505  
FXUS02 KWBC 041550  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1149 AM EDT MON JUN 04 2018  
 
VALID 12Z THU JUN 07 2018 - 12Z MON JUN 11 2018  
 
...HEAT TO CONTINUE FOR THE DESERT SOUTHWEST TO THE SOUTH-CENTRAL  
U.S...  
 
   
..PATTERN OVERVIEW
 
 
UPPER RIDGING IS FORECAST TO REMAIN ANCHORED OVER THE SOUTHERN  
PLAINS LATE THIS WEEK INTO NEXT WEEK WITH TROUGHING ON EITHER SIDE  
OF THE CONUS. THIS WILL MAINTAIN WELL ABOVE AVERAGE TEMPERATURES  
FOR THE SOUTHWEST AND SOUTHERN PLAINS (WIDESPREAD 100S) WITH DAILY  
RECORD MAX TEMPERATURES LIKELY FOR SOME AREAS. A SIGNIFICANT  
TROUGH WILL ATTEMPT TO PUSH INTO THE PACIFIC NORTHWEST LATE IN THE  
PERIOD WHICH WILL INTRODUCE COOLER THAN AVERAGE TEMPERATURES TO AT  
LEAST WASHINGTON/OREGON. THE NORTH CENTRAL AND EASTERN PORTIONS OF  
THE LOWER 48 STAND THE BEST CHANCE OF RAIN ALONG A WAVY FRONTAL  
BOUNDARY AS AREAS OF LOW PRESSURE EXIT THE EAST.  
 
   
..MODEL GUIDANCE/PREDICTABILITY EVALUATION/PREFERENCES
 
 
THE RECENT GFS/ECMWF RUNS PAIRED WELL WITH THE ENSEMBLE MEANS WITH  
THE WELL-FORECAST LONGWAVE PATTERN. DIFFERENCES EXPANDED SOUTH OF  
THE GULF OF ALASKA WITH THE INCOMING TROUGH NEXT WEEK BUT A BLEND  
AMONG THE MODELS/ENSEMBLES OFFERED A GOOD STARTING POINT.  
ELSEWHERE, THE UKMET/CANADIAN OFFERED SOME CORROBORATION TO THE  
GFS/ECMWF TO START BUT OTHERWISE DEPARTED FROM THAT CONSENSUS BY  
ABOUT FRIDAY. SMALLER SCALE UNCERTAINTIES EXIST WITHIN THE PATTERN  
BUT MOST ARE UNRESOLVABLE AT THIS LEAD TIME (E.G. "RIDGE ROLLERS"  
THROUGH THE PLAINS).  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
THE HEAT WAVE WILL BE THE MAIN STORY WITH READINGS 100 DEGREES  
PLUS ANYWHERE FROM THE DESERT SOUTHWEST EASTWARD ALONG THE MEXICAN  
BORDER INTO THE STATE OF TEXAS. DEPARTURES FROM CLIMATOLOGY SHOULD  
BE AROUND 10 DEGREES ALTHOUGH SLIGHTLY HIGHER NUMBERS CAN BE FOUND  
FARTHER NORTH INTO THE REMAINING GREAT PLAINS STATES AND INTO THE  
INTERMOUNTAIN WEST/ROCKY MOUNTAIN CHAIN. WIDESPREAD 80S AND 90S  
ARE LIKELY OVER THESE LOCATIONS (+10 TO +15F ANOMALIES). REGARDING  
COOL SPOTS, THURSDAY SHOULD PROVE TO BE NEAR OR SLIGHTLY BELOW  
CLIMATOLOGY ACROSS THE EAST COAST WITH SUCH CONDITIONS PERSISTING  
INTO THE WEEKEND ACROSS FLORIDA GIVEN IMMENSE CLOUD COVER AND  
RAINFALL. ELSEWHERE, DEEP UPPER TROUGHING OVER THE PACIFIC  
NORTHWEST WILL HOLD TEMPERATURES AROUND 5 TO 10 DEGREES BELOW  
AVERAGE FROM SATURDAY ONWARD.  
 
IT SHOULD REMAIN INTERMITTENTLY WET OVER THE SOUTHEASTERN U.S.,  
PARTICULARLY FLORIDA, GIVEN A STAGNANT UPPER TROUGH/WEAKNESS IN  
CONJUNCTION WITH AN ANOMALOUS MOISTURE FEED. BACK TOWARD THE  
MIDDLE OF THE COUNTRY, MULTIPLE CONVECTIVE COMPLEXES ARE LIKELY TO  
ERUPT NORTH OF THE RIDGE WITH PROPAGATION DOWNSTREAM TOWARD THE  
MID-MISSISSIPPI VALLEY AND INTO THE GREAT LAKES/OHIO VALLEY. SPC  
HAS HIGHLIGHTED THE NORTHERN PLAINS ON THURSDAY FOR SOME ORGANIZED  
SEVERE WEATHER BUT BOUTS OF HEAVY RAINFALL WILL PERSIST INTO NEXT  
WEEK. ELSEWHERE, IT SHOULD PROVE TO BE QUITE WET OVER THE PACIFIC  
NORTHWEST GIVEN THE DEEP CYCLONIC FLOW OVERHEAD. STRONG FORCING  
WITH THE TROUGH AND EVENTUAL FRONTAL PASSAGE COULD SPREAD  
CONSIDERABLE EARLY/MID-JUNE PRECIPITATION TO THE REGION.  
 
FRACASSO/RUBIN-OSTER  
 
WPC MEDIUM RANGE FORECASTS OF 500 MB HEIGHTS, SURFACE SYSTEMS,  
WEATHER GRIDS, QUANTITATIVE PRECIPITATION, AND WINTER WEATHER  
OUTLOOK PROBABILITIES CAN BE FOUND AT:  
 
HTTP://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTP://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTP://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTP://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTP://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
 

 
 
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