Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 PM EDT Wed Aug 03 2022 Valid 12Z Sat Aug 06 2022 - 12Z Wed Aug 10 2022 ...Southwest/Great Basin/Rockies Monsoon Resumes a Very Active Phase Late This Week... ...Heavy rain threat this weekend for the Upper Midwest and Great Lakes... ...Overview... Latest guidance shows a fairly typical summertime pattern with the main band of westerlies across southern Canada and northern tier CONUS, though with upper ridging to the south tending to be somewhat stronger than the climatological mean. An upper low should lift very slowly northeastward offshore the West Coast. The models and ensembles agree on the large scale pattern, but significant shortwave differences develop within the westerlies from fairly early in the forecast. As a result confidence decreases for surface front/wave details and in turn for associated areas of rainfall which could be heavy at times over portions of the northern half of the central/eastern U.S. Meanwhile the monsoonal pattern over the West should become more pronounced again and likely remain fairly active through the weekend and into next week. ...Guidance Evaluation/Predictability Assessment... The WPC medium range product suite was primarily derived from a composite of reasonably compatible guidance from the 06 UTC GFS and 00 UTC ECMWF/UKMET/Canadian and the 13 UTC National Blend of Models (NBM). The blend acts to mitigate lingering small scale variance consistent with predictability. The 00 UTC Canadian and to a lesser degree GEFS/NAEFS/ECMWF ensembles held closed upper low/troughing over the eastern Pacific days 6/7 while the 06 UTC GFS/ECMWF gradually allowed the system to work into the Pacific Northwest. Expect the system to mainly hold offshore given position between two amplified upper ridges. 12 UTC model guidance has trended offshore with this system, bolstering forecast confidence to above normal levels. ...Weather/Hazards Highlights... Over the West, maximum temperatures will tend to be somewhat below normal over the Great Basin/Southwest and vicinity due to persistent clouds and periods of rain. The Northwest should trend more above normal as some degree of upper ridging builds, spreading into the northern Rockies/High Plains into next week. Highs could locally reach 10-12F above normal. For precipitation, the main threats for flash flooding will be associated with monsoonal moisture over the Southwest/Great Basin/Rockies as well as with fronts/waves from the east-central U.S. as northern stream shortwave troughs progress donwstream. The combined signals for rainfall and already wet conditions over the Desert Southwest into the central Rockies/Great Basin late into the weekend support several Slight Risk areas in the experimental days 4-5 Excessive Rainfall Outlooks. Despite frontal progression, deep pooled moisutre and instability also prompted weekend Slight Risk ERO threat areas across the Upper Midwest and Great Lakes in a region with enhanced/ongoing short range QPF. NBM QPF was increased for this potential. Kebede/Schichtel 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