423  
FXUS02 KWBC 160718  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
316 AM EDT MON MAY 16 2022  
 
VALID 12Z THU MAY 19 2022 - 12Z MON MAY 23 2022  
 
...PERSISTENT RECORD-BREAKING HEAT IS LIKELY IN THE SOUTH-CENTRAL  
U.S. THROUGH THIS WEEK WITH ANOMALOUS HEAT EXPANDING INTO THE EAST  
THIS WEEKEND...  
 
...HEAVY RAINFALL AND FLASH FLOODING POSSIBLE ALONG A STRONG COLD  
FRONT ACROSS THE NORTHERN TIER ON THURSDAY...  
 
   
..OVERVIEW
 
 
A DIGGING TROUGH OVER THE WEST AND RISING HEIGHTS ACROSS THE EAST  
LATE THIS WEEK WILL RESULT IN A MORE AMPLIFIED PATTERN ACROSS THE  
LOWER 48 YIELDING COOLER TEMPERATURES AND LOWERING SNOW LEVELS IN  
THE WEST AND A CONTINUED HOT REGIME FOR THE SOUTH AND EAST. A  
CLOSED LOW ACROSS THE NORTHERN TIER THURSDAY-FRIDAY AND A STRONG  
COLD FRONT SHIFTING EAST WILL CHANCES FOR HEAVY RAINFALL AND  
SEVERE WEATHER FOR SOME FROM THE UPPER MISSISSIPPI VALLEY/GREAT  
LAKES INTO THE EAST. THE UPPER TROUGH WILL DIG INTO THE CENTRAL  
AND EASTERN U.S. NEXT WEEKEND AS HEIGHT RISE AGAIN OUT WEST.  
TROPICAL MOISTURE WILL ALSO INCREASE RAIN/THUNDERSTORM CHANCES  
ACROSS FLORIDA LATE THIS WEEK AND INTO THE WEEKEND.  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
MODEL GUIDANCE HAS TRENDED STRONGER WITH A CLOSED LOW ACROSS THE  
NORTHERN HIGH PLAINS INTO THE UPPER MISSISSIPPI VALLEY THURSDAY  
AND FRIDAY, BUT SHOW RELATIVELY GOOD AGREEMENT ON THIS FEATURE,  
WITH MAINLY JUST SOME MINOR TIMING DIFFERENCES AS THE LOW LIFTS  
INTO CENTRAL CANADA AND THE AMPLIFIED TROUGH SLIDES INTO THE OHIO  
VALLEY/NORTHEAST ON SATURDAY. FOR THE FIRST HALF OF THE PERIOD, A  
GENERAL MODEL COMPROMISE WORKED WELL. AFTER THIS, MODEL GUIDANCE  
BEGINS TO SHOW MUCH MORE UNCERTAINTY SURROUNDING A COUPLE OF  
SHORTWAVES THROUGH THE WEST SUNDAY/MONDAY. THE ECMWF IS STRONGER  
WITH AN INITIAL SHORTWAVE DROPPING DOWN BEHIND THE EASTERN TROUGH  
TENDING TO AMPLIFY THIS FEATURE MORE THAN THE OTHER GUIDANCE  
RESULTING IN A STRONGER RIDGE OVER THE WEST. MEANWHILE, THE GFS  
AND THE CMC ARE WEAKER WITH THIS FIRST SHORTWAVE WHICH ALLOWS FOR  
A WEAKNESS TO ROUND THE TOP OF A PACIFIC UPPER HIGH AND SLIDE INTO  
THE WEST. THE WPC BLEND TRENDED TOWARDS THE ENSEMBLE MEANS WHICH  
SEEMED TO SIDE MORE WITH THE GFS AND CMC VS THE ECMWF, BUT STILL  
INCORPORATED SOME MINOR AMOUNTS OF THE ECMWF AND GFS FOR ADDED  
FLOW DEFINITION.  
 
   
..WEATHER/THREAT HIGHLIGHTS
 
 
INITIAL RIDGING ACROSS THE SOUTHERN PLAINS AND RISING HEIGHTS  
FARTHER EAST OVER THE DEEP SOUTH WILL CONTINUE TO PROMOTE A BROAD  
AREA OF HEAT ACROSS MUCH OF THE SOUTHERN U.S. DURING THE PERIOD.  
THE GREATEST AND MOST LASTING ANOMALIES THROUGH THE PERIOD SHOULD  
BE OVER TEXAS (PERSISTING FROM THE SHORT RANGE TIME FRAME) WHERE  
SOME LOCATIONS COULD SEE HIGHS UP TO 15-25F ABOVE NORMAL, WITH  
NUMEROUS DAILY RECORD HIGHS LIKELY. THE HEAT ACROSS TEXAS SHOULD  
FINALLY BEGIN TO MODERATE BY NEXT WEEKEND AS TROUGHING PRESSES  
THROUGH THE WEST. HOWEVER, WARM TO HOT TEMPERATURES ARE ALSO  
FORECAST FOR THE SOUTHEASTERN QUADRANT OF THE U.S. WITH POTENTIAL  
FOR DAILY RECORD HIGHS, AND WARMER THAN AVERAGE TEMPERATURES BY  
10-20F SHOULD EXPAND IN COVERAGE ACROSS THE OHIO VALLEY TO EASTERN  
SEABOARD BY LATER IN THE WEEK.  
 
A WARM FRONT LIFTING THROUGH THE OHIO VALLEY/APPALACHIANS ON  
THURSDAY WILL CONTINUE TO PROVIDE A FOCUS FOR SHOWERS AND STORMS  
ON THURSDAY, WITH A VERY LOCALIZED FLOOD THREAT PARTICULARLY IF  
HEAVY RAINFALL FALLS IN AREAS THAT ARE ALREADY SENSITIVE.  
MEANWHILE, MODERATE TO LOCALLY HEAVY RAINFALL IS LIKELY ALONG A  
STRONG COLD FRONT THROUGH THE NORTHERN TIER ON THURSDAY, WITH  
POTENTIAL FOR FLOOD AND FLASH FLOODING GIVEN VERY WET ANTECEDENT  
CONDITIONS ACROSS THAT REGION. ABOVE AVERAGE MOISTURE AND  
INSTABILITY WILL ALLOW FOR PRECIPITATION TO SPREAD ALONG THE  
FRONTAL BOUNDARY AS IT PUSHES THROUGH THE GREAT LAKES/OHIO VALLEY  
ON FRIDAY AND INTO THE EAST ON SATURDAY. LOCALLY HEAVY RAINFALL IS  
POSSIBLE. THE STORM PREDICTION CENTER HIGHLIGHTS A THREAT FOR  
SEVERE WEATHER AS WELL ACROSS THESE SAME REGIONS ALONG AND AHEAD  
OF THE COLD FRONT THURSDAY AND FRIDAY. BEHIND THIS FRONT,  
UNSEASONABLY COOL TEMPERATURES WILL SLIDE ACROSS THE  
NORTHWEST/NORTHERN ROCKIES ON THURSDAY INTO THE NORTH-CENTRAL U.S.  
FRIDAY AND SATURDAY. THIS IS EXPECTED TO LOWER SNOW LEVELS  
ALLOWING FOR SOME LIGHT SNOW TO FALL EVEN IN NORTHERN PARTS OF THE  
HIGH PLAINS. ELSEWHERE, TROPICAL MOISTURE INCREASING ACROSS THE  
FLORIDA PENINSULA LATE THIS WEEK MAY BRING A ROUND OF HEAVY  
RAINFALL TO PORTIONS OF THE SUNSHINE STATE WHILE PARTS OF THE  
WEST, CENTRAL GREAT BASIN, AND SOUTHWEST MAY AGAIN WARM UP  
UNDERNEATH RIDING MOVING BACK INTO THE REGION.  
 
SANTORELLI/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  
 

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page