Extended Forecast Discussion NWS Weather Prediction Center College Park MD 330 PM EST Fri Feb 11 2022 Valid 12Z Mon Feb 14 2022 - 12Z Fri Feb 18 2022 ...Mid-late week system to bring potential for heavy rain from the south-central to east-central U.S. and wintry weather from the Midwest through Great Lakes and interior Northeast... ...Overview... The dominant focus of the medium range forecast will be on a potent upper low forecast to enter the Pacific Northwest on Monday. This feature should drop southeastward along the West Coast early in the workweek, cross the Southwest around late Tuesday/Wednesday, and become incorporated into a Plains/east-central U.S. mean trough by the latter half of the week. This evolution aloft will lead to surface cyclogenesis and strong frontal systems in the central U.S., drawing moisture northward from the Gulf of Mexico and producing notable precipitation from the Plains eastward next Wednesday into Friday. Expect rain and thunderstorms in southern areas, while snow and wintry weather are likely on the northern and western side of the precipitation shield across the central Rockies/Plains and through the Midwest, Great Lakes, and interior Northeast. ...Guidance Evaluation/Predictability Assessment... 00Z/06Z guidance remains more agreeable and consistent than average for the days 3-5 Monday-Wednesday part of the forecast. Consensus shows a strong East Pacific ridge supporting a southeastward track for the upper low of interest, from the Pacific Northwest during the day Monday and reaching the Southwest by late Tuesday-early Wednesday. Meanwhile upper troughing lifts away from the East and an initial western U.S. ridge broadens as it continues eastward. A blend of the GFS/ECMWF/CMC/UKMET from each model's latest available cycle represented the prevailing themes of the forecast well. New 12Z runs are similar except for the CMC that strays weaker/slower with the upper system Tuesday onward, affecting its forecast farther east through the rest of the week. Uncertainty and guidance spread/run-to-run variability increase somewhat during the latter half of the period. Contributors to the differences include upstream shortwave energy forecast to drop into and through the West during mid-late week as well as important specifics of northern stream flow that may interact with the leading upper low as it ejects beyond the Rockies/Plains. These issues will affect the timing, strength, and track of low pressure as it progresses from near the south-central Plains northeastward after midweek. In recent runs the GFS has tended to be a bit on the deeper side of the operational model spread (and within the deeper part of the GEFS envelope) at some valid times but has been trending weaker since the 00Z run. The CMC has been on the weaker/sheared side. For early next Thursday the 12Z UKMET has come in halfway between the 12Z GFS and 00Z ECMWF for depth. Meanwhile the ECMWF has trended faster over the past couple days and the new 12Z run is a bit weaker and farther east versus the 00Z run. Transitioning the 00Z/06Z model blend to include some 06Z GEFS/00Z ECMWF mean input by days 6-7 Thursday-Friday accounted for the gradual increase of uncertainty and provided good continuity in principle. The forecast yielded a modestly stronger system tracking northeast from the Plains, with additional room for refinement if confidence increases. ...Weather Highlights/Threats... The upper low/trough dropping into the West early in the week will spread an area of precipitation across the region, but totals of coastal/lower elevation rain and mountain snow should remain light to moderate. However, widespread showers and thunderstorms are likely to develop over the central U.S. by Wednesday into Thursday as surface low pressure consolidates in the High Plains and advects substantial moisture from the Gulf of Mexico northward into the Plains, Mississippi/Tennessee/Ohio Valleys, and eventually the Eastern Seaboard. Strong storms could be possible, with the current days 6-7 Storm Prediction Center outlook showing some severe threat from parts of the southern Plains into Tennessee Valley and vicinity. There will also be flash flooding concerns where heavy rainfall occurs. Continue to monitor forecasts as uncertain details of these potential threats become better refined. At the same time, expect a band of snow in the colder air on the northwestern periphery of the system. The best potential for meaningful accumulations currently extends from central parts of the Plains into the Middle Mississippi Valley and Midwest/Great Lakes region into interior New England, while mixed precipitation/ice cannot be ruled out in the transition zone between the snow and rain. Totals/location of any snow will be very sensitive to precise strength and track of the system. Strong winds may be possible in the gradient between the surface low and high pressure to the northwest, and then possibly along parts of the East Coast within the southerly flow ahead of the storm. The change and progression of the overall pattern will be evident in temperatures over the course of next week. Warmer than average temperatures across the Central Great Basin and Southwest Monday will moderate to near normal or slightly below Tuesday and Wednesday underneath the incoming upper trough/low. West Coast states should see readings rebound to moderately above normal for the latter half of the week. Meanwhile a warming trend over the central U.S. should peak around Tuesday-Wednesday as high temperatures reach 10-20F above normal both days with lows 15-25F above normal Wednesday. The system/cold front emerging from the West will then quickly drop temperatures to 5-15F or so below normal for Thursday-Friday. Meanwhile the midweek warmth over the Plains will move into the East for Thursday-Friday with one or two days of highs up to 10-20F above normal and lows exceeding 20F above normal over some areas. This will represent a significant warming trend for the Eastern Seaboard which can expect to start the week with temperatures 10-20F below normal. Rausch/Tate Hazards: - Heavy precipitation across portions of the southern Plains through the Midwest and the lower Great Lakes into far interior New England, Wed-Thu, Feb 16-Feb 17. - Heavy rain across portions of the southern Plains, much of the Deep South, the Northeast, through the lower and mid-Mississippi Valley, as well as the Tennessee and Ohio Valleys and into the southern Appalachians, Wed-Thu, Feb 16-Feb 17. - Severe weather across portions of the southern Plains through the lower and mid-Mississippi Valley toward the Ohio Valley, Wed-Thu, Feb 16-Feb 17. - High winds across portions of the central/southern High Plains toward the upper Midwest, Thu, Feb 17. - High winds across portions of the New England coastal areas, Fri, Feb 18. - Much below normal temperatures across portions of the interior Northeast and the lower Great Lakes, Mon, Feb 14. Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, winter weather outlook probabilities and heat indices are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml