169  
FXUS02 KWBC 161830  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
228 PM EDT THU JUN 16 2022  
 
VALID 12Z SUN JUN 19 2022 - 12Z THU JUN 23 2022  
 
...HEAT OVER THE NORTHERN/CENTRAL PLAINS THROUGH THE WEEKEND  
LIKELY TO SHIFT INTO THE MIDWEST THROUGH SOUTHEAST NEXT WEEK...  
 
   
..OVERVIEW
 
 
THE LATEST GUIDANCE IS CONSISTENT IN SHOWING A TRANSITION FROM AN  
AMPLIFIED TROUGH-RIDGE-TROUGH CONFIGURATION ON SUNDAY TOWARD A  
MORE TYPICAL SUMMERTIME PATTERN BY NEXT WEDNESDAY-THURSDAY,  
FEATURING A BROAD UPPER RIDGE ACROSS MUCH OF THE SOUTHERN HALF OF  
THE COUNTRY AND PROGRESSIVE BAND OF WESTERLIES ACROSS THE NORTHERN  
TIER STATES. WIDESPREAD HOT TEMPERATURES WILL PREVAIL UNDERNEATH  
THE EVOLVING RIDGE, WITH HIGHS REACHING 100F AS FAR NORTH AS THE  
DAKOTAS INTO SUNDAY FOLLOWED BY THE MOST ANOMALOUS HIGH  
TEMPERATURES SHIFTING MORE INTO THE MIDWEST THROUGH SOUTHEAST FROM  
MONDAY ONWARD. THE AMPLIFIED FLOW REGIME IN PLACE THROUGH THE  
WEEKEND SHOULD PROMOTE AN EARLY MONSOON TYPE PATTERN OVER THE FOUR  
CORNERS STATES, WHILE THE STRONG DYNAMICS EJECTING THROUGH THE  
NORTHWESTERN STATES SUNDAY INTO MONDAY MAY HELP TO PRODUCE LOCALLY  
HEAVY PRECIPITATION OVER/NEAR THE FAR NORTHERN ROCKIES. CANADIAN  
LOW PRESSURE ASSOCIATED WITH THIS EJECTING ENERGY WILL PUSH A  
FRONT INTO THE PLAINS, PRODUCING SOME AREAS OF  
SHOWERS/THUNDERSTORMS. FARTHER EAST, THERE WILL BE POTENTIAL FOR  
RAIN AHEAD OF A WARM FRONT ADVANCING INTO THE GREAT  
LAKES/NORTHEAST AND SCATTERED DIURNAL SHOWERS/STORMS ACROSS  
FLORIDA.  
 
   
..GUIDANCE/PREDICTABILITY EVALUATION
 
 
TRENDS IN THE LATEST GUIDANCE SUGGEST A SLIGHTLY MORE PROGRESSIVE  
PATTERN WITH THE GFS TRENDING PARTICULARLY FASTER WITH THE  
PROGRESSION OF THE MEAN TROUGH IN THE WEST. ON DAY 3, A GENERAL  
MODEL BLEND WAS UTILIZED TO MITIGATE TE PROGRESSIVE OUTPUT OF THE  
06Z GFS WITH RESPECT TO THE WESTERN TROUGH BUT ALSO TO FIND A  
MIDDLE GROUND BETWEEN THE CLOSED UPPER LOW THAT IS SHARED BY THE  
00Z EC/CMC AND THE OPEN WAVE CARRIED BY THE 00Z UKMET AND THE 06Z  
GFS. THERE'S REASONABLE AGREEMENT BETWEEN THE SELECTED MODELS ON  
THE GENERAL CONTOURS OF THE UPPER RIDGE CENTERED OVER THE DEEP  
SOUTH/MISSISSIPPI VALLEY. THE 00Z GFS WAS INCLUDED IN THE GENERAL  
MODEL BLEND ON DAY 4 TO HELP EMPHASIZE THE PIECE OF SHORTWAVE  
ENERGY ROTATING THROUGH THE MEAN TROUGH IN MONTANA. BY DAY 5 THE  
00Z GFS IS SWAPPED OUT FOR THE 06Z GEFS TO MODERATE THE ATTEMPT BY  
THE DETERMINISTICS TO SPLIT FLOW OVER THE NORTHWEST. WEIGHTING IS  
HIGHEST FOR THE 00Z EC AND 06Z GFS THROUGH DAY 5. THE 00Z ECE/CMCE  
WERE INTRODUCED THROUGH THE REST OF THE PERIOD WHILE THE 06Z GFS  
AND 00Z CMC REMOVED BY DAY 7. THE 06Z GFS WAS FASTER THAN THE 00Z  
EC WITH THE UPPER LOW PROPAGATING ALONG THE BRITISH COLUMBIA COAST  
ON DAY 6 WHILE THE ENSEMBLE MEANS HAD MORE OF A REASONABLE  
AVERAGED SOLUTION.  
 
   
..SENSIBLE WEATHER/THREAT HIGHLIGHTS
 
 
THE STRONG UPPER TROUGH EJECTING THROUGH THE NORTHWESTERN U.S.  
DURING SUNDAY-MONDAY MAY FOCUS SOME AREAS OF LOCALLY MODERATE TO  
HEAVY PRECIPITATION OVER/NEAR THE FAR NORTHERN ROCKIES. THE  
VIGOROUS DYNAMICS, SUFFICIENT MOISTURE, AND RECENT SIGNIFICANT  
PRECIPITATION SUPPORTED THE INTRODUCTION OF A SLIGHT RISK AREA IN  
THE EXPERIMENTAL DAY 4 EXCESSIVE RAINFALL OUTLOOK (EARLY SUNDAY  
INTO EARLY MONDAY) OVER PARTS OF WESTERN MONTANA. HIGHEST  
ELEVATIONS MAY SEE SOME SNOW WITH THIS SYSTEM. THE UNUSUALLY EARLY  
MONSOON TYPE PATTERN FARTHER SOUTH WILL BRING MUCH ABOVE NORMAL  
MOISTURE FOR THIS TIME OF YEAR NORTHWARD THROUGH THE FOUR CORNERS  
STATES AND VICINITY THROUGH THE WEEKEND, SUPPORTING AN INCREASE IN  
COVERAGE AND INTENSITY OF RAINFALL ACROSS THE REGION.  
RAIN/THUNDERSTORMS SHOULD CONTINUE INTO EARLY NEXT WEEK AS THE  
MOISTURE INTERACTS WITH A FRONT SLOWLY ADVANCING THROUGH THE WEST,  
THOUGH WITH ACTIVITY TENDING TO DECREASE IN THE NORTHWESTERN PART  
OF THE FOUR CORNERS REGION. THERE ARE STILL MIXED SIGNALS OVER HOW  
MUCH RAINFALL THE INTERACTION OF THIS MOISTURE WITH THE WESTERN  
FRONT ADVANCING INTO THE PLAINS WILL PRODUCE. HOWEVER THE  
POTENTIAL FOR SOME TRAINING/REPEAT ACTIVITY MAY HAVE TO BE  
MONITORED AS CONSENSUS SHOWS THIS PLAINS FRONT BECOMING ALIGNED  
WEST-EAST ALONG THE SOUTHERN EDGE OF THE WESTERLIES BY  
WEDNESDAY-THURSDAY. FARTHER EAST, THE EAST COAST/WESTERN ATLANTIC  
UPPER TROUGH AND POSSIBLE EMBEDDED LOW MAY BRING SOME SHOWERS TO  
NEW ENGLAND THROUGH SUNDAY. THEN AN AREA OF SHOWERS AND  
THUNDERSTORMS MAY PUSH ACROSS THE GREAT LAKES AND POSSIBLY INTO  
THE NORTHEAST UNDER NORTHWESTERLY FLOW ALOFT AND AHEAD OF AN  
ADVANCING WARM FRONT, WITH SOME ACTIVITY POSSIBLY ON THE HEAVY  
SIDE. THIS FRONT MAY SLOW DOWN ONCE IT REACHES THE EASTERN GREAT  
LAKES AND MID-ATLANTIC/NORTHEAST. THE FLORIDA PENINSULA SHOULD SEE  
MULTIPLE DAYS OF DIURNAL SHOWERS/STORMS FROM THE WEEKEND INTO NEXT  
WEEK AS THE FRONT PUSHING INTO AREA DECELERATES AND EVENTUALLY  
DISSIPATES.  
 
THE MOST ANOMALOUS TEMPERATURES DURING THE PERIOD WILL BE WITH A  
HEAT WAVE ACROSS THE NORTHERN HALF OF THE PLAINS THROUGH SUNDAY  
AND PUSHING INTO THE UPPER MIDWEST AS WELL BY MONDAY, WITH HIGHS  
REACHING UP TO 20-25F ABOVE NORMAL. SOME DAILY RECORDS FOR HIGHS  
AND WARM LOWS WILL BE POSSIBLE, WITH EVEN SOME POTENTIAL FOR A FEW  
MONTHLY RECORDS FOR WARM LOWS, GIVEN THAT LOWS AT LEAST IN THE  
UPPER 70S ARE FORECAST IN PORTIONS OF THE NORTH-CENTRAL U.S. A  
FRONT MOVING INTO THE PLAINS SHOULD START A COOLING TREND/EASTWARD  
SHIFT OF THE HEAT, ESPECIALLY OVER THE NORTHERN PLAINS. AS THE  
HEAT EXTENDS INTO THE MIDWEST THROUGH SOUTHEAST FROM MONDAY  
ONWARD, PLUS 10-15F OR SO ANOMALIES FOR HIGHS SHOULD BECOME COMMON  
AND MAY CHALLENGE DAILY RECORD HIGHS/WARM LOWS. SOUTHERN PARTS OF  
THE PLAINS WILL STAY HOT THROUGH THE PERIOD BUT WITH ANOMALIES  
TENDING TO BE IN THE PLUS 5-10F RANGE. BEFORE NEXT WEEK'S WARMER  
TREND OVER THE EAST, THE NORTHERN HALF OF THE REGION WILL SEE  
HIGHS 5-10F (LOCALLY MORE) BELOW NORMAL ON SUNDAY, PERHAPS  
LINGERING INTO MONDAY OVER NORTHERN NEW ENGLAND. ALSO FROM SUNDAY  
INTO MONDAY THE UPPER TROUGH CROSSING THE WEST WILL BRING THE  
REGION A COUPLE COOL DAYS WITH HIGHS UP TO 10-15F BELOW NORMAL.  
AFTER MONDAY THE WEST WILL SEE VARIOUS AREAS OF SOMEWHAT ABOVE OR  
BELOW READINGS.  
 
KEBEDE/RAUSCH  
 
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