Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
Versions:
1
047 FXUS06 KWBC 141933 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Fri June 14 2024 6-10 DAY OUTLOOK FOR JUN 20 - 24 2024 Dynamical models remain in very good agreement regarding the 500-hPa height pattern across North America during the 6-10 day period. At the outset of the period, highly amplified ridging is forecast across the eastern CONUS, with the 0z ECENS, GEFS, and CMCE indicating 500-hPa heights near or greater than 594 dam over parts of the Ohio Valley, Mid-Atlantic, and Northeast. Troughing is initially favored across the West, with the mid-level pattern forecast to de-amplify across the CONUS by day-10, resulting in weakening positive height anomalies in the East and increasing positive height anomalies in the West. Todays manual 6-10 day height blend depicts positive 500-hPa height anomalies east of the Rockies, with a maxima exceeding +100 meters over New England. Slightly above-normal heights in the mean are forecast across the West given the transitional pattern, and across Alaska, a weak mid-level trough is expected to drift from the Bering Sea into the Gulf of Alaska, leaving slightly above-normal heights over or near the western Mainland and near- to below-normal heights along the southern tier of the state and the adjacent North Pacific Ocean. Strong ridging and its associated positive height anomalies favor high probabilities of above-normal temperatures throughout much of the eastern and central CONUS. The largest probabilities (above 80 percent) are forecast across the eastern Great Lakes and most of the Northeast where the ECENS depicts 5-day temperatures averaging more than 10 degrees F above normal. Farther west, the amplified mid-level trough will keep temperatures near or below normal for the first day or two, but rebounding heights will engender rising temperatures later in the period, and so above-normal temperatures are favored over the western half of the CONUS as well for the period as a whole. The only part of the CONUS without enhanced chances for above-normal temperatures is southern and western Texas due to the likelihood of persistent, above-normal rainfall. Over Alaska, a weakening mid-level trough drifting southeastward brings slightly enhanced chances for subnormal temperatures to western and northern Alaska including the Aleutians, with marginally-elevated near- to above-normal temperature chances over the remainder of the state. Enhanced above-normal temperature probabilities are favored across Hawaii, consistent with the consolidation forecast tool and expected above-normal sea surface temperatures. A tropical or semi-tropical storm system feature is forecast to be near southern Texas as the 6- to 10-day period gets underway, resulting in heavy rainfall across that region according to the ECENS, CMCE, and GEFS. Thereafter, the evolution of this system is uncertain, with the CMCE pushing heavy rain across Florida and the immediate Gulf Coast region, the ECENS surging moisture farther northward across the central Gulf Coast region and adjacent Southeast, and the GEFS keeping the heaviest rains over the Gulf of Mexico. All of these ensemble means, however, show the potential for at least moderate rains to linger around southern Texas for much of the period. The 6-10 day precipitation outlook reflects a compromise of these solutions, with above-normal precipitation probabilities exceeding 50 percent from south Texas northeastward along western and central portions of the immediate Gulf Coast, and topping 40 percent farther east and north across the rest of the Gulf Coast and adjacent Southeast as well as the Florida Peninsula. Farther west, most guidance shows a surge of semi-tropical moisture and some rainfall pushing into parts of the central and eastern Four Corners region, reflected by a better than 50 percent chance for surplus rainfall from easternmost Arizona through the western half of New Mexico and some adjacent areas. Odds for heavier rains drop off farther west, where the moisture flow will be less robust and in situ dry air may reduce amounts. Troughing aloft early in the period favors above-normal precipitation across the Rockies and High Plains while southerly, anomalously moist flow may interact with a wavering frontal boundary, increasing odds for heavy rainfall across the northern tier of the CONUS from the Great Plains through New England. South of this area, raw and reforecast precipitation guidance from the ECENS and GEFS lean toward subnormal precipitation from the Middle Mississippi Valley through much of the Ohio Valley and into the mid-Atlantic region and South Atlantic States. In contrast, the CMCE favors near- normal or slightly above-normal rainfall across this area. The official outlook favors neither unusually wet nor unusually dry weather due to the inconsistent guidance, except in parts of the Carolinas where the ECENS and GEFS are drier than in other locations. Meanwhile, the rebounding 500-hPa heights over the western CONUS bring enhanced odds for deficient precipitation to parts of northern California, much of Nevada, and some adjacent locales. With weak troughing moving from west of Mainland Alaska into the Gulf of Alaska, elevated above-normal precipitation chances cover most of the state, especially southeastern areas, and above-normal precipitation probabilities are increased across Hawaii. The official 6-10 day 500-hPa height blend consists of 45% of Today`s GFS Superensemble Mean centered on Day 8, 35% 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: Above average, 4 out of 5, due to high confidence regarding high temperatures over much of the country, especially in the East early in the period, offset by some increasing uncertainty in the evolution of mid-level features and the resulting precipitation pattern toward day-10. 8-14 DAY OUTLOOK FOR JUN 22 - 28 2024 Although the models are in good agreement on the mean 500-hPa pattern during week-2, there is some increasing uncertainty due to decreasing amplification of the mid-level pattern across the CONUS. Typically, this results in weaker surface and mid-level features driving the sensible weather across the continent, and such features are always more difficult for the models to forecast accurately, especially later in the period. The pattern evolution during week-2 is expected to feature continued de-amplification of the ridge in the East, marginal troughing lingering near or west of British Columbia, and some expansion of positive height anomalies through much of the western CONUS. The manual height blend for week-2 depicts weakly positive height anomalies across much of the CONUS in the mean, with a maxima between +30 and +60 meters from the Southwest through the middle of the CONUS and across the Northeast. A small region of nominally below-normal heights is anticipated over or near southwestern Canada while slightly positive 500-hPa height anomalies are forecast over Alaska as troughing over the Gulf of Alaska at the outset of the period drifts southeastward. Due to the broad coverage of positive 500-hPa height anomalies, elevated probabilities for above-normal temperatures cover most of the CONUS. The highest probabilities (above 70 percent) are highlighted across the lower Northeast and much of the mid-Atlantic region, which will be on the southern fringe of the larger positive 500-hPa height anomalies with abnormally high temperatures already in place. Across the CONUS, subnormal temperatures are only favored across northwestern Washington, closest to the weak mid-level troughing in southwestern Canada. In Hawaii, above-normal temperatures continue to be favored, consistent with the consolidation tool and anticipated above-normal sea surface temperatures. As in the 6-10 day forecast, there is good agreement regarding increased tropical moisture across the Gulf Coast, particularly from eastern and southern Texas through the central Gulf Coast region and adjacent Lower Mississippi Valley and Southeast. The ECMWF reforecast tool is particularly robust with rainfall totals in this region, but the other ensembles also show above-normal amounts here. These factors support probabilities for surplus rainfall exceeding 50 percent across these areas, with odds of better than 40 percent reaching into central and northeastern Texas, to near the Ohio/Mississippi Rivers confluence, and the western Florida Peninsula. Also similar to the 6- to 10-day period, raw and re-forecast ensemble means show some level of enhanced moisture advection into the Four Corners region, with the ECENS reforecast tool being the most robust. This supports enhanced chances for above-normal precipitation exceeding 50 percent from easternmost Arizona into central New Mexico. In situ dry air and somewhat less moisture advection will likely inhibit precipitation totals farther west. Over the rest of the CONUS, raw and reforecast precipitation guidance generally favors slightly elevated odds for above-normal precipitation, and a nominal tilt of the odds in this direction is depicted in the official forecast. Across Alaska, the lower mid-level heights and onshore surface flow favor below-normal temperatures and above-normal precipitation in Southeastern Alaska while a slight tilt of the odds toward warmer and wetter than typical conditions exists for most of the Mainland. The consolidation tool shows increased chances for above-normal precipitation throughout Hawaii, and this is reflected in the official outlook. The official 8-14 day 500-hPa height blend consists of: 33% of Today`s GFS Superensemble Mean centered on Day 11, 34% of Today`s 0z European Ensemble Mean centered on Day 11, and 33% 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 regarding the pattern evolution, offset by more uncertainty inherent to a less amplified pattern, particularly in regards to the precipitation forecast. FORECASTER: Rich Tinker 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 20. 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: 20070619 - 20010619 - 20030530 - 19940611 - 19590621 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: 20010619 - 20070618 - 19960604 - 19770603 - 19870604 6-10 DAY OUTLOOK TABLE Outlook for Jun 20 - 24 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A N OREGON A B NRN CALIF A B SRN CALIF A N IDAHO A N NEVADA A B W MONTANA A N E MONTANA N A WYOMING A A UTAH A N 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 N A W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A N ARKANSAS A N LOUISIANA A A WISCONSIN A A ILLINOIS A A MISSISSIPPI A N MICHIGAN A A INDIANA A N OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A N NEW YORK A A VERMONT A A NEW HAMP A A MAINE A A MASS A A CONN A A RHODE IS A A PENN A N NEW JERSEY A N W VIRGINIA A N MARYLAND A N DELAWARE A N VIRGINIA A N N CAROLINA A B S CAROLINA A N GEORGIA A N FL PNHDL A A FL PENIN A A AK N SLOPE N N AK ALEUTIAN B N AK WESTERN N N AK INT BSN N A AK S INT N A AK SO COAST N A AK PNHDL N A 8-14 DAY OUTLOOK TABLE Outlook for Jun 22 - 28 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON N A OREGON A N NRN CALIF A N SRN CALIF A N IDAHO A N NEVADA A B W MONTANA A N E MONTANA A A WYOMING A A UTAH A N 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 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 A VERMONT A A NEW HAMP A A MAINE A 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 A FL PENIN A A AK N SLOPE N N AK ALEUTIAN B N AK WESTERN N N AK INT BSN N N AK S INT N A AK SO COAST N 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. $$