166  
FXUS02 KWBC 030647  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
246 AM EDT TUE MAY 03 2022  
 
VALID 12Z FRI MAY 06 2022 - 12Z TUE MAY 10 2022  
 
...ENHANCED RAINFALL THREAT WITH CLOSED LOW TRACK INTO  
FRIDAY/SATURDAY FROM THE OHIO VALLEY TO THE  
APPALACHIANS/MID-ATLANTIC...  
...HEAVY SNOW THREAT FROM THE NORTHWEST TO THE NORTH-CENTRAL GREAT  
BASIN/ROCKIES FRIDAY INTO NEXT WEEK...  
...ACTIVE PATTERN SET TO TRANSITION TO OMEGA-STYLE BLOCKY PATTERN  
BY EARLY NEXT WEEK...  
 
   
..PATTERN OVERVIEW AND GUIDANCE EVALUATION
 
 
GUIDANCE REMAINS VARIED WITH THE PROGRESSION OF A CLOSED UPPER LOW  
TRACKING FROM THE CENTRAL TO EASTERN U.S. THIS PERIOD, WITH THE  
GFS/GEFS MEAN STILL ON THE FAST SIDE COMPARED TO THE BETTER  
CLUSTERED AND SLOWER RECENT ECMWF/UKMET/CANADIAN AND ECMWF  
ENSEMBLE MEAN SOLUTIONS. THE WPC FORECAST CONTINUES TO LEAN  
TOWARDS THE SLOWER SIDE OF THE FORECAST ENVELOPE, GIVEN  
CONTINUITY, BUT ALSO THE GENERAL NATURE OF A SEPARATED SOUTHERN  
STREAM FLOW WITH AN EMBEDDED CLOSED SYSTEM. THE 12 UTC ECMWF/ECMWF  
ENSEMBLE MEAN SEEMED TO OFFER A DECENT REPRESENTATION OF THE  
SLOWER GUIDANCE CLUSTER, BUT THE LATEST 00 UTC ECMWF OFFERS NEW  
UNCERTAINTY WITH A MORE NORTHWARD TRACK TREND.  
 
THIS LESS PROGRESSIVE 12 UTC ECMWF/ECMWF ENSEMBLE MEAN CONSENSUS  
SEEMED TO WORK WELL FOR THE REST OF THE COUNTRY AND MAINTAINS GOOD  
WPC PRODUCT CONTINUITY, THOUGH WITH MORE EMPHASIS ON THE ECMWF  
ENSEMBLE MEAN INTO DAY 6/7 AMID GROWING FORECAST SPREAD. THERE  
REMAINS A GENERAL THEME OF LEADING MAIN UPPER TROUGHING REACHING  
THE COAST THURSDAY, WITH A GROWING SIGNAL TO DEVELOP AND REINFORCE  
AN AMPLIFIED MEAN UPPER TROUGH OVER THE WEST FRIDAY INTO EARLY  
NEXT WEEK AS PART OF A DEVELOPING OMEGA STYLE BLOCK OVER THE LOWER  
48 TO ALSO INCLUDE DOWNSTREAM DEVELOPMENT OF AN AMPLIFIED AND  
WARMING EAST-CENTRAL U.S. UPPER RIDGE AND STORMY WESTERN ATLANTIC  
CLOSED LOW/TROUGH.  
   
..WEATHER/THREAT HIGHLIGHTS
 
 
A CLOSED UPPER TROUGH AND WELL ORGANIZED SURFACE LOW/FRONTAL  
SYSTEM IS EXPECTED TO TRACK FROM THE SOUTH-CENTRAL PLAINS/LOWER  
MISSISSIPPI VALLEY FRIDAY TO THE OHIO VALLEY THEN  
APPALACHIANS/MID-ATLANTIC OVER THE WEEKEND. THE STORM PREDICTION  
CENTER SHOWS A THREAT FOR SEVERE WEATHER INTO FRIDAY ACROSS  
PORTIONS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS. STRONG  
STORMS ARE ALSO POSSIBLE INTO THE WEEKEND WITH SLOW/STEADY  
DOWNSTREAM TRACK OF THE SYSTEM. UPPER DIFFLUENCE, AMPLE MOISTURE  
INFLOW, AND INSTABILITY WILL ALSO OFFER A THREAT FOR ENHANCED  
COMMA HEAD AND WAVY LEAD/TRAILING FRONTAL RAINFALL FOCUS FROM THE  
MID-LOWER MISSISSIPPI AND OHIO VALLEYS TO THE  
APPALACHIANS/MID-ATLANTIC.  
 
ROBUST DIGGING OF A SERIES OF DYNAMIC UPPER SYSTEMS WILL LEAD TO A  
DRAMACTIC CHANGE OVER MUCH OF THE WEST THIS PERIOD AS AN AMPLIFIED  
MEAN UPPER TROUGH AND WAVY/WELL DEFINED FRONTAL SYSTEMS BECOME  
ESTABLISHED OVER THE REGION FRIDAY INTO NEXT WEEK. THIS WILL  
SUPPORT SIGNIFICANT COOLING AND BRING A WIDESPREAD PRECIPITATION  
FOCUS FROM THE NORTHWEST THROUGH THE NORTH-CENTRAL GREAT  
BASIN/ROCKIES TO INCLUDE A SUBSTANTIAL AND LINGERING THREAT FOR  
HEAVY TERRAIN FOCUSING SNOWS. THESE TROUGHS WILL SUPPORT  
TEMPERATURES AS MUCH AS 10-20 DEGREES BELOW NORMAL ACROSS A LARGE  
PORTION OF THE WEST. UPPER DYNAMICS AND SLOW WAVY FRONTAL  
TRANSLATION SHOULD ALSO SUPPORT AN EMERGING CONVECTION/RAINFALL  
PATTERN WITH LOCAL RUNOFF CONCERNS ACROSS THE NORTH-CENTRAL U.S.  
BY LATER WEEKEND/EARLY NEXT WEEK, ALBEIT WITH LESS CERTAIN SYSTEM  
DETAILS AT THESE LONGER TIME FRAMES. THIS COULD LEAD TO RUNOFF  
ISSUES AS THE REGION HAS EXPERIENCED QUITE A BIT OF RAIN IN APRIL.  
 
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  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page