Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1240 PM EST Sat Mar 12 2022 Valid 12Z Tue Mar 15 2022 - 12Z Sat Mar 19 2022 ...Overview... A few waves cross the lower 48 in a progressive pattern that is active for the Pacific Northwest. A leading southern stream system will shift east across the Deep South/Gulf Coast Tuesday into Wednesday before lifting northeast over the Carolinas and off the southern Mid-Atlantic coast Thursday. The next upper trough will push inland over the Pacific Northwest Tuesday and dig a bit as it shifts east over the southern Intermountain West Wednesday and the southern Rockies Wednesday night before turning east-northeast and to the Midwest/Great Lakes through Friday. This should make for a return to wet weather for the south-central at the end of the work week and the Midwest/Northeast next weekend. ...Guidance Evaluation/Predictability Assessment... The 00Z ECMWF/UKMET/CMC and 06Z GFS are in excellent agreement with the strength and timing of the leading southern stream system through Wednesday before the 06Z GFS (and now the 12Z GFS) becomes more progressive with the exit off Cape Hatteras Wednesday night. The GFS remains farther north with the next wave over the southern Rockies Wednesday night and then is more unified with the northern and southern stream troughs as that wave shifts to the Midwest while the 00Z ECMWF/CMC have notable separation. Therefore, a blend of the four main global models for Days 3 and 4 becomes more reliant on ensemble means on Day 5 and are majority ensemble means for 6/7. ...Weather Highlights/Threats... Ample Gulf moisture will be drawn ahead of the Deep South system Tuesday into Wednesday, which should combine with sufficient instability to bring widespread thunderstorms capable of producing heavy rainfall and locally excessive rain, especially over north Florida which is an area that received heavy rain over the past day. Precipitation over the Intermountain West Tuesday night/Wednesday will weaken as Pacific Moisture is cut off from the wave. However, as the wave amplifies over the southern Rockies a moderate return of moisture can be expected from the Gulf of Mexico which will an emerging and expanding area of rain and thunderstorms from the south-central to east-central U.S. Thursday through Saturday, albeit in a pattern with increasing forecast spread with the progression and strength determined by the aforementioned interaction of the northern and southern stream components. Ridging between the Southeast and West systems will bring temperatures 10 to 20 degrees above normal to the central/northern Plains Tuesday. This warm airmass shifts east, reaching the interior Northeast by Friday. Jackson 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 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