261  
FXUS02 KWBC 080707  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
306 AM 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 DEVELOPING OVER  
THE PLAINS/UPPER MIDWEST. THIS IS LIKELY TO BRING AN ARRAY OF  
SIGNIFICANT WEATHER ACROSS THE CONUS... INCLUDING RAIN/SNOW IN THE  
WEST, AND A LEADING HEAVY RAINFALL/SEVERE WEATHER THREAT ACROSS  
THE SOUTH/MIDWEST, WITH LATE SEASON SNOW POSSIBLE TO THE NORTH AND  
WEST OF THE LOW TRACK LATER NEXT WEEK. AMPLIFIED RIDGING OFF THE  
EAST COAST SHOULD DRIVE THIS SYSTEM MORE NORTHWARD INTO EASTERN  
CANADA, AS THE NEXT (LIKELY LESS AMPLIFIED) TROUGH ENTERS THE WEST  
AROUND FRIDAY/DAY 7.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE MAIN SYSTEM OF CONCERN IN THE MEDIUM RANGE PERIOD SURROUNDS AN  
UPPER LOW DROPPING OUT OF THE GULF OF ALASKA IN THE SHORT RANGE,  
REACHING THE PACIFIC NORTHWEST BY DAY 3/MONDAY. RIGHT OFF THE BAT,  
MODELS STRUGGLE WITH THE DETAILS OF THE ENERGY AS IT MOVES ACROSS  
THE WEST DAYS 3-4. DIFFERENCES REALLY BEGIN TO SHOW BY DAY 5 AND  
BEYOND AS THE TROUGH SHARPENS AND MOVES OUT INTO THE PLAINS. THE  
LAST FEW RUNS OF THE GFS HAVE BEEN CONSISTENTLY MUCH QUICKER WITH  
THE DEVELOPING LOW AS IT LIFTS INTO THE UPPER MIDWEST. THE CMC,  
ECMWF, AND THE UKMET ARE SLOWER, BUT WITH LATITUDINAL DIFFERENCES  
IN PLACEMENT. THE ENSEMBLE MEANS GENERALLY SIDE WITH THEIR  
DETERMINISTIC COUNTERPARTS, BUT DO SEEMS TO MORE SUPPORT A SLOWER  
SOLUTION FOR NOW. DESPITE SIGNIFICANT TIMING QUESTIONS, THERE IS  
GOOD AGREEMENT ON A CLOSED LOW FORMING OVER THE PLAINS BY  
WEDNESDAY-THURSDAY AND MAJORITY OF THE GUIDANCE SUGGESTS A DECENT  
STORM SYSTEM TRAVERSING THE CENTRAL PART OF THE COUNTRY. THE BLEND  
FOR THE OVERNIGHT WPC PROGS WEIGHTED THE SLOWER SOLUTIONS MORE,  
WITH INCREASING ENSEMBLE MEANS BY THE LATTER HALF OF THE PERIOD.  
THIS AFFORDED A GOOD MIDDLE GROUND SOLUTION FOR LOW PLACEMENT AND  
ALSO GOOD CONTINUITY WITH THE PREVIOUS FORECAST AS WELL.  
 
BY NEXT FRIDAY, THE NEXT SYSTEM SHOULD NEAR/ENTER THE WEST COAST.  
AGAIN, PLENTY OF TIMING/STRENGTH DIFFERENCES AND GIVEN THE LATE  
PERIOD, A BLEND TOWARDS THE ENSEMBLE MEANS SEEMED BEST AT THIS  
POINT.  
   
..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 POSSIBLY 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. 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. ALSO THE STORM PREDICTION  
CENTER IS MONITORING THE POTENTIAL FOR SEVERE WEATHER OVER SOME  
SOUTHERN AREAS IN THE CENTRAL U.S.. CHECK THEIR LATEST OUTLOOKS  
FOR MORE INFORMATION. FARTHER NORTH, A FRONT DRAPED OVER THE  
MIDWEST COULD ALSO PROVIDE A FOCUS FOR RAINFALL THOUGH LIKELY WITH  
LOWER TOTALS GIVEN LESS MOISTURE/INSTABILITY. THE PATTERN  
CERTAINLY SUGGESTS A HEAVY RAIN/SEVERE WEATHER/WINTRY WEATHER  
THREAT, BUT DETAILS ON WHERE THESE HAZARDS OCCUR AND WHEN REMAINS  
VERY UNCERTAIN STILL WITH PLENTY OF FORECAST REFINEMENTS TO COME.  
 
WESTERN U.S. SHOULD SEE SEVERAL DAYS OF BELOW NORMAL TEMPEATURES,  
WITH DAYTIME HIGHS 20+ DEGREES BELOW NORMAL SHIFTING EASTWARD  
MON-WED. SOME MODERATION LIKELY BY LATER IN THE WEEK ACROSS THE  
WEST, THOUGH STILL BELOW NORMAL WITH ADDITIONAL TROUGHING MOVING  
IN. BY NEXT THURSDAY-FRIDAY, CORE OF THE COLD SHOULD BE OVER THE  
NORTHERN PLAINS WITH ANOMALIES 10-20F BELOW NORMAL. 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.  
 
SANTORELLI/TATE  
 
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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