EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1159 AM EDT FRI OCT 10 2014 VALID 12Z MON OCT 13 2014 - 12Z FRI OCT 17 2014 ...ACTIVE AUTUMN PATTERN WITH HEAVY RAIN AND WIND INVADES THE LOWER 48... OVERVIEW... TWO VERY ENERGETIC MIGRATORY UPPER-LEVEL TROUGHS---WITH ACCELERATING PACIFIC JET SUPPORT---PRODUCES AN ACTIVE SENSIBLE WEATHER PATTERN ALONG THEIR SURFACE COLD FRONTS AND BENEATH THE UPPER JET AXES BETWEEN TUESDAY AND THURSDAY. THE FIRST UPPER WAVE MIGRATES FROM THE MISSISSIPPI RIVER TO THE SOUTHERN NEW ENGLAND COAST...AND THE SECOND WAVE TRACKS FROM THE WEST COAST THE THE NORTHERN CONTINENTAL DIVIDE. UNCERTAINTY ASSESSMENT/MODEL PREFERENCES... HAVE NO ISSUE WITH THE 10/00Z GEFS...ECENS AND NAEFS SOLUTIONS UNTIL 15/12Z (MID-POINT DAY 5)...WHEN CHOOSING THE RIGHT OUTCOME IN THE WEST AND EAST TESTS FORECASTER LOGIC. IF THERE WAS A NICE COMPROMISE SOLUTION WITH THE WHOLE PROGRESSION OF THE FLOW---IT WOULD BE THE 10/00Z GFS-PARALLEL. THE GLOBAL MODEL GUIDANCE IS IN GOOD 'SYNCH' NOW WITH THE IDEA THAT REMNANT TYPHOON 'PHANFONE' MOISTURE AND ENERGY HAS SETTLED THE WAVE PATTERN DOWN ALONG THE WEST COAST OF NORTH AMERICA AND WILL ENTER THE GULF OF ALASKA...NOT THE SOUTHERN BERING SEA. OUT WEST...THE ECENS WAS 'SPOT ON' WITH ITS SHORTWAVE RIDGE/AMPLIFIED SOLUTION FOR OUR EARLY DAY 3 (GOING BACK 48-72 HOURS AGO) VERSUS THE FLATTER GEFS/GFS SOLUTIONS. SEEING NO REASON TO DISCOUNT THE TIMING OF THE LEAD SYSTEM MIGRATING THROUGH THE WEST--AND MORE IMPORTANTLY---CARRYING A NORMAL PROGRESSION AND MIGRATION OF THIS AMPLIFIED WAVELENGTH DOWNSTREAM TO THE MID-MS VALLEY. THAT PUTS THE 10/00Z EC-DERIVED SOLUTION AT ODDS WITH CONTINUITY AND THE REMAINDER OF THE GLOBAL GUIDANCE FOR DAY 5-6 FOR THE EAST CENTRAL US AND NORTHEAST. THE 10/00Z DETERMINISTIC ECMWF AND ECENS LOOKED 'OVER-AMPLIFIED' IN THE GREAT LAKES-NORTHEAST WITH ITS CLOSED 500MB LOW SOLUTION OVER CENTRAL KENTUCKY AT 16/00Z AND BEYOND. UNLESS THERE BECOMES A VERY ABRUPT DEVELOPMENT OF A DOWNSTREAM BLOCK INVOF LABRADOR AND OVER ATLANTIC CANADA ALONG 60W...MOMENTUM (A PUSH OF JET-LEVEL PACIFIC FLOW) SHOULD TAKE ANY HINT OF A CLOSED 250MB-500MB CIRCULATION INTO SOUTHERN QUEBEC BY 16/12Z. GRANTED...THE REASON FOR A CLOSED LOW IN THE FIRST PLACE IS HOW QUICKLY THE PACIFIC NORTHERN STREAM FLOW RACES ACROSS SOUTH CENTRAL CANADA AND DETACHES FROM THE LEAD WAVE...BUT WOULD LIKE TO SEE A TREND FOR AMPLIFICATION UPSTREAM AND DOWNSTREAM. AND THERE IS NO SUCH SIGNAL. THIS DELVES INTO THE ISSUE OF WHEN/WHERE AND FOR HOW LONG...'A SPLIT' IN THE UPPER-LEVEL FLOW EAST OF THE MISSISSIPPI COULD POSSIBLY SUSTAIN A DETACHED SYSTEM SO FAR SOUTH--IE THAT'S WHAT THE 10/00Z ECMWF SOLUTION OFFERS. A SECOND FEATURE OF THE PATTERN IN THE NORTH PACIFIC THAT MAY END UP TRENDING 'NEW WRINKLES' IN THE LATTER HALF OF THE MEDIUM RANGE PERIOD---WILL BE REMNANT MOISTURE AND ENERGY FROM TYPHOON 'VONGFONG'. WHAT IS ATTEMPTING TO OCCUR ACROSS SOUTHEAST CANADA IN THE DAY 4-6 PERIOD...IS NOT UNLIKE WHAT WILL TRY TO DEVELOP IN THE NORTH CENTRAL/NORTHEAST PACIFIC AROUND DAY 5-7 ALONG 140W LONGITUDE. THAT IS...A PACIFIC NORTHERN STREAM 'BURST' ALONG THE 50TH PARALLEL AND THE POSSIBILITY OF A CLOSED 250MB-500MB CIRCULATION OFF THE WEST COAST. SENSIBLE WEATHER HIGHLIGHTS... WHAT APPEARS TO TRANSPIRE IN THE NORTHEAST DAY 5...LOOKS MORE LIKE AN UPPER-LEVEL TROWAL FEATURE...WITH THE CONSENSUS APPROACH ALLOWING FOR WRAP AROUND 'COLD POOL DERIVED' SHOWER ACTIVITY TO GRIND SLOWLY NORTHEASTWARD BEHIND THE FRONTAL PASSAGE OVER THE EASTERN GREAT LAKES...UPPER OHIO VALLEY AND ALONG THE NORTHEASTERN SEABOARD. EXPECTING NARROW BANDS OF MODERATE TO HEAVY RAINFALL ALONG/JUST AHEAD OF THE FRONT...AN APPRECIABLE DRY SLOT AND DEFORMATION CLOUDS/PRECIPITATION TO ACCOMPANY THIS PARTICULAR SYSTEM. THE PACIFIC NORTHWEST ALSO LOOKS INCREASINGLY WET/WINDY NEXT WEEK WITH A GRADUAL ENCROACHMENT OF THE NEXT LONGWAVE TROUGH AND SUBSEQUENT REINFORCING ENERGIES FROM THE ERN PACIFIC. VOJTESAK