944  
FXUS02 KWBC 291902  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 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 ARE MORE CONSISTENT WITH BRINGING TROPICAL  
MOISTURE NORTHEASTWARD INTO SOUTHERN FLORIDA FROM THE EASTERN  
PACIFIC LATE WEEK INTO THE WEEKEND WITH THE APPROACH OF A TROPICAL  
SYSTEM.  
 
   
..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 THE NORTHEAST AND MID-ATLANTIC THURSDAY-FRIDAY. RAIN  
AND THUNDERSTORMS CAN BE EXPECTED ALONG THIS FRONT, AFTER SOME  
INITIAL SHOWERS IN PARTS OF THE NORTHEAST WEDNESDAY NEAR A  
BACKDOOR FRONT. HOWEVER, THE BACK END OF THE MAIN FRONT IS  
FORECAST TO MOVE MORE SLOWLY THROUGH CENTRAL AND SOUTHERN PARTS OF  
THE PLAINS AND MISSISSIPPI VALLEY, 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  
KANSAS, OKLAHOMA, AND POSSIBLY MISSOURI. 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.  
 
THERE IS INCREASING FORECAST AGREEMENT FOR TROPICAL CYCLONE AGATHA  
OVER THE EASTERN PACIFIC TO TURN NORTHEASTWARD AND MOVE 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 ALTHOUGH THE SPECIFICS ARE NOT  
CLEAR AT THIS TIME. 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 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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