070  
FXUS02 KWBC 031921  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
319 PM 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 06Z GFS/GEFS CONTINUES A PATTERN OF MORE PROGRESSIVE AND  
AMPLIFIED TROUGHING IN THE CENTRAL AND EASTERN PORTION OF THE  
COUNTRY EARLY IN THE MEDIUM RANGE PERIOD. A BLEND OF 00Z  
EC/ECE/CMC/UK SEEMS TO MITIGATE THE TIMING AND INTENSITY ISSUES  
CAUSED BY THE GFS/GEFS THROUGH D4 AT WHICH POINT THE MIDWEST-EAST  
COAST SYSTEM SHOULD HAVE PUSHED OUT TO SEA. A 00Z EC/ECE/CMC BLEND  
IS UTILIZED FROM D5-D7 DUE TO THE CONTINUED PROGRESSIVE NATURE OF  
A WESTERN TROUGH IN THE 06Z GFS/GEFS.  
   
..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. STRONG STORMS ARE  
POSSIBLE INTO THE WEEKEND WITH THE 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. THE STORM PREDICTION CENTER  
HAS HIGHLIGHTED AREAS OF CONCERN FOR SEVERE WEATHER OVER PORTIONS  
OF THE CENTRAL PLAINS AND MIDDLE MISSISSPPII VALLEY BETWEEN SUNDAY  
AND MONDAY. LOCALIZED HEAVY RAINFALL COULD LEAD TO RUNOFF ISSUES  
AS THE REGION HAS EXPERIENCED QUITE A BIT OF RAIN IN APRIL.  
 
KEBEDE/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  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND  
THE NORTHERN GREAT BASIN,  
FRI-SAT, MAY 6-MAY 7.  
- HEAVY RAIN ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY AND  
THE NORTHERN PLAINS, SUN-MON, MAY  
8-MAY 9.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS, THE  
GREAT LAKES, THE MID-ATLANTIC, THE  
CENTRAL APPALACHIANS, AND THE OHIO VALLEY, FRI-SAT, MAY 6-MAY 7.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
GREAT BASIN, THE NORTHERN PLAINS,  
AND THE NORTHERN ROCKIES, SUN-TUE, MAY 8-MAY 10.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, AND THE  
SOUTHERN PLAINS, SUN, MAY 8.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER  
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, MON, MAY 9.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL PLAINS, THE  
MIDDLE MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE NORTHERN PLAINS.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE UPPER  
MISSISSIPPI VALLEY AND THE NORTHERN  
PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY  
AND THE SOUTHERN PLAINS, SAT-TUE,  
MAY 7-MAY 10.  
- HIGH WINDS ACROSS PORTIONS OF CALIFORNIA, THE CENTRAL GREAT  
BASIN, THE PACIFIC NORTHWEST, AND THE  
NORTHERN GREAT BASIN, FRI, MAY 6.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE CENTRAL GREAT BASIN,  
THE SOUTHERN ROCKIES, CALIFORNIA, THE SOUTHERN PLAINS, AND THE  
SOUTHWEST, SUN-MON, MAY 8-MAY 9.  
- HIGH WINDS ACROSS PORTIONS OF THE MID-ATLANTIC, SAT-TUE, MAY  
7-MAY 10.  
- ENHANCED WILDFIRE RISK ACROSS PORTIONS OF THE SOUTHERN ROCKIES,  
THE SOUTHERN PLAINS, AND THE  
SOUTHWEST, SUN, MAY 8.  
 
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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