923  
FXUS02 KWBC 281955  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
353 PM EDT SAT MAY 28 2022  
 
VALID 12Z TUE MAY 31 2022 - 12Z SAT JUN 04 2022  
 
...MULTIPLE ROUNDS OF HEAVY RAINFALL/CONVECTION FOCUS ACROSS  
SOUTH-CENTRAL PLAINS NEAR A STATIONARY FRONT NEXT WEEK...  
   
..OVERVIEW
 
 
THE MEDIUM RANGE PERIOD WILL LIKELY BEGIN WITH AN AMPLIFIED TROUGH  
AND A LOW PRESSURE SYSTEM EXITING THE NORTHERN PLAINS INTO  
SOUTH-CENTRAL CANADA NEXT TUESDAY. THE ASSOCIATED TRAILING COLD  
FRONT WILL GRADUALLY PUSH EAST AND SOUTHEAST ACROSS THE NORTHERN  
TIER STATES AND FURTHER INTO THE PLAINS AGAINST A WARM RIDGE OVER  
THE EASTERN U.S. FORECAST TO BE GRADUALLY ERODED BY THE FRONT  
THROUGH THE END OF NEXT WEEK. MOUNTAIN SNOWS INITIALLY OVER THE  
NORTHERN ROCKIES AND GUSTY WINDS/CONVECTION OVER THE NORTHERN  
PLAINS WILL GIVE WAY TO ROUNDS OF THUNDERSTORMS OVER  
CENTRAL/SOUTHERN PLAINS WHERE THE FRONT IS FORECAST TO BECOME  
NEARLY STATIONARY. MEANWHILE, THUNDERSTORMS SHOULD PROGRESS  
THROUGH THE MID-MISSISSIPPI AND OHIO VALLEYS, THE GREAT LAKES, AND  
THEN INTO THE NORTHEAST AS THE WEEK PROGRESSES. FARTHER SOUTH,  
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.  
 
   
..MODEL GUIDANCE EVALUATION/PREFERENCES
 
 
THE ABRUPT MODEL TREND IN THE PAST COUPLE DAYS TOWARD A MORE  
AMPLIFIED UPPER TROUGH OVER THE NORTHERN PLAINS FOR EARLY NEXT  
WEEK HAS STABILIZED, ALTHOUGH THE MOST RECENT MODEL RUNS STILL  
TEND TOWARD A MORE CLOSED OFF SYSTEM, WITH THE ASSOCIATED LEAD  
FRONT PUSHING FASTER TOWARD THE EAST ACROSS THE UPPER MIDWEST.  
THE GFS AND GEFS SHOW THEIR TYPICALLY FASTER SOLUTIONS WITH  
SUBSEQUENT EASTWARD PROGRESSION OF THE FRONT ACROSS THE NORTHEAST  
BY NEXT THURSDAY. BY LATE NEXT WEEK, DETERMINISTIC MODEL  
SOLUTIONS BEGIN TO DIVERGE REGARDING THE TIMING AND AMPLITUDE OF A  
FRONTAL WAVE NEAR NEW ENGLAND COAST. MEANWHILE, MODELS INDICATE  
REASONABLY AGREEABLE TIMING OF THE ARRIVAL OF THE NEXT WAVE OF  
PACIFIC MOISTURE INTO THE NORTHWEST LATER NEXT WEEK DESPITE QUITE  
A BIT OF MODEL SPREAD WITH THE LATITUDE OF THE ASSOCIATED OFFSHORE  
UPPER LOW. OVER FLORIDA, MODELS ARE NOW MORE CONSISTENT WITH  
BRINGING TROPICAL MOISTURE NORTHEASTWARD FROM THE EASTERN PACIFIC  
WHERE TROPICAL CYCLONE AGATHA IS CURRENTLY LOCATED. THE GFS AGAIN  
FAVORS FASTER SOLUTIONS WITH THIS TROPICAL MOISTURE FEED WHEREAS  
THE ECMWF AND CMC INDICATE A SLOWER AND MORE CONSOLIDATED CYCLONIC  
GYRE MOVING ACROSS CENTRAL AMERICA.  
 
THUS 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.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
THE SURFACE LOW PRESSURE SYSTEM LIFTING INTO CENTRAL CANADA  
BEGINNING TUESDAY WILL SEND A COLD FRONT ACROSS THE NORTH-CENTRAL  
U.S. AND ACROSS THE NORTHEASTERN QUADRANT THROUGH THE LATTER PART  
OF THE WORKWEEK. RAIN IS POSSIBLE FIRST ACROSS NORTH DAKOTA AND  
THE UPPER MIDWEST TO GREAT LAKES ALONG THIS FRONT TUESDAY AND THEN  
SHIFTING EASTWARD ACROSS THE OHIO VALLEY AND INTO THE  
NORTHEAST/MID-ATLANTIC BY THURSDAY, AFTER SOME INITIAL SHOWERS IN  
PARTS OF THE NORTHEAST TUESDAY-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 MISSOURI, BUT WITH UNCERTAINTY IN THE  
DETAILS BEYOND THAT.  
 
ELSEWHERE, THERE IS INCREASING FORECAST AGREEMENT FOR TROPICAL  
CYCLONE AGATHA OVER THE EASTERN PACIFIC TO TURN NORTHEASTWARD AND  
MOVE ACROSS CENTRAL AMERICA 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.  
 
THE EASTERN U.S./MISSISSIPPI VALLEY UPPER RIDGE WILL PROMOTE ABOVE  
AVERAGE TEMPERATURES BY 10-20F OVER THE MIDWEST/OHIO VALLEY AND  
PARTS OF THE NORTHEAST/MID-ATLANTIC TUESDAY-WEDNESDAY, WITH SOME  
DAILY RECORD HIGH MAXIMUM AND MINIMUM TEMPERATURES POSSIBLE. THE  
BACKDOOR FRONT REACHING NEW ENGLAND AND POSSIBLY AS FAR SOUTH AS  
THE NORTHERN MID-ATLANTIC WOULD BRING A COOLER TREND TO THESE  
AREAS THOUGH. MEANWHILE UPPER TROUGHING WILL BRING VERY COOL  
TEMPERATURES TO AREAS FROM THE INTERMOUNTAIN WEST THROUGH  
NORTHERN/CENTRAL PLAINS THROUGH MIDWEEK WITH HIGHS FORECAST TO BE  
10-20F OR BELOW NORMAL. THE FLATTENING PATTERN ALOFT WILL PUSH THE  
INITIAL PLAINS COLD FRONT EASTWARD WHILE 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-SATURDAY. THE WEST COAST AND INTO  
THE GREAT BASIN COULD FLIP BACK TO WARMER THAN NORMAL TEMPERATURES  
BY AROUND 5-15F WEDNESDAY AND BEYOND, FOLLOWED BY A MODEST COOLING  
TREND ON FRIDAY-SATURDAY 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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