402  
FXUS02 KWBC 171851  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
250 PM EDT SUN APR 17 2022  
 
VALID 12Z WED APR 20 2022 - 12Z SUN APR 24 2022  
 
...WINTRY STORM THREAT FROM THE WEST TO THE NORTH-CENTRAL U.S.  
LATE WEEK/NEXT WEEKEND...  
 
   
..WEATHER PATTERN OVERVIEW
 
 
THE DEPARTURE OF THE STRONG LOW PRESSURE SYSTEM FROM NEW ENGLAND  
WILL LEAVE A SURFACE HIGH IN ITS WAKE ACROSS THE EASTERN U.S. ON  
WEDNESDAY. AT THE SAME TIME, AN ORGANIZING STORM SYSTEM JUST NORTH  
OF THE CANADIAN BORDER WILL BRING A COLD FRONT EASTWARD ACROSS THE  
NORTH-CENTRAL U.S. WITH A WEAKENING LOW FARTHER SOUTH ACROSS THE  
CENTRAL PLAINS. ATTENTION THEN TURNS TO THE WESTERN U.S. BY FRIDAY  
WITH ADVENT OF AN AMPLIFIED UPPER LEVEL TROUGH/FRONTAL SYSTEM WITH  
AN ENHANCED PRECIPITATION FOCUS. THE COOLING/UNSETTLING SYSTEM  
THEN WORKS INLAND OVER THE INTERMOUNTAIN WEST AND LEADS INTO LATER  
NEXT WEEKEND DEVELOPMENT OF A POTENTIALLY STRONG SURFACE LOW OVER  
THE COOLED CENTRAL/NORTHERN PLAINS TO INCLUDE THE THREAT FOR HEAVY  
WRAPPING WINDS/SNOW/ICE ON THE NORTHERN PERIPHERY OF THE SYSTEM  
AND AN EMERGING PRE-FRONTAL RAINFALL/STRONG CONVECTION AREA  
BROADLY UNDERNEATH AND INTO THE WARMING/MOISTENING EAST-CENTRAL  
U.S. MEANWHILE, A BUILDING DOWNSTREAM UPPER RIDGE AXIS OVER THE  
APPALACHIANS MAY ALLOW CLOSED TROUGH DEVELOPMENT CUT UNDERNEATH  
OVER SOUTHERN FL AND CUBA TO INCREASE/FOCUS NEXT WEEKEND RAINFALL.  
   
..MODEL GUIDANCE EVALUATION
 
 
THE 00/06 UTC MODEL GUIDANCE SUITE APPEARS TO HAVE ABOVE AVERAGE  
AGREEMENT ON THE MAIN SYNOPTIC SCALE FEATURES THROUGH THURSDAY  
NIGHT. BY FRIDAY, THE GFS REMAINS MORE PROGRESSIVE WITH THE AXIS  
OF THE MAIN TROUGH AXIS ACROSS THE WESTERN U.S., AND THIS  
DIFFERENCE IS EVEN MORE APPARENT GOING INTO SATURDAY/SUNDAY ACROSS  
THE HIGH PLAINS. MEANWHILE, THE 00 UTC CMC AND ECMWF ARE IN CLOSE  
AGREEMENT AND DEPICT A CLOSED LOW EVOLVING OVER THE SOUTHWEST BY  
FRIDAY NIGHT, AND THIS ALSO HAS SUPPORT FROM THE 00 UTC UKMET.  
THIS AMPLIFIED AND LESS PROGRESSIVE TREND CONTINUES THROUGH NEXT  
WEEKEND, LEADING INTO DEEPENING TRENDS WITH CYCLOGENESIS OVER THE  
PLAINS. THIS WOULD RESULT IN AN INCREASED AND LESS PROGRESSIVE QPF  
SWATH COMPARED TO THE 13 UTC NBM 4.0.  
ELEMENTS OF THIS DEEPENING SYSTEM CAN BE TRACED BACK TO FORMER  
PACIFIC TYPHOON MALAKAS THAT IS CURRENTLY A DEEP EXTRATROPICAL LOW  
SLAMMING INTO THE ALEUTIANS. ANOTHER DEEP PACIFIC LOW EXPECTED  
TRACK INTO THE ALEUTIANS THEN THE GULF OF ALASKA LATER WEEK/NEXT  
WEEKEND ALSO PORTENDS A SOLUTION ON THE MORE AMPLIFIED SIDE OF THE  
FULL GUIDANCE ENVELOPE DOWNSTREAM OVER THE LOWER 48. ACCORDINGLY,  
MODEL PREFERENCE FOR THE LATER HALF OF THE FORECAST PERIOD FOR THE  
WPC MEDIUM RANGE PRODUCT SUITE WAS A CMC/ECMWF/ECENS MEAN BLEND AS  
A STARTING POINT.  
 
12 UTC MODELS OVERALL REMAIN CONSISTENT WITH THIS PLAN. THE GFS  
TRENDED LESS PROGRESSIVE AND THE ECMWF/CANADIAN SLIGHTLY MORE  
PROGRESSIVE NEXT WEEKEND, A BIT MORE INTO COMMON ALIGNMENT. THIS  
SEEMS TO BOLSTER FORECAST CONFIDENCE IN THE THREAT, ALBEIT WITH  
SLIGHTLY MORE PROGRESSION.  
   
..SENSIBLE WEATHER/THREATS
 
 
IN THE PRECIPITATION DEPARTMENT, THE WEST COAST REGION IS EXPECTED  
TO REMAIN ACTIVE WITH A STRONG COLD FRONT AND ONSHORE FLOW  
DIRECTED INLAND ACROSS THE MOUNTAINOUS TERRAIN OF CENTRAL AND  
NORTHERN CALIFORNIA. THIS SPRING EVENT WILL DELIVER SOME HIGHLY  
BENEFICIAL PRECIPITATION TO DROUGHT-STRICKEN AREAS OF CALIFORNIA,  
WITH THE POTENTIAL FOR SEVERAL INCHES OF RAIN IN SOME AREAS NEXT  
WEEK, AND SEVERAL FEET OF SNOW FOR THE SIERRA. ELSEWHERE ACROSS  
THE CONTINENTAL U.S., IMPROVING WEATHER CAN BE EXPECTED FOR THE  
NORTHEAST AS THE STRONG STORM SYSTEM MOVES OUT OF THE REGION. DEEP  
WARMING OVER THE EAST INTO NEXT WEEKEND MAY BE TEMPERED FROM THE  
NORTHEAST DOWN INTO THE MID-ATLANTIC BY FRONTAL DAMMING THAT MAY  
PROVE SLOWER TO ERODE THAN SHOWN IN THE MODELS. ANOTHER ROUND OF  
ORGANIZED SHOWERS AND STORMS ARE EXPECTED TO DEVELOP ACROSS THE  
CENTRAL U.S. AND EXTENDING NORTHWARD TO THE GREAT LAKES THROUGH  
LATE WEEK AS GULF MOISTURE IS ADVECTED NORTHWARD AHEAD OF THE  
ORGANIZING STORM SYSTEM OVER THE CENTRAL PLAINS. ADDITIONAL  
MODERATE TO HEAVY SNOW IS ALSO EXPECTED FOR PORTIONS OF THE  
NORTHERN ROCKIES FOR FRIDAY AND INTO THE WEEKEND, WITH AN  
INCREASING THREAT FOR HEAVY SNOW TO SPREAD AND INTENSIFY IN  
PARTICULAR ACROSS THE NORTHERN HIGH PLAINS AND DAKOTAS/VICINITY  
NEXT WEEKEND.  
 
SCHICHTEL/HAMRICK  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES ARE  
AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page