Extended Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Sat Sep 12 2020 Valid 12Z Tue Sep 15 2020 - 12Z Sat Sep 19 2020 ..."Nineteen" to intensify to a Tropical Storm and threaten the Gulf Coast... ...Some Welcome Northwest/Northern California rains next week... ...Guidance/Predictability Assessment... Tropical Depression Nineteen is forecast by the National Hurricane Center to intensify into a tropical storm and threaten the Gulf Coast next week along with heavy rainfall. Please refer to the latest advisories from the NHC on "Nineteen" for updated information. Otherwise, the WPC medium range suite was derived from a blend of best clustered guidance from the 12 UTC ECMWF/ECMWF ensemble mean and the 18 UTC GEFS mean. Good WPC continuity is maintained despite a pattern with above average forecast spread, especially with northern stream systems. Recent GFS runs seem too flat given well supported northern Pacific to Alaska upstream flow amplification aided by the influence of former Super Typhoon Haishen. ...Overview and Weather/Hazard Highlights... A complex evolution over the northeastern Pacific should yield a fairly deep trough/closed low that is slated to bring some welcome rainfall and cooler temperatures into the fire stricken Northwest and northern California by early-mid next week, lingering into late next week in a wet late summer pattern. Meanwhile, the threat of heavy rainfall will increase along Gulf Coast next week as "Nineteen" is forecast to intensify to Tropical Storm strength and reach the central Gulf Coast early-midweek. A lingering and slow moving front draped overtop will also help to focus rainfall along the eastern Gulf Coast into Florida as well as along the western Gulf Coast well into next week, but the highest threat of heavy rain and system threats may ultimately be near and just east of where "Nineteen" makes landfall. Deep moisture and slow system translation suggest that heavy rainfall threat may work inland later next week through the MS/TN Valleys with frontal interactions. 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