Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EDT Sun Oct 9 2022 Valid 12Z Wed Oct 12 2022 - 12Z Sun Oct 16 2022 ...General Pattern Overview... An amplified upper level flow pattern will be in place for this forecast period, with a strong ridge centered near the West Coast and a deep trough from the Plains to the East Coast. Two well defined cold fronts are expected to pass from the Northern Plains to the Eastern U.S., thus reinforcing the cool and autumnal airmass with generally below normal temperatures continuing. A potential heavy rain and wind event is becoming more likely for the Northeast U.S. to close out the work week as the mid-upper level trough becomes negatively tilted, and lake effect/enhanced rain/snow is also likely downwind of the Great Lakes. ...Model and Predictability Assessment... The 00Z model guidance suite has come into better synoptic scale agreement on the evolving deep trough expected over the central and eastern U.S., and the progression of the cold front across the eastern U.S. for the Wednesday-Friday time period is faster compared to the previous forecast. The CMC has also joined the model consensus compared to its runs over the past few days. With the second trough building in for next weekend, the ECMWF/CMC have a stronger signal for this compared to the GFS, although the models and ensembles generally agree that the anomalous trough pattern will be here to stay for a while. The WPC fronts/pressures forecast was generally derived from a multi-deterministic composite on Wednesday, and then gradually increased use of the ensemble means along with some previous WPC continuity and GFS/ECMWF going forward. ...Sensible Weather and Potential Hazards... The strong cold front and associated upper trough will likely bring a return to widespread showers and storms from the central Gulf Coast to the Ohio Valley and Great Lakes on Wednesday as deeper moisture is advected northward. The combination of increasing instability and favorable kinematic parameters in the warm sector may lead to some strong to severe storms from Tennessee to the Ohio Valley on Wednesday, and then perhaps across portions of the Northeast on Thursday, although confidence is still limited on exactly where these storms could develop. In terms of the rainfall potential, the latest NBM has some areal 1-3 inch rainfall totals from upstate New York to Maine for the Thursday to Friday night time period as deeper Atlantic moisture is advected towards the northern Appalachians with an increasing low level jet. A Slight Risk area was introduced for the Day 5 period for this region, although downsloping flow off the higher terrain in some areas may limit the rainfall totals in some of the valley locations. Elsewhere, lake enhanced rain and snow showers are likely across portions of Michigan, Ohio, Pennsylvania, and New York for the Thursday through Saturday time period. Most of the Western U.S. should remain dry with perhaps a few isolated showers/storms over Arizona and New Mexico. Much of the northwestern U.S. and California should have above normal temperatures each day with the upper ridge remaining nearly anchored in place near the coast, and a brief warm-up is likely from the ArkLaTex region to the Ohio Valley ahead of the front. This will likely be followed by highs about 5-15 degrees below average to close out the work week and going into next weekend from the Upper Midwest to the Ohio Valley and Great Lakes, with highs only in the 40s and 50s for most of these areas. 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, 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