966  
FXUS02 KWBC 021900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 PM EDT SAT JUL 02 2022  
 
VALID 12Z TUE JUL 05 2022 - 12Z SAT JUL 09 2022  
   
..OVERVIEW
 
 
EXPECT A PERSISTENT UPPER LEVEL RIDGE/HIGH TO BE IN PLACE OVER THE  
SOUTHERN TIER OF THE U.S. WITH A NORTHWARD EXTENSION OF THIS RIDGE  
REACHING INTO THE ROCKIES/HIGH PLAINS, LEADING TO HOT TEMPERATURES  
ACROSS MUCH OF THE CENTRAL CONUS. THE CORE OF THE RIDGE SHOULD  
SHIFT IN EMPHASIS FROM THE LOWER HALF OF THE MISSISSIPPI VALLEY  
INTO THE FOUR CORNERS REGION AROUND FRIDAY-SATURDAY. SURROUNDING  
THE MEAN RIDGE, A RELOADING UPPER LOW/TROUGH JUST OFF THE WEST  
COAST WILL PERSIST UNTIL POSSIBLY EJECTING NORTHEASTWARD TOWARD  
THE END OF THE WEEK WHILE LEADING ENERGY SHOULD FLOW ACROSS THE  
NORTHERN TIER AND FEED INTO A BROAD MEAN TROUGH COVERING EASTERN  
CANADA AND THE NORTHEASTERN U.S. THIS FLOW PATTERN IS FAIRLY  
TYPICAL FOR SUMMER, WITH THE LARGE SCALE FEATURES JUST A LITTLE  
STRONGER THAN THE CLIMATOLOGICAL AVERAGE. A MEAN SURFACE FRONTAL  
BOUNDARY (POSSIBLY REINFORCED BY ONE OR MORE CANADIAN FRONTS)  
DRAPED FROM THE NORTH-CENTRAL PLAINS TO THE MID-ATLANTIC, COMBINED  
WITH SHORTWAVES EMBEDDED IN THE FLOW ALOFT, WILL LIKELY PRODUCE  
MULTIPLE EPISODES OF CONVECTION WITH LOCALLY HEAVY RAINFALL.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE TWO MEDIUM TO LARGER SCALE DISCREPANCIES THAT ARISE IN THE  
GUIDANCE INVOLVE UPPER LEVEL ENERGY THAT MAY LIFT NORTH-NORTHEAST  
FROM BAJA CALIFORNIA INTO THE FOUR CORNERS STATES AROUND MID-LATE  
WEEK AND THE TIMING OF EASTERN PACIFIC UPPER TROUGH EJECTION INTO  
THE PACIFIC NORTHWEST/BRITISH COLUMBIA BY AROUND NEXT SATURDAY.  
THE FIRST FEATURE WILL BE VERY IMPORTANT WITH RESPECT TO THE  
RAINFALL FORECAST OVER THE SOUTHWEST/ROCKIES AND THEN THE  
CONVECTIVE FORECAST AS THIS ENERGY BECOMES EMBEDDED IN THE  
SOUTHERN FRINGE OF THE WESTERLIES AND INTERACTS WITH THE SURFACE  
FRONT TO THE EAST OF THE ROCKIES. UNFORTUNATELY THE FEATURE IS  
SMALL ENOUGH TO HAVE FAIRLY LOW PREDICTABILITY, AND IN ADDITION  
LATEST MODELS HAVE BEEN VERY DIFFERENT AND VARIABLE. GFS RUNS HAD  
BEEN ON THE STRONG AND PROGRESSIVE SIDE OF THE SPREAD BUT THE NEW  
12Z UKMET/CMC HAVE ADJUSTED TOWARD BRINGING THIS FEATURE FARTHER  
NORTH IN SOMEWHAT MORE GFS-LIKE FASHION. THE 12Z ECMWF TRIES TO  
BRING IT NORTH BUT IS SLOW ENOUGH THAT THE ENERGY GETS DEFLECTED  
FARTHER WEST BY THE BUILDING FOUR CORNERS RIDGE. MORE ADJUSTMENTS  
ARE CERTAINLY POSSIBLE IN FUTURE RUNS. AS FOR THE TROUGH OFF THE  
WEST COAST, PREFERENCE CONTINUES TO LEAN MORE TOWARD MODERATELY  
PROGRESSIVE EJECTION AT THE END OF THE WEEK VERSUS SOME SLOWER  
RUNS OF THE GFS/GEFS MEAN. THE 00Z GFS WAS MUCH CLOSER TO  
CONSENSUS WHILE THE 06Z GFS BUILT A LOT MORE RIDGING INTO THE  
NORTH PACIFIC/ALEUTIANS AND THE NEW 12Z RUN STILL GETS FAIRLY  
EXTREME WITH ITS NORTH PACIFIC RIDGE BY NEXT SATURDAY. GIVEN  
BETTER COMPARISON OF THE GEFS MEAN WITH THE MAJORITY FOR FLATTER  
FLOW OVER THE NORTH PACIFIC, IT SEEMS THE GEFS MEAN COULD BE A  
LITTLE SLOW WITH THE TROUGH EJECTION. OTHERWISE, CONFIDENCE IS LOW  
FOR SHORTWAVE SPECIFICS AROUND THE NORTHERN PERIPHERY OF THE CONUS  
RIDGE AND INTO THE EASTERN CANADA/NORTHEAST U.S. MEAN TROUGH. THIS  
IS HIGHLIGHTED BY CURRENT AND RECENT SPREAD IN MODEL SPECIFICS,  
LEADING TO MEANINGFUL DIFFERENCES IN SURFACE FRONT/WAVE DETAILS.  
IT WILL LIKELY TAKE UNTIL THE SHORT RANGE PERIOD TO RESOLVE THESE  
DETAILS, AND EVEN THEN SOME ASPECTS OF THE FORECAST MAY HAVE VERY  
SHORT LEAD TIME GIVEN HOW CHALLENGING IT CAN BE FOR MODELS TO  
LATCH ONTO MESOSCALE FEATURES THAT WILL MATTER GREATLY FOR QPF  
PLACEMENT AND AMOUNTS. CONTINUE TO MONITOR THE FORECAST FOR  
UPDATES GOING FORWARD. BASED ON THE LATEST ARRAY OF GUIDANCE, THE  
UPDATED FORECAST INCORPORATED 00Z/06Z OPERATIONAL MODEL RUNS FOR  
ABOUT THE FIRST HALF OF THE PERIOD AND THEN ADDED IN SOME 06Z  
GEFS/00Z ECMWF MEANS (UP TO ABOUT ONE-THIRD TOTAL WEIGHT) LATE IN  
THE PERIOD. BY DAY 7 SATURDAY THE AFOREMENTIONED PREFERENCES LED  
TO TILTING GFS INPUT MORE TO THE 00Z RUN THAN THE 06Z VERSION AND  
ENSEMBLE MEAN INPUT SLIGHTLY MORE TO THE ECMWF MEAN THAN GEFS.  
 
   
..SENSIBLE WEATHER AND HAZARDS
 
 
SCATTERED SHOWERS AND STORMS ARE LIKELY ACROSS MUCH OF THE U.S. AT  
TIMES NEXT WEEK, WITH ENHANCED TOTALS IN THE VICINITY OF A COUPLE  
OF FRONTAL BOUNDARIES STRETCHING GENERALLY WEST TO EAST ACROSS THE  
NORTHERN HALF OF THE COUNTRY. NORTHWESTERLY FLOW ALOFT AND  
ABUNDANT MOISTURE AND INSTABILITY WILL CREATE A FAVORABLE PATTERN  
FOR MESOSCALE CONVECTIVE SYSTEMS AND HIGH RAINFALL RATES WITHIN A  
BROAD AREA FROM THE NORTHERN PLAINS/MIDWEST/UPPER GREAT LAKES INTO  
THE OHIO VALLEY AND APPALACHIANS TO THE EAST COAST. THERE IS A  
SLIGHT RISK IN THE DAY 4 WPC EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK IN THE CENTRAL APPALACHIANS WHERE THERE IS SOME SIGNAL FOR  
THIS ACTIVITY COULD FOCUS AND GREATER SENSITIVITY TO HEAVY  
RAINFALL EXISTS. SOME ENHANCED RAINFALL COULD OCCUR FARTHER  
NORTHWEST OF THIS AREA AS WELL AS OVER PARTS OF THE NORTHEAST BUT  
WITH LESSER CONFIDENCE IN DETAILS. RAINFALL THAT COULD BE  
SUFFICIENTLY HEAVY TO CAUSE FLASH FLOODING MAY PERSIST BEYOND THE  
DAY 4 TIME FRAME BUT WITH CONSIDERABLE UNCERTAINTY IN THE  
PLACEMENT OF HEAVY RAIN AMOUNTS. SCATTERED THUNDERSTORMS ARE ALSO  
LIKELY IN THE SOUTHEAST THROUGH THE WEEK, AND SOME ADDITIONAL  
MID-ATLANTIC TO NORTHEAST RAIN EVENTS ARE POSSIBLE AS WELL  
DEPENDING ON FRONTAL POSITIONS. MEANWHILE MONSOONAL MOISTURE COULD  
PERSIST THROUGH MUCH OF THE WEEK WITH MOIST SOUTHWESTERLY  
FLOW/EMBEDDED SHORTWAVES LEADING TO MAINLY DIURNALLY DRIVEN  
SHOWERS AND STORMS OVER THE FOUR CORNERS STATES. THE SOUTHERN  
PLAINS AND DESERT SOUTHWEST/GREAT BASIN SHOULD BE THE MOST  
CONSISTENTLY DRY AREAS DURING THE PERIOD.  
 
THE GREATEST CONCERN FOR TEMPERATURES IS WITH THE HEAT EXPECTED TO  
BUILD ACROSS THE CENTRAL U.S. IN RESPONSE TO A STRENGTHENING UPPER  
LEVEL RIDGE. HIGHS OF 10-15 DEGREES ABOVE NORMAL ARE LIKELY OVER  
THE CENTRAL PLAINS TO MIDDLE MISSISSIPPI VALLEY AT LEAST DURING  
TUESDAY-THURSDAY, EQUATING TO TEMPERATURES IN THE MID 90S TO LOW  
100S. A SOUTHWARD-DRIFTING SURFACE FRONT AND ASSOCIATED CONVECTION  
COULD ERODE THIS HEAT SOMEWHAT TOWARD THE END OF THE WEEK. HOWEVER  
WARMER THAN AVERAGE TEMPERATURES SHOULD BUILD INTO THE NORTHERN  
ROCKIES/HIGH PLAINS LATE IN THE WEEK, LEADING TO SOME HOT READINGS  
OF UP TO 10-15F ABOVE NORMAL BY NEXT SATURDAY. SOUTHERN PLAINS  
LOCATIONS WILL SEE HOT TEMPERATURES THROUGH THE PERIOD BUT WITH  
LESS EXTREME ANOMALIES. MEANWHILE THE WEST WILL SEE COOLER THAN  
NORMAL HIGHS THROUGH AT LEAST MIDWEEK DUE TO THE INITIAL EASTERN  
PACIFIC UPPER TROUGH AND LEADING MOISTURE OVER THE FOUR CORNERS  
STATES. THEN TEMPERATURES SHOULD MODERATE CLOSER TO NORMAL, AND  
EVEN ABOVE NORMAL IN THE DESERT SOUTHWEST AND CALIFORNIA BY  
FRIDAY-SATURDAY. THE EAST IS LIKELY TO BE NEAR AVERAGE  
TEMPERATURE-WISE.  
 
RAUSCH/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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