EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1244 AM EDT MON MAR 28 2016 VALID 12Z THU MAR 31 2016 - 12Z MON APR 04 2016 GENERAL FLOW PATTERN ~~~~~~~~~~~~~~~~~~~~ THE AMPLIFIED NORTHWEST RIDGE-HUDSON BAY TO SOUTHWEST TROUGH PATTERN WEAKENS THIS PERIOD AS AN UPPER TROUGH ACROSS THE EASTERN PACIFIC BEGINS TO ERODE THE WESTERN RIDGE. PER A BRIEFING FROM SUNDAY DAY SHIFT, THERE HAS BEEN A MULTI-DAY TREND SEEN IN THE ENSEMBLE MEANS TO WEAKEN THE RIDGE SLIGHTLY MORE FROM DAY TO DAY. THE WEAKENING RIDGE ALLOWS THE TRAPPED UNDER LOW UNDER ITS BASE TO GET KICKED EASTWARD THROUGH THE SOUTHERN TIER OF THE COUNTRY. MODEL DIFFERENCES/PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THERE WERE A FEW SIGNIFICANT ISSUES WITH THE GUIDANCE FROM SUNDAY. AFTER THE NOW WELL-CLUSTERED CYCLONE MOVES THROUGH THE GREAT LAKES THURSDAY INTO EASTERN CANADA, DIFFERENCES HAVE APPEARED WITH THE CLIPPER CYCLONE IN ITS WAKE, WITH THE 18Z GFS/12Z UKMET A BIT QUICKER THAN THE 12Z ECMWF/12Z CANADIAN SOLUTIONS. SINCE THE 12Z ENSEMBLE LOW CLUSTERING WAS TIGHT (AND INCLUDED GEFS MEMBERS), PREFERRED THE 12Z ECMWF/12Z CANADIAN WITH THE CLIPPER. DIFFERENCES EMERGE WITH THE PROGRESSION OF A SYSTEM THROUGH THE EASTERN PACIFIC TOWARDS WESTERN NORTH AMERICA, WITH THE 12Z ECMWF UNCHARACTERISTICALLY SPEEDY WITH THE SYSTEM -- THE 18Z GFS/12Z CANADIAN WERE IN LINE WITH THE ENSEMBLE MEANS HERE. THE SYSTEM IT KICKS EASTWARD -- THE SOUTHWEST CLOSED LOW/UPPER TROUGH -- SHOWED TIMING ISSUES IN RESPONSE TO THE UPSTREAM ISSUE IN THE EASTERN PACIFIC. THE 18Z GFS WAS MOST IN LINE WITH THE ENSEMBLE MEANS HERE. FOR THE PRESSURES/WINDS, A COMPROMISE OF THE 18Z GFS/12Z UKMET/12Z ECMWF WAS IDEAL WITH THE PATTERN OVER THE LOWER 48 ON THURSDAY AND FRIDAY. FROM LATE FRIDAY UNTIL LATE SATURDAY, A COMPROMISE OF THE 12Z CANADIAN/12Z ECMWF WAS MOST PREFERRED. FROM SUNDAY MORNING INTO NEXT MONDAY MORNING, A COMBINATION OF THE 12Z CANADIAN/18Z GEFS MEAN/12Z ECMWF ENSEMBLE MEAN SOLUTION WAS USED TO ACCOUNT FOR THE UNCERTAINTY. MANUALLY ADDED A SURFACE WAVE MOVING FROM THE BAY OF CAMPECHE THROUGH THE FL STRAITS INTO THE BAHAMAS BASED ON LIMITED ENSEMBLE MEMBER CLUSTERING AND THE PREFERRED UPPER LEVEL PATTERN, AS THE EJECTING SHORTWAVE SHOULD HAVE SOME SURFACE PRESSURE RESPONSE IN THE FORM OF A LOW PRESSURE AREA. TEMPERATURES/CLOUDS/DEW POINTS/PRECIPITATION CHANCES WERE BASED ON A 40/30/30 BLEND OF THE 12Z ECMWF ENSEMBLE MEAN/18Z GEFS MEAN/12Z NAEFS MEAN TO ACCOUNT FOR THE USUAL MEDIUM RANGE UNCERTAINTY IN THESE QUANTITIES. WEATHER HIGHLIGHTS ~~~~~~~~~~~~~~~~~~ TEMPERATURES INCREASE AND PRECIPITATION CHANCES DECLINE AS THE TROUGHING LEAVES THE SOUTHWEST, WHILE THE NORTHWEST SEES TEMPERATURES MODERATE AS THE RIDGE ALOFT WEAKENS. THE STRONG CLIPPER MOVING BY THE GREAT LAKES BRINGS THE PROMISE OF LAKE EFFECT SNOWS AND COLDER THAN AVERAGE TEMPERATURES FOR EARLY APRIL TO THE NORTHERN PLAINS/GREAT LAKES/NORTHEAST FROM THIS WEEKEND INTO EARLY NEXT WEEK. THE SOUTHEAST/FL LOOK WET THIS PERIOD, WITH THE SOUTHEAST AT THE MERCY OF AN INVADING FRONT EARLY ON, AND FL SEEING RAIN CHANCES WITH THE FLAT WAVE EXPECTED TO TRACK NEAR THE STATE EARLY NEXT WEEK. WIDELY SCATTERED RECORD HIGH MINIMA ARE POSSIBLE IN THE SOUTHEAST FROM WEDNESDAY INTO SATURDAY PRIOR TO THE COLD FRONT'S PASSAGE. THE NORTHEAST COULD SEE RECORD HIGH MINIMA ON FRIDAY SHOULD WARM OVERNIGHT READINGS FROM THURSDAY NIGHT/FRIDAY MORNING NOT BE ECLIPSED BY FRIDAY NIGHT MIDNIGHT WITHIN THE WEAK COLD ADVECTION IN THE WAKE OF THE FRONTAL PASSAGE. ROTH