Extended Forecast Discussion NWS Weather Prediction Center College Park MD 254 PM EDT Mon Oct 10 2022 Valid 12Z Thu Oct 13 2022 - 12Z Mon Oct 17 2022 ...Heavy rain and gusty winds are likely Thursday-Friday in the Northeast ahead of a strong cold front... ...Pattern Overview... A more active fall weather pattern is expected to evolve by the end of this week and continuing into the weekend as a couple of cold fronts associated with an Eastern U.S. amplifying upper level trough (and embedded shortwaves) move across the central and eastern states. The first cold front will be crossing the Appalachians by early Thursday with widespread showers and storms likely ahead of it across the East Coast region and heavy rain and wind for portions of the Northeast. By this weekend, a second cold front dropping southward from Canada is expected to reinforce the cool airmass across the eastern half of the nation. The opposite is expected to be the case across the West Coast region as an upper ridge brings a period of much above normal temperatures from California to the Pacific Northwest. ...Model and Predictability Assessment... Synoptically, the latest suite of 00z/06z model guidance shows very good agreement all the way through day 7 on the overall pattern which shows amplified troughing over the Eastern U.S., an amplified ridge over the Northwest, and a very slow moving upper low off the southern California coast which may slowly drift inland over the Southwest by early next week. The main differences during the period lie in handling of individual smaller scale shortwaves embedded within the larger trough, leading to some timing differences with associated cold fronts. By next Monday/day 7, there is also uncertainty on whether an upper low will close off over the Upper Great Lakes or remain well to the north/an open trough. There was enough run to run variability with this feature to require use of modest amounts of the ensemble mean solutions by day 6 and 7, in addition to deterministic solutions as well. Overall though, this still maintains very good consistency with the previous WPC forecast. For QPF, major changes to the starting point NBM mainly involved increasing amounts across the Great Lakes early in the period, and then also an increase in the coverage and amounts of QPF across the southern Plains to Midwest ahead of the cold front. ...Sensible Weather and Potential Hazards... The first strong cold front and the associated upper trough will bring a return to widespread showers and storms from the Mid-Atlantic to the Northeast on Thursday. Rainfall amounts are likely to be highest in the interior Northeast Thursday and continuing into Friday across Maine as deeper Atlantic moisture is advected towards the northern Appalachians with an increasing low level jet and anomalously high PWs. A Slight Risk area remains in place in WPC's experimental Day 4 Excessive Rainfall Outlook for this region. Terrain could enhance rain totals across the Adirondacks and the White and Green Mountains, but lower elevations could see heavy rainfall as well with a broad risk for some flooding. If the heavier rainfall rates are more limited, then the flooding potential should be mitigated some. Strong and gusty winds are also a concern there as the trough becomes negatively tilted and the pressure gradient tightens. Elsewhere, lake enhanced rain and snow showers are likely across the Great Lakes for the Thursday through Saturday time period, and showers could become more widespread with another frontal system by Sunday. Most of the West should remain dry through the latter part of the week with perhaps a few isolated showers/storms over Arizona and New Mexico into Texas, with coverage likely increasing next weekend as the upper low slowly moves inland over the Desert Southwest. 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. Although, daytime highs could be 10-15 degrees above normal, the resulting actual temperatures in the 80s (north) to 90s (California) should not present a heat hazard. The opposite will hold true across the north-central U.S. and extending to the East Coast, with highs about 5-15 degrees below average to close out the workweek and going into next weekend, with highs only in the 40s and 50s from the Great Lakes to the Northeast on most days. Santorelli/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