Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Thu Oct 10 2019 Valid 12Z Sun Oct 13 2019 - 12Z Thu Oct 17 2019 ...Pattern Overview and Guidance/Uncertainty Assessment... Deep upper low over the Arrowhead of Minnesota on Sunday will lift toward James Bay by Tuesday as broad cyclonic flow remains anchored over the eastern half of the CONUS. A front entering the Pacific Northwest will dive through the Plains Tuesday then lift into the Northeast next Wed/Thu. At that time, another front (or pair of fronts) may push into Washington/Oregon. The 12Z ECMWF offered the best clustering near the 18Z GEFS mean and 12Z ECMWF ensemble mean, followed by the GFS/UKMET/Canadian to varying degrees Sun-Tue. Timing differences have been the main challenge over the past few days but ensemble spread continues to decrease in concert with lead time. By next Wed/Thu, higher uncertainty spreads out of the northeast Pacific, augmented/perpetrated by the extratropical transition of current Super Typhoon Hagibis. Ensemble blend sufficed for now given the multiple players upstream. ...Weather Highlights/Threats... Rainfall will focus around the front in the Southeast Sun-Tue as it stalls and then lifts back northward. Questions remain as to how much precipitation can be realized but precipitable water values should rise to about 1.50" (or +1 to +1.5 sigma). Also at question is the amount of Pacific moisture that may stream eastward across the Mexican plateau, which usually limits its influence. As the western front reaches the central states, added dynamics should increase coverage/intensity from the lower Mississippi Valley eastward Wed/Thu. Colder than average temperatures will linger over the northern Plains with only gradual moderation by the middle of next week. Fresh snow cover will likely limit maximum temperatures to the middle 30s which is about 20-25 degrees below average over the Dakotas. The South will see above average temperatures Mon/Tue ahead of the front but trending cooler by next Wed/Thu. Fracasso 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