EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 110 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... DEEP TROUGHING IN THE EAST THIS WEEKEND WILL GIVE WAY TO A PERHAPS POTENT SOUTHERN STREAM SHORTWAVE TUE-WED WHILE THE WEST WILL SEE RISING THEN FALLING HEIGHTS. WHAT STARTS OUT AS A RATHER DRY AND COLD WEEKEND IN THE EAST WILL TRANSITION TO LESS COLD EARLY NEXT WEEK AS A DEVELOPING SYSTEM MOVES ALONG THE GULF COAST AND SOUTHEAST. THIS IS FORECAST TO TURN UP THE COAST TUE/WED WITH SOME WINTRY CONSEQUENCES. PRECIPITATION IN THE WEST WILL BE CONFINED TO THE NORTHWEST -- WA/OR/ID/MT -- AS CALIFORNIA REMAINS UNDER THE CONTROL OF AN UPPER HIGH SLIDING SOUTHEASTWARD INTO OLD MEXICO NEXT WEEK. ...GUIDANCE ASSESSMENT... THE GFS REMAINS SLOWER THAN THE ECMWF/ECENS MEAN WITH THE INCOMING SHORTWAVE INTO WA/OR ON SATURDAY... AS HAS BEEN THE CASE FOR A FEW DAYS. THE GFS HAS BEEN MOST INCONSISTENT WITH THIS FEATURE WHILE THE ECMWF/CMC AND THE ECMWF EPS SEEM TO HAVE A BETTER HANDLE ON IT. USED THAT CLUSTER THROUGH MUCH OF THE FORECAST. IN THE EAST, THE ECMWF AND ITS ENSEMBLES WERE STILL A BIT DEEPER WITH THE TROUGH THAN THE GFS/GEFS THIS WEEKEND... AGAIN, AS HAS BEEN THE CASE. BY SUN/MON, THE DIFFERENCES AMONG THE MODELS MANIFEST MORE AT THE SURFACE AS LOW PRESSURE STARTS TO ORGANIZE OVER TEXAS AND THE LOWER MS VALLEY. STILL FAVORED THE ECMWF/CMC-LED CLUSTER AS THE GFS EMPHASIZED THE NORTHERN STREAM ENERGY MORE SO THAN THE SOUTHERN... WHICH IS WHAT THE ECMWF SHOWED A FEW DAYS AGO BUT HAS SINCE ADJUSTED. EITHER WAY, BY TUESDAY ALL MODELS SHOW LOW PRESSURE DEEPENING NEAR OR OFF THE SOUTHEAST COAST AND TURNING NORTHEASTWARD. GFS RUNS HAVE BEEN TO THE EAST/OFFSHORE WHILE THE ECMWF AND ITS MEAN HAVE RECENTLY SHOWN AN INLAND RUNNER ALONG I-95/91 INTO NEW ENGLAND. THE CANADIAN LIED JUST TO THE EAST OF THE ECMWF NEAR THE GEFS MEAN. OPTED TO TREND TOWARD A MULTI-MODEL/ENSEMBLE BLEND BY TUES EVENING WHICH INCLUDED THE 18Z GEFS MEAN. LOTS OF DETAILS TO SORT OUT BUT THE SIGNAL/AGREEMENT IN THE ENSEMBLE MEANS IS SIGNIFICANT. BACK TO THE WEST BY NEXT WEDNESDAY AND THERE REMAINS A LARGE AMOUNT OF SPREAD WITH THE DEPTH/SPEED OF THE NEXT TROUGH TO MOVE TOWARD THE PAC NW. GEFS MEMBERS WERE MOSTLY SLOWER THAN THE ECMWF ENSEMBLES BUT SOMETHING IN BETWEEN SHOULD SUFFICE GIVEN THE LACK OF CONTINUITY. ...SENSIBLE WEATHER HIGHLIGHTS... VERY COLD IN THE EAST THIS WEEKEND -- MANY RECORD LOW MINS AND LOW MAXES -- AS THE CANADIAN ARCTIC AIRMASS DROPS RIGHT THROUGH THE NORTHEAST. SOUTHWESTERN STATES WILL BE NEARLY THE OPPOSITE WITH RECORD HIGH MAX/MIN TEMPERATURES PROBABLE IN CA/AZ INTO THE PACIFIC NORTHWEST. TEMPERATURES IN THE CENTRAL STATES WILL TREND WARMER FROM WEST TO EAST. PRECIPITATION IN THE WEST WILL COME IN WAVES AS SUCCESSIVE SHORTWAVES AND SURFACE BOUNDARIES MOVE INLAND. THIS SHOULD FAVOR THE COASTAL RANGE AND CASCADES MOST AND THEN ALSO INTO THE BITTERROOTS. NORTHERN PLAINS SHOULD SEE MOSTLY LIGHT QPF AS NORTHERN STREAM ENERGY MOVES THROUGH... THOUGH SOME MODELS/ENSEMBLES SHOW ABOUT A HALF INCH OVER 24-48 HRS. THE EAST WILL BECOME INCREASINGLY COMPLICATED IN BOTH PRECIP TYPE, TIMING, AND AMOUNT AS THE COASTAL SYSTEM DEVELOPS. ANTECEDENT COLD AIRMASS WILL LIKELY MEAN A PERIOD OF WINTRY WEATHER IN THE SOUTHERN APPALACHIANS AND INTERIOR SOUTHEAST WITH ICING A VERY REAL THREAT AS THE WARM AIR OVERRIDES THE IN SITU COLD AIRMASS. STORM TRACK WILL ULTIMATELY DETERMINE SPECIFICS. QPF FROM THE SYSTEM PER THE ENSEMBLES IS ALREADY ON THE MODERATE/HIGH SIDE INDICATING THAT SOME LOCATIONS WILL SEE QUITE A BIT OF PRECIPITATION -- PROBABLY OF ALL TYPES. FRACASSO