Extended Forecast Discussion NWS Weather Prediction Center College Park MD 252 AM EDT Fri Mar 26 2021 Valid 12Z Mon Mar 29 2021 - 12Z Fri Apr 02 2021 ...Overall Weather Pattern... The overall mid-upper level pattern across the continental U.S. is expected to be rather amplified next week. The departing trough/cold front off the East Coast Monday will allow for an upper ridge to briefly build with an embedded southern stream disturbance tracking across the southeastern U.S. through Wednesday. Meanwhile, the next major storm system will be in place over the Rockies and Intermountain West to begin the week, and this storm system will steadily across the central and eastern U.S., reaching the East Coast around Thursday. A large surface high should settle in across the Plains and Midwest for the end of the week. ...Model Guidance and Predictability... The deterministic model guidance indicates above average agreement on the main synoptic scale features, particularly across the northern half of the U.S., through Wednesday evening. The 00Z CMC becomes slower with the next storm system approaching the Pacific Northwest for the end of the week, and it's farther west with the downstream upper ridge axis across western Canada. The 00Z UKMET is faster with the arrival of the western U.S. trough across the High Plains by midweek and ahead of the model consensus, and similar to its 12Z run. A southern stream shortwave over the southern Plains Monday continues to show some uncertainty regarding timing, and potential interaction with the larger scale trough to the west, as it crosses the southeastern U.S. The GFS is weaker overall than the other deterministic guidance and currently not the favored solution for this region. The WPC medium range product suite was primarily derived from a composite blend of the 12Z ECMWF/CMC/some GFS/UKMET for the Monday through Wednesday time period, and then less of the CMC for Thursday and Friday owing to the slower solution across the West. This maintains good WPC product continuity from the previous forecast cycle. ...Sensible weather and potential hazards... The strong East Coast storm system will be exiting the Northeast Monday morning, with strong and gusty winds and colder weather in its wake, and some snow showers for northern New England. The next system crosses the Intermountain West with a strong surface low trekking across southern Canada for the beginning of the week. This will bring another round of rain and mountain snow to the central and northern Rockies through Tuesday. As the cold front reaches the Central U.S. by Monday/Tuesday, it should advect enough Gulf moisture northward to produce showers and storms from Texas to the Deep South, and locally heavy rainfall is possible across the Appalachians by mid-week, although models differ on the axis of heaviest rainfall. Strong winds are also expected across the northern Plains and Upper Midwest through Tuesday owing to the strong pressure gradient that will be in place. Temperatures are expected to be well above average ahead of the cold front advancing across the Plains, especially on Monday when highs could be pushing 70 degrees as far north as the Canadian border. An abrupt return to reality ensues by the middle of the week as a much colder airmass advects into the region behind the front, with readings about 5-15 degrees below average. The good news is the cold weather should be relatively brief as highs return to above average levels by Friday ahead of the next storm system, whereas readings are considerably colder for the East Coast states by then as a Canadian surface highs builds into the region. Hamrick 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