INT BSN N A AK S INT N A AK SO COAST N A AK PNHDL N 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. $$