Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6
000 FXUS02 KWBC 190730 PMDEPD EXTENDED FORECAST DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 230 AM EST FRI DEC 19 2014 VALID 12Z MON DEC 22 2014 - 12Z FRI DEC 26 2014 ...AN ACTIVE HOLIDAY WEATHER PATTERN NEXT WEEK... ...GUIDANCE/UNCERTAINTY ASSESSMENT.. WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS HAVE BEEN PRIMARILY DERIVED FROM THE 12 UTC ECMWF ENSEMBLE MEAN. THIS OFFERS A BIT MORE AMPLITUDE AND OVERALL CLOSER WPC CONTINUITY COMPARED TO GFS/NAEFS ENSEMBLE MEANS. THIS SEEMS CONSISTENT WITH UPSTREAM FLOW AMPLITUDE...BUT WPC PROGS DID HEDGE IN A LITTLE 18 UTC GFS ENSEMBLE MEAN AND 12 UTC NAEFS ENSEMBLE MEAN CONSIDERING AVERAGE TO BELOW AVERAGE PATTERN PREDICTABILITY. THIS UNCERTAINTY IS PARTICULARLY EVIDENT IN RECENT DETERMINISTIC MODEL RUN TO RUN CONTINUITY ISSUES THAT PRECLUDED WPC USAGE. ...PATTERN AND SENSIBLE WEATHER HIGHLIGHTS... AN AMPLIFIED MID-UPPER LEVEL TROUGH AND PCPN FOCUSING LEAD SURFACE LOW/FRONTAL SYSTEM DEVELOPS OVER THE CENTRAL US BY EARLY NEXT WEEK AS EMBEDDED IMPUSLES DIG TO THE LEE OF AN AMPLIFIED ERN PACIFIC RIDGE ALOFT. THE SUPPORTING AND INCREASINGLY NEG-TILT TROUGH ALOFT WORKS OVER THE ERN US AND OUT THROUGH THE NERN STATES INTO DAYS 5/6 WED/THU. SUSPECT A THREAT EXISTS FOR ORGANIZED WINTER WEATHER IN LEAD FLOW OVER A COOLED NRN NEW ENG AIRMASS TUE WITH LOW INDUCED WRAP-AROUND SNOWS SPREADING FROM THE UPPER MIDWEST AND GREAT LAKE STATES/MIDWEST LINGERING PAST TUE/WED THAT WORK MORE IN ERNEST OUT THROUGH THE APPALACHIANS AND MAINLY INTERIOR NRN MID-ATLANTIC/NERN US ON CHRISTMAS EVE AND CHRISTMAS. MEANWHILE...NRN/NERN PACIFIC MID-UPPER TROUGH ENERGIES SHOULD WORK SHARPLY SEWD THROUGH AND TO THE LEE OF AN AMBIENT DOWNSTREAM MEAN RIDGE POSITION TO SPREAD DYNAMICALLY DRIVEN PCPN INTO THE PAC NW WED AND FURTHER INLAND ACROSS THE N-CENTRAL INTERMOUNTAIN WEST/ROCKIES CHRISTMAS INTO NEXT FRI. THIS WILL INCLUDE A THREAT FOR MODERATELY HEAVY SNOWS FOCUSING OVER FAVORED INLAND TERRAIN. THIS WRN US SYSTEM REACHES THE CENTRAL US IN ABOUT A WEEK PROMPTING CYCLO/FRONTOGENESIS AND PCPN/INFLOW RECOVERY OUT FROM THE GULF OF MEXICO IN THE WAKE OF THE LEAD/EXITING ERN/NERN US STRONG LOW SYSTEM INCLUDING SOME WINTERY PCPN THREAT ON THE NW PERIPHERY OF THE OVERALL PCPN SHIELD SPREADING NEWD FROM THE CENTRAL PLAINS TO THE GREAT LAKES STATES RIDING OVERTOP WARM SECTOR CONVECTIVE RAINS. SCHICHTEL $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.