059  
FXUS02 KWBC 102136  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
534 PM EDT TUE MAY 10 2022  
 
VALID 12Z FRI MAY 13 2022 - 12Z TUE MAY 17 2022  
 
...LINGERING BLOCKY PATTERN TO EXTEND RECORD HEAT FROM THE  
SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY TO THE MIDWEST/NORTHEAST  
LATE WEEK ALONG WITH EPISODES OF CENTRAL U.S. CONVECTION AND AN  
EMERGING ONSHORE RAINFALL FOCUS TO THE CAROLINAS...  
...DEVELOPING HEAT THREAT FOR CALIFORNIA AND THE SOUTHWEST FROM  
THE WEEKEND INTO NEXT WEEK WHILE HEAT PERSISTS EASTWARD OVER FAR  
SOUTHERN TIER AREAS...  
 
   
..OVERVIEW
 
 
THE BLOCKY LARGE SCALE PATTERN OVER THE SHORT RANGE PERIOD WILL  
PERSIST THROUGH THE EARLY MEDIUM RANGE PERIOD WITH AN UPPER LOW  
RETROGRADING OVER THE SOUTHEASTERN U.S. WITH RIDGING ATOP THE LOW,  
WHILE UPPER TROUGHING ACROSS THE WESTERN U.S. GRADUALLY GIVES WAY  
TO HIGHER HEIGHTS. THE PATTERN SHOULD TRANSITION TOWARD AN EASTERN  
PACIFIC TROUGH, WESTERN U.S. INTO HIGH PLAINS RIDGE, AND EASTERN  
U.S. TROUGH EARLY NEXT WEEK. A BROAD AREA OF MUCH ABOVE NORMAL  
TEMPERATURES INTO LATE THIS WEEK FROM THE SOUTHERN PLAINS INTO  
GREAT LAKES/NORTHEAST, WITH NUMEROUS DAILY RECORDS POSSIBLE, WILL  
EVENTUALLY MODERATE OVER THE NORTHERN TWO-THIRDS OF THE COUNTRY AS  
A WAVY FRONT OVER THE PLAINS (A POSSIBLE FOCUS FOR AT LEAST SOME  
LOCALLY HEAVY RAINFALL) PUSHES FARTHER EASTWARD AHEAD OF THE  
APPROACHING TROUGH. MEANWHILE AN UPPER LOW REACHING THE SOUTHEAST  
BY FRIDAY WILL QUICKLY OPEN UP AS IT LIFTS NORTHWARD, SPREADING  
RAINFALL INTO AND NORTH FROM THE CAROLINAS. THE UPPER RIDGE  
BUILDING INTO/THROUGH THE WEST WILL MODERATE INITIALLY CHILLY  
TEMPERATURES OVER THE NORTHWEST WHILE BRINGING A PERIOD OF VERY  
WARM TO HOT WEATHER ACROSS THE SOUTHERN HALF OF THE WEST SATURDAY  
ONWARD, CONNECTING WITH THE HEAT EXPECTED TO PERSIST OVER AND NEAR  
THE SOUTHERN PLAINS. HIGHS MAY CHALLENGE DAILY RECORDS OVER SOME  
LOCATIONS ACROSS THESE AREAS.  
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
RECENT GUIDANCE CONTINUES TO SHOW REASONABLY GOOD AGREEMENT WITH  
THE OVERALL PATTERN DESCRIBED ABOVE, BUT WITH LINGERING  
DIFFERENCES IN THE SMALLER SCALE DETAILS. ONE SUCH SMALLER-SCALE  
FEATURE IS A SHORTWAVE LOCATED OVER THE PACIFIC NORTHWEST EARLY  
FRIDAY THAT TRACKS EASTWARD TO POTENTIALLY JOIN OR AT LEAST  
INTERACT WITH A SMALL UPPER LOW FORMING OVER SOUTH-CENTRAL CANADA  
NEAR THE U.S. BORDER BY SATURDAY. EVEN FOR THE END OF THIS WEEK,  
THE SHORTWAVE VARIATIONS LEAD TO DIFFERENCES IN THE QPF OVER THE  
PACIFIC NORTHWEST (WHICH THIS UPDATED FORECAST TRENDED A BIT  
HEAVIER WITH) AND A SURFACE LOW PRESSURE SYSTEM. THE 00Z CMC  
ESPECIALLY AND TO SOME EXTENT THE UKMET CONTINUED TO BE A BIT  
DEEPER WITH THE SHORTWAVE FEATURE THAN THE GFS AND ECMWF RUNS AND  
THE BULK OF ENSEMBLE MEMBERS. GOING FORWARD INTO EARLY NEXT WEEK,  
THE DEPTH OF THE 00Z CMC LEADS TO A FARTHER SOUTH AND SLOWER UPPER  
LOW. THE NEWER 12Z CMC SEEMS TO BE TRENDING SOMEWHAT CLOSER TO  
CONSENSUS.  
 
OTHER ASPECTS OF THE FORECAST AGREE FAIRLY WELL IN PRINCIPLE AS AN  
UPPER HIGH GROWS ITS RIDGING INFLUENCE ACROSS PARTS OF THE  
SOUTHWESTERN AND SOUTH-CENTRAL U.S. EARLY NEXT WEEK, WHILE  
TROUGHING IS LIKELY ACROSS THE NORTHWEST THOUGH AGAIN WITH SOME  
DETAIL DIFFERENCES. THUS THE WPC FORECAST BEGAN WITH A BLEND OF  
THE (LATEST AVAILABLE) 00Z ECMWF AND 00Z/06Z DETERMINISTIC GFS  
RUNS WITH SMALLER PORTIONS OF THE 00Z UKMET AND CMC, PHASING OUT  
THE LATTER MODELS AS THE PERIOD PROGRESSED IN FAVOR OF THE GEFS  
AND EC ENSEMBLE MEANS.  
   
..WEATHER/THREAT HIGHLIGHTS
 
 
WITHIN THE BROAD AREA OF ABOVE NORMAL TEMPERATURES FROM THE  
SOUTHERN PLAINS THROUGH GREAT LAKES AND NORTHEAST ON FRIDAY, THE  
BEST POTENTIAL FOR SOME DAILY RECORDS WILL BE ACROSS THE SOUTHERN  
TIER AND GREAT LAKES/NORTHEAST. HIGHEST ANOMALIES OF PLUS 10-20F  
OR SLIGHTLY HIGHER SHOULD BE ACROSS NORTHERN AREAS FROM FRIDAY  
INTO THE WEEKEND. MEANWHILE POTENTIAL RECORD HEAT COULD PERSIST  
OVER/NEAR EASTERN TEXAS INTO NEXT WEEK, AND MAY EXPAND OVER MORE  
OF THE SOUTHERN PLAINS/SOUTH EARLY NEXT WEEK, WITH TEMPERATURES  
WELL INTO THE 90S AND 100S IN SOME AREAS.  
 
THE RIDGE BUILDING OVER THE WEST WILL LEAD TO A PRONOUNCED WARMING  
TREND DURING THE WEEKEND, WITH BROAD COVERAGE OF HIGHS 10-15F  
ABOVE NORMAL OVER THE SOUTHERN HALF OF THE REGION ON SATURDAY INTO  
SUNDAY AND PERSISTING INTO TUESDAY. THIS HEAT COULD CHALLENGE  
DAILY RECORD HIGHS OVER SOME SOUTHERN AREAS AND ULTIMATELY  
INCREASE TEMPERATURES OVER THE SOUTHERN PLAINS ONCE AGAIN NEXT  
WEEK. THE PACIFIC NORTHWEST AND NORTHERN ROCKIES WILL BE CHILLY ON  
FRIDAY WITH HIGHS 5-15F BELOW NORMAL, FOLLOWED BY SOME MODERATION.  
SHORTWAVES EJECTING FROM THE EASTERN PACIFIC UPPER TROUGH AND  
ASSOCIATED SURFACE FRONTS MAY PRODUCE MULTIPLE EPISODES OF  
PRECIPITATION OVER THE NORTHWEST. SOME OF THIS ACTIVITY COULD BE  
LOCALLY MODERATE/HEAVY DEPENDING ON EXACT DETAILS THAT HAVE LOW  
PREDICTABILITY AT THIS TIME.  
 
MOISTURE STREAMING IN AHEAD OF A COUPLE OF FRONTAL SYSTEMS COULD  
BRING MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS OVER OR JUST  
WEST OF THE MISSISSIPPI VALLEY LATE THIS WEEK. THE FRONTS SHOULD  
CONSOLIDATE AND BECOME MORE PROGRESSIVE AS UPPER TROUGHING HEADS  
TOWARD AND INTO THE EAST. SOME RAINFALL ALONG THE FRONT COULD  
STILL BE FAIRLY INTENSE BUT THE GREATER PROGRESSION MAY TEMPER  
MAXIMUM TOTALS OVER THE EAST. THE TRAILING PART OF THE FRONT  
SHOULD STALL AND MAY LIFT BACK AS A WARM FRONT EARLY NEXT WEEK,  
POTENTIALLY SERVING AS A FOCUS FOR SOME CONVECTION. THE SOUTHEAST  
UPPER LOW THAT QUICKLY OPENS UP FRIDAY INTO SATURDAY WILL SPREAD  
AN AREA OF RAIN INTO THE CAROLINAS AND AREAS TO THE NORTH. SOME  
LOCALIZED ENHANCEMENT WILL BE POSSIBLE OVER THE CAROLINAS/VIRGINIA  
BUT RAPID OPENING OF THE UPPER LOW SHOULD TEND TO DECREASE THE  
FOCUS OF MOISTURE FARTHER NORTHWARD.  
 
TATE/RAUSCH  
 
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:  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE UPPER MISSISSIPPI  
VALLEY AND THE NORTHERN PLAINS.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE MIDDLE MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, THE  
UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY  
AND THE NORTHERN PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF CALIFORNIA, SAT-MON, MAY  
14-MAY 16.  
- EXCESSIVE HEAT ACROSS PORTIONS OF CALIFORNIA AND THE SOUTHWEST,  
SUN-TUE, MAY 15-MAY 17.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE  
SOUTHERN PLAINS, FRI-TUE, MAY 13-MAY 17.  
- MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE GREAT  
LAKES, THE MID-ATLANTIC, THE NORTHEAST, THE CENTRAL APPALACHIANS,  
AND THE UPPER MISSISSIPPI VALLEY, FRI-SAT, MAY 13-MAY 14.  
 
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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