061  
FXUS02 KWBC 270700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST SAT JAN 27 2018  
 
VALID 12Z TUE JAN 30 2018 - 12Z SAT FEB 03 2018  
 
...ACTIVE NWRN US FLOW AND EMERGING CENTRAL TO ERN US RAIN AND  
WINTER WEATHER THREAT...  
 
   
..GUIDANCE/PATTERN OVERVIEW AND WEATHER HIGHLIGHTS/THREATS
 
 
AN AMPLIFIED MID-UPPER LEVEL TROUGH OVER THE ERN US EJECTS  
OFFSHORE TUE AS A LEAD COASTAL LOW AND FRONTAL SYSTEM FOCUSES A  
LINGERING SNOW THREAT FROM ERN NEW ENGLAND TO THE CANADIAN  
MARITIMES. A COLD HIGH DIGS ACROSS THE EAST-CENTRAL TO ERN US TUE  
INTO WED AND ACTS TO ENHANCE GREAT LAKE SNOWS IN THE WAKE OF LEAD  
WAVY FRONTAL SYSTEM PASSAGE.  
 
MEANWHILE UPSTREAM...PACIFIC HEIGHT FALLS/SYSTEM PASSAGE ACROSS  
THE NWRN US THEN N-CENTRAL ROCKIES TUE INTO WED WILL SUPPORT  
WIDESPREAD PRECIPITATION INCLUDING COASTAL/TERRAIN ENHANCED RAINS  
AND LOWERING SNOW LEVELS INLAND. FLOW AMPLIFICATION AND A LESS  
CERTAIN STREAM OF IMPULSES DIGGING TO THE LEE OF AN ERN PACIFIC  
MID-UPPER LEVEL RIDGE WOULD BRING PERIODIC ADDITIONAL PCPN BURSTS  
LATER WEEK INTO NEXT WEEKEND. WPC WINTER WEATHER OUTLOOK  
PROBABILITIES AND QPF/WEATHER GRIDS ETC. SPECIFY THIS POTENTIAL.  
 
AHEAD OF THIS...A MID-UPPER LEVEL RIDGE WILL PROGRESS FROM THE  
WARMED SRN CA/SWRN US AND CENTRAL US TUE TO THE ERN SEABOARD BY  
WED AND PROVIDE ANOTHER TASTE OF SPRING. LEAD LOWER ATMOSPHERIC  
WARM AIR ADVECTION AND AN INCREASING RETURN FLOW OF GULF OF MEXICO  
MOISTURE AHEAD OF CENTRAL NOAM CYCLOGENESIS AND FRONTOGENESIS  
WOULD BE AVAILABLE TO FUEL AN EMERGING CENTRAL TO ERN US  
PRECIPITATION PATTERN. BY WED/THU THIS INCLUDES POTENTIAL FOR SOME  
HEAVIER CONVECTION OVER MID-SRN LATITUDES AND SNOWS OVER THE  
COOLER NRN TIER STATES MORE UNDER THE INFLUENCE OF PASSING NRN  
STREAM IMPULSES AND POST-SYSTEM LOWER LEVEL COLD AIR RETURN. THIS  
COLD AIR IS EXPECTED TO SETTLE OVER MUCH OF THE LOWER 48 LATER  
WEEK AND NEXT WEEKEND UNDER A BROAD CYCLONIC FLOW PATTERN ALOFT.  
 
A WAVY FRONT ON THE LEADING EDGE OF THIS COLD AIR FRI INTO NEXT  
WEEKEND OFFERS AMPLE WINTER WEATHER THREAT AS PER A SHARP  
BAROCLINIC ZONE AND POTENTIAL LOW DEVELOPMENTS. WPC WINTER WEATHER  
OUTLOOK PROBABILITIES AND QPF/WEATHER GRIDS ETC. SHOW POTENTIAL  
FROM THE GREAT LAKES AND OH/TN VALLEYS THROUGH THE APPALACHIANS  
AND MID-ATLANTIC/NERN STATES. THE MODELS HAVE BEEN SHOWING WIDELY  
DIFFERENCE LOW SPECIFICS RECENTLY RANGING FROM FLAT LOWS TO DEEP  
LOWS...BUT THE LATEST 00 UTC GFS/ECMWF RUNS HAVE TRENDED TOWARD A  
NEAR MIDDLE OF THE ROAD SOLUTION THAT IS MORE IN LINE WITH THEIR  
ENSEMBLES.  
 
OVERALL...THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED  
FROM A BLEND OF GEFS/ECMWF ENSEMBLE MEANS WITH ONLY MINIMAL  
DETERMINISTIC MODEL INPUT AMID REASONABLY SIMILAR LARGER SCALE  
FLOW EVOLUTIONS BUT MORE VARIED SMALLER SCALE EMBEDDED SYSTEM  
DEVELOPMENTS.  
 
SCHICHTEL  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page