941  
FXUS02 KWBC 042127  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
524 PM EDT MON APR 04 2022  
 
VALID 12Z THU APR 07 2022 - 12Z MON APR 11 2022  
 
...HEAVY RAINFALL/CONVECTION AND RUNOFF THREAT TO FOCUS ACROSS THE  
SOUTH NEXT WEEK...  
...PACIFIC NORTHWEST HEAVY RAIN AND TERRAIN/MOUNTAIN HEAVY SNOW  
THREAT INLAND TO THE NORTHERN ROCKIES...  
 
19Z UPDATE: THE 12Z GUIDANCE SUITE HAS A VERY GOOD OVERALL  
DEPICTION OF THE AMPLIFYING PATTERN AS THE DEEP UPPER TROUGH  
BUILDS OVER THE NORTH-CENTRAL U.S. NEXT WEEK. ALTHOUGH STILL  
SLIGHTLY PROGRESSIVE, THE 12Z RUN OF THE GFS HAS TRENDED CLOSER TO  
THE NON-NCEP MODEL CONSENSUS, AND THEREFORE A DETERMINISTIC MODEL  
BLEND SUFFICED AS A GOOD STARTING POINT IN THE FORECAST PROCESS.  
HOWEVER, DIFFERENCES ARE MORE APPARENT FOR THE NORTHWESTERN U.S.  
AS THE NEXT SYSTEM APPROACHES, WITH THE GFS WELL AHEAD OF THE  
MODEL CONSENSUS BY FRIDAY, AND A CMC/ECMWF/ECENS BLEND APPROACH  
WORKS WELL FOR THE WEST COAST REGION. IN TERMS OF THE HEAVY  
RAINFALL THREAT ACROSS THE DEEP SOUTH AND GULF COAST REGION, THE  
CORRIDOR OF HEAVIEST RAINFALL IS FAVORED FROM THE RED RIVER VALLEY  
OF TX/OK EASTWARD TO CENTRAL AL AND THE SOUTHERN APPALACHIANS,  
WITH SOME SCATTERED 3+ INCH TOTALS WITHIN THE REALM OF  
POSSIBILITY. MULTIPLE ROUNDS OF STRONG TO SEVERE STORMS AND  
LIKELY A SQUALL LINE ARE ALSO EXPECTED ACROSS MANY OF THESE SAME  
AREAS. THE PREVIOUS DISCUSSION FOLLOWS BELOW. /HAMRICK  
--------------------  
   
..OVERVIEW
 
 
THE LARGE SCALE PATTERN WILL UNDERGO A DRAMATIC CHANGE OVER THE  
COURSE OF THE PERIOD, AS FAIRLY LOW-AMPLITUDE PROGRESSIVE FLOW  
LEADING INTO THE START OF THE PERIOD EARLY MONDAY TRANSITIONS TO A  
WESTERN RIDGE/EAST-CENTRAL U.S. UPPER TROUGH WITH A CLOSED LOW  
CURRENTLY EXPECTED TO TRACK FROM THE NORTHERN PLAINS INTO THE  
GREAT LAKES BY AROUND WEDNESDAY-FRIDAY. A STRONG JET ARRIVING  
INTO THE NORTHWEST EARLY IN THE WEEK WILL INITIALLY FOCUS HEAVY  
PRECIPITATION OVER THAT PART OF THE COUNTRY AND THEN THE  
DEVELOPING UPPER TROUGH/ASSOCIATED SURFACE EVOLUTION WILL SPREAD  
PRECIPITATION ACROSS MUCH OF THE EASTERN HALF OF THE LOWER 48 WITH  
HEAVIEST TOTALS FORECAST TO BE ACROSS THE SOUTH. THE UPPER RIDGE  
BUILDING INTO THE WEST WILL BRING ANOTHER EPISODE OF UNSEASONABLY  
WARM TEMPERATURES TO THAT PART OF THE COUNTRY.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
LATEST MODELS AND MEANS OFFER GOOD AGREEMENT WITH THE OVERALL  
PATTERN EVOLUTION WHILE EXHIBITING SOME TYPICAL DETAIL DIFFERENCES  
THAT HAVE MEDIUM TO LOW PREDICTABILITY. OF PARTICULAR NOTE,  
LATEST GFS RUNS HAVE BEEN ON THE SOUTHERN SIDE OF THE SPREAD FOR  
THE UPPER LOW THAT TRACKS OVER THE PLAINS AND MIDWEST LATE TUESDAY  
THROUGH WEDNESDAY AND GFS RUNS HAVE TENDED TO BE MORE EAGER TO  
BRING PACIFIC SHORTWAVE ENERGY INTO THE NORTHERN PART OF THE  
WESTERN RIDGE LATE IN THE PERIOD (WHICH THE NEW 00Z ECMWF HAS  
ADJUSTED TOWARD). AS THE MAIN SYSTEM OF INTEREST REACHES THE EAST  
LATE IN THE WEEK, DIFFERENCES ARE FAIRLY MODEST FOR A DAYS 6-7  
FORECAST WITH THE GFS/GEFS SLIGHTLY NORTHEAST OF THE ECMWF/CMC AND  
THEIR MEANS. A STARTING POINT CONSISTING OF A 12Z/18Z MODEL BLEND  
EARLY AND THEN A MODEL/ENSEMBLE MEAN BLEND LATER ON PROVIDED A  
GOOD INTERMEDIATE SOLUTION WITH ONLY MODEST REFINEMENTS TO  
CONTINUITY.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
A STRONG UPPER JET PUSHING INTO THE NORTHWEST EARLY NEXT WEEK WILL  
BRING AN EPISODE OF ENHANCED COASTAL/TERRAIN RAIN AND MOUNTAIN  
SNOW TO THE PACIFIC NORTHWEST WITH SIGNIFICANT TOTALS EXTENDING  
INTO THE NORTHERN ROCKIES. AFTER THIS MOISTURE DEPARTS, THE UPPER  
RIDGE BUILDING INTO THE WEST WILL BRING DRY WEATHER TO MUCH OF THE  
REGION WEDNESDAY-FRIDAY. DOWNSTREAM UPPER TROUGH AMPLIFICATION  
AND SURFACE LOW/FRONT EVOLUTION WILL PROMOTE ACTIVE WEATHER OVER  
THE CENTRAL/EASTERN U.S. WITH TYPICAL RUN-TO-RUN REFINEMENTS AND  
SOME SPREAD IN THE DETAILS, THERE IS A PERSISTENT SIGNAL FOR HEAVY  
RAINFALL POTENTIAL FROM NEAR THE SOUTHEASTERN PLAINS INTO THE  
SOUTHEAST DURING THE FIRST HALF OF THE WEEK. THIS REGION HAS THE  
BEST OVERLAP OF MOIST GULF INFLOW AND INSTABILITY, ALONG WITH  
FOCUS FROM A COUPLE SURFACE FRONTS. THE STORM PREDICTION CENTER  
IS ALSO MONITORING THIS SYSTEM FOR STRONG TO SEVERE CONVECTION,  
WITH MORE DETAILS FORTHCOMING AS PREDICTABILITY IMPROVES OVER  
FUTURE GUIDANCE RUNS. OTHER PARTS OF THE CENTRAL/EASTERN U.S.  
COULD SEE POCKETS OF LOCALLY MODERATE TO HEAVY RAIN AS WELL.  
MEANWHILE SOME SNOW COULD BE POSSIBLE ALONG THE NORTHERN TIER, ON  
THE COLD SIDE OF THE UPPER LOW TRACK, AS WELL AS INTO PARTS OF NEW  
ENGLAND.  
 
THE UPPER RIDGE BUILDING INTO THE WEST WILL SUPPORT ANOTHER PERIOD  
OF WELL ABOVE NORMAL TEMPERATURES ACROSS THE REGION BY  
WEDNESDAY-FRIDAY. THE GREATEST ANOMALIES FOR DAYTIME HIGHS SHOULD  
BE FROM CALIFORNIA AND SOUTHERN OREGON INTO THE GREAT BASIN, WITH  
HIGHS 10-20F ABOVE NORMAL AND SOME LOCATIONS REACHING 20-25F ABOVE  
NORMAL. SOME DAILY RECORDS FOR HIGHS/WARM LOWS WILL BE POSSIBLE  
LATE IN THE WEEK. AHEAD OF THE RIDGE, COOL AIR UNDER THE  
AMPLIFYING UPPER TROUGH WILL BRING HIGHS DOWN TO 5-15F BELOW  
NORMAL OVER THE NORTHERN ROCKIES ON TUESDAY AND PROGRESSING INTO  
THE EAST-CENTRAL U.S. BY FRIDAY. LEADING WARM/MOIST FLOW AHEAD OF  
THE UPPER TROUGH/SURFACE SYSTEM WILL BRING A COUPLE DAYS OF ABOVE  
NORMAL READINGS (ESPECIALLY FOR MORNING LOWS) TO THE EAST AROUND  
WEDNESDAY-THURSDAY.  
 
RAUSCH/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  
 
HAZARDS:  
- HEAVY SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE  
NORTHERN GREAT BASIN, SAT-SUN, APR  
9-APR 10.  
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES, SUN, APR 10.  
- SEVERE WEATHER ACROSS PORTIONS OF THE SOUTHEAST AND THE  
MID-ATLANTIC, THU, APR 7.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE GREAT LAKES, THE MIDDLE  
MISSISSIPPI VALLEY, THE SOUTHERN  
PLAINS, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE SOUTHERN  
PLAINS, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS,  
THU, APR 7.  
- MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
GREAT BASIN, CALIFORNIA, AND THE  
NORTHERN GREAT BASIN, THU-FRI, APR 7-APR 8.  
- ENHANCED WILDFIRE RISK ACROSS PORTIONS OF THE CENTRAL PLAINS AND  
THE SOUTHERN PLAINS, THU, APR 7.  
 
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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