935  
FXUS02 KWBC 231900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT SAT JUL 23 2022  
 
VALID 12Z TUE JUL 26 2022 - 12Z SAT JUL 30 2022  
 
...DANGEROUS HEAT WAVE PERSISTS OVER THE SOUTH-CENTRAL U.S. INTO  
MIDWEEK BEFORE FINALLY MODERATING, WHILE HEAT ALSO BUILDS ACROSS  
THE NORTHWEST NEXT WEEK...  
 
   
..OVERVIEW
 
 
A WEST-EAST ORIENTED RIDGE WILL PERSIST ACROSS THE SOUTHERN TIER  
OF THE U.S. THROUGH MUCH OF NEXT WEEK. INITIALLY PROGRESSIVE  
SYSTEMS ARE FORECAST TO SLIDE ALONG THE NORTHERN PERIPHERY OF THE  
RIDGE ACROSS THE NORTHERN TIER STATES BEFORE ENERGY CONSOLIDATES  
INTO A DEEPER UPPER LOW MOVING ACROSS SOUTH-CENTRAL AND  
SOUTHEASTERN CANADA THROUGH THE WORKWEEK. THIS ENERGY/FLOW PATTERN  
AS WELL AS A SURFACE FRONT DRAPED FROM THE MID-ATLANTIC TO THE  
CENTRAL PLAINS LIFTING NORTHWARD AHEAD OF THE NEXT COLD FRONT  
SHOULD HELP FOCUS HEAVY RAIN POTENTIAL OVER PARTS OF THE  
CENTRAL/EASTERN U.S., PARTICULARLY THE OHIO VALLEY/CENTRAL  
APPALACHIANS THROUGH AROUND MIDWEEK AND BACK INTO THE MIDDLE/LOWER  
MISSISSIPPI AND TENNESSEE VALLEYS AS THE SECOND FRONT SETTLES  
SOUTHWARD. THIS WILL ALSO SUPPORT A MODERATING TEMPERATURE TREND  
EAST OF THE ROCKIES. MEANWHILE A STRONG RIDGE OVER THE  
NORTHEASTERN PACIFIC WILL SHIFT INLAND ACROSS THE WEST COAST,  
ESTABLISHING A MULTI-DAY PERIOD OF HOT WEATHER OVER THE NORTHWEST  
(WITH HIGHS LOOKING TO REACH 15-20F ABOVE NORMAL) THAT SHOULD LAST  
INTO NEXT WEEKEND. ADDITIONALLY, A PERIOD OF ENHANCED MONSOONAL  
MOISTURE FROM THE SHORT TO MEDIUM RANGE PERIOD WILL PROMOTE DAILY  
RISKS OF LOCALLY HEAVY SHOWERS AND STORMS THAT MAY PRODUCE  
INSTANCES OF FLASH FLOODING IN PARTS OF THE SOUTHWEST.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS AGREEABLE WITH THE  
LARGE SCALE PATTERN SHOWING EXPANSIVE AND PERSISTENT RIDGING FROM  
THE NORTHWEST TO THE SOUTHERN HALF OF THE U.S., WITH AN INITIAL  
SHORTWAVE SHIFTING OFF THE EAST COAST ON TUESDAY, AND AS ANOTHER  
MORE CONSOLIDATED TROUGH (STEMMING FROM A SOUTHERN CANADA UPPER  
LOW) DIGS ACROSS THE NORTHERN PLAINS/GREAT LAKES AROUND MIDWEEK  
AND INTO THE MIDWEST/NORTHEAST NEXT FRIDAY-SATURDAY. WITHIN THE  
NORTHERN STREAM JET THERE ARE SOME DIFFERENCES IN GUIDANCE WITH  
THE SMALLER SCALE DETAILS, BUT THE DIFFERENCES WERE WELL WITHIN  
REASON FOR A MEDIUM RANGE FORECAST, AND WITH NO PARTICULAR  
OUTLIERS IN THE 00/06Z MODEL CYCLE. THUS THE WPC FORECAST WAS  
BASED ON A BLEND OF THE DETERMINISTIC GUIDANCE THROUGH DAY 5, WITH  
SOME INCREASING PROPORTION OF THE GEFS AND EC ENSEMBLE MEANS BY  
DAY 6-7 TO SMOOTH OUT THE DIFFERENCES. THIS MAINTAINS GOOD  
CONTINUITY WITH THE PREVIOUS WPC FORECAST, WITH ONLY TYPICAL SMALL  
SHIFTS IN FRONTS AND QPF BASED ON THE MOST RECENT GUIDANCE.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE SOUTH-CENTRAL U.S. HAS SEEN PROLONGED EXCESSIVE HEAT IN RECENT  
WEEKS, AND THIS IS FORECAST TO LAST INTO AT LEAST MIDWEEK FOR THE  
SOUTHERN HALF OF THE PLAINS AND MISSISSIPPI VALLEY. WIDESPREAD  
TEMPERATURES NEAR OR ABOVE 100 DEGREES (WITH HIGHER HEAT INDICES)  
WILL CONTINUE THE DANGEROUS HEATWAVE IN THIS REGION. HOWEVER, THE  
NEXT FRONT THAT REACHES THE NORTHERN PLAINS EARLY NEXT WEEK LOOKS  
TO HAVE A STRONGER SOUTHWARD PUSH WITH MORE UPPER-LEVEL SUPPORT,  
BRINGING MODERATELY BELOW NORMAL HIGHS TO THE NORTHERN-CENTRAL  
PLAINS TUESDAY ONWARD, WITH FINALLY SOME MODERATING TEMPERATURES  
BACK TOWARDS NORMAL FOR THE SOUTHERN PLAINS AS WELL FOR THE LATTER  
HALF OF THE WEEK. MEANWHILE, A LINGERING QUASI-STATIONARY FRONT  
THROUGH THE MID-ATLANTIC AND TENNESSEE VALLEY AND POINTS WESTWARD  
WILL FOCUS DAILY ROUNDS OF SHOWERS AND THUNDERSTORMS ALONG IT  
ACROSS A GOOD PORTION OF THE MID-ATLANTIC WESTWARD THROUGH THE  
NORTHERN/CENTRAL PLAINS. INITIALLY, THE HIGHEST RAINFALL TOTALS  
SEEM FAVORED OVER/NEAR THE OHIO VALLEY INTO THE CENTRAL/SOUTHERN  
APPALACHIANS, WHERE A SLIGHT RISK WAS MAINTAINED AND EXPANDED  
SOMEWHAT ON THE DAY 4 EXPERIMENTAL ERO BASED ON LATEST FORECAST  
TRENDS. THEN THE SECOND, STRONGER, FRONT SHOULD PRODUCE NORTHERN  
PLAINS CONVECTION THAT EXTENDS SOUTH/EAST WITH TIME, POTENTIALLY  
REPEATING ACTIVITY OVER AN ALREADY SOGGY OHIO VALLEY/CENTRAL  
APPALACHIANS REGION, LEADING TO ADDITIONAL CHANCES OF FLASH  
FLOODING. CONVECTION SHOULD SINK SOUTHWARD WITH THE FRONT,  
REACHING THE SOUTHERN HALF OF THE MISSISSIPPI VALLEY AND INTO THE  
TENNESSEE VALLEY LATE WEEK. EXPECT PERIODS OF SHOWERS AND  
THUNDERSTORMS OVER PORTIONS OF FLORIDA AND THE GULF COAST AS WELL  
AS AN AREA OF ENHANCED MOISTURE PASSES THROUGH FROM EAST TO WEST.  
 
OVER THE WEST, PERSISTENT MONSOONAL MOISTURE AND VARIOUS SHORTWAVE  
IMPULSES WILL SUPPORT DIURNALLY FAVORED SHOWERS/STORMS WITH SOME  
LOCALLY HEAVY RAINFALL OVER THE FOUR CORNERS/GREAT BASIN REGION  
THROUGH NEXT WEEK. A SLIGHT RISK OF EXCESSIVE RAINFALL WAS  
INTRODUCED FOR DAY 4 (TUESDAY) AS THAT ANOMALOUS MOISTURE STAYS  
PUT OVER LIKELY WET SOIL FROM ACTIVITY IN THE SHORT RANGE PERIOD.  
SOME OF THIS MOISTURE IS EXPECTED TO INTERACT WITH THE CENTRAL  
PLAINS FRONT TO ENHANCE RAINFALL TOTALS FARTHER NORTH AND EAST  
INTO NEW MEXICO AND COLORADO MIDWEEK, WHICH COULD LEAD TO FLASH  
FLOODING THERE. MEANWHILE, UPPER RIDGING THAT BUILDS OVER THE  
NORTHWEST NEXT WEEK WILL BRING MULTIPLE DAYS OF HOT WEATHER, WITH  
SOME LOCATIONS LIKELY TO SEE HIGHS REACH UP TO 10-20F ABOVE  
NORMAL. THIS EQUATES TO HIGHS IN THE LOW TO MID 100S FOR THE  
COLUMBIA BASIN, AND 90S ARE EXPECTED TO REACH AS FAR WEST AS  
PORTLAND AND SEATTLE. SOME DAILY RECORDS FOR HIGHS/WARM LOWS WILL  
BE POSSIBLE ACROSS INTERIOR PORTIONS OF THE NORTHWEST.  
 
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  
 
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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