558  
FXUS02 KWBC 182037  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
436 PM EDT MON APR 18 2022  
 
VALID 12Z THU APR 21 2022 - 12Z MON APR 25 2022  
 
...ADDITIONAL SNOW AND COLD WEATHER ANTICIPATED FOR PORTIONS OF  
THE NORTHERN PLAINS FRIDAY NIGHT INTO SATURDAY NIGHT...  
   
..WEATHER PATTERN OVERVIEW
 
 
A QUASI-ZONAL FLOW PATTERN ALOFT BECOMES MORE AMPLIFIED THURSDAY  
NIGHT AS A LARGE LOW OFF THE PACIFIC NORTHWEST OPENS AND DIGS  
SOUTHEAST OVER CALIFORNIA BEFORE CROSSING THE INTERMOUNTAIN WEST  
FRIDAY AND SLOWING AS IT CLOSES AGAIN AS IT DRIFTS OVER THE  
NORTHERN PLAINS LATE FRIDAY NIGHT THROUGH SATURDAY NIGHT. SURFACE  
CYCLOGENESIS OVER THE CENTRAL HIGH PLAINS IS EXPECTED BY FRIDAY  
EVENING BEFORE TRACKING UP THROUGH THE NORTH-CENTRAL PLAINS INTO  
SUNDAY. SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF THE LOW ON  
BOTH ON THE WARM AND COLD FRONTS WITH SUBSTANTIAL RAIN FOR THE  
MID-SOUTH LIKELY IN THE SUNDAY TIMEFRAME. MEANWHILE, A DOWNSTREAM  
RIDGE AXIS BUILDS ACROSS THE EASTERN U.S. AND RESULTS IN A  
CONSIDERABLE WARMING TREND FOR THE WEEKEND CONTINUING INTO NEXT  
WEEK.  
   
..MODEL GUIDANCE EVALUATION
 
 
ABOVE AVERAGE AGREEMENT ON THE MAIN SYNOPTIC SCALE FEATURES ARE  
APPARENT AMONG THE LATEST GLOBAL GUIDANCE INTO THIS WEEKEND.  
SIMILAR TO RECENT DAYS, THE 06Z GFS WAS MORE PROGRESSIVE WITH THE  
AXIS OF THE MAIN TROUGH ACROSS THE CENTRAL/NORTHERN PLAINS, AND  
DEFINITELY STRONGER BY 12Z SATURDAY COMPARED TO THE 00Z  
ECMWF/CMC/UKMET WHICH WERE IN CLOSE AGREEMENT WITH THEIR DEPICTION  
OF THE CLOSED LOW EVOLVING OVER THE DAKOTAS BY EARLY SUNDAY. SO  
FAR AMONG 12Z GUIDANCE, THE 12Z GFS/CMC/UKMET HAVE SLOWED, LIKELY  
LEAVING THE 12Z GFS STILL THE MOST PROGRESSIVE DETERMINISTIC  
SOLUTION WITH THE DEEPEST NORTHERN PLAINS LOW. BY SUNDAY,  
DETERMINISTIC GUIDANCE ARE IN DECENT AGREEMENT ON THE DEPICTION OF  
THE NEXT STORM SYSTEM NEAR THE GULF OF ALASKA, BUT CONSIDERABLE  
MODEL SPREAD IS APPARENT WITH THE TIMING OF THE SURFACE LOW OVER  
THE NORTH-CENTRAL U.S. WITH THE 12Z CMC THE SLOWEST. A  
MULTI-DETERMINISTIC MODEL BLEND WAS USED FOR DAYS 3-5 WITH MINOR  
INCLUSIONS OF THE 06Z GEFS/00Z ECENS BEYOND THE 144HR FORECAST  
PERIOD OF THE UKMET (DAYS 6/7).  
   
..SENSIBLE WEATHER/THREATS
 
 
MODERATE TO HEAVY PRECIPITATION WITH SNOW LEVELS GENERALLY 5500FT  
TO 6500FT WILL CONTINUE TO SPREAD DOWN THE SIERRA NEVADA THURSDAY  
BEFORE EASING THURSDAY NIGHT AS THE DIGGING UPPER TROUGH MOVES  
INLAND. THIS SPRING EVENT WILL DELIVER SOME HIGHLY BENEFICIAL  
PRECIPITATION TO DROUGHT-STRICKEN AREAS OF CALIFORNIA, WITH THE  
POTENTIAL FOR 1-2+ INCHES OF RAIN IN SOME AREAS OF CENTRAL AND  
NORTHERN CALIFORNIA, AND 1-3 FEET OF SNOW FOR THE HIGH SIERRA.  
MODERATE TO LOCALLY HEAVY RAIN/MOUNTAIN SNOW (SNOW LEVELS  
GENERALLY ABOUT 7000FT) THEN PROGRESSES AHEAD OF THE UPPER TROUGH  
ACROSS THE INTERMOUNTAIN WEST THURSDAY NIGHT THROUGH FRIDAY.  
 
ORGANIZED SHOWERS AND THUNDERSTORM ARE EXPECTED TO DEVELOP ACROSS  
THE CENTRAL PLAINS/MIDWEST AND NORTH THURSDAY NIGHT THROUGH THIS  
WEEKEND AS GULF MOISTURE IS ADVECTED NORTHWARD AHEAD OF THE  
WESTERN TROUGH. ADDITIONAL MODERATE TO HEAVY SNOW IS EXPECTED FOR  
PORTIONS OF THE NORTHERN ROCKIES FRIDAY, SPILLING ONTO THE  
NORTHERN HIGH PLAINS FRIDAY NIGHT INTO SATURDAY NIGHT. THE THREAT  
FOR HEAVY SNOW REMAINS ACROSS THE WESTERN DAKOTAS AND EASTERN  
MONTANA/WYOMING, LIKELY AFFECTING THE SIMILAR AREAS TO THE RECENT  
BLIZZARD AND SUBSEQUENT STORMS.  
 
IN TERMS OF TEMPERATURES, A MAJOR WARMING TREND IS FORECAST FOR  
MUCH OF THE EASTERN HALF OF THE NATION GOING INTO THE WEEKEND,  
ALONG WITH INCREASING HUMIDITY LEVELS, IN RESPONSE TO DEEP  
SOUTHERLY FLOW AHEAD OF THE CENTRAL U.S. STORM SYSTEM. ONE OF THE  
CAVEATS IN THE TEMPERATURE FORECAST WILL BE THE PRESENCE OF A BACK  
DOOR COLD FRONT/COLD AIR DAMMING FOR THE MID-ATLANTIC AND  
NORTHEAST U.S. THIS WEEKEND, WITH POTENTIALLY A BIG CONTRAST OVER  
A RELATIVELY SHORT DISTANCE NEAR THE WEDGE FRONT. IT WILL LIKELY  
REMAIN UNCOMFORTABLY COLD FROM MONTANA TO NORTH DAKOTA AND  
NORTHERN MINNESOTA WITH NEAR-FREEZING HIGHS RUNNING 20 TO 25  
DEGREES BELOW NORMAL.  
 
JACKSON  
 
HAZARDS:  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE SIERRA NEVADA, THU,  
APR 21.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF NORTH DAKOTA, FRI-SAT,  
APR 22-APR 23.  
- HEAVY SNOW ACROSS PORTIONS OF NORTH DAKOTA INTO NORTHEASTERN  
MONTANA, FRI-SAT, APR 22-APR 23.  
- HEAVY RAIN ACROSS PORTIONS OF IOWA INTO NORTHERN ILLINOIS,  
THU-FRI, APR 21-APR 22.  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS AND INTO THE  
MIDWEST, SAT-SUN, APR 23-APR 24.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN PLAINS TO THE  
MID-MISSISSIPPI VALLEY, MON, APR 25.  
- SEVERE WEATHER ACROSS PORTIONS OF CENTRAL TO NORTHERN PLAINS,  
FRI, APR 22.  
- FLOODING POSSIBLE ACROSS PORTIONS OF GEORGIA.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF GEORGIA AND  
THE LOWER MISSISSIPPI VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN ROCKIES  
INTO CENTRAL AND SOUTHERN HIGH PLAINS, FRI, APR 22.  
- HIGH WINDS ACROSS PORTIONS OF THE NORTHERN HIGH PLAINS AND THE  
NORTHERN ROCKIES, FRI-SAT, APR 22-APR 23.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN  
PLAINS, SAT-MON, APR 23-APR 25.  
 
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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