Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM 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 amplifying upper level troughs/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 a upper ridge and mostly sunny skies will prevail and lead to September-like temperatures from California to the Pacific Northwest. ...Model and Predictability Assessment... The 00Z model guidance suite has a very good depiction of the main synoptic scale features across the nation to close out the work week, which includes a Rex block near the West Coast and a big trough building over the east-central U.S. Model agreement is still good going into Saturday, although some differences emerge over southern Canada that could affect the timing and strength of the second cold front that will reinforce the cool airmass already in place, with the GFS indicating a broader closed low whereas the CMC/ECMWF indicate a slightly more defined shortwave that will then merge with the main trough axis. Overall, the decrease in model/ensemble spread has improved nicely over the past couple of days. In terms of preferences for fronts/pressures, a multi-deterministic model blend works quite well as a starting point in the forecast process for both Thursday and Friday with above average confidence on the synoptic scale level, and then incorporating some of the ensemble means going into the Saturday through Monday time period. ...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 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 possibly increasing next weekend as the upper low slowly moves to the east across 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. 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. 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