617  
FXUS02 KWBC 280651  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
251 AM EDT SUN AUG 28 2022  
 
VALID 12Z WED AUG 31 2022 - 12Z SUN SEP 04 2022  
   
..OVERVIEW
 
 
AN AMPLIFIED FLOW PATTERN IS EXPECTED TO START THE FORECAST PERIOD  
FEATURING STRONG RIDGING THROUGH THE INTERIOR WEST WITH DEEPER  
TROUGHING ACROSS THE EASTERN PACIFIC AS WELL AS THE GREAT LAKES  
INTO THE NORTHEAST U.S., THE LATTER OF WHICH HELPS DRIVE A COLD  
FRONT ACROSS MUCH OF THE CENTRAL TO EASTERN U.S. MID TO LATE WEEK.  
DRIER AND EARLY FALL-LIKE TEMPERATURES CAN BE EXPECTED IN ITS WAKE  
FROM THE UPPER MIDWEST TO THE EAST COAST WHILE THE WEST IS LIKELY  
TO SEE MUCH ABOVE NORMAL TEMPERATURES. THE COLD FRONT IS FORECAST  
TO SETTLE ALONG THE SOUTHERN TIER OF THE U.S. FROM THE TEXAS GULF  
COAST EASTWARD TO FLORIDA LATE IN THE WEEK INTO NEXT WEEKEND, AND  
THIS WILL BE FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND  
THUNDERSTORMS EACH DAY, SOME OF WHICH COULD PRODUCE LOCALLY HEAVY  
RAINFALL.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THROUGH DAY 5, THE LATEST MODEL GUIDANCE SHOWS STRONG AGREEMENT  
AND RUN TO RUN CONSISTENCY WITH THE UPPER LEVEL PATTERN AND  
WEATHER FEATURES ACROSS THE CONUS. THE AMPLIFIED RIDGE IS EXPECTED  
TO PERSIST OR EVEN BUILD SOME OVER THE FOUR CORNERS REGION  
NORTHWARD THROUGH THE INTERIOR WEST WHILE EASTERN PACIFIC  
TROUGHING DIGS AND THE GREAT LAKES TROUGH BEGINS TO FLATTEN OUT  
SOMEWHAT. AT THE START OF THE PERIOD, A COLD FRONT WILL BE  
SWEEPING ACROSS MUCH OF THE CENTRAL TO EASTERN U.S. AND THE LATEST  
RUNS OF THE GFS, ECMWF, CMC, AND UKMET SHOW FAIRLY HIGH  
CONSISTENCY AND AGREEMENT. THAT FRONT IS EXPECTED TO SETTLE ALONG  
THE GULF COAST AND BACK ACROSS TEXAS, WHERE ALOFT THERE CONTINUE  
TO BE HINTS OF A WEAKNESS IN THE RIDGE THAT MAY HELP SUPPORT  
UNSETTLED WEATHER ACROSS TEXAS, THE GFS BEING THE MORE AGGRESSIVE  
MODEL SHOWING THIS SCENARIO. OTHERWISE, ANOTHER AREA OF MODEL  
DIFFERENCES IS DAY 5 ONWARD OVER THE NORTHWEST. WHILE THE ENSEMBLE  
MEANS SHOW THE EASTERN PACIFIC SHORTWAVE ENERGY LIFTING MORE INTO  
BRITISH COLUMBIA, THE RECENT DETERMINISTIC RUNS, PARTICULARLY THE  
GFS AND CMC, SHOW A MORE COMPACT SHORTWAVE TROUGHING ADVANCING  
FASTER AND FURTHER SOUTH, TRACKING ACROSS THE PACIFIC NORTHWEST  
LATE IN THE WEEK INTO EARLY NEXT WEEKEND. GIVEN THE TYPICAL FAST  
BIAS THERE AND THE UNCERTAINTY FOR A DAY 6/7 FORECAST, THE WPC  
BLEND LEANED ON THE ENSEMBLE MEANS FOR ABOUT 50 PERCENT OF THE  
BLEND AND THE LATEST ECMWF/GFS FOR THE OTHER HALF, WHICH TRENDED  
WELL WITH THE LATEST TRENDS AND MAINTAINED WPC CONTINUITY.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
A COLD FRONT SWEEPING ACROSS THE CENTRAL TO EASTERN U.S. MID TO  
LATE WEEK WILL BE THE MAIN SENSIBLE WEATHER FEATURE OF NOTE ACROSS  
THE CONUS. AHEAD OF IT, ENOUGH WARM AND MOIST AIR WILL LIFT  
NORTHWARD TO SUPPORT SCATTERED TO NUMEROUS SHOWERS AND  
THUNDERSTORMS, SOME OF WHICH COULD BE LOCALLY HEAVY ACROSS  
PORTIONS OF NEW ENGLAND WEDNESDAY INTO THURSDAY WHERE THE SYSTEM  
WILL HAVE BETTER DYNAMICS/LIFT TO SUPPORT MORE ORGANIZED  
CONVECTION. FURTHER SOUTH ALONG THE SOUTHWARD MOVING BOUNDARY,  
BETTER INSTABILITY AND MOISTURE ACROSS THE SOUTHERN PLAINS AND  
POTENTIALLY ALONG THE FLORIDA GULF COAST COULD SUPPORT INTENSE  
RAIN RATES AND LOCALIZED HEAVY RAINFALL. THE FRONT THEN IS  
EXPECTED TO SETTLE ACROSS THE SOUTHERN TIER OF THE U.S. AND WILL  
BE THE FOCUS FOR DAILY SHOWERS AND THUNDERSTORMS, SOME OF WHICH  
COULD BE LOCALLY HEAVY NEXT WEEKEND ACROSS TEXAS EASTWARD ALONG  
THE GULF COAST. ELSEWHERE, THE REST OF THE COUNTRY LOOKS TO BE  
MAINLY DRY ASIDE FROM LIGHT PRECIPITATION CHANCES ACROSS THE  
COLORADO ROCKIES AND A FRONTAL PASSAGE POSSIBLY CLIPPING THE  
PACIFIC NORTHWEST BRINGING GENERALLY LIGHT PRECIPITATION.  
 
THE GREATEST TEMPERATURE ANOMALIES THROUGH THE PERIOD WILL BE  
FOUND ACROSS THE WESTERN U.S. MID TO LATE WEEK, PARTICULARLY  
ACROSS THE NORTHWEST INTO NORTHERN ROCKIES WHERE HIGHS COULD REACH  
10-20F ABOVE NORMAL AND SOME DAILY HIGH TEMPERATURE RECORDS COULD  
BE CHALLENGED. AS THE CALENDAR TURNS TO METEOROLOGICAL FALL, MUCH  
OF THE UPPER MIDWEST, GREAT LAKES, AND NORTHEAST SHOULD SEE AT OR  
SLIGHTLY BELOW NORMAL HIGHS, WITH COOL LOWS IN THE 40S TO 50S IN  
PORTIONS OF THOSE AREAS. AS THE UPPER FLOW PATTERN BECOMES MORE  
ZONAL NEXT WEEKEND, THE ABOVE NORMAL TEMPERATURES LOOK TO SPREAD  
ACROSS MUCH OF THE NORTHERN TIER OF THE U.S. WITH HIGHS NEXT  
WEEKEND POSSIBLY 5-10F ABOVE NORMAL. CONVERSELY, THE SOUTHERN U.S.  
IS LIKELY TO SEE NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES  
THROUGH THE PERIOD, PARTICULARLY THE SOUTHERN PLAINS AND GULF  
COAST WHERE WIDESPREAD CLOUDS AND PRECIPITATION LOOK TO KEEP  
TEMPERATURES IN CHECK.  
 
TAYLOR/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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