911  
FXUS02 KWBC 281854  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
253 PM EDT THU JUL 28 2022  
 
VALID 12Z SUN JUL 31 2022 - 12Z THU AUG 04 2022  
 
...DANGEROUS HEAT WAVE OVER THE NORTHWEST/GREAT BASIN PERSISTS  
THROUGH SUNDAY BEFORE THE HEAT SHIFTS EAST ACROSS THE NORTHERN  
TIER STATES NEXT WEEK...  
 
...EXCESSIVE RAIN THREAT FROM THE TENNESSEE VALLEY INTO THE  
SOUTHERN MID-ATLANTIC INTO MONDAY, WITH CONTINUED MONSOONAL  
FLOODING IN THE SOUTHWEST...  
 
   
..OVERVIEW
 
 
THE UPPER LEVEL PATTERN BY LATE SUNDAY WILL BE A RIDGE CENTERED  
OVER THE INTERMOUNTAIN WEST, AN UPPER LOW OFF OREGON, AND BROAD  
TROUGHING OVER THE GREAT LAKES SOUTH OF A LARGE GYRE OVER THE  
NORTHERN HUDSON BAY. THIS PATTERN WILL SLOWLY SHIFT EAST THROUGH  
NEXT WEEK (WITH THE PACNW LOW EVENTUALLY OPENING AND EJECTING  
EAST) AS THE HUDSON BAY GYRE REMAINS IN PLACE. HEAT UNDER THE  
UPPER RIDGE AXIS WILL SHIFT EAST (THOUGH TIMING IS UNCERTAIN)  
ENDING THE DANGEROUS HEAT WAVE IN THE NORTHWEST, BUT RESULT IN HOT  
DAYS ACROSS THE NORTHERN STATES THROUGH NEXT WEEK. ONGOING  
EXCESSIVE RAIN THREATS FROM THE TENNESSEE VALLEY TO THE SOUTHERN  
MID-ATLANTIC WILL PERSIST INTO MONDAY ALONG A WARM FRONT BEFORE IT  
LIFTS NORTH. THE PIVOTING UPPER RIDGE OUT WEST WILL MAINTAIN THE  
SOUTHWEST MONSOON THROUGH THE MIDDLE OF NEXT WEEK WITH DAILY  
LOCALIZED FLOODING CONCERNS.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
WHILE THE OVERALL FLOW PATTERN IS IN GOOD AGREEMENT, UNCERTAINTY  
REMAINS WITH THE MOVEMENT OF AN UPPER LOW THAT DEVELOPS WELL OFF  
THE PACNW COAST WEST TOMORROW. THE GFS REMAINS THE MOST  
PROGRESSIVE, BRINGING THE LOW TO THE OREGON COAST SUNDAY NIGHT.  
THIS WAS IN SOMEWHAT AGREEMENT WITH THE 00Z UKMET. HOWEVER, THE  
PARTICULARLY STRONG RIDGE OVER THE NORTH-CENTRAL PACIFIC (600DM  
HEIGHTS ON DAY 4) AND THE RIDGE OVER THE INTERMOUNTAIN WEST FAVOR  
KEEPING THE LOW OFFSHORE WHICH HAS BEEN FEATURED BY THE EC/CMC FOR  
A FEW DAYS. THE 12Z GFS/UKMET CONTINUE A SLOWER TREND, OFFERING  
CREDENCE TO A MODEL PREFERENCE TOWARD THE EC/CMC CAMP WITH THIS  
FEATURE. THE KEY WITH THE TIMING OF THIS TROUGH IS THE TIMING OF  
THE HEAT WAVE CESSATION OVER THE INLAND NORTHWEST (AND THE TIMING  
OF THE HEAT MAX FARTHER EAST). HOWEVER, THE 00Z (AND NOW 12Z) EC  
KEEPS THE LOW OFFSHORE INTO WEDNESDAY WHICH BECOMES A SLOW OUTLIER  
BY DAY 5. OVERALL, TROUGHING IS LIKELY TO PERSIST ALONG THE PACNW  
COAST INTO THE MIDDLE OF NEXT WEEK, EVEN IF IT IS A REINFORCING  
TROUGH, NOT JUST ONE UPPER LOW. A GENERAL BLEND OF THE  
DETERMINISTIC GUIDANCE FAVORING THE EC/CMC WAS USED FOR DAYS 3/4,  
THEN MORE OF A GENERAL MODEL BLEND WITH INCREASING INCORPORATION  
OF THE 06Z GEFS/00Z ECENS MEANS WAS USED FOR DAYS 5-7.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE HEAT WAVE IN THE NORTHWEST/GREAT BASIN CONTINUES THROUGH  
SUNDAY NIGHT WITH THE HEAT AXIS SHIFTING EAST AHEAD OF AN UPPER  
TROUGH APPROACHING THE PACIFIC NORTHWEST MONDAY. HOWEVER, THIS  
RELIEF MAY BE DELAYED AS LATEST INDICATIONS ARE THAT THE UPPER  
TROUGH MAY BE DELAYED. EVENTUALLY, THE ANOMALOUS HEAT SHIFTS EAST  
EAST ACROSS THE NORTHERN AND CENTRAL PLAINS THROUGH THE FIRST HALF  
OF NEXT WEEK WHERE DAYTIME HIGHS COULD ONCE AGAIN APPROACH OR  
EXCEED 100F. TEMPERATURES SHOULD ALSO BE ON THE RISE FROM THE OHIO  
VALLEY INTO THE NORTHEAST AS HEIGHTS BEGIN TO BUILD THROUGH THE  
MIDDLE OF NEXT WEEK. MEANWHILE, SLIGHTLY ABOVE NORMAL HEAT AND  
HUMIDITY CONTINUES SOUTH OF A FRONTAL SYSTEM OVER THE MID-SECTION,  
CONTINUING THE RECORD HOT SUMMER FOR MUCH OF THE SOUTHERN PLAINS  
AND SOUTHEAST THROUGH THE NEXT WEEK.  
 
A QUASI-STATIONARY BOUNDARY REMAINING OVER THE MID-SOUTH TO THE  
SOUTHERN MID-ATLANTIC BY SUNDAY MORNING BEFORE LIFTING NORTH AS A  
WARM FRONT LATER SUNDAY. HOWEVER, HEAVY RAIN REMAINS A THREAT FROM  
PARTS OF THE TENNESSEE VALLEY INTO THE SOUTHERN MID-ATLANTIC WHERE  
SLIGHT RISKS OF EXCESSIVE RAIN REMAIN FOR DAY 4. THE THREAT FOR  
CONTINUED RAIN OVER THE GREATLY IMPACTED TENNESSEE VALLEY AND  
WESTERN SLOPES OF THE SOUTHERN APPALACHIANS INTO MONDAY WARRANTS  
ANOTHER SLIGHT RISK FOR DAY 5. THERE IS POTENTIAL FOR AN UPGRADE  
TO THE FLASH FLOOD RISK ESPECIALLY FOR PARTS OF THE TENNESSEE  
VALLEY AND SOUTH-CENTRAL APPALACHIANS PARTICULARLY FOR SUNDAY  
AFTER GREAT IMPACTS ALREADY AND CONTINUED HEAVY RAIN THREATS IN  
THE SHORT RANGE. PERSISTENT MONSOONAL MOISTURE WILL CONTINUE TO  
SUPPORT DIURNALLY FAVORED HEAVY SHOWERS/STORMS WITH LOCALLY  
EXCESSIVE RAINFALL OVER AN ALREADY VERY SOGGY SOUTHWEST THROUGH  
THE MIDDLE OF NEXT WEEK. A PROGRESSIVE COLD FRONT THROUGH THE  
GREAT LAKES ON SUNDAY MAY BRING SOME MODERATE TO LOCALLY HEAVY  
SHOWERS AS WELL.  
 
JACKSON  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE CENTRAL GREAT BASIN,  
THE SOUTHERN ROCKIES, THE SOUTHERN PLAINS, AND THE SOUTHWEST,  
SUN-THU, JUL 31-AUG 4.  
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE  
CENTRAL APPALACHIANS, THE  
TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC,  
THE SOUTHERN APPALACHIANS, THE  
SOUTHEAST, AND THE OHIO VALLEY, SUN, JUL 31.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS, THE  
CENTRAL APPALACHIANS, THE OHIO  
VALLEY, AND THE TENNESSEE VALLEY, MON, AUG 1.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS,  
THE MID-ATLANTIC, THE CENTRAL  
APPALACHIANS, THE OHIO VALLEY, AND THE TENNESSEE VALLEY.  
- FLOODING OCCURRING OR IMMINENT 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, SUN, JUL 31.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHEAST, THE  
MID-ATLANTIC, THE LOWER MISSISSIPPI VALLEY,  
THE SOUTHERN PLAINS, AND THE TENNESSEE VALLEY, SUN-THU, JUL 31-AUG  
4.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN  
PLAINS, THE TENNESSEE VALLEY, THE GREAT LAKES, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI  
VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY, MON-THU, AUG  
1-AUG 4.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS, THE UPPER  
MISSISSIPPI VALLEY, THE MIDDLE  
MISSISSIPPI VALLEY, THE NORTHERN PLAINS, AND THE NORTHERN ROCKIES,  
MON-WED, AUG 1-AUG 3.  
 
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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