327  
FXUS02 KWBC 111855  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
253 PM EDT MON APR 11 2022  
 
VALID 12Z THU APR 14 2022 - 12Z MON APR 18 2022  
 
   
..OVERVIEW
 
 
A STRONG SPRINGTIME LOW PRESSURE SYSTEM WILL DEPART FROM THE UPPER  
MIDWEST AS THE PERIOD BEGINS THURSDAY, WITH THE ATTENDANT COLD  
FRONT SLIDING THROUGH THE EAST. BEHIND THIS STORM, EXPECT LOWER  
AMPLITUDE MEAN FLOW ALOFT ACROSS THE LOWER 48. GUIDANCE GENERALLY  
SHOWS A SHORTWAVE PROGRESSING INTO/THROUGH THE WEST DURING THE  
WEEKEND AND INTO THE PLAINS/MISSISSIPPI VALLEY BY EARLY NEXT WEEK.  
THIS FEATURE MAY PRODUCE ANOTHER ROUND OF PRECIPITATION OVER THE  
NORTHERN AND EASTERN PART OF THE COUNTRY. ALTHOUGH THERE IS SOME  
AGREEMENT WITH THE LARGE SCALE PATTERN, THERE IS STILL PLENTY OF  
UNCERTAINTY WITH RESPECT TO SPECIFIC SYSTEM/PRECIPITATION DETAILS  
ALL THE WAY FROM THE WEST COAST INTO THE EAST.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE FIRST HALF OF THE UPDATED FORECAST REFLECTED A COMPOSITE OF  
00Z/06Z MODEL GUIDANCE. THIS TILTED THE BLEND SOMEWHAT SLOWER THAN  
THE GFS FOR THE ENTIRE SEQUENCE OF NORTHERN STREAM FEATURES: LOW  
PRESSURE AND SUPPORTING DYNAMICS REACHING THE PACIFIC NORTHWEST ON  
THURSDAY, THE SYSTEM DEPARTING FROM THE UPPER MIDWEST, AND A WEAK  
WAVE THAT MAY TRACK OFFSHORE NEW ENGLAND. THIS ALSO PROVIDED AN  
INTERMEDIATE (THOUGH SLOWER THAN PRIOR CONSENSUS) TIMING OF THE  
NEXT PACIFIC SYSTEM REACHING THE WEST BY SATURDAY. GUIDANCE SPREAD  
FOR BOTH WEST COAST SYSTEMS WOULD SUGGEST BELOW AVERAGE CONFIDENCE  
IN ANY SPECIFIC SOLUTION. TOWARD SUNDAY-MONDAY THE 00Z CMC  
CONTINUES TO BE A FAST/FLAT EXTREME WITH UPPER FLOW OVER THE LOWER  
48, REQUIRING PHASING OUT ITS CONTRIBUTION. THE NEW 12Z CMC FITS  
THE CONSENSUS BETTER. VERSUS THE FLATTER 00Z GEFS RUN, THE 06Z  
GEFS MEAN MADE A NOTABLE TREND TOWARD THE WESTERN RIDGE AND PLAINS  
OR EAST-CENTRAL U.S. TROUGH DEPICTED IN THE 00Z ECMWF/CMC MEANS.  
ECMWF RUNS FALL INTO THIS TEMPLATE BUT IT REMAINS TO BE SEEN IF AN  
EMBEDDED DEEP CLOSED LOW WILL EVOLVE. GFS RUNS HAVE TENDED TO LEAN  
A BIT ON THE FLATTER SIDE. MEANWHILE 06Z/12Z GFS RUNS ARE SOMEWHAT  
SOUTH/SOUTHEAST OF CONSENSUS FOR THE TROUGH/UPPER LOW REACHING THE  
EASTERN PACIFIC BY NEXT MONDAY. THESE CONSIDERATIONS LED TO  
PLACING THE GREATEST WEIGHT ON THE ENSEMBLE MEANS AND 00Z ECMWF  
LATE IN THE PERIOD, REFLECTING THE DOMINANT GUIDANCE CLUSTER WHILE  
TONING DOWN ECMWF SPECIFICS.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
SOME LINGERING SNOW IS POSSIBLE ACROSS THE UPPER MIDWEST AT THE  
START OF THURSDAY, BUT THE HEAVIEST SHOULD BE RAPIDLY COMING TO AN  
END AS THE DEEP LOW DEPARTS INTO CANADA. HOWEVER GUSTY WINDS ARE  
LIKELY TO CONTINUE INTO FRIDAY WITH BLOWING AND DRIFTING OF SNOW  
AND POSSIBLE HAZARDOUS TRAVEL CONDITIONS. THE STORM'S ASSOCIATED  
COLD FRONT PUSHING THROUGH THE EAST THURSDAY INTO FRIDAY WILL  
BRING AREAS OF LOCALLY MODERATE TO HEAVY RAINFALL. THE BEST CHANCE  
FOR HEAVIER TOTALS SHOULD BE ACROSS PARTS OF THE SOUTHEAST WHERE  
THE BETTER MOISTURE AND INSTABILITY WILL BE PRESENT. RAINFALL  
ACROSS THE SOUTHEAST COULD LINGER INTO THE WEEKEND AS THE WESTERN  
EDGE OF THE BOUNDARY STALLS AND THEN TRIES TO LIFT NORTH AS A WARM  
FRONT BEFORE WEAKENING AHEAD OF ANOTHER APPROACHING FRONT. OUT  
WEST, A COUPLE SYSTEMS MAY BRING RAIN/MOUNTAIN SNOW TO PARTS OF  
THE PACIFIC NORTHWEST AND CALIFORNIA INTO THE NORTHERN ROCKIES  
LATE THIS WEEK INTO THE WEEKEND. SOME OF THE ACTIVITY FROM THE  
WEST COAST INTO THE CASCADES COULD BE MODERATE TO HEAVY BUT THERE  
IS CONSIDERABLE UNCERTAINTY OVER SPECIFICS OF EACH SYSTEM, SO  
CONFIDENCE IS LOWER THAN AVERAGE FOR DETERMINING COVERAGE/TIMING  
OF THE MOST SIGNIFICANT PRECIPITATION. MOISTURE SHOULD SPREAD EAST  
BEYOND THE ROCKIES BY NEXT SUNDAY-MONDAY AS LOW PRESSURE/FRONTS  
REACH THE CENTRAL/EASTERN U.S. AT LEAST SOME PRECIPITATION ACROSS  
THE NORTHERN TIER MAY BE IN THE FORM OF SNOW WHILE RAINFALL  
COVERAGE/INTENSITY OVER THE EAST WILL DEPEND ON CURRENTLY  
UNCERTAIN SYSTEM DETAILS. THE CENTRAL ROCKIES/HIGH PLAINS COULD  
SEE A BRIEF PERIOD OF STRONG WINDS AROUND SUNDAY WITH SYSTEM  
PASSAGE.  
 
EXPECT THE CORE OF BELOW NORMAL TEMPERATURES TO PERSIST ACROSS THE  
NORTHERN HIGH PLAINS INTO EARLY NEXT WEEK, WITH DAYTIME HIGHS  
GENERALLY 20-30F BELOW NORMAL. LOCALLY COLDER READINGS (ESPECIALLY  
FOR DAYTIME HIGHS) ARE POSSIBLE LATE THIS WEEK WHEN SOME LINGERING  
DAILY RECORDS FOR LOWS/COLD HIGHS ARE POSSIBLE. OVER THE WEST,  
THURSDAY-SATURDAY WILL FEATURE CHILLY READINGS OVER THE NORTHERN  
HALF OF THE REGION (MINUS 10-15F ANOMALIES FOR HIGHS) AND CLOSER  
TO NORMAL TEMPERATURES FARTHER SOUTH. AN UPPER RIDGE BUILDING OVER  
THE REGION BY THE START OF NEXT WEEK SHOULD BRING NORTHERN  
LOCATIONS TOWARD NORMAL AND SOUTHERN AREAS MODERATELY ABOVE  
NORMAL. ABOVE NORMAL TEMPERATURES ALONG THE EASTERN SEABOARD ON  
THURSDAY SHOULD RETURN TO NEAR NORMAL NEXT WEEKEND. THE SYSTEM  
POTENTIALLY REACHING THE EAST BY NEXT MONDAY COULD DRAW SOME OF  
THE CHILLY NORTHERN PLAINS AIR SOUTHWARD AND EASTWARD BEHIND IT,  
WITH EXPANDING COVERAGE OF MINUS 10-20F ANOMALIES.  
 
RAUSCH/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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