697  
FXUS02 KWBC 301741  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
138 PM EDT THU JUN 30 2022  
 
VALID 12Z SUN JUL 03 2022 - 12Z THU JUL 07 2022  
   
..OVERVIEW
 
 
BROAD CYCLONIC FLOW ALOFT WILL BE IN PLACE ACROSS THE  
NORTH-CENTRAL TO NORTHEAST U.S. FOR THE BEGINNING OF THE PERIOD  
SUNDAY-MONDAY AS AN ANOMALOUS UPPER LOW LINGERS OVER FAR NORTHERN  
QUEBEC. EVENTUALLY THIS LOW SHOULD LIFT NORTHWARD NEXT WEEK AS A  
FEW WEAKER SHORTWAVES MOVE THROUGH ACROSS THE FAR NORTHERN TIER  
STATES. OUT WEST, ANOTHER SYNOPTIC SCALE UPPER LOW WILL WEAKEN AND  
LIFT THROUGH THE PACIFIC NORTHWEST AS A SECOND LOW DROPS DOWN FROM  
THE GULF OF ALASKA, OFFERING RENEWED TROUGHING ALONG THE WEST  
COAST FOR MUCH OF THE PERIOD. IN BETWEEN, AND UPPER LEVEL RIDGE  
WILL BUILD FROM THE ROCKIES INTO THE PLAINS WITH ANOMALOUSLY WARM  
TEMPERATURES, ESPECIALLY THE EARLY PART OF NEXT WEEK. AT THE  
SURFACE, A QUASI-STATIONARY FRONTAL BOUNDARY DRAPED FROM THE  
NORTH-CENTRAL PLAINS TO THE MID-ATLANTIC WILL FOCUS SHOWERS AND  
STORMS, WITH SOME LOCALLY HEAVY RAINFALL.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE 00Z/06Z SUITE OF GUIDANCE REMAINS IN VERY GOOD AGREEMENT ON  
THE SYNOPTIC PATTERN THROUGH MUCH OF THE PERIOD. THERE REMAIN,  
HOWEVER, SOME MESOSCALE DETAIL DIFFERENCES WITH THE INDIVIDUAL  
SHORTWAVES THAT WILL GOVERN THE MAGNITUDE AND EXTENT OF HEAVY RAIN  
ACROSS THE PLAINS AND MIDWEST. THESE DIFFERENCES COULD TAKE UNTIL  
THE SHORT RANGE TO FULLY RESOLVE. REGARDLESS, A BLEND OF THE  
DETERMINISTIC MODELS WORKED WELL THROUGH DAY 5. AFTER THIS,  
INCREASED THE BLEND OF THE ENSEMBLE MEANS TO HELP TEMPER SOME  
ADDITION DIFFERENCES, WITH LESS OF THE CMC BY LATE PERIOD DUE TO  
ISSUES WITH A SHORTWAVE IN WEST-CENTRAL CANADA. THIS APPROACH  
MAINTAINED REASONABLE CONTINUITY WITH THE PREVIOUS WPC FORECAST AS  
WELL.  
   
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
 
 
SCATTERED SHOWERS AND STORMS ARE EXPECTED ACROSS THE SOUTHEAST  
THIS WEEKEND WITH THE PRESENCE OF A WEAKENING FRONTAL BOUNDARY AND  
WEAK IMPULSES MOVING THROUGH THE FLOW ALOFT. FARTHER NORTH, A  
FRONT INITIALLY ORIENTED FROM THE NORTHEAST INTO THE OHIO VALLEY  
AND CENTRAL PLAINS WILL PUSH GRADUALLY EASTWARD DURING THE WEEKEND  
AND SUPPORT ORGANIZED AREAS OF SHOWERS AND STORMS ALONG AND AHEAD  
OF IT. SOME RAINFALL MAY BE LOCALLY HEAVY FROM THE CENTRAL PLAINS  
INTO THE MID-ATLANTIC ON SUNDAY AS MOISTURE CONVERGES ALONG A  
QUASI-STATIONARY FRONTAL ZONE. THIS FRONT MAY CONTINUE TO BE A  
FOCUS FOR RAINFALL INTO EARLY NEXT WEEK AS WELL. MONSOONAL  
MOISTURE OVER THE SOUTHERN ROCKIES IS ALSO EXPECTED TO LEAD TO  
MAINLY DIURNALLY DRIVEN SHOWERS AND STORMS, WITH WEAK SHORTWAVES  
AND MOISTURE LIFTING NORTHWARD BETWEEN UPPER RIDGING TO THE EAST  
AND THE TROUGH NEAR THE WEST COAST. THE WEST COAST TROUGH WILL  
LIKELY PRODUCE PERIODS OF RAINFALL OVER PARTS OF THE NORTHWEST,  
AND THERE CONTINUES TO BE A SIGNAL FOR A PERIOD OF HEAVIER  
RAINFALL NEAR THE CANADIAN BORDER EARLY NEXT WEEK. SOME MESOSCALE  
CONVECTIVE SYSTEMS COULD ALSO EXTEND ACROSS THE NORTHERN  
PLAINS/UPPER MIDWEST, AIDED BY NORTHERN TIER SURFACE FEATURES AND  
SHORTWAVES EMERGING FROM THE WEST, WITH MODELS SHOWING POTENTIAL  
FOR AT LEAST LOCALLY HEAVY TO EXCESSIVE RAINS. A SLIGHT RISK WAS  
ADDED TODAY TO THE DAY 5 EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOK  
FOR PARTS OF THE UPPER MIDWEST WHERE MODELS SHOW THE BEST SIGNAL  
FOR HEAVY RAINS, WITHIN AN AREA OF SIGNIFICANT MOISTURE AND  
INSTABILITY PRESENCE.  
 
THE GREATEST CONCERN FOR TEMPERATURES WILL BE WITH HEAT EXPECTED  
TO BUILD AGAIN ACROSS THE CENTRAL AND NORTHERN PLAINS BY EARLY  
NEXT WEEK IN RESPONSE TO A STRENGTHENING UPPER LEVEL RIDGE. HIGHS  
OF 5-15 DEGREES ABOVE NORMAL ARE POSSIBLE OVER THE CENTRAL PLAINS,  
EQUATING TO TEMPERATURES IN THE MID 90S TO LOW 100S. SOUTHERN  
PLAINS LOCATIONS WILL SEE A SLIGHTLY HOTTER TREND AS WELL, BUT  
WITH LESS EXTREME ANOMALIES. OUT WEST, BELOW NORMAL HIGHS WILL  
SPREAD GRADUALLY INLAND FROM THE WEST COAST DURING THE WEEKEND  
INTO EARLY NEXT WEEK DUE TO NEARBY UPPER TROUGHING. A FEW  
LOCATIONS MAY SEE HIGHS 10-15F BELOW NORMAL AROUND SUNDAY-MONDAY.  
EXPECT A MODERATING TREND CLOSER TO NORMAL HEADING INTO MIDWEEK.  
ACROSS THE EASTERN U.S., A STABLE UPPER PATTERN OF WESTERLIES  
ACROSS THE NORTHEAST AND RIDGING OVER THE SOUTH SHOULD KEEP BOTH  
DAYTIME HIGHS AND OVERNIGHT LOWS WITHIN A FEW DEGREES OF  
CLIMATOLOGICAL AVERAGES THROUGH MOST OF THE PERIOD.  
 
SANTORELLI/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  
 
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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