EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1042 AM EST FRI FEB 10 2017 VALID 12Z MON FEB 13 2017 - 12Z FRI FEB 17 2017 PATTERN OVERVIEW/GUIDANCE EVALUATION/MODEL PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ THE MODELS AND ENSEMBLES SHOW A PERSISTENT CENTRAL TO EASTERN PACIFIC TROUGH....WITH DOWNSTREAM HIGH AMPLITUDE RIDGING ACROSS THE PACIFIC NORTHWEST AND WESTERN CANADA. THIS FAVORS A DOWNSTREAM TROUGH OVER THE GREAT LAKES AND NORTHEAST. DIFFERENCES REMAIN FOR THE SYSTEM MOVING ACROSS THE SOUTHERN TIER OF THE COUNTRY. THE FLOW PATTERN FAVORS A SLOWER MOTION TO THIS SYSTEM AS NO KICKER SHORTWAVES APPEAR TO BE PRESENT TO EJECT THE LOW QUICKLY AWAY FROM THE SOUTHWEST. THE USE OF THE CANADIAN AND GEFS MEANS COUNTERS THE FASTER MOTION OF THE ECMWF AND ITS ENSMEBLES. WE USED A CONSENSUS OF THE 00Z NAEFS MEAN, 00Z ECMWF/00Z ECMWF ENSEMBLE MEAN, 06Z GFS/00Z GEFS MEAN FOR PRESSURES, WIND GRIDS, AND 500 HPA HEIGHTS FOR MONDAY INTO WEDNESDAY. THE 00Z UKMET WAS AN OUTLIER IN MOVING THE NORTHEAST CYCLONE FASTER OFF THE COAST MON 13 FEB AND TUE 14 FEB...AND NOT USED DUE TO OUTSTANDING CLUSTERING AMONG THE 06Z GFS/00Z ECMWF/00Z CANADIAN GLOBAL AND THEIR RESPECTIVE ENSEMBLE MEANS. THE SPREAD AMONG SOLUTIONS GROWS DAYS 6 THU 16 FEB AND FRI 17 FEB. THE 06Z GFS BACKED OFF THE 00Z RUN IDEA OF AN INTENSE 700-500 MB CLOSED LOW OVER SOUTHEAST CANADA NEAR LK HURON...BUT THEN LED TO A FASTER PROGRESSION OF THE TROUGH OFF THE EAST COAST. LIKEWISE...OUT WEST...THERE ARE TIMING DIFFERENCES WHICH DEVELOP. THE 06Z GFS TRENDED FASTER MOVING A 500 MB WAVE ONSHORE NEXT FRI 17 FEB BUT THE 06Z GEFS MEAN WAS SEVERAL HOURS SLOWER...IN BETTER AGREEMENT WITH THE 00Z GFS RUN. LIKEWISE...THE ECMWF SHOWED RUN TO RUN CHANGES IN TIMING OF THE APPROACHING WAVES...LEADING TO LOW CONFIDENCE IN THE FORECASTS. GIVEN THE SLOWER TIMING OF THE ECMWF/CANADIAN/GEFS ENSEMBLE MEANS...AND A HIGH AMPLITUDE DOWNSTREAM RIDGE...A BLEND OF THE 00Z NAEFS/06Z GEFS/00Z ECMWF ENSEMBLE MEANS WAS USED. UPSTREAM IN THE PACIFIC OCEAN...BOTH THE ECMWF AND GEFS MEANS SHOW STRONGLY CONFLUENT FLOW WITH A POWERFUL 400-200 MB JET (I.E. THE ECMWF MEAN SHOWS A 170 KT JET FROM 160-180W BETWEEN 30-40N. FASTER MOVING WAVES WITHIN THIS FLOW ARE DIFFICULT TO TIME...SO PREDICTABILITY LOOKS TO DROP TO BELOW AVERAGE FROM FRI 17 FEB ONWARD. WEATHER HIGHLIGHTS/THREATS ~~~~~~~~~~~~~~~~~~~~~~~~~~ THE SOUTHWESTERN UPPER LOW WILL LIKELY GENERATE SOME ENHANCED AREAS OF RAIN AND HIGHER ELEVATION SNOW OVER THE FOUR CORNERS REGION AND SOUTHERN ROCKIES INTO THE START OF NEXT WEEK. AS THIS FEATURE DRIFTS EAST, IT SHOULD PROMOTE A THREAT FOR HEAVY RNFL ACROSS MUCH OF TEXAS AND LOWER MISSISSIPPI VALLEY. WITH THE DOWNSTREAM FRONT STALLING NEAR FL...A SHOWERY PERIOD IS EXPECTED. THE NEXT PACIFIC CYCLONE OFF THE COAST NEXT THU AND POSSIBLY ONSHORE FRI SHOULD GET CLOSE ENOUGH TO PRODUCE WIDESPREAD PRECIPITATION FROM NORTHERN CA NORTH ACROSS OR AND WA...EVENTUALLY EXTENDING INLAND INTO THE NORTHERN ROCKIES. THE RAPIDLY INTENSIFYING CYCLONE JUST OFF THE NEW ENGLAND COAST ON MONDAY PROVIDES POTENTIAL FOR A MAJOR PRECIPITATION AND WIND/WAVE EVENT. THERE ARE MULTIPLE ENSEMBLE MEMBERS AND MODELS SHOWING POTENTIAL FOR HEAVY SNOW ACROSS INTERIOR NEW ENGLAND TO COASTAL MAINE WITH GOOD CLUSTERING ON THE SUNDAY NIGHT-MONDAY EVENT AND BIGGER SPREAD ON THE WED-THU POTENTIAL EVENT IN IN EASTERN NEW ENGLAND DUE TO DIFFERENCES INVOLVING A DEEP CYCLONE NEAR NEW ENGLAND AND THE CANADIAN MARITIMES WHICH HAVEN'T BEEN RESOLVED YET. THE NORTHERN PLAINS AND UPPER MS VALLEY ALSO SEE ABOVE NORMAL TEMPERATURES AS THE DEEP LAYER RIDGE OUT WEST STARTS DRIFTING EAST INTO THE HIGH PLAINS. ABOVE NORMAL TEMPERATURES ACROSS A WIDE PORTION OF THE ROCKIES/GREAT BASIN/SOUTHWEST US FOR DAYS 3-6. ON FRI 17 FEB WITH AN INCREASE IN CLOUDS AND PRECIP...TEMPERATURE REVERT TO NORMAL OR SLIGHTLY BELOW FROM COASTAL CA NORTH ACROSS OR AND WA. PETERSEN/ROTH