EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1043 AM EST SAT DEC 26 2015 VALID 12Z TUE DEC 29 2015 - 12Z SAT JAN 02 2016 ...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT... THE LATEST MODELS AND ENSEMBLES SEEM REASONABLY COMPATABLE/WELL CLUSTERED WITH DEPPICTION OF AN AMPLIFIED FLOW PATTERN WITH BELOW NORMAL FORECAST SPREAD AND UNCERTAINTY. GUIDANCE REMAINS CONSISTENT IN SHOWING A GRADUAL MIGRATION/TRANSITION OF A WRN-CENTRAL US UPPER TROUGH INTO THE EAST WHILE A RIDGE ALOFT BUILDS INTO WRN NOAM. THIS EVOLUTION WILL EVENTUALLY SUPPORT A DRYING TREND ACROSS MUCH OF THE LOWER 48 AND BRING AN END TO THE EXCEPTIONALLY WARM ERN US TEMPS. ACCORDINGLY...THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A COMPOSITE BLEND OF DETERMINISTIC AND ENSEMBLE GUIDANCE. WPC CONTINUITY IS WELL MAINTAINED. ...SENSIBLE WEATHER HIGHLIGHTS... A POTENT LEAD SYSTEM AFFECTING THE NERN/ERN US TUE WILL LIKELY SUPPORT WINTRY WEATHER FROM THE UPPER MS VALLEY OUT TO THE NRN TIER OF THE NORTHEAST WHILE WARM SECTOR RNFL SHOULD BE ON THE DECREASE. AFTER ONLY A BRIEF BREAK UPPER ENERGY EJECTING FROM THE WEST SHOULD SUPPORT SOME NRN TIER SNOW AND ANOTHER MOISTURE SURGE FROM THE GULF COAST NEWD...WITH HIGHEST TOTALS EXPECTED INLAND FROM THE CENTRAL GULF COAST AND SOUTHEAST WITH ACTIVITY ENHANCED BY ONE OR MORE FRONTAL WAVES. PASSAGE OF THIS SECOND SYSTEM SHOULD FINALLY BRING A MUCH DRIER TREND TO THE EAST ASIDE FROM PERIODS OF SNOW TO THE LEE OF THE GREAT LAKES. FARTHER WWD...AN EARLY WEEK COMPACT SYSTEM DROPPING TOWARD THE PAC NW SHOULD BE ACCOMPANIED BY MODEST PRECIPITATION. MUCH OF THE WEST SHOULD BE FAIRLY DRY BY THE LATTER HALF OF THE PERIOD AS RIDGING ALOFT BUILDS INTO THE REGION. MOST GUIDANCE SHOWS LOW LATITUDE FLOW ALOFT FROM THE ERN PAC ACROSS NRN MEXICO PPSSIBLY BRINGING SOME OVERRUNNING MOISTURE INTO THE RIO GRANDE VALLEY AND OUT ACROSS THE GULF COAST HEADING INTO NEXT WEEKEND...WITH TEMPS PSBLY COLD ENOUGH FOR WINTRY PCPN BACK ACROSS THE SRN ROCKIES/HI PLAINS. WITHIN A BROAD AREA OF BELOW NORMAL WRN-CNTRL CONUS TEMPS THE GREATEST NEGATIVE ANOMALIES ARE STILL FCST TO BE OVER/NEAR THE SRN HIGH PLAINS NEWD WITH THE HELP OF SNOW COVER FROM THIS WEEKEND'S STORM. THE NRN TIER MAY TREND ABOVE NORMAL BY LATE IN THE PERIOD. IN CONSIDERABLY MODIFIED FORM THE COLD AIR WILL SPREAD EWD...BRINGING SLIGHTLY BELOW NORMAL HIGHS TO THE CENTRAL-SRN EAST COAST BY NEXT SAT. WHILE ANOMALIES SHOULD BE RELATIVELY MODEST IT WILL LIKELY FEEL QUITE CHILLY GIVEN RECENT BALMY WARMTH. BEFORE THE COOL AIR ARRIVES MORE DAILY RECORD WARM LOWS ARE POSSIBLE OVER THE SOUTHEAST. SCHICHTEL