ALASKA EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 153 PM EST TUE NOV 04 2014 VALID 12Z SAT NOV 08 2014 - 12Z WED NOV 12 2014 ...REMNANTS OF TYPHOON 'NURI' TO AFFECT THE ALEUTIANS THIS WEEKEND... THE MEDIUM RANGE FORECAST WILL BE DOMINATED BY THE EXTRATROPICAL TRANSITION OF SUPER TYPHOON 'NURI'. AT 4/1500Z---PACKING MAXIMUM WINDS OF 120+ KNOTS INVOF 23.4N 136.6E. THE DETERMINISTIC GFS FROM 4/12Z IS A FASTER SOLUTION THAN THE 4/00Z ECMWF...HAVING THE SUB-924MB LOW CENTER REACHING THE BERING SEA AND DATELINE NEAR 56N LATITUDE AROUND 8/06Z (THE 4/12Z GFS VERSION). COMPARATIVELY SPEAKING...THE 4/00Z ECMWF CARRIES A SIMILAR DEPTH AND A SUB-924MB LOW CENTER AT 56N NEAR 169E LONGITUDE AT 8/06Z. THE 4/12Z GFS 850MB HEIGHT ANOMALIES FOR THIS STORM SYSTEM ARE CONSISTENTLY 4-5 STANDARD DEVIATIONS (SDs) BELOW NORMAL BETWEEN 8/12Z AND 10/00Z AND REMAINS IN THE 2-4 SD RANGE UNTIL 12/00Z. INITIALIZING OFF THIS 56N LATITUDE MARK...THE DAY 4 (8/12Z) LOW CENTER---USING THE BLENDED 4/00Z ECENS/GEFS MEANS AND DETERMINISTIC ECMWF---YIELDS A 936MB LOW CENTERED ON 56N 172.6E. AND ON DAY 5 (9/12Z)...A 956MB LOW INVOF 58.3N 178.5E. THERE IS ROOM FOR ADJUSTMENT AND JUST BECAUSE THE WPC FORECAST CALLS FOR A SLIGHT WEAKENING OF THE CENTRAL PRESSURE...DOES NOT HOWEVER---AND SHOULD NOT---DIMINISH THE SYSTEM'S INTENSE NATURE AND TREMENDOUS POTENTIAL---FOR WIND AND WAVES...FAR REMOVED FROM THE LOWEST CENTRAL PRESSURE. PRECIPITATION... IN LIQUID...FREEZING AND FROZEN FORM (AN ELEVATION-DEPENDENT VARIABLE)---AND HEAVY IN INTENSITY AT TIMES---WILL BE FELT WELL AHEAD OF THE LOW PRESSURE CENTER FROM DAY 4 FORWARD AS THE SYSTEM TRACKS ON AN EASTERLY AND EAST-SOUTHEASTERLY TRAJECTORY. 850MB MOISTURE FLUX ANOMALIES ARE 5 STANDARD DEVIATIONS ABOVE NORMAL ACROSS THE ALEUTIANS AND OVER THE OPEN SOUTH CENTRAL BERING SEA THROUGH THE LIFE CYCLE OF THIS STORM. A DOWNSTREAM UPPER-LEVEL RIDGE IN PLACE ALONG THE MOUNTAINS OF WESTERN CANADA WILL SERVE TO SHEAR AND STEER A SERIES OF 'RELATIVELY WEAK' SHORTWAVES---EJECTING INTO THE GULF OF ALASKA AND NORTHWARD ALONG THE WESTERN COAST AND SOUTHWEST INTERIOR. THESE WILL LIKELY BE LOCALLY HEAVY PRECIPITATION PRODUCERS GIVEN THEIR MOISTURE FLUX ANOMALIES OF 3 STANDARD DEVIATIONS. THROUGH THE FIRST HALF OF THE MEDIUM RANGE PERIOD...WARM/MOIST AIR SATURATES AN INCREASINGLY DEEPER LAYER---CAUSING THE BOUNDARY LAYER TEMPERATURES ALONG THE IMMEDIATE COAST LINE TO GRADUALLY RISE ABOVE FREEZING. BUT A GRADUAL RISE IN TEMPERATURES AND LOCALIZED NATURE OF THE PRECIPITATION WILL LIKELY CREATE---P-TYPE FORECAST CHALLENGES AWAY FROM THE COAST---ESPECIALLY IN SHELTERED COASTAL RIVER VALLEYS AND ALONG THE INSIDE PASSAGE OF THE PANHANDLE AFTER DAY 5. PLEASE MONITOR INFORMATION PROVIDED BY YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE FOR FORECAST DETAILS AND THE LOCALLY-VARIABLE CONDITIONS...INHERENT TO YOUR SPECIFIC AREA. THIS INCLUDES INTERESTS IN THE BERING SEA AND GULF OF ALASKA. VOJTESAK