143  
FXUS02 KWBC 181958  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
357 PM EDT MON JUL 18 2022  
 
VALID 12Z THU JUL 21 2022 - 12Z MON JUL 25 2022  
 
...DANGEROUS HEAT TO PERSIST OVER THE CENTRAL U.S. THROUGH THE  
START OF NEXT WEEK...  
   
..OVERVIEW
 
 
A STRONG UPPER RIDGE CENTERED OVER THE SOUTHWEST/FOUR CORNERS  
REGION AS OF EARLY THURSDAY MAY SHIFT ITS EMPHASIS SOMEWHAT  
EASTWARD BY THE WEEKEND, THOUGH WITH INCREASING UNCERTAINTY OVER  
EXACTLY WHERE RIDGING WILL BE LOCATED. THIS RIDGE WILL KEEP HOT  
AND HUMID WEATHER OVER THE CENTRAL/SOUTHERN PLAINS FOR A MAJORITY  
OF THE PERIOD. SOME SOUTHERN LOCATIONS COULD SEE READINGS APPROACH  
OR BREAK DAILY RECORDS FOR HIGHS AND VERY WARM NIGHTTIME LOWS.  
WITH SOMEWHAT LESS EXTREME ANOMALIES, AREAS FROM THE  
TENNESSEE/OHIO VALLEYS THROUGH MID-ATLANTIC/NEW ENGLAND WILL  
EXPERIENCE MULTIPLE HOT DAYS AS WELL. THE WEST SHOULD MODERATE  
AFTER MIDWEEK WITH THE APPROACH/EJECTION OF EASTERN PACIFIC UPPER  
TROUGH ENERGY. THIS ENERGY AND OTHER FEATURES ACROSS SOUTHERN  
CANADA AND THE NORTHERN TIER U.S. WILL FLOW AROUND THE RIDGE AND  
FEED INTO A BROAD NORTHEASTERN U.S. MEAN TROUGH, SUPPORTING ONE OR  
MORE WAVES/FRONTAL SYSTEMS AND EPISODES OF SHOWERS AND  
THUNDERSTORMS FROM THE NORTHERN TIER INTO THE EAST. MONSOONAL  
MOISTURE OVER THE SOUTHWEST/SOUTHERN ROCKIES WILL PROMOTE DAILY  
CHANCES OF SHOWERS AND STORMS, SOME OF WHICH COULD LEAD TO FLASH  
FLOODING. SOME INCREASE OF THIS ACTIVITY WILL BE POSSIBLE DURING  
THE WEEKEND IF THE FOUR CORNERS RIDGE DOES INDEED ADJUST EASTWARD  
FOR A TIME.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE OVERALL SYNOPTIC PATTERN OF TROUGHING ALONG THE NORTHERN TIER  
STATES AND RIDGING IN THE SOUTH DURING THE MEDIUM RANGE WAS  
CAPTURED WELL BY THE DETERMINISTICS THROUGH DAY 4 AND ENSEMBLES  
LATER IN THE PERIOD. A GENERAL MODEL BLEND OF THE 00Z EC/UK/CMC  
AND 06Z GFS SUITE WERE UTILIZED TO CAPTURE THE INCOMING  
UPPER-LEVEL LOW IN THE PACIFIC NORTHWEST. THERE WERE SOME  
DIFFERENCES IN POSITION AND INTENSITY OF THE UPPER TROUGH AS IT  
MOVES ACROSS THE NORTHWEST ON DAY 5, SO ENSEMBLES WERE  
INCORPORATED HERE. BY DAYS 6 & 7, A PRIMARILY ENSEMBLE MEAN SPREAD  
WAS USED TO ACCOUNT FOR UNCERTAINTIES POSED BY THE DETERMINISTIC  
GUIDANCE.  
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
THE MOST ANOMALOUS HEAT OVER THE CENTRAL U.S. WILL LIKELY FOCUS  
OVER THE CENTRAL PLAINS WHERE THE BEST POTENTIAL EXISTS FOR  
MULTIPLE DAYS OF HIGHS 10-15F ABOVE NORMAL. SOME OF THE HEAT MAY  
ALSO EVENTUALLY DRIFT INTO PARTS OF THE TENNESSEE VALLEY. TOWARD  
SUNDAY-MONDAY A COLD FRONT MAY SUPPRESS THE HEAT OVER THE  
NORTH-CENTRAL PLAINS. TYPICALLY HOTTER SOUTHERN PLAINS LOCATIONS  
WILL SEE LESS EXTREME ANOMALIES BUT OVERALL THERE WILL BE A BROAD  
AREA WITH HIGHS REACHING OR EXCEEDING 100F FOR HIGHS, WHILE VERY  
WARM LOWS IN THE UPPER 70S TO LOW 80S WILL PROVIDE LITTLE  
NIGHTTIME RELIEF. THIS HEAT WAVE WILL LIKELY BRING SCATTERED  
RECORDS, MOST LIKELY OVER THE SOUTHERN PLAINS TO LOWER/MID MS  
VALLEY.  
 
OVER THE WEST, MONSOONAL MOISTURE AND ASSOCIATED DIURNALLY FAVORED  
SHOWERS/STORMS WITH LOCALLY HEAVY RAINFALL MAY KEEP PARTS OF THE  
FOUR CORNERS/GREAT BASIN REGION WITHIN A FEW DEGREES ON EITHER  
SIDE OF NORMAL DURING THROUGH THE PERIOD. THE MOST LIKELY SCENARIO  
OF AN EASTWARD SHIFT OF UPPER RIDGING AFTER LATE THIS WEEK WOULD  
LEAD TO AN INCREASE OF MOISTURE/RAINFALL NEXT WEEKEND AND PERHAPS  
A BIT OF A WESTWARD SHIFT IN THE OVERALL MOISTURE AXIS. HOWEVER  
THERE IS A LOWER PROBABILITY POTENTIAL FOR THE FOUR CORNERS UPPER  
RIDGE TO BE MORE PERSISTENT, WHICH WOULD TEND TO MAINTAIN THE  
EXISTING LATE WEEK PATTERN. THE APPROACH/EJECTION OF PACIFIC  
TROUGH ENERGY SHOULD BRING HIGHS DOWN TO NEAR NORMAL LEVELS OVER  
AN INCREASING PORTION OF THE WEST BY FRIDAY-SATURDAY. A REBOUND OF  
UPPER RIDGING OVER THE NORTHWEST MAY BRING HIGHS TO 5-10F OR SO  
ABOVE NORMAL OVER THAT REGION BY SUNDAY-MONDAY.  
 
THE FAIRLY VIGOROUS LATE WEEK SYSTEM OVER EASTERN CANADA AND ITS  
TRAILING FRONT INTO THE EASTERN U.S. MAY PRODUCE SOME LOCALLY  
HEAVY RAINFALL. THERE WILL LIKELY BE OTHER AREAS OF ENHANCED  
RAINFALL FROM THE NORTHERN TIER INTO THE EAST DURING THE REST OF  
THE PERIOD, BUT WITH MUCH LESS CONFIDENCE IN SPECIFICS DUE TO  
GUIDANCE DIFFICULTY IN RESOLVING THE DETAILS WITHIN SOUTHERN  
CANADA/NORTHERN U.S. FLOW ALOFT, INCLUDING EJECTING PACIFIC ENERGY  
THAT JOINS THIS STREAM. THE MID-ATLANTIC AND NORTHEAST WILL BE ON  
THE VERY WARM TO HOT SIDE, WITH SOME LOCATIONS POSSIBLY SEEING  
MORE CONSECUTIVE DAYS OF PLUS 5-10F ANOMALIES FOR HIGHS THAN  
PREVIOUSLY EXPERIENCED SO FAR THIS SUMMER. THE FRONT REACHING THE  
EAST COAST BY FRIDAY COULD LEAD TO A BRIEF AND SLIGHT DIP IN  
TEMPERATURES BEFORE IT WEAKENS DURING THE WEEKEND. PERSISTENT  
MOISTURE WILL ALLOW FOR MULTIPLE EPISODES OF SHOWERS/THUNDERSTORMS  
OVER THE SOUTHEAST/FLORIDA AND CENTRAL GULF COAST REGION.  
CONTINUES TO EXPECT NEAR NORMAL TEMPERATURES OVER THOSE AREAS.  
 
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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL GREAT BASIN AND THE  
SOUTHWEST, SAT-MON, JUL 23-JUL 25.  
- HEAVY RAIN ACROSS PORTIONS OF THE GREAT LAKES, THE MIDDLE  
MISSISSIPPI VALLEY, THE CENTRAL APPALACHIANS, THE OHIO VALLEY, AND  
THE UPPER MISSISSIPPI VALLEY, SAT-SUN, JUL 23-JUL 24.  
- SEVERE WEATHER ACROSS PORTIONS OF THE NORTHEAST, THU, JUL 21.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN  
PLAINS.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI  
VALLEY, THE SOUTHERN APPALACHIANS, THE SOUTHEAST, THE SOUTHERN  
PLAINS, AND THE OHIO VALLEY, THU-MON, JUL 21-JUL 25.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE SOUTHEAST, THE  
MID-ATLANTIC, THE SOUTHERN APPALACHIANS, AND THE TENNESSEE VALLEY,  
SAT-MON, JUL 23-JUL 25.  
- HEAVY RAIN ACROSS PORTIONS OF THE ALASKA PANHANDLE AND MAINLAND  
ALASKA, THU-SUN, JUL 21-JUL 24.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF MAINLAND  
ALASKA, THU-FRI, JUL 21-JUL 22.  
 
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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