Extended Forecast Discussion NWS Weather Prediction Center College Park MD 256 PM EDT Wed Mar 30 2022 Valid 12Z Sat Apr 2 2022 - 12Z Wed Apr 6 2022 ...Heavy rain becoming more likely for portions of the south-central U.S. next week... 19Z Update: The 12Z model guidance suite is initially in above average agreement on the synoptic scale for this weekend, with the GFS slightly more progressive with the shortwave trough over the Midwest and Ohio Valley. By Monday, the CMC becomes slower and a bit more amplified with the building trough over the southwestern U.S., whereas the GFS is slightly more progressive than the ensemble means as this disturbance crosses the Gulf Coast region by mid-week. Additionally, consensus has improved with a well developed closed upper low forming over the Upper Midwest by next Wednesday as the overall pattern becomes more amplified. In terms of heavy rainfall prospects next week, there is an increasing likelihood of heavy rain and strong storms from eastern Texas and across the Deep South as favorable dynamics and instability parameters are expected, with some 2-4 inch rainfall totals possible. The previous forecast discussion is appended below for reference. /Hamrick ...Guidance Evaluation/Predictability Assessment... The WPC medium range product suite was mainly derived from a blend of reasonably well clustered mid-larger scale guidance from the 18 UTC GFS/GEFS mean and the 12 UTC ECMWF/UKMET/Canadian/ECMWF ensemble mean along with the 01 UTC National Blend of Models days 3-7 (Sat-next Wed). However, embedded smaller scale system differences and ample run to run continuity variances remain problematic. Accordingly, blend weighting was transitioned from primarily the models days 3-5 to the ensemble means days 6/7 to mitigate less predictable forecast components amid steadily growing forecast spread. Overall, WPC product continuity is best maintained with this plan and the forecast seems in line with a similar composite of newer 00 UTC guidance. ...Overview and Weather Highlights/Threats... A closed upper trough and deepened surface low will work into the Canadian maritimes by Saturday. Expect lingering high winds across New England in the wake of the low. The southern portion of a trailing western Atlantic cold front will slow over Florida, the Gulf of Mexico and into Mexico. Scattered to widespread showers are expected near the front, particularly across Florida and possibly the Gulf coast Saturday. Across the West, a leading series of upper troughs and low pressure systems with modest precipitation potential are expected track through with varying degrees of uncertainty through the weekend. Infusion of highly energetic Pacific jet flow will then up the ante and work increasingly inland from the Northwest to the Rockies/Plains early-mid next week. This should act to transport deeper moisture to fuel an emerging precipitation focus for some heavier rains and mountain enhancing snows, mainly across the Northwest. Downstream progression and systems out from the West and increasing northern stream phasing potential over time may combine to support uncertain cyclogenesis/frontogenesis over the central and eastern states next week. There is a growing guidance signal for development of a building area of moderate to heavy rainfall across the east-central U.S. and especially a more unstable/convective South early-mid next week as deeper Gulf moisture returns and interacts with the complex series of wavy fronts and a stalled lead front. Schichtel 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, experimental excessive rainfall outlook, 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/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml