647  
FXUS02 KWBC 221911  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
310 PM 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 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, 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 BY  
THE MIDDLE OF NEXT WEEK, ESTABLISHING A MULTI-DAY PERIOD OF HOT  
WEATHER OVER THE NORTHWEST (WITH HIGHS LOOKING TO REACH 15-20F  
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  
RISKS OF LOCALLY HEAVY SHOWERS AND STORMS THAT MAY PRODUCE  
INSTANCES OF FLASH FLOODING.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE LATEST MODEL AND ENSEMBLE GUIDANCE REMAINS AGREEABLE WITH THE  
LARGE SCALE PATTERN OF HIGH HEIGHTS IN THE SOUTHERN TIER AND  
SHORTWAVE IMPULSES MOVING THROUGH THE QUASI-ZONAL JET STREAM IN  
THE NORTHERN TIER THROUGH THE MIDDLE OF NEXT WEEK. GUIDANCE VARIES  
SOMEWHAT WITH THE SMALL-SCALE DETAILS OF INDIVIDUAL SHORTWAVES,  
WHICH CAN AFFECT FRONTAL AND RAINFALL PLACEMENT, BUT NOTHING TOO  
EGREGIOUS FOR THE MEDIUM RANGE TIME FRAME. THE EARLY PART OF THE  
FORECAST PERIOD WAS BASED ON A BLEND OF THE 00/06Z DETERMINISTIC  
MODELS AS THEY SHOWED GOOD OVERALL AGREEMENT.  
 
THE PATTERN LOOKS TO TRANSITION TO SLIGHTLY MORE AMPLIFIED BY  
LATER IN THE WEEK AS RIDGING BUILDS IN THE NORTHWEST, AND  
MEANWHILE ENERGY COULD CONSOLIDATE AROUND MIDWEEK TO STRENGTHEN AN  
UPPER LOW CENTERED IN SOUTH-CENTRAL CANADA, WITH TROUGHING  
STEMMING INTO THE NORTHERN HALF OF THE PLAINS AND SHIFTING  
EASTWARD THROUGH THE LATTER PART OF THE WORKWEEK. THE 00Z UKMET  
WAS SLIGHTLY WEAKER THAN CONSENSUS WITH LOW/TROUGH FEATURE BY DAY  
5/WED. 00/06Z GFS RUNS SHOW THE UPPER LOW TRACKING EAST JUST A BIT  
MORE QUICKLY THAN THE 00Z ECMWF BY THURSDAY-FRIDAY, THOUGH STILL  
WITHIN REASON, BUT THE 12Z GFS AND ECMWF HAVE CONVERGED EVEN A BIT  
MORE WITH THE GFS SLOWING DOWN AND THE ECMWF SPEEDING UP A BIT.  
THE WPC FORECAST WAS ABLE TO MAINTAIN OVER HALF DETERMINISTIC  
GUIDANCE IN THE FORECAST BLEND THROUGH THE PERIOD, THOUGH WITH  
SOME INCLUSION OF THE GEFS AND EC ENSEMBLE MEANS. THIS MAINTAINED  
GOOD CONTINUITY WITH PREVIOUS WPC FORECASTS, WITH JUST SOME  
TYPICAL SLIGHT SHIFTS IN FRONTAL PLACEMENT BASED ON THE NEWER  
GUIDANCE.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE MAIN WEATHER HAZARD WILL BE THE PROLONGED EXCESSIVE HEAT  
ACROSS ESPECIALLY THE SOUTHERN HALF OF THE PLAINS AND MISSISSIPPI  
VALLEY 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 U.S. SHOULD ALSO START THE WEEK WARM AND  
ABOVE NORMAL, BUT A COLD FRONT PASSING THROUGH NEXT MONDAY-TUESDAY  
SHOULD BRING SOME RELIEF TO THE HEAT IN THE EAST. THEN 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. 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 WILL  
SPREAD RAIN AND STORMS TO THE NORTHEAST AND MID-ATLANTIC, WHILE  
THE FRONT FARTHER WEST LOOKS TO BECOME QUASI-STATIONARY AND MAY  
INITIALLY FAVOR HIGHEST RAINFALL TOTALS OVER THE MIDWEST AND OHIO  
VALLEY. SLIGHT RISKS WERE PLACED ON BOTH THE DAY 4 AND 5  
EXPERIMENTAL EROS ACROSS EASTERN KENTUCKY/TENNESSEE AND INTO WEST  
VIRGINIA AND WESTERN 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 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. MEANWHILE, 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 10-20F OR SO  
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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL/SOUTHERN PLAINS, THE  
CENTRAL/SOUTHERN ROCKIES, THE  
CENTRAL GREAT BASIN, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI  
VALLEY, THE CENTRAL/SOUTHERN  
APPALACHIANS, THE OHIO VALLEY, AND THE SOUTHWEST, MON-THU, JUL  
25-JUL 28.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN  
PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF CALIFORNIA, THE CENTRAL GREAT  
BASIN, THE PACIFIC NORTHWEST, THE  
NORTHERN ROCKIES, AND THE NORTHERN GREAT BASIN, MON-FRI, JUL  
25-JUL 29.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL/SOUTHERN PLAINS,  
THE LOWER/MIDDLE MISSISSIPPI  
VALLEY, THE TENNESSEE VALLEY, AND THE SOUTHEAST, MON-THU, JUL  
25-JUL 28.  
 
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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