776  
FXUS02 KWBC 250653  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
253 AM EDT FRI APR 25 2025  
 
VALID 12Z MON APR 28 2025 - 12Z FRI MAY 02 2025  
 
 
...POTENT ROCKIES TO CENTRAL U.S. SPRING STORM EXPECTED EARLY NEXT  
WEEK...  
   
..OVERVIEW
 
 
THE PRIMARY FOCUS EARLY NEXT WEEK WILL BE ON EJECTING ROCKIES  
UPPER TROUGH ENERGY AND ASSOCIATED NORTHERN PLAINS THROUGH UPPER  
GREAT LAKES SURFACE SYSTEM, BRINGING SOME HEAVY RAIN POTENTIAL TO  
THE NORTHERN TIER AND POSSIBLE SEVERE WEATHER TO CENTRAL/EAST-  
CENTRAL U.S. THE NORTHERN PART OF THIS SYSTEM WILL CONTINUE ONWARD  
BUT THE TRAILING PART OF THE FRONT SHOULD STALL AND DEVELOP SOME  
WAVINESS AHEAD OF WEAKER SOUTHWESTERN SHORTWAVE ENERGY, PROVIDING A  
FOCUS FOR ENHANCED CENTRAL U.S. RAINFALL AROUND MIDWEEK. UPSTREAM  
ENERGY SHOULD PUSH THE EVOLVING SYSTEM AND RAINFALL EASTWARD  
THEREAFTER, WITH AN UPPER TROUGH AXIS REACHING THE EAST-CENTRAL  
STATES BY FRIDAY. A TRAILING UPPER RIDGE SHOULD MOVE INTO THE WEST  
AFTER EARLY WEDNESDAY, LIKELY FOLLOWED BY A TROUGH/COLD FRONT  
NEARING THE WEST COAST BY FRIDAY.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
A 12Z/18Z OPERATIONAL MODEL COMPOSITE PROVIDED A REASONABLE  
DEPICTION OF SIGNIFICANT FEATURES DURING THE FIRST HALF OF THE  
PERIOD. THERE IS DECENT CLUSTERING WITH ONLY TYPICAL DETAIL  
VARIATIONS FOR NORTHERN PLAINS LOW PRESSURE THAT SHOULD TRACK  
ACROSS THE UPPER GREAT LAKES AND THEN EASTERN CANADA, WITH THE  
TRAILING FRONT ULTIMATELY STALLING OVER THE PLAINS AS WEAK  
SHORTWAVE ENERGY LINGERS OVER THE SOUTHWESTERN U.S. BY THE LATTER  
HALF OF THE WEEK THERE IS STILL BETTER THAN AVERAGE AGREEMENT AMONG  
MODEL/ENSEMBLE GUIDANCE THAT INCOMING SHORTWAVE ENERGY SHOULD  
EJECT THE SOUTHWESTERN SHORTWAVE, LEADING TO A SURFACE WAVE  
REACHING THE VICINITY OF THE EASTERN GREAT LAKES BY EARLY FRIDAY.  
HOWEVER SHORTWAVE DETAIL UNCERTAINTIES INCREASE AT THAT TIME AND  
MACHINE LEARNING (ML) MODELS SHOW MORE SPREAD FOR THE EASTERN U.S.  
SURFACE PATTERN, SO CONFIDENCE IS A BIT LOWER THAN WHAT MIGHT BE  
SUGGESTED BY THE DYNAMICAL MODEL/ENSEMBLE CLUSTERING.  
 
MEANWHILE THERE ARE ALSO DEVELOPING DIFFERENCES WITH THE UPPER  
TROUGH NEARING THE WEST COAST BY NEXT FRIDAY. THE MOST PROMINENT  
DIFFERENCE IS THAT GFS RUNS ARE FASTER AND LESS AMPLIFIED THAN THE  
DYNAMICAL/ML MODEL CONSENSUS FOR A MAJORITY OF THE TROUGH. THE GEFS  
MEAN IS CLOSER TO THE MAJORITY SCENARIO. WHILE A LEADING MEAN  
RIDGE MOVES OVER THE WEST LATE IN THE WEEK, THERE MAY BE WEAK  
TROUGH/UPPER LOW ENERGY THAT REACHES THE SOUTHEAST/GREAT BASIN BUT  
WITH VERY LOW CONFIDENCE FOR SPECIFICS. LATE WEEK PREFERENCES SIDED  
MOSTLY WITH THE 12Z ECMWF AND THE 18Z GEFS/00Z ECENS MEANS GIVEN  
COMPARISONS ALONG THE WEST COAST, WHILE THIS SOLUTION REPRESENTED  
CONSENSUS OVER THE EAST.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE EARLY WEEK ROCKIES INTO CENTRAL U.S. STORM WILL BRING HIGH  
ELEVATION SNOW TO THE NORTH-CENTRAL ROCKIES ALONG WITH A HEAVY  
RAINFALL THREAT FARTHER EAST ALONG THE NORTHERN TIER IN ASSOCIATION  
WITH ANOMALOUS MOISTURE AND FAVORABLE DYNAMICS/SURFACE FOCUS. THE  
DAY 4/MONDAY EXCESSIVE RAINFALL OUTLOOK DEPICTS A MARGINAL RISK  
AREA THAT INCLUDES PORTIONS OF THE NORTHERN HIGH PLAINS INTO UPPER  
MIDWEST. SOME LOCALLY HEAVY RAIN MAY FALL FARTHER SOUTH OVER THE  
MISSISSIPPI VALLEY AND VICINITY BUT WITHOUT A SUFFICIENTLY CLEAR  
SIGNAL TO MERIT A RISK AREA FOR NOW. BY TUESDAY INTO EARLY  
WEDNESDAY THE PLAINS PART OF THE SYSTEM'S TRAILING FRONT SHOULD  
STALL AND PROVIDE A FOCUS FOR TRAILING/REPEAT CONVECTION. THE DAY  
5/TUESDAY ERO REFLECTS THE RUNOFF THREATS WITH A MARGINAL RISK AREA  
FROM CENTRAL TEXAS INTO THE LOWER OHIO VALLEY. MEANWHILE THE STORM  
PREDICTION CENTER CONTINUES TO MONITOR FOR SEVERE WEATHER THREATS  
OVER CENTRAL/EAST-CENTRAL U.S. MONDAY-TUESDAY.  
 
THE CENTRAL U.S. HEAVY RAIN POTENTIAL WILL LIKELY CONTINUE THROUGH  
THE REST OF WEDNESDAY BEFORE UPPER DYNAMICS AND SURFACE  
WAVINESS/FRONTS PROGRESS INTO THE EAST WITH SOMEWHAT LESSER RAIN  
TOTALS. FARTHER WEST, SHORTWAVE ENERGY PUSHING THROUGH THE WEST  
SHOULD SPREAD RAIN AND SOME HIGH ELEVATION SNOW FROM THE NORTHWEST  
THROUGH THE NORTHERN AND CENTRAL ROCKIES OVER THE COURSE OF THE  
WEEK.  
 
VERY WARM TEMPERATURES OVER THE PLAINS/MISSISSIPPI VALLEY ON  
MONDAY WILL PROGRESS INTO THE EAST AHEAD OF AN ADVANCING COLD  
FRONT, WITH HIGHS UP TO 10-20F ABOVE NORMAL AND MORNING LOWS EVEN A  
LITTLE MORE ANOMALOUS. THE WAVY FRONT MAY NOT REACH PARTS OF THE  
SOUTHEAST/MID-ATLANTIC, WHERE TEMPERATURES COULD REMAIN SOMEWHAT  
ABOVE NORMAL THROUGH FRIDAY. COOL READINGS FROM THE SOUTHWEST TO  
NORTHERN HIGH PLAINS ON MONDAY SHOULD MODERATE AS THE AIR MASS  
CONTINUES EASTWARD. THEN EXPECT A TREND TO ABOVE NORMAL  
TEMPERATURES OVER THE WEST MID-LATE WEEK AS AN UPPER RIDGE BUILDS  
IN. HIGHS MAY REACH 10-15F ABOVE NORMAL FROM THE PACIFIC NORTHWEST  
INTO NORTHERN ROCKIES.  
 
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  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL  
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT  
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:  
 
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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW  
 

 
 
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