Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1159 AM EDT Mon Oct 28 2019 Valid 12Z Thu Oct 31 2019 - 12Z Mon Nov 04 2019 ...Much below normal temperatures over the Rockies/Plains will moderate by this weekend... ...Developing storm affects the eastern U.S. Thu-Fri... ...Overview and Guidance/Uncertainty Assessment... Models and ensemble means agree that a persistent eastern Pacific ridge will promote broad cyclonic flow downstream, with a mean trough axis tending to align over the east-central states. Guidance consensus and continuity provide fairly high confidence in the large scale pattern but individual embedded features have lower predictability. By early next week there are also some aspects to the forecast that become more uncertain near the West Coast and the northern Plains. The most notable weather feature in the medium range is the upper trough over the central U.S. as of early Thu that ejects north-northeastward thereafter, supporting development of surface low pressure that tracks from the central Ohio Valley into Quebec through Friday. The CMC continues to be an outlier with a more phased/open system aloft leading a faster and less wound-up wave, so the CMC was not included in the blend beyond Day 3. The forecast blend through Day 4 is a blend of 00Z ECMWF/UKMET and 06Z GFS. Behind the eastern system the aforementioned model blend represented consensus well for the upstream trough aloft amplifying into the lower 48 along with the associated cold front which progresses through the central part of the U.S. Sat. There is decent agreement and consistency with the next frontal system expected to reach the northern tier/Great Lakes by days 6-7/Sun-Mon. There is some uncertainty with low pressure off CA by Sunday with the GFS stronger, but by Monday the system is in pretty close agreement with 06Z GFS/GEFS and 00Z ECWMF/ECENS. An increasing usage of the 06Z GEFS/00Z ECENS is used in the blend with good agreement across the CONUS. ...Weather Highlights/Threats... Widespread precipitation shield across the northeastern U.S. is expected into this weekend with some snow possible in the northwestern periphery of the system (Midwest to Upper Great Lakes) and areas of heavy rainfall along with pockets of strong convection in the warm sector. Expect highest rainfall totals from early Thu onward to extend from along and just west of the Appalachians into the Northeast. A brief period of strong winds will occur over parts of the Great Lakes/Northeast. Behind this system expect periods of lake effect rain/snow with periodic light precipitation over other parts of the northern tier in association with a couple fronts dropping south from Canada. The front trailing from the late week eastern storm will settle over the Florida Peninsula and could provide a focus for light rain into early next week. The Rockies and Plains will remain quite chilly for the rest of the work week with a fairly broad area seeing temperatures 10-30F below normal. These areas should trend much closer to average by Sun-Mon while locations closer to the West Coast should see highs up to 5-10F above normal from the weekend onward as the Pacific ridge aloft extends its influence a little farther eastward. Meanwhile frontal passage over the East will replace initial warmth (plus 10-20F anomalies for morning lows and moderately warm highs on Thu) with cooler readings generally 5-15F below normal. Jackson 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