700  
FXUS02 KWBC 050651  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
250 AM EDT THU MAY 05 2022  
 
VALID 12Z SUN MAY 08 2022 - 12Z THU MAY 12 2022  
 
...HEAVY SNOW THREAT OVER A COLD NORTH-CENTRAL GREAT BASIN/ROCKIES  
TO CONTRAST NORTH-CENTRAL U.S. CONVECTION AND SOUTH-CENTRAL U.S TO  
MIDWEST RECORD HEAT AS PART OF OMEGA-STYLE BLOCK DEVELOPMENT OVER  
THE LOWER 48 AND ADJOINING OCEANS THIS WEEKEND INTO NEXT WEEK...  
 
   
..PATTERN OVERVIEW AND GUIDANCE EVALUATION
 
 
A COMPOSITE OF THE 18 UTC GFS/GEFS ALONG WITH THE 12 UTC  
ECMWF/UKMET/CANADIAN, ECMWF ENSEMBLE MEAN AND 01 UTC NATIONAL  
BLEND OF MODELS SEEMS TO PRESENT A REASONABLE FORECAST BASIS WHILE  
TENDING TO MITIGATE EMBEDDED SYSTEM VARIANCE CONSISTENT WITH A  
PATTERN WITH NEAR NORMAL PREDICTABILITY SUNDAY INTO MONDAY. THE  
GFS/ECMWF AND GEFS/ECMWF ENSEMBLE MEANS REMAIN BEST CLUSTERED AND  
IN LINE WITH WPC CONTINUITY AND THE NBM TUESDAY-NEXT THURSDAY.  
DESPITE BETTER SIMILARITIES, RECENT RUN-RUN GUIDANCE CONTINUITY  
ISSUES STILL SUGGESTS SOME CAUTION WITH EMBEDDED FEATURE DETAILS,  
ESPECIALLY DAYS 5-7. MOST OF THE NEWER 00 UTC GUIDANCE MAINTAIN  
SIMILAR TRENDS FROM EARLIER GUIDANCE, WITH THE CANADIAN REMAINING  
THE MOST OUT OF PHASE WITH OTHER GUIDANCE WITH THE TIMING/EMPHASIS  
ON SYSTEMS DIGGING INTO THE WESTERN U.S.UPPER TROUGH.  
   
..WEATHER/THREAT HIGHLIGHTS
 
 
A CLOSED UPPER TROUGH AND WELL ORGANIZED SURFACE LOW/FRONTAL  
SYSTEM WILL TRACK OFF THE MID-ATLANTIC SUNDAY. THE LOW STALLS AND  
RETROGRADES OVER THE WESTERN ATLANTIC BACK TOWARD THE SOUTHEAST  
COAST MID-LATER NEXT WEEK WITH WRAPPING RAINS WITHIN A DEVELOPING  
OMEGA-STYLE BLOCK.  
 
ROBUST DIGGING OF A SERIES OF DYNAMIC UPPER SYSTEMS WILL LEAD TO A  
DRAMATIC CHANGE OVER MUCH OF THE WEST LATER THIS WEEKEND INTO NEXT  
WEEK AS AN AMPLIFIED MEAN UPPER TROUGH AND WAVY FRONTAL SYSTEMS  
BECOME ESTABLISHED OVER THE REGION. THIS WILL SUPPORT SIGNIFICANT  
COOLING TO INCLUDE SPOTTY RECORD VALUES ALONG WITH A WIDESPREAD  
PRECIPITATION FOCUS FROM THE NORTHWEST/SIERRA THROUGH THE  
NORTH-CENTRAL GREAT BASIN/ROCKIES. THIS WILL INCLUDE A SUBSTANTIAL  
AND LINGERING THREAT FOR WIDESPREAD HEAVY SNOWS AS FURTHER  
ENHANCED IN FAVORED TERRAIN. EXPECT TEMPERATURES TO RANGE AS MUCH  
AS 10-20 DEGREES BELOW NORMAL.  
 
UPPER SYSTEM EJECTIONS CHANNELED BETWEEN AMPLIFIED EASTERN PACIFIC  
UPPER RIDGING/UPPER TROUGHING OVER THE WEST AND AMPLIFIED  
EAST-CENTRAL U.S. UPPER RIDGING AS PART OF THE AFOREMENTIONED  
OMEGA-STYLE BLOCK OVER THE LOWER 48 AND ADJOINING OCEANS WILL TRAP  
A SLOW MOVING AND WAVY FRONTAL ZONE OVER THE NORTH-CENTRAL U.S. TO  
SUPPORT AN EMERGING BUT UNCERTAIN CONVECTION/RAINFALL PATTERN.  
THIS OFFERS A RUNOFF THREAT GIVEN MOIST AMBIENT NORTHERN PLAINS  
SOIL CONDITIONS. THE STORM PREDICTION CENTER ALSO HIGHLIGHTS A  
CONCERN FOR SEVERE WEATHER INTO THE EASTERN CENTRAL PLAINS FOR AT  
LEAST SUNDAY AND MONDAY. THE PATTERN MEANWHILE FAVORS RECORD HIGH  
TEMPERATURES OVER THE SOUTH-CENTRAL U.S., WITH PRE-FRONTAL WARMTH  
GRADUALLY BUILDING NORTHEASTWARD NEXT WEEK THROUGH THE MS/TN  
VALLEYS/MIDWEST UNDER THE UPPER RIDGE, IN STARK CONTRAST TO THE  
WINTRY CONDITIONS OVER THE WEST AND MODERATED/COOLED HIGH PRESSURE  
DAMMED AIRMASS TO LINGER OVER THE EAST ON THE BACKSIDE OF A  
DIFFICULT TO DISLODGE WESTERN ATLANTIC CIRCULATION.  
 
SCHICHTEL  
 
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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