Extended Forecast Discussion NWS Weather Prediction Center College Park MD 153 PM EDT Wed Mar 25 2020 Valid 12Z Sat Mar 28 2020 - 12Z Wed Apr 01 2020 ...Central Plains/Midwest through Northeast Storm Threat Saturday-Monday... ...Guidance/Predictability Assessment... The medium range period is expected to feature fast flow aloft with several anomalous shortwaves moving through the flow. To start the period, a deepening area of low pressure is forecast to track from the Upper Midwest/Great Lakes through the Northeast. The Pacific Northwest will experience several periods of heavy precipitation. Toward the end of the forecast period, a southern stream system may organize an area of low pressure across the south-central Plains and Gulf Coast regions. Unseasonably warm conditions are expected over the South ahead of the initial system could result in daily records for highs/lows this weekend. The updated WPC product suite was composed initially from the 06Z GFS, 00Z ECMWF, 00Z UKMET with near equal weighting as the guidance has converged on a similar solution for the Midwest/Great Lakes system on day 3-4. Later in the forecast period, guidance diverges with respect to the progression and latitudinal spread for the southern stream system. The 06Z GFS remained well ahead of the rest of the deterministic guidance as well as further north with its area of low pressure over the Deep South by Day 7. It is worth noting that the 06Z run did trend slower compared to its 00Z run, and is slowly moving toward the ECMWF solution, which advertises a slower, more southerly solution. The model blend preference for day 6-7 leaned heavily on the ECENS ensemble mean with some inclusion of the GEFS ensemble mean as well. ...Weather/Hazard Highlights... Amplified upper trough ejection should result in a deepening area of low pressure that is expected to track from the Central Plains early Friday to the Midwest/Great Lakes and Northeast Saturday through early next week. In the warm sector, stronger convection is possible while interactions along a stationary/wavy frontal boundary will focus heavier rainfall from the Ohio Valley through portions of the central Appalachians and Mid-Atlantic. The signal remains for a northern tier banded precipitation which could bring a threat for heavier precipitation from portions of the north-central Plains to the Upper Midwest/Great Lakes and Northeast with lead triple point to coastal low transition. The Northwest will see periods of rain and mountain snow of varying intensity as progressive flow from the northeast Pacific carries along multiple features. Especially by the latter half of the period there is rapidly decreasing confidence in the southern extent of precipitation and system timings. Highest totals for the five-day period should be along favored Olympics/Washington Cascades terrain. A positively tilted upper trough axis is forecast to swing through the Southwest U.S. in the day 5-6 time frame. Model guidance differs on placement, but an area of low pressure may develop across the south-central Plains before tracking eastward through the Deep South or Gulf Coast regions. Enhanced rainfall as a result of deeper Gulf moisture advected northward may develop but details and confidence on timing/rainfall and other impacts are much below normal. Taylor Additional 3-7 Day Hazards information can be found on the WPC medium range hazards 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