131  
FXUS02 KWBC 020702  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 AM EDT SAT APR 02 2022  
 
VALID 12Z TUE APR 05 2022 - 12Z SAT APR 09 2022  
 
...HEAVY RAINFALL/CONVECTION AND RUNOFF THREAT TO EXTEND INTO THE  
SOUTHEAST NEXT TUESDAY...  
   
..OVERVIEW
 
 
GUIDANCE CONTINUES TO AGREE UPON THE TRANSITION OF THE UPPER LEVEL  
PATTERN TO AN AMPLIFIED AND SLOWLY EVOLVING REGIME CONSISTING OF A  
TROUGH DRIFTING OVER THE CENTRAL-EASTERN U.S. (CONTAINING A  
NORTHERN PLAINS INTO GREAT LAKES LOW) AND RIDGE BUILDING OVER THE  
WEST. AN UPSTREAM PACIFIC TROUGH SHOULD REACH THE WEST COAST BY  
AROUND NEXT SATURDAY, PUSHING THE RIDGE AXIS INTO THE NORTHERN  
PLAINS THROUGH SOUTHERN ROCKIES. AHEAD OF THE AMPLIFYING UPPER  
TROUGH, SOUTHERN TIER CONVECTION PRODUCING SOME HEAVY RAINFALL  
EXPECTED TO BE ALREADY IN PROGRESS AT THE START OF THE PERIOD  
EARLY TUESDAY SHOULD EXTEND THROUGH THE SOUTHEAST AND VICINITY  
TUESDAY-TUESDAY NIGHT, HELPED ALONG BY A LOWER MISSISSIPPI VALLEY  
THROUGH MID-ATLANTIC SURFACE WAVE. THE SYSTEM MORE DIRECTLY  
ASSOCIATED WITH THE UPPER TROUGH WILL ALSO PRODUCE PRECIPITATION  
ACROSS THE EASTERN HALF OF THE COUNTRY MID-LATE WEEK WITH  
POTENTIAL FOR SOME AREAS OF ENHANCED TOTALS. THE UPPER RIDGE  
BUILDING INTO THE WEST WILL BRING ANOTHER PERIOD OF UNSEASONABLY  
WARM TEMPERATURES THAT SHOULD PEAK AROUND THURSDAY-FRIDAY.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
FOR THE MOST PART THE MODELS AND ENSEMBLES REMAIN IN GOOD  
AGREEMENT FOR THE OVERALL EVOLUTION OF THE AMPLIFIED  
CENTRAL-EASTERN U.S. UPPER TROUGH AND ASSOCIATED SURFACE  
EVOLUTION, WITH FAIRLY TYPICAL SCATTERING OF INDIVIDUAL SOLUTIONS.  
REVIEWING RUNS THROUGH THE 12Z/18Z CYCLES, THE GFS/GEFS CONTINUED  
THEIR RECENT TENDENCY TO BE A LITTLE ON THE SOUTHERN/SOUTHEASTERN  
SIDE OF THE FULL SPREAD FOR THE PORTION OF THE UPPER LOW TRACK  
OVER THE NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY AND THEN A BIT  
FASTER WITH NORTHEASTWARD PROGRESSION OF THE SURFACE REFLECTION  
OVER THE EAST. PREFERENCE REMAINED WITH AN INTERMEDIATE APPROACH  
FAIRLY CLOSE TO CONTINUITY. THE NEW 00Z GFS OFFERS FAVORABLE  
TRENDS IN BOTH REGARDS. BY DAYS 6-7 FRIDAY-SATURDAY, THE DETAILS  
WITHIN THE CORE OF THE UPPER TROUGH BECOME MORE AMBIGUOUS AS  
SOLUTIONS VARY WITH WHERE THE INITIAL UPPER LOW MAY TRACK AND  
WHETHER SEPARATE ENERGY COULD YIELD ANOTHER LOW CENTER. MEANWHILE  
THE TUESDAY-WEDNESDAY WAVE TRACKING FROM THE LOWER MISSISSIPPI  
VALLEY THROUGH MID-ATLANTIC DISPLAYS TYPICAL SCATTER BUT GOOD  
CONTINUITY FOR THE OVERALL CONSENSUS.  
 
GUIDANCE HAS BEEN SHOWING SOME DIFFICULTY IN RESOLVING THE DETAILS  
OF PACIFIC FLOW PUSHING INTO THE WESTERN RIDGE LATE IN THE PERIOD,  
AS DEMONSTRATED BY A WIDENING ENSEMBLE SPREAD OVER THE EASTERN  
PACIFIC/WESTERN U.S. BY FRIDAY-SATURDAY. THROUGH THE 12Z/18Z  
CYCLES, THE ENSEMBLE MEANS AND 12Z ECMWF REPRESENTED THE MAJORITY  
SCENARIO OF KEEPING THE WESTERN RIDGE FAIRLY STRONG INTO FRIDAY  
WHILE A PACIFIC TROUGH REACHES NEAR THE WEST COAST AROUND EARLY  
SATURDAY. THE 18Z GFS WAS SOMEWHAT SLOWER WHILE THE PAST COUPLE  
CMC RUNS HAVE BEEN SOMEWHAT FAST/AMPLIFIED WITH THE TROUGH. THE  
NEW 00Z GFS HAS ADJUSTED CLOSER TO THE MEANS/12Z ECMWF.  
 
MODEL/ENSEMBLE COMPARISONS AND CONTINUITY LED TO FAVORING AN  
OPERATIONAL MODEL BLEND DURING THE FIRST HALF OF THE PERIOD AND  
THEN A TRANSITION TO A MODEL/MEAN MIX WITH THE INCREASE OF DETAIL  
UNCERTAINTY. THIS YIELDED A 60-70 PERCENT TILT TOWARD THE ECMWF  
CLUSTER WHERE DIFFERENCES EXISTED AND THE NEW 00Z GFS ADDS SUPPORT  
FOR LEANING AWAY FROM SOME SPECIFICS OF EARLIER GFS CYCLES.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
A LEADING CENTRAL-EASTERN U.S. SHORTWAVE AND LOWER MISSISSIPPI  
VALLEY THROUGH MID-ATLANTIC SURFACE LOW WILL HELP TO FOCUS AREAS  
OF HEAVY RAINFALL OVER THE SOUTHEAST AND VICINITY TUESDAY INTO  
TUESDAY NIGHT, EXTENDING AN EVENT THAT SHOULD INITIATE FARTHER  
WESTWARD IN THE SHORT-RANGE TIME FRAME. THE DEEP UPPER LOW  
TRACKING OVER THE NORTHERN PLAINS AND GREAT LAKES WILL SUPPORT A  
CORRESPONDING SURFACE LOW WHILE LEADING HEIGHT FALLS WILL BRING A  
FRONT TO THE EAST COAST, WITH A TRIPLE POINT WAVE POSSIBLY  
BECOMING THE DOMINANT SURFACE FEATURE BY THE END OF THE WEEK.  
OVER THE COURSE OF THE PERIOD THESE FEATURES MAY PRODUCE SOME  
AREAS OF HEAVY PRECIPITATION OVER THE NORTHERN AND EASTERN U.S.  
BUT WITH UNCERTAINTY OVER SPECIFICS AT THIS TIME. REGIONS OF  
POTENTIAL INTEREST INCLUDE PARTS OF THE MIDWEST TO LAKE SUPERIOR  
WITH THE PARENT SYSTEM, PORTIONS OF THE NORTHEAST WHERE A COASTAL  
WAVE COULD FOCUS MOISTURE, AND LOCATIONS FARTHER SOUTH ALONG THE  
TRAILING COLD FRONT. CHECK THE STORM PREDICTION CENTER'S LATEST  
OUTLOOKS FOR MORE INFORMATION REGARDING SEVERE THREATS ACROSS THE  
SOUTHERN TIER. EXTREME NORTHERN AREAS FROM THE UPPER MIDWEST INTO  
INTERIOR NEW ENGLAND MAY SEE SOME PRECIPITATION FALL IN THE FORM  
OF SNOW. OVER THE WEST, THE STRONG JET INITIALLY CROSSING THE  
REGION SHOULD PRODUCE SOME LIGHT TO MODERATE RAIN/HIGH ELEVATION  
SNOW DURING TUESDAY. THEN EXPECT MOST OF THE REGION TO BE DRY  
UNTIL LATE IN THE WEEK WHEN LIGHT PRECIPITATION MAY REACH THE  
NORTHWEST AHEAD OF AN APPROACHING UPPER TROUGH.  
 
EXPECT THE SOUTHWEST TO SEE HIGHS UP TO 10-15F ABOVE NORMAL  
THROUGH THE PERIOD. THE UPPER RIDGE BUILDING INTO THE WEST WILL  
EXPAND COVERAGE OF ABOVE NORMAL TEMPERATURES MID-LATE WEEK,  
FOLLOWED BY SOME MODERATION ON SATURDAY AS THE PACIFIC TROUGH  
ARRIVES. MUCH OF CALIFORNIA SHOULD SEE HIGHS AT LEAST 10F ABOVE  
NORMAL WEDNESDAY AND GREATEST ANOMALIES (PLUS 10-20F AND LOCALLY  
HIGHER) WILL LIKELY EXTEND FROM CALIFORNIA AND SOUTHERN OREGON  
INTO THE GREAT BASIN THURSDAY-FRIDAY. SOME DAILY RECORDS FOR  
HIGHS/WARM LOWS WILL BE POSSIBLE LATE IN THE WEEK. MEANWHILE COOL  
AIR UNDER THE AMPLIFYING UPPER TROUGH WILL BRING HIGHS DOWN TO  
5-15F BELOW NORMAL OVER THE NORTHERN ROCKIES ON TUESDAY, THE  
CENTRAL U.S. WEDNESDAY-THURSDAY, AND EASTERN STATES BY  
FRIDAY-SATURDAY. FLOW AHEAD OF THE UPPER TROUGH/SURFACE SYSTEM  
WILL BRING A COUPLE DAYS OF ABOVE NORMAL READINGS (ESPECIALLY FOR  
MORNING LOWS) TO THE EAST AROUND WEDNESDAY-THURSDAY.  
 
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, 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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