EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 254 AM EDT WED APR 25 2018 VALID 12Z SAT APR 28 2018 - 12Z WED MAY 02 2018 TREND TOWARD WESTERN TROUGHING AND EASTERN RIDGING WILL BE UNDERWAY BY THE WEEKEND AS AN UPPER LOW SLIDES INTO NORTHERN CALIFORNIA AND A TROUGH IN THE EAST STARTS TO LIFT OUT. THE MODELS/ENSEMBLES HAVE COME INTO A BIT BETTER AGREEMENT BUT THE GFS/GEFS REMAIN QUICKER AND TO THE NORTH OF THE ECMWF/CMC/UKMET CONSENSUS IN THE WEST, AND WAS GIVEN ONLY A SMALL MINORITY WEIGHTING. THE 00Z ECMWF ENSEMBLE MEAN OFFERED THE MOST REASONABLE FORECAST (SEVERAL DAYS RUNNING NOW) INTO THE START OF NEXT WEEK. DESPITE THE DIFFERENCES IN THE DAYS 3-5 TIME FRAME, THERE BECOMES RATHER REMARKABLE AGREEMENT BY NEXT TUE/WED WITH A TRAILING SHORTWAVE TUGGING BACK THE TROUGH AXIS INTO THE SOUTHWEST STATES AS THE LEAD FORMER UPPER LOW WEAKENS THROUGH THE HIGH PLAINS. ENSEMBLE AGREEMENT IS STRONG IN A RATHER AMPLIFIED TROUGH/RIDGE PATTERN THAT WILL BRING MUCH ABOVE AVERAGE TEMPERATURES TO THE EAST FOR THE FIRST COUPLE DAYS OF MAY. THE WEST WILL SEE UNSETTLED WEATHER WITH MOSTLY LIGHT TO MODERATE RAIN AND HIGH ELEVATION SNOW BUT LOWERING SNOW LEVELS WITH TIME AS HEIGHTS FALL AND COOLER TEMPERATURES FILTER IN. AREAS TO THE NORTH OF THE UPPER LOW TRACK (OREGON TO IDAHO TO MONTANA) STAND TO SEE THE MOST PRECIPITATION THIS WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE TO THE EAST WILL ALLOW MOISTURE TO FLOW NORTHWARD FROM THE WESTERN GULF THROUGH THE SOUTHERN PLAINS WHERE CONVECTION WILL BE LIKELY ONCE THE FRONT GETS EAST OF THE FOOTHILLS. THE EAST WILL THEN DRY OUT NEXT WEEK WITH HARDLY ANY PRECIPITATION EAST OF ABOUT I-65 (INDIANA TO ALABAMA). FRACASSO ASSOCIATED WPC MEDIUM RANGE FORECASTS OF 500 MB HEIGHTS...SURFACE SYSTEMS...WEATHER GRIDS...QUANTITATIVE PRECIPITATION FORECASTS (QPF)...AND WINTER WEATHER OUTLOOK SNOW/SLEET PROBABILITIES CAN BE FOUND AT... http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4