269  
FXUS02 KWBC 021601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT SAT JUN 02 2018  
 
VALID 12Z TUE JUN 05 2018 - 12Z SAT JUN 09 2018  
   
..HEAT WAVE FROM THE DESERT SOUTHWEST TO THE SOUTH-CENTRAL U.S
 
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY EVALUATION
 
 
MODEL AND ENSEMBLE GUIDANCE OFFER A SIMILAR AND PERSISTENT LARGER  
SCALE PATTERN OVER THE NATION AS HIGHLIGHTED ALOFT BY SIGNIFICANT  
MEAN TROUGHS OFF THE NORTHWESTERN U.S. AND DOWNSTREAM OVER THE  
EAST THAT SANDWICH AN AMPLIFIED/HOT SOUTHWEST/S-CENTRAL US RIDGE.  
RECENT GUIDANCE HAS TRENDED A BIT TOWARD A BIT MORE AMPLITUDE AND  
PATTERN LONGEVITY. THIS TREND SEEMS REASONABLE. THE DEPICTION AND  
INTERACTIONS OF A MULTITUDE OF MID-SMALLER SCALE SYSTEMS EMBEDDED  
WITH THE FLOW HOWEVER IS PROVING TO BE QUITE PROBLEMATIC DAYS 3-7  
AND FORECAST UNCERTAINTY WITH THESE IS PRODUCING SIGNIFICANT RUN  
TO RUN MODEL ISSUES. THIS IS PARTICULARLY EVIDENT WITH  
DISTURBANCES TRACKING ACROSS THE NORTHERN TIER OF THE U.S. AROUND  
THE NORTHERN PERIPHERY OF THE UPPER RIDGE AND INTO THE EASTERN US  
MEAN TROUGH POSITION. THESE DISTURBANCES AND ASSOCIATED HEIGHT  
FALLS WILL BECOME A LOCAL FOCUS FOR POTENTIALLY HEAVY RAINFALL.  
 
OVERALL, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED  
FROM A COMPOSITE BLEND OF THE 00 UTC GFS/ECMWF AND 00 UTC  
GEFS/NAEFS/ECMWF ENSEMBLE MEANS. 00 UTC GUIDANCE SEEMED TO CLUSTER  
BEST OVERALL AND MAINTAIN MAX CONTINUITY IN THIS PATTERN.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
PRECIPITATION CAN BE EXPECTED FROM THE NORTH-CENTRAL STATES TO NEW  
ENGLAND WITH THE UPPER LOW AND TROUGH, ALONG WITH A SURFACE LOW  
DEVELOPING OFFSHORE. ANOTHER AREA OF CONCENTRATED SHOWERS AND  
STORMS IS EXPECTED ACROSS THE DAKOTAS AND THE UPPER MIDWEST BY THE  
MIDDLE OF NEXT WEEK AS A DISTURBANCE CROSSES NEAR THE CANADIAN  
BORDER. MODEL GUIDANCE IS ALSO SIGNALING POSSIBLE MESOSCALE  
CONVECTIVE SYSTEMS (MCS) DEVELOPING FROM THE SOUTH-CENTRAL PLAINS  
AND PROPAGATING SOUTHEAST IN NORTHWEST FLOW ALOFT EARLY IN THE  
WEEK.  
 
A POTENT MID-UPPER LEVEL RIDGE OVER THE SOUTHWEST TO SOUTH-CENTRAL  
U.S. WILL SUPPORT A HEAT WAVE FROM THE DESERT SOUTHWEST TO THE  
SOUTH-CENTRAL U.S WHERE DAILY MAXIMUM TEMPERATURE RECORDS WILL BE  
THREATENED.  
 
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  
 
SCHICHTEL  
 

 
 
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