EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1159 AM EDT SUN SEP 17 2017 VALID 12Z WED SEP 20 2017 - 12Z SUN SEP 24 2017 ...OVERVIEW/GUIDANCE EVALUATION/PREFERENCES... BASED ON SOME OF THE LATEST OPERATIONAL/ENSEMBLE GUIDANCE...WHAT IS CURRENTLY HURRICANE JOSE SPINNING WELL NORTHEAST OF THE BAHAMAS WILL CONTINUE TO LIFT NORTHWARD WHERE IT WILL EVENTUALLY MAKE A SHARP EASTWARD TURN TOWARD THE 40N/70W BENCHMARK BY EARLY WEDNESDAY. THEREAFTER...THE TROPICAL CIRCULATION WILL MIGRATE TOWARD THE EAST WHERE THERE ARE NUMEROUS UNCERTAINTIES ON THE ULTIMATE PATH OF JOSE. THE GUIDANCE CONTINUES TO WAVER ON WHETHER TO INGEST IT INTO THE WESTERLIES AND CARRY IT INTO THE CANADIAN MARITIMES LIKE THE 00Z CMC OR ALLOW IT TO LINGER OFFSHORE OF NEW ENGLAND. THE GROWING TREND IS TO DEPICT SOME SORT OF ANTICYCLONIC LOOP IN THE OFFSHORE WATERS ALTHOUGH THE PLETHORA OF SOLUTIONS BECOME QUITE NUMEROUS BEYOND DAY 4/THURSDAY. DURING THE INITIAL TIME STEPS...DAY 3/4...WEDNESDAY/THURSDAY...THE 00Z ECMWF/UKMET SIT WELL WEST OF THE CURRENT NHC FORECAST TRACK. THE INITIAL BEST FIT TO THIS OFFICIAL TRACK IS A COMBINATION OF THE 00Z GFS/CMC AND THE PREVIOUS 12Z ECMWF BEFORE THE FORMER TWO SOLUTIONS QUICKLY DIVERGE BECOMING FASTER. BY DAY 4/THURSDAY...SOME BLEND OF THE 00Z GEFS/ECMWF ENSEMBLE MEANS AND THE PREVIOUS 12Z ECMWF WOULD SEEM TO SUFFICE HERE. THE FORECAST TRACK WILL LIKELY CHANGE IN UPCOMING NHC FORECASTS GIVEN THE VOLATILITY OF THE MODEL SUITES. ACROSS THE CONTINENTAL U.S...THE LARGE-SCALE PATTERN WILL CONTINUE TO FEATURE WELL BELOW NORMAL HEIGHTS OVER THE WESTERN STATES WHILE POSITIVE HEIGHT ANOMALIES REMAIN OVER THE EAST. COMPARED TO MID/LATE SEPTEMBER CLIMATOLOGY...500-MB HEIGHT DEPARTURES SHOULD BE AROUND 2.5 TO 3 STANDARD DEVIATIONS BELOW AVERAGE BASED ON THE 00Z GFS. THIS IS PRIMARILY FOCUSED ALONG THE WESTERN THIRD OF THE COUNTRY AS SHARPENING HEIGHT FALLS DIG INTO THE DESERT SOUTHWEST. BY THE END OF THE FORECAST...SEPTEMBER 24...NOT MUCH EASTWARD PROGRESSION IS NOTED WITH THE TROUGH AXIS GENERALLY SPANNING THE INTERMOUNTAIN WEST/ROCKY MOUNTAIN REGION. MULTI-DAY ENSEMBLE SPAGHETTI PLOTS SHOWED A DECIDED SLOWING A COUPLE OF MODEL RUNS AGO WITH THIS TREND REMAINING A FIXTURE IN THE FORECAST. CLUSTERING OF THE 90 ENSEMBLE MEMBERS IS REASONABLE INTO EARLY NEXT WEEKEND ALTHOUGH THE OPERATIONAL MODELS VARY IN DEPTH/TIMING. IN PARTICULAR...THE 00Z GFS BECOMES A BIT QUICKER CARRYING THE FRONTAL ZONE TOWARD THE GREAT PLAINS WHICH HAS BEEN A COMMON THEME THE PAST DAY OR SO. MEANWHILE...A VAST MAJORITY OF THE 00Z ECMWF ENSEMBLE MEMBERS ARE DISPLACED SOUTHWEST AS THE TROUGH DIGS MORE THAN THE OTHER SOLUTIONS. ALL AND ALL...THERE ARE DETAIL DIFFERENCES BUT THE SYNOPTIC-SCALE PATTERN SEEMS WELL AGREED UPON. THE LARGEST ISSUE REMAINS WITH THE HANDLING OF JOSE BEYOND DAY 3/WEDNESDAY. THE FORECAST WAS HEAVILY WEIGHTED TOWARD THE HANDLING OF JOSE WHICH LED TO UTILIZING A MORE ENSEMBLE MEANS BASED APPROACH BEYOND DAY 5/FRIDAY IN SPITE OF THE GOOD AGREEMENT OVER THE WESTERN U.S. EARLY ON...WENT WITH A COMBINATION OF THE 00Z GFS/CMC AND THE PREVIOUS 12Z ECMWF IN CONJUNCTION WITH THE ENSEMBLE MEANS BEFORE THE 00Z GFS/CMC DIVERGE FROM THE NHC TRACK FORECAST. BY THURSDAY...WENT WITH A BLEND OF THE PREVIOUS 12Z ECMWF AND 00Z GEFS/ECMWF ENSEMBLE MEANS BEFORE GOING SOLELY MEANS BY FRIDAY EVENING. CONFIDENCE REMAINS ABOVE AVERAGE WITHIN SYNOPTIC FEATURES BUT BELOW AVERAGE WITH HOW TO HANDLE JOSE INTO NEXT WEEKEND. ...SENSIBLE WEATHER/HIGHLIGHTS... WELL BELOW NORMAL TEMPERATURES ARE EXPECTED ACROSS THE WESTERN STATES WITH DEPARTURES LIKELY TO REACH THE 20 DEGREE MARK. THIS WILL GENERALLY CONCENTRATE FROM THE PACIFIC NORTHWEST/EXTREME NORTHERN CA EASTWARD THROUGH THE CENTRAL GREAT BASIN AND INTO THE UPPER INTERMOUNTAIN WEST/NORTHERN ROCKIES. THIS FAVORS HIGH TEMPERATURES IN THE 50S OVER A VAST MAJORITY OF THE REGION WITH A BOWL OF 40S ACROSS THE ELEVATED TOPOGRAPHY. EVEN SOME MID/UPPER 30S ARE POSSIBLE OVER THE TETONS. GIVEN WIDESPREAD PRECIPITATION LIKELY OVER THE REGION...SOME SNOWFALL IS EXPECTED OVER SUCH HIGHER ELEVATIONS. FARTHER DOWNSTREAM OVER THE GREAT LAKES AND INTERIOR NEW ENGLAND WHERE MID-LEVEL HEIGHTS WILL BE 1.5 TO 2 STANDARD DEVIATIONS ABOVE CLIMATOLOGY...WARMTH IS LIKELY WITH HIGHS AROUND 10 TO 15 DEGREES ABOVE AVERAGE. IT SHOULD BE QUITE MILD EAST OF THE ROCKIES AS WIDESPREAD 80S ENCOMPASS THE REGION WHILE 90S WILL PREVAIL FROM THE SOUTHERN PLAINS INTO THE MID-SOUTH AND SOUTHEASTERN U.S. THE WARMEST DAY SHOULD BE WEDNESDAY AS HIGHS REACH THE MID/UPPER 90S OVER MUCH OF CENTRAL TX. OVERNIGHT...SOME RECORD WARM MINIMA ARE POSSIBLE ON FRIDAY ACROSS SOME LOCATIONS OF THE CENTRAL U.S. GIVEN THE CLOSE PROXIMITY OF JOSE TO THE MID-ATLANTIC/NEW ENGLAND COAST IN SOME OF THE GUIDANCE...RAINFALL WILL BE POSSIBLE CLOSER TO THE COASTAL LOCALES. DEPENDING ON THE INTENSITY OF THE CIRCULATION...A TIGHT PRESSURE GRADIENT WILL LEAD TO GUSTY WINDS AS WELL AS ROUGH SURF ACROSS THE ATLANTIC WATERS. ELSEWHERE...PERSISTENT MID-LEVEL SOUTHWESTERLY FLOW ACROSS THE CENTRAL PLAINS UP TO THE NORTHERN PLAINS/UPPER MIDWEST MAY LEAD TO A HEAVY RAINFALL EVENT BETWEEN FRIDAY AND SUNDAY. DETAILS ARE UNCERTAIN BUT THE PATTERN APPEARS RIPE FOR SUCH A SITUATION TO TAKE SHAPE. RUBIN-OSTER