EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1158 AM EDT FRI MAY 05 2017 VALID 12Z MON MAY 08 2017 - 12Z FRI MAY 12 2017 ...PATTERN OVERVIEW AND GUIDANCE EVALUATION... THE TWO MAIN FEATURES THAT ARE DOMINANT OVER THE MEDIUM RANGE PERIOD WILL BE A LINGERING CLOSED LOW OVER THE NORTHEAST AND ANOTHER CLOSED LOW EJECTING FROM THE SOUTHWEST TO THE SOUTHERN PLAINS. BOTH MODELS/ENSEMBLES ARE IN GOOD AGREEMENT OVERALL ON THE EVOLUTION OF BOTH LOWS WITH SOME SMALL DIFFERENCES. BEGINNING WITH THE LOW OVER THE NORTHEAST -- IT WILL BASICALLY STAY IN PLACE OVER THIS REGION THROUGH MOST OF THE MEDIUM RANGE PERIOD. BY THURSDAY, IT FINALLY MOVES NORTHEASTWARD OVER THE ATLANTIC TO THE CANADIAN MARITIMES. THE GFS/ECMWF/CANADIAN ALONG WITH THEIR ENSEMBLES WERE CONSISTENT WITH EACH OTHER ON THE TIMING OF THIS. MEANWHILE, THE LOW ACROSS THE SOUTHWEST WILL MEANDER TOWARDS THE SOUTHERN PLAINS AND INTO THE MISSISSIPPI VALLEY BY FRIDAY. THE ECMWF HAS BEEN PERSISTENT WITH THE SLOWER TRACK OF THIS LOW WHILE THE GFS INITIALLY HAD THE FASTER SOLUTION BUT THE 06Z GUIDANCE WAS MORE IN STEP WITH THE ECMWF. THUS, MADE A BLEND OF THE ECMWF/GFS ALONG WITH THEIR ENSEMBLE MEANS WITH MORE EMPHASIS ON THE ECMWF AND ITS ENSEMBLE MEAN. ...WEATHER HIGHLIGHTS... AN UPPER LOW ALONG WITH AN ACCOMPANYING SURFACE COLD FRONT WILL MOVE ACROSS THE PACIFIC NORTHWEST ON TUESDAY AND PROGRESS OVER THE INTERMOUNTAIN WEST THROUGH THE WEEK. ONSHORE FLOW WILL BRING PRECIPITATION TO THIS REGION AND HIGHER ELEVATION SNOW. THE CLOSED LOW MOVING ACROSS THE DESERT SOUTHWEST WILL BRING PRECIPITATION THROUGHOUT THE CENTRAL GREAT BASIN AND DESERT SOUTHWEST ALONG WITH HIGHER ELEVATION SNOW. AS THE LOW CONTINUES ITS EASTERLY TREK, PRECIPITATION WILL EXPAND INTO THE PLAINS. SEVERE CONVECTION MAY BE POSSIBLE IN THE TEXAS PANHANDLE/RED RIVER VALLEY ON WEDNESDAY -- SEE THE LATEST SPC OUTLOOKS. SHOWERS AND THUNDERSTORMS COULD ALSO FIRE OFF ALONG THE FRONT BY THURSDAY AND INTO FRIDAY FROM THE SOUTHERN PLAINS TO THE SOUTHEAST. THE CLOSED LOW WOBBLING ALONG THE NORTHEAST COULD ALSO BRING SNOW IN THE HIGHEST ELEVATIONS ON MONDAY AND TUESDAY (ADIRONDACKS, GREEN/WHITE MOUNTAINS, AND MAHOOSUCS). BELOW AVERAGE TEMPERATURES ARE EXPECTED ACROSS THE NORTHEAST AND MID-ATLANTIC THROUGH THE MEDIUM RANGE PERIOD WITH CYCLONIC FLOW OVER THE REGION. IN ADDITION, THE DESERT SOUTHWEST CAN ALSO EXPECT BELOW AVERAGE TEMPERATURES DUE TO THE UPPER LOW/PRECIPITATION. THE UPPER RIDGE DOMINATING OVER THE PLAINS/MISSISSIPPI VALLEY WILL BRING ABOVE AVERAGE TEMPERATURES FOR MOST OF THE WEEK AND ONCE THE COLD FRONT MOVES EASTWARD INTO THE SOUTHERN PLAINS/MISSISSIPPI VALLEY TEMPERATURES WILL BE BROUGHT DOWN CLOSE TO AVERAGE. REINHART