032  
FXUS02 KWBC 081907  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
306 PM EDT FRI APR 08 2022  
 
VALID 12Z MON APR 11 2022 - 12Z FRI APR 15 2022  
 
...ACTIVE WEATHER IS LIKELY NEXT WEEK, WITH HEAVY SNOW SPREADING  
FROM HIGHER ELEVATIONS OF THE WEST INTO THE NORTH-CENTRAL U.S. AND  
HEAVY RAIN AND SEVERE THUNDERSTORM CHANCES ACROSS THE SOUTH...  
   
..OVERVIEW
 
 
THE LATEST GUIDANCE CONTINUES TO SUPPORT AN AMPLIFIED AND ACTIVE  
WEATHER PATTERN ACROSS THE LOWER 48 NEXT WEEK. A REINFORCED  
WESTERN U.S. TROUGH SHOULD FINALLY EMERGE INTO THE PLAINS BY  
AROUND MIDWEEK AND A VIGOROUS LOW PRESSURE SYSTEM WILL DEVELOP  
OVER THE PLAINS/UPPER MIDWEST. THIS IS LIKELY TO BRING AN ARRAY OF  
SIGNIFICANT WEATHER ACROSS THE CONUS, INCLUDING HEAVY SNOW IN SOME  
HIGHER ELEVATIONS OF THE WEST EARLY IN THE WORKWEEK, WHICH IS  
EXPECTED TO SPREAD NORTH AND WEST OF THE SURFACE LOW TRACK INTO  
NORTHERN/CENTRAL PARTS OF THE PLAINS AROUND MIDWEEK. IN THE WARM  
SECTOR OF THE SYSTEM, SEVERE WEATHER AND HEAVY RAIN ARE LIKELY IN  
SOUTHERN/CENTRAL PARTS OF THE PLAINS AND MISSISSIPPI VALLEY AND  
POTENTIALLY EASTWARD. BY LATE WEEK, THE CLOSED UPPER LOW MAY BEGIN  
TO LIFT DUE TO AMPLIFIED RIDGING IN THE WESTERN ATLANTIC, WHILE  
ADDITIONAL (LIKELY LESS AMPLIFIED) TROUGHING ENTERS THE WEST  
AROUND FRIDAY/DAY 7.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THOUGH MODEL GUIDANCE IS UNITED IN SHOWING THE DEVELOPING WESTERN  
TROUGH BECOMING A CLOSED UPPER LOW AS IT TRACKS INTO THE CENTRAL  
U.S., AMPLE DIFFERENCES REMAIN WITH THE TIMING AND TRACK OF THE  
UPPER AND SURFACE LOW FEATURES. AS THE PERIOD BEGINS MONDAY, GFS  
RUNS FROM THE 00/06Z AS WELL AS THE 12Z MODEL CYCLE REMAIN  
STRONGEST WITH THE INITIAL SHORTWAVE OVER THE UPPER MIDWEST  
COMPARED TO OTHER GUIDANCE, AFFECTING FRONTAL POSITION. MEANWHILE  
MOST GUIDANCE CONTINUES TO SHOW A SMALL CLOSED UPPER LOW NEAR THE  
PACIFIC NORTHWEST, THOUGH THE ECMWF HAS BEEN WEAKER BUT MAY HAVE  
STRENGTHENED A BIT WITH THE 12Z RUN. THIS ALSO IMPACTS THE  
STRENGTH AND POSITION OF AN ASSOCIATED SURFACE LOW; THE 12Z CMC  
MAY BE A GOOD COMPROMISE BETWEEN THE STRONGER AND FARTHER NORTH  
GFS RUNS AND WEAKER AND FARTHER SOUTH ECMWF RUNS.  
 
GOING INTO TUESDAY AND BEYOND, THE INITIAL SHORTWAVE DIFFERENCES  
GROW QUICKLY AND AFFECT THE MAIN TROUGH/LOW'S AXIS AND EXTENT  
SOUTHWARD. THE GFS RUNS HAVE REMAINED THE QUICKEST AND FARTHEST  
NORTH WITH THE DEVELOPING UPPER LOW, WHILE THE EC HAS BEEN  
CONSISTENTLY DEEPER AND SLOWER. THE CMC CLUSTERS BETTER WITH THE  
ECMWF, AND EACH MODEL'S ENSEMBLE MEMBERS TEND TO CLUSTER NEAR ITS  
DETERMINISTIC RUN WITHOUT CONSIDERABLE OVERLAP. THESE DIFFERENCES  
WITH THE TROUGH/LOW ARE ALSO INFLUENCED BY ADDITIONAL UPSTREAM  
ENERGY DIVING SOUTH FROM THE ARCTIC/ALASKA/NORTHWESTERN CANADA, A  
LOW PREDICTABILITY FEATURE THAT ALSO SHOWS QUITE A BIT OF  
VARIABILITY AMONG GUIDANCE. THE WPC FORECAST CONTINUED TO FAVOR A  
SLOWER SOLUTION WITH THE UPPER LOW, MORE LIKE THE EC/EC  
MEAN/CMC/CMC MEAN COMPARED TO THE FASTER GFS/GEFS, CONSIDERING  
CONTINUITY AS WELL AS TYPICAL MODEL BIASES. PERHAPS BY AROUND DAY  
6/THURSDAY OR SO, THE ECMWF AND CMC MAY BE A BIT TOO SLOW IN  
LIFTING THE SURFACE LOW OUT, BUT IT SHOULD BE A WRAPPED UP SYSTEM  
SO IT IS POSSIBLE.  
 
FARTHER UPSTREAM, THERE IS CONSIDERABLE VARIABILITY WITH THE FLOW  
BEHIND THE MAIN LOW, WITH POTENTIAL FOR A BOUT OF LOW AMPLITUDE  
RIDGING IN THE CENTRAL U.S. LATE WEEK (THOUGH THIS IS PARTICULARLY  
SEEN IN THE GFS SUITE THAT WAS NOT FAVORED) BEFORE ANOTHER SYSTEM  
MAY ENTER THE WEST. THE ENSEMBLE MEANS PROVIDED A FAIR STARTING  
POINT FOR THIS UNCERTAIN FLOW PATTERN.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
EARLY IN THE PERIOD EXPECT THE BEST RAIN/MOUNTAIN SNOW FOCUS TO BE  
OVER THE PACIFIC NORTHWEST AND CENTRAL WEST COAST. HOWEVER THE  
DETAILS OF LOCATION AND INTENSITY ARE UNUSUALLY UNCERTAIN FOR A  
FORECAST ONLY 3 DAYS OUT IN TIME AS GUIDANCE VARIES WIDELY FOR THE  
STRENGTH AND TRACK OF ARRIVING LOW PRESSURE. LIGHTER ACTIVITY  
SHOULD PREVAIL EASTWARD THROUGH THE NORTHERN ROCKIES. THEN SOME  
MOISTURE SHOULD EXTEND SOUTHWARD INTO THE SIERRA NEVADA, WITH RAIN  
AND MOUNTAIN SNOW EXTENDING ACROSS CENTRAL AND POSSIBLY SOME  
SOUTHERN PARTS OF THE WEST. BY TUESDAY, THE SOUTHERN MONTANA INTO  
COLORADO ROCKIES AND NORTH-CENTRAL HIGH PLAINS SHOULD BEGIN TO SEE  
A FAVORABLE COMBINATION OF UPPER TROUGH DYNAMICS AND LOW LEVEL  
UPSLOPE FLOW THAT WOULD INCREASE PRECIPITATION OVER THOSE AREAS,  
WITH THE HIGH PLAINS SEEING SOME SPRINGTIME SNOW IN ADDITION TO  
THE ROCKIES. POTENTIALLY STRONG LOW PRESSURE THAT MAY TRACK FROM  
THE PLAINS INTO THE UPPER MIDWEST WOULD EXTEND SNOW FARTHER  
NORTHEAST ACROSS THE NORTHERN TIER ALONG WITH STRONG WINDS,  
POSSIBLY CREATING BLIZZARD CONDITIONS. MEANWHILE IN THE WARM  
SECTOR, THERE WILL BE INCREASING COVERAGE AND INTENSITY OF  
RAINFALL OVER THE EASTERN PLAINS/MISSISSIPPI VALLEY WITH THE  
ESTABLISHMENT OF MOIST LOW LEVEL FLOW FROM THE GULF OF MEXICO.  
PERSISTENCE OF THE GULF INFLOW SHOULD LEAD TO A COUPLE DAYS OR SO  
WITH A HEAVY RAIN THREAT OVER OR NEAR THE LOWER MISSISSIPPI VALLEY  
WITH SOME POTENTIAL FOR FLASH FLOODING. ALSO THE STORM PREDICTION  
CENTER IS MONITORING THE POTENTIAL FOR SEVERE WEATHER OVER PARTS  
OF THE PLAINS AND MISSISSIPPI VALLEY. CHECK THEIR LATEST OUTLOOKS  
FOR MORE INFORMATION. THE PATTERN CERTAINLY SUGGESTS A HEAVY  
RAIN/SEVERE WEATHER/WINTRY WEATHER THREAT, BUT DETAILS ON WHERE  
THESE HAZARDS OCCUR AND WHEN REMAINS UNCERTAIN STILL, WITH PLENTY  
OF FORECAST REFINEMENTS TO COME.  
 
THE WESTERN U.S. SHOULD SEE SEVERAL DAYS OF BELOW NORMAL  
TEMPERATURES, WITH DAYTIME HIGHS 20+ DEGREES BELOW NORMAL SHIFTING  
EASTWARD MON-WED. SOME MODERATION IS LIKELY BY LATER IN THE WEEK  
ACROSS THE WEST, THOUGH STILL BELOW NORMAL WITH ADDITIONAL  
TROUGHING MOVING IN. BY NEXT THURSDAY-FRIDAY, THE CORE OF THE COLD  
SHOULD BE OVER THE NORTHERN PLAINS WITH LOW TEMPERATURES 10-20F  
BELOW NORMAL AND HIGHS EVEN APPROACHING 30F BELOW AVERAGE.  
MEANWHILE, AHEAD OF THE BIG STORM, EXPECT TEMPERATURES FROM THE  
SOUTH-CENTRAL U.S. TO THE EAST TO BE ABOVE NORMAL, BUT TRENDING  
BACK TOWARDS NORMAL FOLLOWING PASSAGE OF THE COLD FRONT.  
 
TATE/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  
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE  
TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE SOUTHEAST,  
THE SOUTHERN PLAINS, AND THE OHIO VALLEY, MON-THU, APR 11-APR 14.  
- HEAVY SNOW ACROSS PORTIONS OF CALIFORNIA, THE CENTRAL GREAT  
BASIN, THE PACIFIC NORTHWEST, AND THE NORTHERN GREAT BASIN, MON,  
APR 11.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, AND THE  
NORTHERN ROCKIES, MON-TUE, APR 11-APR 12.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL PLAINS, THE UPPER  
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, TUE-THU, APR 12-APR  
14.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI  
VALLEY, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO VALLEY,  
MON-WED, APR 11-APR 13.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHEAST.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST  
AND THE MIDDLE MISSISSIPPI VALLEY.  
- FLOODING LIKELY ACROSS PORTIONS OF THE SOUTHEAST.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHERN PLAINS, MON-WED,  
APR 11-APR 13.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE CENTRAL GREAT BASIN, THE SOUTHERN ROCKIES, THE  
SOUTHERN PLAINS, AND THE SOUTHWEST, MON-WED, APR 11-APR 13.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
PLAINS, THE SOUTHERN PLAINS, THE UPPER MISSISSIPPI VALLEY, AND THE  
NORTHERN PLAINS, WED-THU, APR 13-APR 14.  
- ENHANCED WILDFIRE RISK ACROSS PORTIONS OF THE SOUTHERN ROCKIES,  
THE CENTRAL PLAINS, THE SOUTHERN PLAINS, AND THE SOUTHWEST,  
MON-TUE, APR 11-APR 12.  
 
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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