EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 202 AM EDT TUE MAR 20 2018 VALID 12Z FRI MAR 23 2018 - 12Z TUE MAR 27 2018 ...OVERVIEW... TROUGH/RIDGE/TROUGH PATTERN WILL TRANSLATE EASTWARD AND FLATTEN A BIT THIS WEEKEND INTO NEXT WEEK. THIS WILL CARRY A SYSTEM OUT OF THE ROCKIES ON FRIDAY AND THROUGH THE PLAINS/CENTRAL MS VALLEY INTO THE OH/TN VALLEY AND SOUTHEAST THIS WEEKEND. TROUGHING WILL BE SLOW TO LIFT OUT OF THE WEST WITH A TRAILING SHORTWAVE POSSIBLE THAT WILL HELP LIFT THE FRONT OUT OF THE SOUTHERN PLAINS NEXT WEEK. THE MODELS/ENSEMBLES WERE LARGELY IN AGREEMENT, BUT THE GFS AND GEFS REMAINED A BIT BEHIND THE ECMWF/ECMWF ENSEMBLES WITH THE TRENDS. HOWEVER, EVEN THE ECMWF ENSEMBLES HAVE SHIFTED THEIR UPPER LOW/HIGH CENTERS ACROSS NORTHERN CANADA INTO THE NORTH ATLANTIC WHICH AFFECTS HOW THE CONUS FLOW EVOLVES. A BLEND OF THE RECENT GUIDANCE WAS REASONABLE TO START THE PERIOD (FRI-SAT) BEFORE TRANSITIONING TO A BLEND OF JUST THE ECMWF/ECMWF ENSEMBLE MEAN AS THEY WERE THE ONLY ONES TO KEEP MORE RIDGING SOUTH OF THE ALEUTIANS THAT FIT WITH TELECONNECTIONS TO THE UPPER LOW OVER THE CANADIAN ARCHIPELAGO (CANADIAN WAS PERHAPS TOO DEEP IN THE WEST WITH THE TROUGH AND DID NOT MAINTAIN RIDGING IN THE NORTHEAST). ...WEATHER HIGHLIGHTS/THREATS... AS THE SYSTEM EXITS THE ROCKIES, SNOW TO THE NORTH AND RAIN TO THE SOUTH WILL EXPAND ACROSS THE HIGH PLAINS AND UPPER MIDWEST SOUTHEASTWARD INTO THE MISSISSIPPI VALLEY. SNOW ACCUMULATIONS MAY BE SIGNIFICANT ACROSS NORTH DAKOTA INTO WESTERN MINNESOTA. RAPIDLY DIVERGING SOLUTIONS FOR LOW PRESSURE EMERGING FROM THE PLAINS ON SATURDAY KEEP CONFIDENCE LOW IN DETERMINING THE LOCATION/INTENSITY OF PRECIP EXTENDING EAST-SOUTHEASTWARD THROUGH THE OH VALLEY INTO THE MID-ATLANTIC/SOUTHEAST. AT THE VERY LEAST IT APPEARS THAT SOME AREAS OVER THE EASTERN HALF OF THE CONUS SHOULD SEE A PERIOD OF WINTRY PRECIP WITH RAIN FARTHER SOUTH. AS THE FRONT STALLS ACROSS TX/OK/AR, RAINFALL SHOULD INCREASE NEXT WEEK WITH LOCALLY MODERATE AMOUNTS ALONG THE BOUNDARY. ABOVE AVERAGE TEMPERATURES JUST EAST OF THE CENTRAL/SOUTHERN ROCKIES FRI-SUN WILL DIMINISH IN TIME AS THE FRONT APPROACHES AND PRECIPITATION EXPANDS. HIGHS WILL BE IN THE 80S (KS/OK) AND 90S (CENTRAL/SOUTH TEXAS) FRI-SAT. MUCH OF THE WEST AND EAST WILL SEE BELOW AVERAGE TEMPERATURES. FRACASSO