965  
FXUS02 KWBC 190701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EDT SAT MAR 19 2022  
 
VALID 12Z TUE MAR 22 2022 - 12Z SAT MAR 26 2022  
 
...STRONG LOW PRESSURE SYSTEM WILL LIKELY PRODUCE HEAVY  
RAIN/SEVERE STORMS ACROSS THE SOUTHEASTERN QUADRANT OF THE U.S.  
INTO TUESDAY-WEDNESDAY WITH SOME WINTRY WEATHER ON THE NORTHERN  
SIDE...  
   
..OVERVIEW
 
 
THE DOMINANT FOCUS OF THE MEDIUM RANGE FORECAST WILL BE AN UPPER  
LOW EXPECTED TO TRACK FROM THE SOUTHERN/CENTRAL PLAINS TUESDAY  
INTO THE MIDWEST WEDNESDAY-THURSDAY, OPENING UP AS NORTHERN STREAM  
ENERGY PHASES WITH IT LATE IN THE WEEK. THIS FEATURE WILL SUPPORT  
REASONABLY STRONG LOW PRESSURE THAT SHOULD TRACK FROM THE SOUTHERN  
PLAINS TUESDAY NORTHEASTWARD ACROSS THE MID-MISSISSIPPI VALLEY AND  
GREAT LAKES. HEAVY RAIN THAT COULD CAUSE FLASH FLOODING IS  
EXPECTED FOR THE LOWER MISSISSIPPI AND OHIO/TENNESSEE VALLEYS WITH  
SOME CHANCE FARTHER EAST AS WELL, WHILE SEVERE STORMS ARE FORECAST  
FOR THE GULF COAST STATES. POSSIBLY HEAVY SNOW OVER THE CENTRAL  
ROCKIES SHOULD BE ENDING BY EARLY TUESDAY, BUT SOME PRECIPITATION  
IN THE NORTHERN FRINGE OF THE MOISTURE SHIELD COULD BE IN THE FORM  
OF SNOW IN THE NORTHERN HALF OF THE PLAINS, MIDWEST/GREAT LAKES,  
AND INTO THE INTERIOR NORTHEAST PARTICULARLY IN HIGHER ELEVATIONS.  
BEHIND THIS SYSTEM A STRONG UPPER RIDGE WILL BUILD INTO THE WEST,  
BRINGING MOSTLY DRY AND WARM WEATHER TO THE REGION, AND THE  
ANOMALOUS WARMTH OVER THE WEST COULD BRING RECORD HIGHS TO PARTS  
OF CALIFORNIA AROUND TUESDAY-THURSDAY. THE PATTERN SHOULD  
DEAMPLIFY SOMEWHAT BY LATE NEXT WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODEL GUIDANCE FROM THE 12/18Z YESTERDAY CYCLE REMAINED CONSISTENT  
AND AGREEABLE WITH THE PERIOD STARTING TUESDAY WITH A CENTRAL U.S.  
(AND CANADA) TROUGH AND EMBEDDED CLOSED LOW, WHICH SHOULD TRACK  
NORTHEASTWARD THROUGH MIDWEEK. SMALLER SCALE SHORTWAVES WITHIN THE  
TROUGH/LOW ARE MORE VARIABLE, AND THESE DO CAUSE SOME MINOR  
DIFFERENCES IN THE SPECIFICS OF THE MAIN SURFACE LOW'S POSITION  
AND DEPTH. MEANWHILE, MODELS ALSO AGREE THAT THE UPPER RIDGE  
BUILDING INTO THE WEST SHOULD BE STRONGEST TUESDAY-WEDNESDAY.  
OVERALL, A MULTI-MODEL CONSENSUS OF DETERMINISTIC GUIDANCE LED BY  
THE 12Z ECMWF AND 18Z GFS WORKED WELL FOR THE WPC FORECAST WITH  
THE BLEND SERVING TO SMOOTH OUT THE SMALLER DIFFERENCES, AND THIS  
MAINTAINED GOOD CONTINUITY FROM THE PREVIOUS FORECAST.  
 
BY AROUND DAY 5/THURSDAY, MORE NOTABLE MODEL DIFFERENCES ARISE  
BOTH WITH THE MAIN TROUGH/LOW FEATURE AND UPSTREAM WITH PACIFIC  
SHORTWAVE ENERGY THAT COULD SERVE TO DAMPEN THE NORTHERN PART OF  
THE WESTERN NORTH AMERICA RIDGE, WHICH ARE INTERCONNECTED. FOR THE  
12Z/18Z CYCLE, THE ECMWF/CMC MAINTAINED A CLOSED LOW FOR THE MAIN  
FEATURE THROUGH THURSDAY WITH A BROADER MORE ROUNDED TROUGH, WHILE  
ESPECIALLY THE 12Z AND SOMEWHAT THE 18Z GFS ARE MORE OPEN/PHASED  
WITH THE NORTHERN STREAM. THERE HAVE ALSO BEEN RUN TO RUN AND  
MODEL DIFFERENCES WITH HOW MUCH ENERGY EXTENDS BACK SOUTHWEST INTO  
THE SOUTH-CENTRAL U.S. AND NORTHERN MEXICO AROUND THU-FRI, WITH  
BETTER CONSENSUS FOR SOME COMPARED TO ABOUT A DAY AGO, BUT GFS  
RUNS (ESPECIALLY THE 12Z) HAVE SHOWN MORE EXTENSION SOUTHWEST THAN  
THE OVERALL CONSENSUS. THE WPC FORECAST MAINTAINED A SIMILAR  
COMPROMISE APPROACH TO THE PREVIOUS FORECAST, ADDING THE INFLUENCE  
OF THE GEFS AND EC ENSEMBLE MEANS TO TEMPER THE OPERATIONAL MODEL  
DIFFERENCES. THE NEWER 00Z GUIDANCE CONTINUES TO SHOW SOME OF  
THESE DIFFERENCES PERSISTING, WITH ESPECIALLY THE CMC PRESENTING A  
DIFFERENT SOLUTION WITH THE UPPER TROUGH/LOW, MUCH MORE ROUNDED  
AND CLOSED THROUGH SATURDAY COMPARED TO ANY OTHER GUIDANCE FROM  
MULTIPLE CYCLES.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
AMPLE GULF OF MEXICO MOISTURE FLOWING INTO THE SURFACE/UPPER-LEVEL  
LOWS TRACKING NORTHEASTWARD OVER THE CENTRAL U.S. WILL LEAD TO  
WIDESPREAD RAIN AND THUNDERSTORMS FOR THE MISSISSIPPI VALLEY TO  
THE EAST COAST PARTICULARLY ON TUESDAY AND WEDNESDAY AHEAD OF THE  
COLD FRONTS. STORMS COULD BE SEVERE ACROSS THE DEEP SOUTH TUE/WED  
PER THE STORM PREDICTION CENTER. FURTHERMORE, HEAVY RAIN IS LIKELY  
TO CAUSE AREAS OF FLASH FLOODING PARTICULARLY DUE TO HIGH RAIN  
RATES, WITH A SLIGHT RISK INDICATED TUESDAY FOR PORTIONS OF THE  
LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS IN THE EXPERIMENTAL  
WPC MEDIUM RANGE EXCESSIVE RAINFALL OUTLOOK. SOME ISOLATED FLASH  
FLOODING IS ALSO POSSIBLE WEDNESDAY FOR THE SOUTHERN/CENTRAL  
APPALACHIANS AND SOUTHEAST AS THE FRONT PROGRESSES EASTWARD AND  
SPREADS RAINFALL TO THE EASTERN SEABOARD. ADDITIONALLY, SOME  
PRECIPITATION APPEARS LIKELY FROM THE NORTHERN PARTS OF THE PLAINS  
THROUGH THE NORTHEAST, WHICH COULD BE IN THE FORM OF SNOW.  
CURRENTLY THE HIGHEST PROBABILITIES FOR NOTABLE SNOW ARE IN THE  
UPPER GREAT LAKES REGION. IN THE WEST, MAINLY DRY WEATHER IS  
EXPECTED, WITH POSSIBLY A LITTLE LIGHT/SCATTERED PRECIPITATION  
ACTIVITY THAT COULD INCREASE SLIGHTLY IN COVERAGE BY THE END OF  
NEXT WEEK.  
 
THE STRONG UPPER RIDGE BUILDING INTO THE WEST WILL LEAD TO A BROAD  
AREA OF HIGHS 10-20F ABOVE NORMAL TUESDAY-SATURDAY WITH SLIGHTLY  
HIGHER LOCALIZED ANOMALIES POSSIBLE. THE BEST POTENTIAL TO REACH  
DAILY RECORD HIGHS WILL BE OVER CALIFORNIA DURING  
TUESDAY-THURSDAY. LEADING UPPER LEVEL TROUGHING SHOULD SUPPORT  
TEMPERATURES 10-20F BELOW AVERAGE ACROSS THE CENTRAL/SOUTHERN HIGH  
PLAINS TUESDAY AND WEDNESDAY. THE COOLER AIR SHOULD MODERATE  
CLOSER TO NORMAL BY THE LATTER PART OF NEXT WEEK AS IT PROGRESSES  
EASTWARD. AHEAD OF THE TROUGH AND COLD FRONTS, GENERALLY WARMER  
THAN NORMAL CONDITIONS ARE LIKELY ACROSS MUCH OF THE EASTERN THIRD  
OF THE U.S. FOR MUCH OF THE WEEK, TRANSITIONING TO NEAR NORMAL  
TEMPERATURES BY FRIDAY AND SATURDAY. ISOLATED RECORD HIGHS ARE  
POSSIBLE OVER PARTS OF FLORIDA TUESDAY-WEDNESDAY.  
 
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  
 
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/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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