792  
FXUS02 KWBC 140631  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 AM EDT THU APR 14 2022  
 
VALID 12Z SUN APR 17 2022 - 12Z THU APR 21 2022  
 
...OVERVIEW AND GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT..  
 
COMPARED TO WHAT HAS BEEN A PRETTY AMPLIFIED AND ACTIVE WEATHER  
PATTERN THE PAST FEW DAYS, RELATIVELY LOW AMPLITUDE MEAN FLOW  
SHOULD CONTINUE THROUGH ABOUT SUNDAY OR MONDAY ACROSS MUCH OF THE  
LOWER 48. THIS FEATURES SHORTWAVE ENERGY THROUGH THE NORTHEAST,  
WITH A POSSIBLE CLOSED LOW DEVELOPMENT OVER THE CANADIAN  
MARITIMES, WHILE A SHORTWAVE AND ASSOCIATED SURFACE LOW PRESSURE  
SYSTEM MOVES OVER THE NORTHERN TIER. CHANCES ARE INCREASING THAT  
THIS MAY BRING ANOTHER ROUND OF SPRING SNOW TO PARTS OF THE  
NORTHERN PLAINS ON SUNDAY INTO MONDAY. AFTER THIS, THE PATTERN IS  
EXPECTED TO TRANSITION TO A MORE AMPLIFIED FLOW, AS AN UPPER  
TROUGH/CLOSED LOW REACHING THE WEST COAST BY TUESDAY SHOULD ACT TO  
BUILD A DOWNSTREAM RIDGE AND AMPLIFY THE NORTHERN TIER SHORTWAVE  
AS IT DIGS THROUGH THE GREAT LAKES AND NORTHEAST BY MID NEXT WEEK.  
MEANWHILE, AS THE WESTERN U.S. TROUGH ENERGY PROGRESSES THROUGH  
THE NORTHWEST, IT COULD AGAIN FACE AMPLIFICATION IN RESPONSE TO  
YET ANOTHER UPPER LOW/AMPLIFIED TROUGH TOWARDS THE WEST COAST NEXT  
WEDNESDAY-THURSDAY.  
 
THE LATEST 12Z/18Z (APR 13) SUITE OF GUIDANCE SHOWS GOOD AGREEMENT  
ON THE LARGE SCALE THROUGH DAY 4/MONDAY, WITH PLENTY OF LINGERING  
UNCERTAINTIES IN THE DETAILS. A GENERAL DETERMINISTIC MODEL BLEND  
HOWEVER SUFFICED FOR THIS PERIOD AND HELPED TO SMOOTH OUT THOSE  
DIFFERENCES. AMPLIFICATION OF THE NEXT SYSTEM THROUGH THE NORTHERN  
PLAINS INTO THE GREAT LAKES IS OF COURSE HIGHLY DEPENDENT ON  
UNCERTAIN DETAILS OF THE WEST COAST UPPER LOW/TROUGH ON MONDAY  
INTO TUESDAY. THE NOTABLE OUTLIER HERE IS THE UKMET WHICH IS  
QUICKER TO CLOSE OFF A LOW OVER THE NORTHEAST ON TUESDAY, AND ALSO  
FARTHER SOUTH. AS SUCH, IT WAS NOT INCLUDED IN THE BLEND TONIGHT.  
THE GFS AND GEFS MEAN BOTH GET FAST WITH THIS ENERGY ON WEDNESDAY  
AS IT SWINGS THROUGH THE CANADIAN MARITIMES. TIMING AND DETAIL  
DIFFERENCES BECOME MORE APPARENT BY NEXT TUESDAY AS THE WEST COAST  
TROUGH SHIFTS INLAND. THE GFS IS FASTER WITH THE ENERGY, BUT THE  
ECMWF IS QUITE A BIT FARTHER NORTH, WITH THE CMC FORMING A DECENT  
MIDDLE GROUND SOLUTION. THESE DIFFERENCES CONTINUE INTO WEDNESDAY  
AND THURSDAY TOO AS THE SYSTEM SLIDES ACROSS THE GREAT LAKES.  
HOWEVER, FOR A DAY 6-7 FORECAST AND GIVEN CONTINUED RUN TO RUN  
UNCERTAINTIES, NEITHER MODEL PRESENTS A CLEAR OUTLIER. THE BLEND  
FOR THE LATTER PERIODS TRANSITIONED MORE TOWARDS THE ENSEMBLE  
MEANS (ECENS MEAN AND NAEFS) TO ACCOUNT FOR THE DETAIL  
DIFFERENCES, BUT ALSO CONTINUED SLIGHT MAJORITY OF THE  
DETERMINISTIC GFS/ECMWF/CMC FOR ADDED SYSTEM DEFINITION.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
MOISTURE AND INSTABILITY INTERACTING WITH A WARM FRONT LIFTING  
THROUGH THE SOUTH/SOUTHEAST THIS WEEKEND AND APPROACH OF A COLD  
FRONT FROM THE NORTH SHOULD BRING AREAS OF MODERATE TO LOCALLY  
HEAVY RAINFALL TO PARTS OF THOSE AREAS, BUT WITH LOWER CONFIDENCE  
IN EXACT PLACEMENT OF HEAVIEST TOTALS. FARTHER NORTH, A LOW  
PRESSURE SYSTEM INTO THE NORTHERN PLAINS ON SUNDAY MAY AGAIN BRING  
A ROUND OF ACCUMULATING SPRING SNOW TO NORTHERN LOCATIONS, WITH  
RAINFALL FARTHER SOUTH ALONG THE ATTENDENT COLD FRONT INTO THE  
MIDWEST. MOISTURE REACHES THE EAST EARLY NEXT WEEK, WITH SOME  
POTENTIAL FOR ENHANCED RAINFALL ALONG THE CAROLINA COAST AS WELL  
AS PRECIPITATION (MAYBE SOME SNOW) NORTH AND WEST OF A SURFACE LOW  
DEVELOPING OFF THE NEW ENGLAND COAST. SOME GUSTY WINDS ARE ALSO  
POSSIBLE ACROSS THE NORTHEAST TUESDAY INTO WEDNESDAY. OUT WEST,  
EXPECT ANOTHER EPISODE OF PRECIPITATION FROM THE PACIFIC  
NORTHWEST/NORTHERN CALIFORNIA INTO THE NORTHERN ROCKIES THROUGH  
EARLY NEXT WEEK, WITH SOME ENHANCED TOTALS POSSIBLE OVER FAVORED  
COASTAL/TERRAIN AREAS. PRECIPITATION POTENTIAL MAY INCREASE AGAIN  
INTO NEXT MIDWEEK WITH APPROACH OF ANOTHER AMPLIFIED UPPER TROUGH  
AND FRONTAL PROGRESSION.  
 
THE CORE OF BELOW NORMAL TEMPERATURES ACROSS THE NORTHERN PLAINS  
AND VICINITY WILL LIKELY PERSIST INTO EARLY NEXT WEEK, WITH  
DAYTIME HIGHS GENERALLY 20-30F BELOW NORMAL, AND MODERATING SLOWLY  
WITH TIME. THE SYSTEM REACHING THE MIDWEST/EAST EARLY NEXT WEEK  
COULD DRAW SOME OF THE CHILLY NORTHERN PLAINS AIR SOUTHWARD AND  
EASTWARD BEHIND IT, WITH EXPANDING COVERAGE OF MINUS 10-20F  
ANOMALIES SUNDAY-TUESDAY. WARM ANOMALIES ACROSS THE SOUTHERN  
PLAINS AND SOUTHWEST ON SUNDAY SHOULD PROGRESS SLOWLY NORTH AND  
EASTWARD AS UPPER LEVEL RIDGING BUILDS AND MOVES THROUGH.  
 
SANTORELLI  
 
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  
 

 
 

 
 
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