243  
FXUS02 KWBC 230700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM 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 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 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) WHICH SHOULD LAST INTO NEXT WEEKEND. AN  
INITIAL SURFACE FRONT DRAPED FROM THE MID-ATLANTIC TO THE CENTRAL  
PLAINS WILL BECOME QUASI-STATIONARY EARLY NEXT WEEK BEFORE  
EVENTUALLY LIFTING NORTH AS A WARM FRONT AHEAD OF THE NEXT COLD  
FRONT APPROACHING AROUND THURSDAY WHICH MAY AGAIN SETTLE ACROSS  
PARTS OF THE MID-SOUTH BY NEXT WEEKEND. THESE BOUNDARIES 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  
TUESDAY ONWARD 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, AS ANOTHER  
TROUGH DIGS ACROSS THE NORTHERN PLAINS/GREAT LAKES AND INTO THE  
MIDWEST/NORTHEAST NEXT FRIDAY-SATURDAY. ITS WITHIN THESE  
SHORTWAVES WHERE THE GUIDANCE DIFFERS ON SOME OF THE SMALLER SCALE  
DETAILS. LARGER DIFFERENCES COME INTO PLAY BY DAY 6-7 CONCERNING A  
CLOSED LOW NEAR/OVER HUDSON BAY, AND ADDITIONAL ENERGY DROPPING  
DOWN THE WEST SIDE OF THE TROUGH INTO CENTRAL CANADA AND POSSIBLY  
THE FAR NORTHERN U.S. TIER NEXT WEEKEND. THE CMC SEEMS TO BE AN  
OUTLIER IN SHOWING A SECOND CLOSED LOW INTO CENTRAL CANADA, WITH  
WEAKER TROUGHING INTO THE NORTHEAST NEXT SATURDAY. THE ENSEMBLES  
AND ECMWF AND GFS SUGGEST A MUCH WEAKER SECONDARY WAVE WITH MORE  
AMPLIFIED TROUGHING ACROSS THE NORTHEAST. AS SUCH, THE CMC WAS  
EXCLUDED FROM THE MODEL BLEND BEYOND DAY 5.  
 
THE WPC FORECAST FOR TONIGHT USED A COMPOSITE BLEND OF THE LATEST  
DETERMINISTIC RUNS FOR DAYS 3-5, AMIDST GOOD MODEL AGREEMENT.  
AFTER THIS, THE ECMWF AND GFS WERE BLENDED WITH THE ENSEMBLE MEANS  
TO HELP MITIGATE SOME OF THE SMALLER SCALE DIFFERENCES. THIS  
MAINTAINS GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST.  
   
..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. WIDESPREAD TEMPERATURES NEAR OR  
ABOVE 100 DEGREES (WITH HIGHER HEAT INDICES) WILL CONTINUE THE  
DANGEROUS HEATWAVE IN THIS REGION. 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/MIDWEST, AND NORTHERN/CENTRAL PLAINS.  
INITIALLY, THE HIGHEST RAINFALL TOTALS SEEM FAVORED OVER/NEAR THE  
OHIO VALLEY, WHERE A SLIGHT RISK WAS MAINTAINED ON THE DAY 4  
EXPERIMENTAL ERO ACROSS EASTERN KENTUCKY/TENNESSEE AND INTO WEST  
VIRGINIA AND FAR WESTERN VIRGINIA. THE SECOND, STRONGER, 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. POTENTIAL STILL EXISTS FOR SOME OF THIS  
MOISTURE TO EVENTUALLY INTERACT WITH CENTRAL PLAINS FRONT 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, 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.  
 
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  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page