231  
FXUS02 KWBC 220656  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
255 AM EDT FRI JUL 22 2022  
 
VALID 12Z MON JUL 25 2022 - 12Z FRI JUL 29 2022  
 
...DANGEROUS HEAT WAVE PERSISTS OVER THE SOUTH-CENTRAL U.S. INTO  
MIDWEEK AS HEAT ALSO BUILDS ACROSS INTERIOR PORTIONS OF THE  
NORTHWEST NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE WESTERN RIDGE WHICH IS CURRENTLY CENTERED OVER THE DESERT  
SOUTHWEST IS EXPECTED TO STEADILY DRIFT EAST THROUGH THE MIDDLE OF  
NEXT WEEK, AS PROGRESSIVE SYSTEMS SLIDE ALONG THE NORTHERN  
PERIPHERY OF THE RIDGE ACROSS THE NORTHERN TIER STATES. A STRONG  
RIDGE DEVELOPING OVER THE NORTHEASTERN PACIFIC THROUGH EASTERN  
ALASKA BY THE START OF THE MEDIUM RANGE PERIOD SHOULD SHIFT INLAND  
ACROSS THE WEST COAST THROUGH THE MIDDLE OF NEXT WEEK,  
ESTABLISHING A MULTI-DAY PERIOD OF HOT WEATHER OVER THE NORTHWEST  
(WITH HIGHS LOOKING TO REACH 15F ABOVE NORMAL) INTO PERHAPS NEXT  
WEEKEND. AN INITIAL SURFACE FRONT DRAPED FROM THE MID-ATLANTIC TO  
THE CENTRAL PLAINS WILL BECOME QUASI-STATIONARY EARLY NEXT WEEK  
AHEAD OF THE NEXT COLD FRONT APPROACHING SOON THEREAFTER. THIS  
SHOULD HELP TO FOCUS HEAVY RAIN POTENTIAL OVER PARTS OF THE  
CENTRAL/EASTERN U.S. AND SUPPORT A MODERATING TEMPERATURE TREND  
EAST OF THE ROCKIES. A PERIOD OF ENHANCED MONSOONAL MOISTURE FROM  
MONDAY ONWARD WILL PROMOTE DAILY RISK OF LOCALLY HEAVY SHOWERS AND  
STORMS THAT MAY PRODUCE INSTANCES OF FLASH FLOODING.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
OVERALL, THE LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW VERY  
GOOD AGREEMENT ON THE LARGE SCALE, THOUGH WITH SOME CONTINUED  
DIFFERENCES FOR LOW-PREDICTABILITY SHORTWAVE DETAILS WITHIN  
NORTHERN U.S./SOUTHERN CANADA, PARTICULARLY BY MIDWEEK AND ONWARD.  
THESE DIFFERENCES AFFECT FRONTAL PLACEMENT ACROSS THE EAST AND  
CENTRAL U.S. WITH IMPACTS ON LOCATION AND INTENSITY OF RAINFALL,  
PARTICULARLY ACROSS THE OHIO VALLEY. MODELS CONTINUE TO SHOW VERY  
GOOD CLUSTERING ON THE EXPANSIVE RIDGE ACROSS THE SOUTHERN HALF OF  
THE U.S. AND BUILDING OVER THE NORTHWEST BY THE MIDDLE TO LATTER  
PART OF NEXT WEEK. THIS CYCLE OF THE WPC FORECAST UTILIZED A BLEND  
OF THE DETERMINISTIC MODELS FOR DAYS 3-5, WITH INCREASING  
INCORPORATION OF THE ENSEMBLE MEANS BY DAYS 6-7 TO HELP MITIGATE  
THE SMALLER SCALE DIFFERENCES. THIS MAINTAINS GOOD CONTINUITY WITH  
PREVIOUS WPC FORECASTS AS WELL.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE MAIN WEATHER HAZARD WILL BE THE PROLONGED EXCESSIVE HEAT  
ACROSS ESPECIALLY THE SOUTHERN HALF OF THE PLAINS INTO AT LEAST  
MIDWEEK, WITH SOME MODERATION THEREAFTER. WIDESPREAD TEMPERATURES  
NEAR OR ABOVE 100 DEGREES (WITH HIGHER HEAT INDICES) WILL CONTINUE  
THE DANGEROUS HEATWAVE IN THIS REGION. PARTS OF THE EASTERN AND  
SOUTHEAST U.S. SHOULD START THE WEEK WARM AND ABOVE NORMAL, BUT A  
COLD FRONT MOVING INTO THE REGION NEXT MONDAY-TUESDAY SHOULD BRING  
SOME RELIEF TO THE HEAT IN THE EAST. THE NEXT FRONT THAT REACHES  
THE NORTHERN PLAINS EARLY NEXT WEEK LOOKS TO HAVE A STRONGER  
SOUTHWARD PUSH, 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. BOTH OF THESE FRONTS WILL FOCUS EPISODES OF  
SHOWERS AND THUNDERSTORMS, WITH SOME SEVERE WEATHER AND HEAVY  
RAINFALL POSSIBLE. THE LEADING FRONT HEADING INTO THE EAST LOOKS  
TO BECOME QUASI-STATIONARY AND MAY INITIALLY FAVOR HIGHEST  
RAINFALL TOTALS FROM THE MIDWEST/LOWER OHIO VALLEY INTO THE  
NORTHEAST/MID-ATLANTIC. A SLIGHT RISK WAS PLACED ON BOTH THE DAY 4  
AND 5 EXPERIMENTAL EROS ACROSS EASTERN KENTUCKY INTO WEST VIRGINIA  
WHERE THE SETUP SEEMS MOST FAVORABLE OVER A SOMEWHAT SENSITIVE  
REGION AND GIVEN RECENT HEAVY RAINS. THE SECOND FRONT SHOULD  
PRODUCE NORTHERN PLAINS CONVECTION THAT EXTENDS SOUTH/EAST WITH  
TIME, POTENTIALLY REPEATING ACTIVITY OVER AN ALREADY SOGGY OHIO  
VALLEY. 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. GUIDANCE CONTINUES TO SUGGEST THAT THE PATTERN  
EVOLUTION WILL SUPPORT A MORE ACTIVE PERIOD WITH GREATER COVERAGE  
AND INTENSITY OF RAINFALL, ESPECIALLY FOR PARTS OF THE SOUTHERN  
ARIZONA. AS A RESULT, A SMALL SLIGHT RISK WAS PLACED ACROSS  
SOUTHEAST ARIZONA ON THE DAY 4 ERO WHERE REPEAT ACTIVITY FROM THE  
SHORT RANGE PERIOD SEEMS MOST FAVORABLE. POTENTIAL STILL EXISTS  
FOR SOME OF THIS MOISTURE TO INTERACT WITH CENTRAL PLAINS FRONTS  
TO ENHANCE RAINFALL TOTALS FARTHER NORTH AND EAST INTO NEW MEXICO  
AND COLORADO. UPPER RIDGING THAT BUILDS OVER THE NORTHWEST NEXT  
WEEK WILL BRING MULTIPLE DAYS OF HOT WEATHER TO THAT REGION, WITH  
SOME LOCATIONS LIKELY TO SEE HIGHS REACH UP TO 10-15F OR SO ABOVE  
NORMAL, EQUATING TO TEMPERATURES IN THE LOW TO MID 100S FOR  
ESPECIALLY THE COLUMBIA BASIN. SOME DAILY RECORDS FOR HIGHS/WARM  
LOWS WILL BE POSSIBLE ACROSS INTERIOR PORTIONS OF THE NORTHWEST.  
 
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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