Extended Forecast Discussion NWS Weather Prediction Center College Park MD 1156 AM EDT Mon Sep 16 2019 Valid 12Z Thu Sep 19 2019 - 12Z Mon Sep 23 2019 ...Gulf of Mexico disturbance offers a Texas heavy rainfall threat... ...Overview and Guidance Evaluation/Preferences... The 00Z/06Z global model suite is in much better agreement with the flow pattern coming off the Pacific and across the western CONUS than recent days. There is great uncertainty among the latest guidance in the Atlantic with Humberto and its interaction with a trough which keeps off the CONUS. The NHC track is used for Humberto with the Atlantic surface fronts and pressures conformed to it. Flow will be highlighted by an amplified upper trough that ejects northeast out from The West and across the northern Plains through Friday and sprawling/hot late summer east-central states upper ridge into the weekend. The 00Z CMC/UKMET are slower with the ejection. The WPC medium range product suite was primarily derived from a composite blend of the 06Z GFS/GEFS, 00Z ECMWF/ECENS with more deterministic guidance through Day 4 while Days 6 and 7 were primarily means. A general model blend works for the slow moving upper low over east TX through Day 4. ...Weather Highlights/Threats... A slow moving disturbance will have moved into east TX by Wednesday night. This system offers a significant threat of locally excessive rainfall dependent on track. The current track brings it north up east TX where WPC QPF is focused. As pooled tropical moisture lifts farther inland into east-central U.S. convection later week into the weekend in advance of an approaching surface front, especially over the east-central Plains and Mid-MS Valley. As the associated surface low with the western trough spreads onto the northern Plains, expect an organized convective focus with locally heavy downpours and potential for severe thunderstorms Friday into Saturday. This focus this then shifts east to the Great Lakes and east-central Plains/Mid-MS Valley/Midwest for the weekend. Deepened moisture ahead of the cold front may support some record high minimum temperatures Friday and Saturday over the northern Plains and MN. Strong ridging downstream over the east-central U.S. will cause well-above average temperatures to spread east to the coast. Northerly flow will lead to below normal temperatures midweek along the Eastern Seaboard. 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