607  
FXUS02 KWBC 051901  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT TUE APR 05 2022  
 
VALID 12Z FRI APR 08 2022 - 12Z TUE APR 12 2022  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL SEE AN AMPLIFIED AND REASONABLY  
PROGRESSIVE PATTERN IN THE UPPER LEVELS, BEGINNING LATE WEEK WITH  
AN UPPER LOW/TROUGH TRACKING THROUGH THE EAST BEFORE A GRADUAL BUT  
DRAMATIC SWITCH TO WESTERN TROUGHING AND EASTERN RIDGING THROUGH  
THE EARLY PART OF NEXT WEEK. THIS EVOLUTION WILL LEAD TO SOME  
DRAMATIC TEMPERATURE CHANGES DURING THE PERIOD AS MUCH ABOVE  
NORMAL TEMPERATURES OVER THE WEST ON FRIDAY TREND TOWARD WELL  
BELOW NORMAL READINGS BY THE FIRST PART OF NEXT WEEK, WHILE CHILLY  
TEMPERATURES OVER THE EASTERN HALF OF THE COUNTRY FRIDAY INTO THE  
WEEKEND REBOUND TO ABOVE NORMAL LEVELS BY MONDAY-TUESDAY.  
MEANWHILE RAIN AND HIGHER ELEVATION SNOW WILL SPREAD OVER THE WEST  
AND LOW LEVEL GULF INFLOW SHOULD EVENTUALLY CONTRIBUTE TO RAINFALL  
OVER THE MISSISSIPPI VALLEY AND VICINITY. A SHOWERY PATTERN OVER  
THE EAST DURING FRIDAY-SATURDAY UNDER THE UPPER TROUGH SHOULD GIVE  
WAY TO DRIER WEATHER THEREAFTER.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
RECENT MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT WITH THE  
AMPLIFIED PATTERN DESCRIBED ABOVE, SO CONFIDENCE IS REASONABLY  
HIGH FOR THE OVERALL PATTERN, BUT THERE ARE LINGERING  
UNCERTAINTIES WITH THE SMALLER-SCALE DETAILS. ONE NOTABLE DETAIL  
DIFFERENCE OCCURS BY EARLY SUNDAY WITH SHORTWAVE ENERGY WITHIN THE  
WESTERN TROUGH. THERE HAVE BEEN SOME RUN TO RUN VARIATIONS WITH A  
POSSIBLE SHORTWAVE ON THE EASTERN SIDE OF THE BASE OF THE TROUGH  
AROUND THE NORTHERN PLAINS, CAUSING DIFFERENCES IN THE PROGRESSION  
OF THE NORTHERN STREAM COLD FRONT. THE 00/06Z GUIDANCE CYCLE  
INDICATED SUPPORT FOR THE EASTERN SHORTWAVE, ASIDE FROM THE UKMET,  
WHILE THE NEWER 12Z GUIDANCE IS NOT AS EXCITED ABOUT IT. THESE ARE  
SOMEWHAT SMALL DIFFERENCES FOR A DAY 5 FORECAST, BUT COULD BE  
MARGINALLY IMPACTFUL SINCE IT AFFECTS THE COLD FRONTAL POSITION,  
BUT GIVEN THE SMALL SCALE OF THE FEATURE IT MAY TAKE A WHILE  
LONGER TO RESOLVE.  
 
THE WESTERN TROUGH IS FORECAST TO GRADUALLY DEEPEN THROUGH DAY  
7/NEXT TUESDAY, WITH A POSSIBLE EMBEDDED UPPER LOW OVER THE GREAT  
BASIN ORIGINATING FROM ENERGY OVER THE GULF OF ALASKA AT THE START  
OF THE PERIOD. THE EXACT EVOLUTION OF THE DEEPENING TROUGH REMAINS  
UNCERTAIN, PARTICULARLY CONSIDERING DIFFERENCES WITH DIGGING  
ENERGY ON THE WEST SIDE OF THE TROUGH. THE ECMWF MAY BE THE MOST  
CONSISTENT OF THE GUIDANCE, WHILE THE 12Z CMC TRENDED DEEPER THAN  
ITS 00Z RUN BUT THE 12Z GFS TRENDED FLATTER WITH THE TROUGH'S  
DEPTH DUE TO UNCERTAIN SHORTWAVE DEPTH AND PROGRESSION. WITH THE  
OVERALL GOOD AGREEMENT ESPECIALLY FOR THE FIRST HALF OF THE  
PERIOD, THE WPC FORECAST WAS BASED ON A MULTI-MODEL DETERMINISTIC  
BLEND EARLY ON, WITH ADDITION OF SOME EC AND GEFS ENSEMBLE MEAN  
GUIDANCE BY THE LATTER PART OF THE PERIOD GIVEN TYPICALLY  
INCREASING DETAIL UNCERTAINTY.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
A COASTAL/TRIPLE POINT LOW PRESSURE SYSTEM FORMING NEAR NEW  
ENGLAND EARLY FRIDAY WILL SUPPORT ORGANIZED RAINFALL THERE, WHICH  
SHOULD TAPER OFF BY SATURDAY AS THE LOW MOVES AWAY. HOWEVER, COLD  
AIR ALOFT ASSOCIATED WITH THE UPPER TROUGH WILL LIKELY PROMOTE  
AREAS OF DIURNALLY ENHANCED SHOWERS FROM THE MIDWEST/GREAT LAKES  
AND OHIO/TENNESSEE VALLEYS INTO THE APPALACHIANS AND  
MID-ATLANTIC/NORTHEAST THROUGH ESPECIALLY SATURDAY. SOME  
PRECIPITATION COULD BE IN THE FORM OF SNOW, WITH THE BEST CHANCES  
ACROSS THE PEAKS OF THE CENTRAL APPALACHIANS IN WEST VIRGINIA.  
MEANWHILE, PRECIPITATION SHOULD BEGIN LATE THIS WEEK IN THE  
PACIFIC NORTHWEST AND NORTHERN ROCKIES AND SPREAD SOUTHEASTWARD  
INTO NEXT WEEK UNDERNEATH AND JUST AHEAD OF THE INCOMING UPPER  
TROUGH, EVENTUALLY REACHING CALIFORNIA AND THE SOUTHWEST. LOWER  
ELEVATION/COASTAL RAIN AND HIGHER ELEVATION SNOW ARE FORECAST,  
WITH ENHANCEMENT OF TOTALS IN HIGHER TERRAIN, FIRST IN THE  
CASCADES AND THEN INTO THE ROCKIES EARLY NEXT WEEK AS UPSLOPE FLOW  
MAY ADD TO PRECIPITATION AMOUNTS. PRECIPITATION COULD BE IN THE  
FORM OF SNOW EVEN FOR NORTHERN/CENTRAL PARTS OF THE HIGH PLAINS AS  
WELL BY AROUND MONDAY-TUESDAY, BUT CONFIDENCE IN THE DETAILS IS  
LACKING AT THIS POINT. FARTHER SOUTHEAST IN THE WARM SECTOR,  
EXPECT RAIN TO DEVELOP OVER THE MISSISSIPPI VALLEY AND VICINITY  
DURING THE FIRST HALF OF NEXT WEEK AS GULF MOISTURE INFLOW  
INCREASES.  
 
THE WEST WILL SEE ONE MORE DAY OF VERY WARM TO HOT TEMPERATURES ON  
FRIDAY WITH HIGHS REACHING 15-25F ABOVE NORMAL ESPECIALLY FROM  
CALIFORNIA INTO THE GREAT BASIN, WITH SOME DAILY RECORDS FOR  
HIGHS/WARM LOWS. THEN THE UPPER TROUGH STEADILY DEEPENING OVER THE  
REGION WILL BRING A PRONOUNCED COOLING TREND. MUCH OF THE  
NORTHWEST/NORTHERN ROCKIES MAY SEE HIGHS OF 10-15F BELOW NORMAL BY  
SUNDAY, AND HIGHS OF 10-20F BELOW NORMAL SHOULD BE COMMON OVER A  
MAJORITY OF THE WEST AS WELL AS NORTHERN HIGH PLAINS BY NEXT  
TUESDAY. MEANWHILE THE EASTERN HALF OF THE COUNTRY WILL TREND FROM  
MOSTLY BELOW NORMAL TEMPERATURES (UP TO MINUS 10-20F ANOMALIES)  
FRIDAY-SATURDAY, WITH POTENTIAL FOR A LATE FROST ACROSS PARTS OF  
THE SOUTHEASTERN QUADRANT OF THE COUNTRY, TO ABOVE NORMAL READINGS  
(PLUS 5-15F ANOMALIES) FROM WEST TO EAST BY NEXT SUNDAY-TUESDAY.  
 
TATE/RAUSCH  
 
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 SNOW ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE  
NORTHERN GREAT BASIN, FRI-SUN, APR  
8-APR 10.  
- HEAVY SNOW ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN,  
THE NORTHERN PLAINS, AND THE NORTHERN ROCKIES, SUN-TUE, APR 10-APR  
12.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE  
SOUTHERN PLAINS, MON, APR 11.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE GREAT LAKES, THE MIDDLE  
MISSISSIPPI VALLEY, THE SOUTHERN  
PLAINS, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY.  
- HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL  
ROCKIES, THE CENTRAL GREAT BASIN,  
THE SOUTHERN ROCKIES, THE SOUTHERN PLAINS, AND THE SOUTHWEST,  
SUN-TUE, APR 10-APR 12.  
- MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF CALIFORNIA,  
THE CENTRAL GREAT BASIN, THE  
PACIFIC NORTHWEST, THE NORTHERN GREAT BASIN, AND THE SOUTHWEST,  
FRI, APR 8.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY, THE CENTRAL  
APPALACHIANS, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY,  
THE MID-ATLANTIC, THE SOUTHERN  
APPALACHIANS, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO  
VALLEY, FRI-SUN, APR 8-APR 10.  
 
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