Extended Forecast Discussion NWS Weather Prediction Center College Park MD 348 PM EST Thu Mar 07 2019 Valid 12Z Sun Mar 10 2019 - 12Z Thu Mar 14 2019 ...Weather Pattern Overview... The stormy weather pattern continues as two major systems thrive during the medium range period. A lead Great Lakes storm Sund will bring widespread rain/thunderstorms to the eastern U.S. and heavy snow with a threat of blizzard conditions to the Upper Midwest and Great Lakes before exiting into eastern Canada Mon. A second potent system works from the Pacific inland to CA and the Southwest Mon/Tue, with central U.S. storm genesis likely through midweek. ...Guidance and Uncertainty Assessment... The deterministic models are in good overall agreement regarding the placement and overall strength of the surface low crossing the Great Lakes region on Sunday and into eastern Canada by Monday. Speed differences are much more apparent with the GFS/GEFS mean and to a lesser extent the FV3 remaining more progressive with the midweek storm system across the central U.S. than the ECMWF/UKMET/CMC and ECMWF ensemble mean. The increasingly short wavelength spacing with upstream kicker energy digging through the West now seems sufficient to trend the latest WPC product suite to a solution faster than WPC continuity. The bottom line is that even though timing has been an issue with this storm threat, there has been a consistent and strong signal for significant storm development that should not be downplayed in a pattern ripe with deep/dynamic low developments. ...Weather Highlights and Hazards... Heavy snow is still expected across interior portions of New England as the surface low lifts northeastward across eastern Canada Sun into Mon, and heavy lake enhanced snow will persist on the windy backside flow around the exiting deep low. Areas of rain and thunderstorm activity will persist across the Gulf Coast region and over the East Sunday underneath along/ahead of a trailing cold front. Some severe thunderstorms will also be possible across parts of the Southeast on Sunday ahead of the cold front, and this is something that the Storm Prediction Center is continuing to monitor. Looking ahead for early-mid week, the pattern again favors an amplified mid-upper level trough developing off the West Coast this weekend. This will support another round of precipitation over the southwestern U.S. as the trough moves inland on Monday. Additional widespread rain is expected to develop across the central and southern Plains to the Mississippi Valley/Midwest during the Tuesday and Wednesday time period as the trough induces another deepening surface low east of the Rockies. There is also the potential for severe weather with this storm system, and details on this will become more evident in the upcoming days. Another round of heavy snow and potential blizzard conditions is becoming more probable across parts of the central plains and the Upper Midwest as the surface low intensifies and colder air in drawn in behind the low. ...Bullet Points from Medium Range Hazards Chart... - Heavy precipitation across portions of the Northeast, Sun, Mar 10. - Heavy rain across portions of the Central Plains, the Mississippi Valley, and the Southern Plains, Mon-Tue, Mar 11-Mar 12. - Heavy rain across portions of the Lower/Middle Mississippi Valley, the Tennessee Valley, the Southeast, and the Southern/Central Appalachians, Wed-Thu, Mar 13-Mar 14. - Heavy precipitation across portions of the Central Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Mon-Wed, Mar 11-Mar 13. - Heavy snow across portions of the Central/Northern Plains, the Great Lakes, and the Upper Mississippi Valley, Mon-Wed, Mar 11-Mar 13. - Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Mon-Tue, Mar 11-Mar 12. - Heavy snow across portions of the Southern Rockies, the Central Rockies, and the Central Great Basin, Mon-Thu, Mar 11-Mar 14. - Severe weather across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley, Sun, Mar 10. - Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, and the Upper Mississippi Valley. - Flooding occurring or imminent across portions of the Southeast, the Middle Mississippi Valley, the Lower Mississippi Valley, the Ohio Valley, and the Tennessee Valley. - Much below normal temperatures across portions of the Northern/Central Rockies, the Northern/Central Plains, and the Northern Great Basin, Sun-Mon, Mar 10-Mar 11. Schichtel 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