EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1027 AM EST WED FEB 10 2016 VALID 12Z SAT FEB 13 2016 - 12Z WED FEB 17 2016 ...RECORD COLD FOR PORTIONS OF THE NORTHEAST THIS WEEKEND... ...POTENT WINTER STORM POSSIBLE NEXT TUE-WED IN THE EAST... ...OVERVIEW... FOR THE EAST PAC...PACIFIC NORTHWEST AND SOUTHWEST---A RIDGE OF HIGH PRESSURE ANCHORED OVER THE GREAT BASIN MAINTAINS A DRY AND MILD PATTERN--- AND STEERS A SERIES OF PROGRESSIVE NORTHEAST PACIFIC SYSTEMS INTO THE PACIFIC NORTHWEST...BRITISH COLUMBIA AND DOWNSTREAM ACROSS THE ROCKY MOUNTAINS FROM WYOMING/MONTANA NORTHWARD INTO CENTRAL ALBERTA. DOWNSTREAM...THE WEST-TO-NORTHWEST FLOW PATTERN EXITING THE ROCKY MOUNTAINS SPREADS EASTWARD INTO THE CENTRAL PLAINS AND GREAT LAKES AND BEGINS TO INTERACT WITH AND DISPLACE (ERODE) --- THE WESTERN PERIPHERY OF A COLD TROUGH IN THE EASTERN PORTION OF THE NORTH AMERICAN CONTINENT. DEEP AND COLD --- UPPER-LEVEL TROUGH AND SURFACE HIGH IN THE EAST ON DAYS 3-4 WILL GRADUALLY MODIFY AND BECOME 'ENTANGLED' WITH SEVERAL SHORTWAVES APPROACHING FROM THE WEST. A KEY FEATURE OF THIS 'ENTANGLEMENT' IS THE EMERGENCE OF A SOUTHERN STREAM SHORTWAVE MIGRATING ACROSS THE NORTHERN GULF COAST AND SOUTHEAST --- AND ITS INTERACTION WITH THE NORTHERN STREAM FLOW AND MID-LEVEL ENERGY WITH ORIGINS IN THE NORTHEAST PACIFIC AND WEST CENTRAL CANADA --- CREATES THE POTENTIAL FOR WINTER WEATHER ACROSS THE NORTHEAST QUARTER OF THE NATION (DAYS 5-7). HENCE...MAINTAINED THE HEADLINES FROM THE MIDSHIFT. ...MODEL PREFERENCES... HAVE NO CONCERN WITH THE DAY3-4 DETAILS EMBEDDED WITHIN THE LEAD PACIFIC WAVE ENERGY AND SOLUTIONS THAT ALLOW THE MAJORITY OF THE VORTICITY TO SHEAR EASTWARD --- AND EAST OF THE CONTINENTAL DIVIDE (ACROSS THE ENTIRE STRETCH OF THE MISSOURI AND PLATTE RIVER VALLEYS). THE 10/00Z UKMET REALLY IS THE ONLY SOLUTION THAT CONTINUES TO PROJECT A 'WEST OF THE DIVIDE' STORM TRACK SOLUTION --- AND IS A SOUTHERN OUTLIER OVER THE FOUR CORNERS FOR A SECOND 00Z CYCLE IN A ROW. BECAUSE IT IS A 'FOUR CORNERS' SOLUTION --- IT WILL CERTAINTY MAINTAIN A MORE VOLATILE AND AGGRESSIVE SOLUTION ACROSS THE SOUTHERN PLAINS. THE EVOLVING FLOW PATTERN DOWNSTREAM SEEMS TO 'DEBUNK' THE AGGRESSIVE UKMET APPROACH MID-PERIOD. DO HAVE TO GO WITH A 10/00Z ECENS...NAEFS AND GEFS BLEND (50/30/20 WEIGHTING) AFTER 15/00Z DUE TO THE DETERMINISTIC VARIANCE AT 500MB...SURFACE AND ALIGNMENTS OF THE PRECIPITATION DISTRIBUTIONS ALONG AND EAST OF THE MISSISSIPPI/OHIO VALLEYS. THIS DOES NOT ALTER THE NATURE OF THE PREVIOUS WPC DAY3-7 SYNOPTIC FRONTS --- EAST OF THE MS RIVER --- BUT THIS PACKAGE DOES EMPHASIZE A SLIGHT ADJUSTMENT TO THE SPACING OF THE PRIMARY FEATURES WEST OF THE MISSISSIPPI AND NORTH OF THE PLATTE RIVER VALLEYS. ...UNCERTAINTY ASSESSMENT... THE 10/00Z FORECAST CYCLE OFFERS SOME VERY DIFFERENT APPROACHES (SOLUTIONS) FOR THE DAY 4-6 SYNOPTIC-SCALE SYSTEM ANTICIPATED TO MIGRATE --- FROM THE MS VALLEY/GREAT LAKES TO THE MID-ATLANTIC REGION AND NORTHEAST COAST. THE 10/00Z DETERMINISTIC GFS/CANADIAN AND ECMWF SEEMED TO BE IN DECENT AGREEMENT (INVOF THE OZARKS) UNTIL 15/00Z BEFORE THE 10/00Z GFS ALLOWS A NORTHERN STREAM SHORTWAVE TO BECOME THE MORE DOMINANT SYNOPTIC-SCALE ENTITY IN THE FLOW. THE RESULT BEING...MORE OF A POSITIVE-TILT TROUGH AXIS (ALBEIT A BRIEF ONE) ALONG THE EAST COAST BY 17/00Z. THIS SOLUTION...BUT MORE SO---THE 10/00Z UKMET SEEM TO BE THE LEAST LIKELY DETERMINISTIC SCENARIOS. THAT SAID...THE 10/00Z DETERMINISTIC CANADIAN/ECMWF...10/00Z GFS-PARALLEL AND 10/06Z DETERMINISTIC GFS (OPERATIONAL RUN) SEEM TO BE THE BETTER REPRESENTATIONS HEADING INTO DAY 6. GIVEN THE 10/00Z ENSEMBLE GUIDANCE SCENARIO --- AND THEIR PROJECTIONS FOR MID-LEVEL TROUGH AMPLITUDE EXITING THE EASTERN SEABOARD --- THE 10/00Z AND 10/06Z CYCLES (DETERMINISTIC VIEWPOINT) BEYOND DAY 5 AND HEADING INTO DAY 6 SEEMED TO BE "FAR FROM A PERFECT PROG SNAP SHOT". LACKING THE RUN-TO-RUN CONTINUITY OVER THE GREAT LAKES AND NEW ENGLAND AFTER 16/00Z (LATE DAY 5) --- THIS POINTS TO A BLEND OF THE 10/00Z GEFS...ECENS AND NAEFS ENSEMBLE MEANS FOR DAY 6-7 ...AND TO MANUALLY ADJUST THE UPSTREAM SPACING FROM THE COLUMBIA BASIN EASTWARD INTO THE DAKOTAS. ...SENSIBLE WEATHER HIGHLIGHTS... PREVAILING CHILL LINGERS ACROSS THE EASTERN THIRD OF THE NATION HEADING INTO MONDAY MORNING ---AND THE COLD CANADIAN SURFACE RIDGE IS STUBBORNLY RETREATING (NORTHEASTWARD) ALONG THE NORTHEAST COAST AND GULF OF MAINE---EVEN OUT TO DAY 5-6. BECAUSE OF THE STUBBORN SURFACE RIDGE AND ENTRAINMENT OF MOISTURE AND ENERGY ALONG THE SOUTHERN AND WESTERN FLANKS (AND ATOP) THIS RIDGE--- EXPECT SOME LOCALLY MODERATE-TO-HEAVY CONCENTRATIONS OF OVER-RUNNING PRECIPITATION (AND WINTRY P-TYPE SCENARIOS) WITH EMBEDDED ENERGY APPROACHING FROM TWO DIRECTIONS...THE GREAT LAKES (A MID-LEVEL FOCUS) AND THE NORTHEAST GULF OF MEXICO (A LOW-LEVEL FOCUS). MORE MILD AND DRY ACROSS THE SOUTHWEST --- SHOULD CONTINUE THROUGH MOST OF THIS FORECAST PERIOD AND THE SCENARIO FOR A SPLITTING UPPER-LEVEL TROUGH DOWNSTREAM ALONG A MAJOR PORTION OF THE CONTINENTAL DIVIDE --- MAY PRODUCE SOME PRECIPITATION AND ADDITIONAL CLOUDINESS AND WINDS ALONG THE WESTERN SIDE---BUT WILL PRIMARILY BECOME A FORECAST CHALLENGE FOR TEMPERATURES (EAST SIDE OF THE DIVIDE). VOJTESAK