129  
FXUS02 KWBC 170622  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
221 AM EDT THU MAR 17 2022  
 
VALID 12Z SUN MAR 20 2022 - 12Z THU MAR 24 2022  
 
***STRONG LOW PRESSURE SYSTEM WILL LIKELY PRODUCE HEAVY RAIN AND  
SEVERE STORMS ACROSS PORTIONS OF THE SOUTHERN U.S. BY EARLY NEXT  
WEEK***  
   
..OVERVIEW
 
 
A RATHER ACTIVE WEATHER PATTERN WILL BE DEVELOPING ACROSS MUCH OF  
THE NATION BEGINNING THIS WEEKEND, AND PARTICULARLY INTO THE  
BEGINNING OF NEXT WEEK AS A DEEP UPPER LEVEL TROUGH DEVELOPS OVER  
THE INTERMOUNTAIN WEST AS PACIFIC SHORTWAVE ENERGY MOVES INLAND.  
THIS WILL LIKELY EVOLVE INTO A CLOSED UPPER LOW BY MONDAY ALONG  
WITH AN INTENSIFYING SURFACE LOW OVER THE CENTRAL/SOUTHERN PLAINS  
THAT WILL EVENTUALLY RESULT IN HEAVY RAIN AND SEVERE STORMS FROM  
TEXAS TO THE DEEP SOUTH BY THE MIDDLE OF THE WEEK. THERE WILL  
ALSO BE A WELL ORGANIZED STORM SYSTEM EXITING THE NORTHEAST U.S.  
SUNDAY AHEAD OF THE CENTRAL U.S. EVENT.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE 00Z MODEL GUIDANCE SUITE IS GENERALLY IN ABOVE AVERAGE  
AGREEMENT THROUGH MONDAY NIGHT WITH THE OVERALL SYNOPTIC SCALE  
PATTERN AND THE EVOLUTION OF THE MAIN UPPER LEVEL TROUGH/CLOSED  
LOW OVER THE ROCKIES AND SOUTHERN PLAINS. MODEL DIFFERENCES  
BECOME MORE APPARENT AS THE UPPER LOW BEGINS LIFTING OUT AND  
EVOLVING INTO A POSITIVELY TILTED OPEN WAVE FEATURE BY THE MIDDLE  
OF THE WEEK, WITH THE CMC CONSIDERABLY SLOWER AND KEEPS THE TROUGH  
AXIS IN PLACE LONGER ACROSS THE PLAINS, WHEREAS THE GFS AND ECMWF  
INDICATE A NORTHERN STREAM SHORTWAVE AMPLIFYING THE TROUGH OVER  
THE GREAT LAKES AND OHIO VALLEY REGION BY THURSDAY. THE MODELS  
ARE STILL STRUGGLING WITH THE ARRIVAL OF SHORTWAVE ENERGY CROSSING  
THE NORTHERN PERIPHERY OF THE UPPER RIDGE OVER THE WEST COAST  
LATER IN THE PERIOD THAT WOULD AFFECT THE PACIFIC NORTHWEST, WITH  
THE PAST FEW RUNS OF THE GFS DIFFERING THE MOST FROM THE MODEL  
CONSENSUS.  
 
TAKING THESE FACTORS INTO ACCOUNT, THE WPC FORECAST WAS PRIMARILY  
BASED ON A MULTI-DETERMINISTIC MODEL BLEND AS A STARTING POINT  
THROUGH TUESDAY MORNING, AND THEN INCORPORATED MORE OF THE  
ENSEMBLE MEANS WHILST STILL MAINTAINING SMALLER CONTRIBUTIONS FROM  
THE ECMWF/GFS/CMC GOING FORWARD THROUGH THURSDAY.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
THE SURFACE LOW OVER THE NORTHEAST ON SUNDAY WILL LIKELY BE  
ACCOMPANIED BY SOME LINGERING SNOW SHOWERS ACROSS NORTHERN  
PORTIONS OF NEW ENGLAND, AND THEN DRIER WEATHER COMMENCES FOR THIS  
REGION IN TIME FOR THE BEGINNING OF THE WORK WEEK. ATTENTION THEN  
TURNS TO THE PLAINS AND GULF COAST REGION AS A SURFACE LOW BECOMES  
BETTER ORGANIZED BY LATE MONDAY OVER NORTHERN TEXAS/OKLAHOMA AND  
TAPS INTO A SURGE OF GULF MOISTURE ACROSS TEXAS AND THE CENTRAL  
GULF COAST REGION. THERE IS A STRONG MODEL SIGNAL FOR EPISODES OF  
HEAVY RAINFALL THAT COULD RESULT IN INSTANCES OF FLASH FLOODING,  
MAINLY LATER IN THE DAY MONDAY AND ESPECIALLY INTO TUESDAY AND  
PERSISTING INTO EARLY WEDNESDAY. THE BEST PROSPECTS FOR THIS  
WOULD BE FROM THE ARKLATEX REGION TO THE SOUTHERN APPALACHIANS.  
THERE IS ALSO AN INCREASING THREAT OF SEVERE THUNDERSTORMS WITH  
FAVORABLE DYNAMICS AND INSTABILITY PARAMETERS IN PLACE, MAINLY  
ACROSS EASTERN TEXAS AND THE LOWER MISSISSIPPI RIVER VALLEY. THE  
STORM PREDICTION CENTER HAS ADDITIONAL INFORMATION PERTAINING TO  
THE SEVERE WEATHER POTENTIAL.  
 
IN TERMS OF TEMPERATURES, HIGHS ARE EXPECTED TO BE WELL ABOVE  
AVERAGE ACROSS MOST OF THE CENTRAL AND NORTHERN PLAINS AND  
MIDWEST, WITH HIGHS UP TO 25 DEGREES ABOVE AVERAGE ON SUNDAY.  
THERE WILL ALSO BE A SURGE OF HUMIDITY ACROSS THE GULF COAST  
REGION AHEAD OF THE COLD FRONT FROM THE CENTRAL U.S. LOW. WARM  
WEATHER RETURNS TO THE WEST COAST REGION FOR THE TUESDAY THROUGH  
THURSDAY TIME PERIOD AS AN UPPER RIDGE BUILDS IN BEHIND THE  
DEPARTING TROUGH. SOME BELOW AVERAGE READINGS ARE LIKELY ACROSS  
THE ROCKIES AND WESTERN HIGH PLAINS FOR EARLY IN THE WEEK IN  
ASSOCIATION WITH THE UPPER TROUGH, BUT NO MAJOR SURGES OF ARCTIC  
AIR ARE EXPECTED.  
 
HAMRICK  
 
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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