Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Mon Sep 16 2019 Valid 12Z Thu Sep 19 2019 - 12Z Mon Sep 23 2019 ...Hurricane Humberto to track increasingly out to sea... ...Gulf of Mexico disturbance offers a Texas heavy rainfall threat... ...Overview and Guidance Evaluation/Preferences... The latest models and ensembles still offer a reasonably similar and amplified larger scale pattern over the lower 48 and vicinity for much of the upcoming medium range period. Forecast spread and uncertainty for small-mid scale embedded features remains mostly improved, bolstering forecast confidence. Flow will be highlighted by an amplified and unsettling mean upper trough to eject out from the West and sprawling/hot late summer east-central states workweek upper ridge. The WPC medium range product suite was primarily derived from a composite blend of the 18 UTC GFS/GEFS, 12 UTC ECMWF/ECMWF ensemble means and the National Blend of Models. An exception is with repsect to a current northern Gulf of Mexico disturbance that offers an emerging Texas heavy rainfall threat over the next few days, but mainly into Wednesday/Thursday. The ECMWF and ECMWF ensembles and to a lesser extent the UKMET/Canadian seem to offer a more realistic system depiction with a slow lifting into Texas within the ridge aloft. The GFS instead shifts the system down the Texas coast. ...Weather Highlights/Threats... Hurricane Humberto is forecast by the NHC to track increasingly out to sea away from the Southeast U.S. early this week. Meanwhile, a slow moving disturbance over the northern Gulf of Mexico may track into Texas into mid-late week. This system offers a significant threat of locally excessive rainfall dependent on ultimate track. Trended WPC QPF upwards over Texas and as pooled tropical moisture lifts further 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 an upper trough amplifies from the Pacific Northwest expect widespread rains (some very high elevation snow) to WA/OR Wednesday, spreading inland/south to MT/ID and northern NV/CA on Thursday. As the associated surface low spreads onto the northern Plains, expect an organized convective focus with locally heavy downpours shifts to the northern Plains Friday into Saturday before shifting east to the Great Lakes and east-central Plains/Mid-MS Valley/Midwest next weekend. Deepened moisture may support some leading record high minimum temperatures. In this pattern expect subtropical moisture out of Mexico on southwest flow aloft over the Southwest/Four Corners states with rain chances mainly Wed/Thu. Strong ridging downstream over the east-central U.S. then will meanwhile favor well-above average temperatures with some near record Deep South heat. Schichtel 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