EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 211 AM EDT FRI OCT 09 2015 VALID 12Z MON OCT 12 2015 - 12Z FRI OCT 16 2015 ...OVERVIEW... THE NORTHEAST PACIFIC AND GULF OF ALASKA WILL BE A REGION OF ACTIVE WEATHER THAT TRANSLATES A SERIES OF TRAILING CANADIAN FRONTS DOWNSTREAM INTO THE NORTHERN TIER...INCLUDING THE NORTHERN PLAINS...GREAT LAKES AND NORTHEAST. ...MODEL PREFERENCES/UNCERTAINTY ASSESSMENT... FAVORED THE 8/12Z ECENS SOLUTION AND ITS DETERMINISTIC SOLUTION THROUGH DAY 6. THOUGHT THE ACTIVE FLOW PATTERN EMERGING ACROSS THE NORTH PACIFIC OCEAN AND GULF OF ALASKA---AND THE HANDLING OF 'OHO' AND 'CHOI-WAN' REMNANTS DOWNSTREAM ACROSS NORTH AMERICA...HAVE BEEN BEST CAPTURED BY THIS SOLUTION. FROM 12/12Z TO 14/12Z...THE ECENS/ECMWF SOLUTION CARRIES SLIGHTLY MORE DEPTH AND PROGRESSION OF THE COLD FRONT ON DAY 3-4 THROUGH THE GREAT LAKES AND NORTHEAST/MID-ATLANTIC STATES...AND MORE SECONDARY WAVE ENERGY IN A MID-LEVEL WEST-NORTHWEST FLOW BEHIND THE PRIMARY 500MB TROUGH AXIS. BOTH SYNOPTIC-SCALE FEATURE WILL CONTAIN SOME REMNANTS OF 'OHO'---THE TROPICAL SYSTEM UNRAVELING ---AT THE MOMENT--- SOUTHWEST OF HAIDA GWAII. A MORE AMPLIFIED TROUGH OVER EASTERN NORTH AMERICA AND A DEEP UPPER-LEVEL LOW OVER NORTHERN HUDSON BAY IS THE END RESULT OF THIS ENERGY/MOISTURE TRANSFER. AFTER 14/12Z...WILL HAVE TO HEDGE AND/OR TREND IN ONE DIRECTION OR THE OTHER ALONG 130W WITH EITHER---A FLATTER (ZONAL) FLOW SOLUTION OF THE GEFS/GFS AND NAEFS/CANADIAN---OR TAKE THE MORE AMPLIFIED ECENS/ECMWF APPROACH. THE FALLOUT IS STRAIGHT-FORWARD---AND CONCERNS THE TRAJECTORY OF A CUTOFF 500MB LOW---CURRENTLY OVER SONORA (NORTHWEST MEXICO). THROUGH DAY 5...THIS SYSTEM WILL LIKELY MAINTAIN A SLOW DRIFT TO THE WEST-SOUTHWEST. BY DAY 6...THIS CIRCULATION WILL BE MIGRATING BACK TOWARDS THE CALIFORNIA COAST. A FLATTER FLOW ALLOWS THE CIRCULATION TO GAIN FORWARD SPEED AND SHEAR APART. A MORE-AMPLIFIED SOLUTION---ALLOWS IT THE MAINTAIN ITS INTEGRITY AS A CIRCULATION AND MIGRATE AT A SLOWER PACE ACROSS THE SOUTHWEST. PREFER THE SLOWER SOLUTION HERE AND LET REMNANTS OF 'CHOI-WAN' DICTATE THE EMERGING WAVE-TRAIN SEQUENCE IN THE NORTH CENTRAL PACIFIC...LATE IN THE FORECAST PERIOD. ...SENSIBLE WEATHER HIGHLIGHTS... THE PRECIPITATION PATTERN IS NOT APPRECIABLY WET ONE DURING THIS FOUR-DAY PERIOD---WITH THE NORTHEAST QUARTER OF THE LOWER 48 RECEIVING MUCH OF IT DURING THE FRONTAL PASSAGE ON DAYS 3-4. A BRIEF PERIOD OF CONVECTIVE SHOWER ACTIVITY---ACROSS THE SOUTHEAST AND GULF COAST---DEVELOPS ALONG THE TRAILING END OF THIS FRONT ON DAY 4. THE CUTOFF LOW OVER NORTHWEST MEXICO GENERATES SOME SENSIBLE WEATHER FOR THE SOUTHERN HALF OF CALIFORNIA AND THE SOUTHERN GREAT BASIN ON DAY 6-7 AS IT MOVES INLAND. LOWEST TEMPERATURES---BUT NOT APPRECIABLY COLD ONES FOR MID-OCTOBER---ARE CONFINED TO THE UPPER GREAT LAKES...NORTHERN NEW ENGLAND AND THE HIGHER ELEVATIONS OF THE NORTHERN AND CENTRAL ROCKIES. AND MILD WEATHER IS ANTICIPATED FOR THE SOUTHERN HALF OF THE LOWER 48---WITH NEAR TO ABOVE NORMAL TEMPERATURES PREVAILING OVER A LARGE PORTION OF THE SOUTH AND WEST CENTRAL MIDWEST. VOJTESAK