Extended Forecast Discussion NWS Weather Prediction Center College Park MD 229 AM EDT Thu Mar 14 2019 Valid 12Z Sun Mar 17 2019 - 12Z Thu Mar 21 2019 ...Overview... Upper ridge/trough pattern over the west/east will slowly slide eastward next week in a rather dry pattern for the CONUS except for Florida. Weak northern stream moisture-starved fronts will sweep through the east early in the week while a cold front stalls near the Florida Keys. This front will be a focus for rainfall later next week that may be heavy in places. The west will initially be protected from a complicated/evolving frontal system offshore due to the upper ridge, but only until about Wednesday when it will send a front into California. ...Guidance Assessment/Preferences... Large scale pattern remains well-forecast but smaller details remain elusive. Trend in the central/eastern states is a bit flatter by Tue but would only modulate the weak frontal positioning in the Southeast back to the southern/central Plains. Still expect a wave to form along the front near Cuba but that depends on the strength of the shortwave ejecting out of Mexico and through the Gulf. Blended solution among the GFS/ECMWF and their ensemble means was a good starting point. For the west, issue remains how exactly the eastern Pacific unfolds in a complicated/meridional pattern. ECMWF has trended quicker while the GFS has trended slower, and each passed each other a couple cycles ago. Ensembles followed the lead of each deterministic model so a blended position (near the 12Z Canadian) was preferred--mostly in line with continuity. ...Weather Highlights and Hazards... Florida will see the most rainfall during the period, centered around Tuesday. Southern third to half of the peninsula will see more rain than the northern portion. This will keep temperatures several degrees cooler than average through the period. Larger negative departures will center over Texas, especially near the Mexican border. Rest of the lower 48 will be nearly precipitation-free except for some light rain/snow north of I-40 near the weak surface fronts/upper level shortwaves. California will see rainfall spread slowly inland starting late Tue into Wed and increasing in coverage on Thursday as the upper low moves inland. Areas between San Francisco to San Diego eastward will likely see at least measurable rain and higher elevation (Sierra but also San Gabriel/Bernadino/Jacinto peaks) snowfall. This will also move into Nevada/Utah on Thursday. 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