783  
FXUS02 KWBC 291936  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
335 PM EDT SUN MAY 29 2022  
 
VALID 12Z WED JUN 01 2022 - 12Z SUN JUN 05 2022  
 
...MULTIPLE ROUNDS OF HEAVY RAINFALL/CONVECTION FORECAST TO FOCUS  
ACROSS THE SOUTH-CENTRAL PLAINS NEAR A FRONT LATE  
TUESDAY-THURSDAY...  
...LATE WEEK HEAVY RAIN THREAT INCREASING OVER SOUTHERN FLORIDA  
AHEAD OF A TROPICAL SYSTEM...  
   
..OVERVIEW
 
 
A COLD FRONT EXTENDING FROM A DEEP UPPER LOW OVER SOUTH-CENTRAL  
CANADA IS FORECAST TO BECOME NEARLY STATIONARY ACROSS THE  
SOUTH-CENTRAL PLAINS WHERE MULTIPLE ROUNDS OF CONVECTION WITH  
HEAVY RAINFALL ARE FORECAST TO IMPACT THE AREA FROM LATE TUESDAY  
TO THURSDAY. ADDITIONAL ROUNDS OF CONVECTION/HEAVY RAIN ARE  
POSSIBLE OVER THE CENTRAL PLAINS BY THE WEEKEND. THE FRONT COULD  
TRIGGER AREAS OF HEAVY RAIN OVER INTERIOR NEW ENGLAND AND THE  
MID-ATLANTIC WEDNESDAY AND THURSDAY. MEANWHILE, TROPICAL MOISTURE  
CAN BE EXPECTED TO INCREASE ACROSS SOUTHERN FLORIDA THROUGH THE  
MEDIUM-RANGE PERIOD AS A SUBTROPICAL JET IS FORECAST TO INTERACT  
WITH MOISTURE COMING UP FROM TROPICAL CYCLONE AGATHA CURRENTLY  
LOCATED IN THE EASTERN PACIFIC. ELSEWHERE, UPPER-LEVEL RIDGING IS  
FORECAST TO BUILD ACROSS THE INTERIOR WEST WHILE AN EAST PACIFIC  
UPPER LOW PRODUCES TROUGHING AND UNSETTLED WEATHER INTO THE  
NORTHWEST.  
 
   
..MODEL GUIDANCE EVALUATION/PREFERENCES
 
 
MODEL GUIDANCE THIS MORNING ARE IN REASONABLY GOOD AGREEMENT WITH  
ONE ANOTHER REGARDING THE SYNOPTIC EVOLUTION ACROSS THE U.S.  
THROUGH THE MEDIUM-RANGE PERIOD. THE 00Z ECMWF WAS NOTABLY SLOWER  
THAN THE REST OF THE GUIDANCE REGARDING THE SOUTHWARD PROGRESSION  
OF THE COLD FRONT MOVING THROUGH THE CENTRAL PLAINS ON WEDNESDAY  
INTO THURSDAY, RESULTING IN THE ASSOCIATED HEAVY RAINFALL AXIS  
BEING NOTICEABLY FARTHER TO THE NORTH. ON THE OTHER HAND, THE 00Z  
EC MEAN WAS FARTHER SOUTH WITH THE FRONTAL PLACEMENT. THUS THE  
SLOW ECMWF SOLUTION IS NOT PREFERRED. ACROSS THE NORTHEAST,  
MODELS CONTINUE TO TREND TOWARD A FLATTER FLOW REGIME AS A FRONTAL  
WAVE FORMS JUST OFF THE NORTHERN MID-ATLANTIC COAST AND MOVES OUT  
TO SEA. ALONG THE WEST COAST, MODELS ARE IN GOOD AGREEMENT WITH  
THE TIMING OF THE ARRIVAL OF THE NEXT ROUND OF MOISTURE LATE THIS  
WEEK. THE EC SOLUTIONS FAVOR A REINFORCING SURGE OF MOISTURE INTO  
NORTHERN CALIFORNIA AND NORTHWARD DURING THE WEEKEND, A SCENARIO  
NOT AS PROMINENTLY INDICATED IN THE GFS, GEFS, AS WELL AS THE CMC  
SOLUTIONS. BY NEXT WEEKEND, ENSEMBLE MEANS ARE IN GENERAL  
AGREEMENT FOR A WARM FRONT TO LIFT NORTHWARD INTO THE CENTRAL  
PLAINS AS COOLER AIR EDGES SOUTHWARD INTO THE NORTHERN PLAINS.  
 
FARTHER SOUTH, MODELS CONTINUE TO SHOW MORE CONSISTENCY WITH  
BRINGING TROPICAL MOISTURE NORTHEASTWARD INTO SOUTHERN FLORIDA  
FROM THE EASTERN PACIFIC LATE WEEK INTO THE WEEKEND WITH THE  
APPROACH OF A TROPICAL SYSTEM. THE RECENT CMC SOLUTIONS WERE THE  
FASTEST AMONG THE GUIDANCE, TAKING THE CENTER OF THIS SYSTEM  
ACROSS THE FLORIDA PENINSULA OVER THE WEEKEND.  
 
THE WPC MEDIUM RANGE FORECAST WAS BASED ON A MULTI-MODEL AND  
ENSEMBLE BLEND OF 40% FROM THE 06Z GFS/GEFS, 40% FROM THE 00Z  
ECMWF/EC MEAN, AND 20% FROM THE 00Z CMC/CMC MEAN, TRANSITIONING TO  
MOSTLY THE ENSEMBLE MEANS BY DAY 7, DISCOUNTING THE 00Z CMC BY DAY  
5. THE RESULTS ARE COMPARABLE TO PREVIOUS WPC FORECASTS.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
A SURFACE LOW WELL INTO CENTRAL CANADA BY WEDNESDAY WILL SEND ITS  
TRAILING COLD FRONT ACROSS THE GREAT LAKES AND OHIO VALLEY  
WEDNESDAY AND THEN ACROSS THE NORTHEAST AND MID-ATLANTIC  
THURSDAY-FRIDAY. RAIN AND THUNDERSTORMS CAN BE EXPECTED ALONG  
THIS FRONT WHERE LOCALLY HEAVY RAIN IS POSSIBLE OVER INTERIOR NEW  
ENGLAND AND THE MID-ATLANTIC. HOWEVER, THE TRAILING PORTION OF  
THE MAIN FRONT IS FORECAST TO MOVE MUCH MORE SLOWLY THROUGH  
CENTRAL AND SOUTHERN PARTS OF THE PLAINS, AND WILL PROVIDE A FOCUS  
FOR RAIN AND THUNDERSTORMS FOR MULTIPLE DAYS AROUND  
TUESDAY-THURSDAY. FLASH FLOODING IS POSSIBLE ESPECIALLY WHERE  
STORMS REPEAT OVER THE SAME AREA, WHICH AT THIS POINT APPEARS MOST  
LIKELY TO OCCUR AROUND SOUTHERN KANSAS TO OKLAHOMA. UNCERTAINTY  
REMAINS WITH THE AXIS OF THE CONVECTION EACH DAY/NIGHT, BUT A  
SLIGHT RISK OF EXCESSIVE RAINFALL IN WPC'S EXPERIMENTAL DAY 4  
OUTLOOK SEEMED WARRANTED GIVEN MOISTURE AND INSTABILITY WILL BE  
ABUNDANT ALONG WITH A FOCUS FOR LIFT WITH THE FRONT IN PLACE, AND  
CONSIDERING ANTECEDENT CONDITIONS COULD BE QUITE WET WITH  
TUESDAY'S RAIN. SOME ADDITIONAL ROUNDS OF HEAVY RAIN IS POSSIBLE  
ON THURSDAY SLIGHTLY FARTHER SOUTH ACROSS OKLAHOMA. BY THE  
WEEKEND, THE FRONT IS FORECAST TO LIFT NORTHWARD AS A WARM FRONT  
WHILE COOLER AIR FROM CANADA IS FORECAST TO EDGE SOUTHWARD INTO  
THE NORTHERN PLAINS. THIS SCENARIO WILL HELP SPARK ADDITIONAL  
ROUNDS OF ENHANCED RAINFALL OVER THE CENTRAL PLAINS DURING THE  
WEEKEND.  
 
THERE IS INCREASING FORECAST AGREEMENT FOR TROPICAL CYCLONE AGATHA  
OVER THE EASTERN PACIFIC TO MOVE NORTHEASTWARD ACROSS MEXICO OVER  
THE NEXT FEW DAYS. SCATTERED SHOWERS AND THUNDERSTORMS ARE  
EXPECTED TO BECOME MORE FREQUENT AND WIDESPREAD ACROSS SOUTHERN  
FLORIDA LATER NEXT WEEK. FACTORS THAT INFLUENCE THE TIMING AND  
AMOUNTS OF RAINFALL WILL INCLUDE (A) THE INTERACTION OF A  
SUBTROPICAL JET WITH TROPICAL MOISTURE COMING FROM AGATHA, AND THE  
CYCLONE'S SUBSEQUENT TRACK AND INTENSITY AFTER CROSSING CENTRAL  
AMERICA, (B) THE PROXIMITY OF AN UPPER LOW FORECAST TO GRADUALLY  
GAIN SOME TROPICAL CHARACTERISTICS NEAR AND NORTHEAST OF THE  
BAHAMAS MIDWEEK, AND (C) POSSIBLE INTERACTION WITH A TROPICAL WAVE  
MOVING INTO THE WESTERN CARIBBEAN SEA.  
 
ADDITIONALLY, RAIN CHANCES ARE EXPECTED TO INCREASE IN THE  
NORTHWEST DURING THE LATTER HALF OF THE WEEK GIVEN THE TROUGH AXIS  
NEAR THE WEST COAST AND A COUPLE OF FRONTAL SYSTEMS. THE SOUTHWEST  
SHOULD REMAIN DRY AND HOT THOUGH. ROUNDS OF RAIN ARE POSSIBLE IN  
THE CENTRAL U.S. NEXT WEEKEND, BUT WITH CONSIDERABLE UNCERTAINTY  
IN THE DETAILS AT THIS POINT.  
 
UPPER RIDGING AHEAD OF THE CENTRAL U.S./CANADA TROUGH/LOW WILL  
PROMOTE ABOVE AVERAGE TEMPERATURES BY 10-20F OVER THE MIDWEST/OHIO  
VALLEY AND PARTS OF THE NORTHEAST/MID-ATLANTIC WEDNESDAY, WITH THE  
EXCEPTION OF PARTS OF NEW ENGLAND DUE TO THE BACKDOOR FRONT.  
MEANWHILE UPPER TROUGHING WILL BRING CONTINUED COOL TEMPERATURES  
ACROSS THE ROCKIES AND CENTRAL HIGH PLAINS THROUGH MIDWEEK WITH  
HIGHS FORECAST TO BE 10-20F OR BELOW NORMAL. THE FLATTENING  
PATTERN ALOFT WILL PUSH THE COLD FRONT EASTWARD, LEADING TO A  
MODERATING TREND FOR BELOW NORMAL TEMPERATURES OVER THE CENTRAL  
U.S., WITH MOSTLY SINGLE-DIGIT NEGATIVE ANOMALIES BY  
THURSDAY-FRIDAY, THOUGH AROUND 10F BELOW NORMAL IN RAIN-COOLED  
KANSAS AND OKLAHOMA. THE EAST SHOULD SEE SHRINKING COVERAGE OF  
WARM TEMPERATURES ON THURSDAY AND ESPECIALLY FRIDAY INTO THE  
WEEKEND. THE WEST COAST AND INTO THE GREAT BASIN CAN EXPECT WARMER  
THAN NORMAL TEMPERATURES BY AROUND 5-15F WEDNESDAY AND BEYOND,  
FOLLOWED BY A MODEST COOLING TREND ON FRIDAY-SUNDAY ALONG THE  
IMMEDIATE WEST COAST WITH THE ARRIVAL OF A PACIFIC FRONT.  
 
KONG/TATE  
 
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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