327  
FXUS02 KWBC 290536  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
136 AM EDT WED JUN 29 2022  
 
VALID 12Z SAT JUL 02 2022 - 12Z WED JUL 06 2022  
   
..OVERVIEW
 
 
GUIDANCE AGREES FAIRLY WELL ON THE LARGE SCALE PATTERN, FEATURING  
A REX BLOCK CONFIGURATION WITH RIDGING OVER NORTHWEST CANADA AND  
AN UPPER LOW ANCHORING A MEAN TROUGH OFF THE WEST COAST.  
MEANWHILE, A BROAD MEAN TROUGH OVER EASTERN CANADA WILL EXTEND  
INTO THE NORTHEASTERN U.S., WHILE SOUTHERN TIER U.S. RIDGING HOLDS  
STRONG AND ALSO BUILDS INTO THE ROCKIES AND NORTHERN PLAINS. THE  
EASTERN NORTH AMERICA MEAN TROUGH WILL SUPPORT ONE OR MORE  
RAINFALL-FOCUSING FRONTAL SYSTEMS TO THE EAST OF THE ROCKIES WHILE  
THE TROUGH NEAR THE WEST COAST WILL KEEP NEARBY TEMPERATURES ON  
THE COOL SIDE AND OCCASIONALLY BRING UNSETTLED WEATHER TO THE  
NORTHWEST. THE NATIONAL HURRICANE CENTER IS MONITORING A BROAD  
AREA OF LOW PRESSURE OVER THE NORTHWESTERN GULF OF MEXICO, WITH  
FLOW AROUND THE SOUTHERN TIER UPPER RIDGE POSSIBLY BRINGING THIS  
FEATURE AND ITS MOISTURE INTO THE WESTERN GULF COAST REGION.  
EXPECT HOT TEMPERATURES TO EXPAND OVER THE CENTRAL U.S. DURING THE  
FIRST HALF OF NEXT WEEK AS THE PLAINS RIDGE ALOFT BECOMES MORE  
PRONOUNCED.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
THE LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW VERY GOOD  
CONSENSUS ON THE LARGE SCALE PATTERN, THOUGH WITH SOME LINGERING  
UNCERTAINTIES IN THE DETAILS, WHICH MAY TAKE UNTIL THE SHORT RANGE  
PERIOD TO RESOLVE. THIS INCLUDES INDIVIDUAL SHORTWAVES WITHIN THE  
CANADIAN TROUGH WHOSE INFLUENCE AFFECTS FRONTAL POSITIONS EAST OF  
THE ROCKIES, AS WELL AS THE DETAILS OF THE UPPER TROUGH NEAR THE  
WEST COAST. IN THE WEST, MODELS SUGGEST SOME INTERACTION/MERGING  
OF AN INITIAL LOW OFF THE PACIFIC NORTHWEST WITH A COMPACT LOW  
DROPPING SOUTH OUT OF THE GULF OF ALASKA. THIS SHOULD ACT TO  
REINFORCE THE UPPER TROUGH THROUGH THE PERIOD, WITH A SLIGHT  
WEST-NORTHWEST DRIFT OF ITS MAIN AXIS. BY EARLY NEXT WEEK,  
SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH SHOULD EJECT INTO  
THE NORTHWEST, BUT THERE ARE SOME TIMING DIFFERENCES WITH THIS  
WHICH HAS IMPLICATIONS FOR QPF ACROSS THE NORTHERN ROCKIES/HIGH  
PLAINS LATE PERIOD. FOR THE NORTHWESTERN GULF FEATURE, LATEST  
MODEL RUNS HAVE BACKED OFF SLIGHTLY AND MOSTLY DON'T SHOW MUCH OF  
A SURFACE OR UPPER LEVEL REFLECTION BY THE START OF THE MEDIUM  
RANGE PERIOD. THE ECMWF IS THE MOST PRONOUNCED WITH THIS FEATURE,  
ALTHOUGH HESITATE TO CALL IT AN OUTLIER BECAUSE GIVEN THE TROPICAL  
NATURE OF THIS FEATURE, ITS NOT OUT OF THE REALM OF POSSIBILITIES.  
REGARDLESS, UNCERTAINTY IS LOW AT BEST FOR BOTH PERSISTENCE OF  
THIS FEATURE AND EXACTLY WHERE IT WILL TRACK.  
 
THE WPC FORECAST FOR THE OVERNIGHT PACKAGE USED A BLEND OF THE  
OPERATIONAL DETERMINISTIC MODELS FOR DAYS 3-5 WITH MORE INCLUSION  
OF THE ENSEMBLE MEANS DAYS 6-7 (UP TO 50 PERCENT) TO TRY TO  
MITIGATE THE DIFFERENCES SEEN WITH THE WESTERN U.S. TROUGH. THIS  
MAINTAINS GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST AS WELL.  
 
   
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
 
 
MOISTURE ASSOCIATED WITH A TROPICAL FEATURE INTO THE WEST GULF  
REGION MAY ENHANCE RAINFALL ACROSS PARTS OF THE LOWER MISSISSIPPI  
VALLEY AND INTO THE DEEP SOUTH, THOUGH VERY UNCERTAIN ON BOTH QPF  
AMOUNTS AND IMPACTS. SEE THE LATEST FROM THE NATIONAL HURRICANE  
CENTER ON THIS. SHOWERS AND STORMS MAY ALSO LINGER FARTHER EAST  
INTO THE SOUTHEAST INTO THIS WEEKEND WITH THE PRESENCE OF A  
WEAKENING BOUNDARY AND IMPULSES MOVING THROUGH THE FLOW ALOFT.  
FARTHER NORTH, A FRONT INITIALLY ORIENTED FROM THE GREAT LAKES  
INTO THE MIDWEST WILL PUSH GRADUALLY SOUTHEASTWARD AND SUPPORT  
ORGANIZED AREAS OF SHOWERS AND STORMS ALONG AND AHEAD OF IT. SOME  
RAINFALL MAY BE HEAVY FROM THE CENTRAL PLAINS INTO THE  
MID-ATLANTIC AND SOUTHERN NEW ENGLAND, WITH DECELERATION OF THE  
FRONT LATER IN THE WEEKEND HELPING TO MAINTAIN THE POTENTIAL FOR  
SOME LOCALLY SIGNIFICANT TOTALS. POSSIBLE INTERACTION WITH  
SOUTHERN TIER MOISTURE IS YET ANOTHER FACTOR THAT WILL REQUIRE  
MONITORING. MONSOONAL MOISTURE OVER THE FOUR CORNERS REGION MAY  
PROMOTE SCATTERED AREAS OF HEAVIER RAINFALL WITH IMPULSES AND  
MOISTURE LIFTING NORTHWARD BETWEEN UPPER RIDGING TO THE EAST AND  
THE TROUGH NEAR THE WEST COAST. THIS WEST COAST TROUGH MAY PRODUCE  
PERIODS OF RAINFALL OVER PARTS OF THE NORTHWEST AND THERE IS A  
SIGNAL FOR INCREASING RAINFALL NEAR THE CANADIAN BORDER AROUND  
EARLY NEXT WEEK AS SOME ENERGY EJECTS FROM THE TROUGH.  
MOISTURE/CONVECTION COULD ALSO EXTEND ACROSS THE NORTHERN  
PLAINS/UPPER MIDWEST BY NEXT MONDAY-TUESDAY AHEAD OF A HIGH PLAINS  
WAVE AND LEADING WARM FRONT WITH EVENTUALLY MAY STALL ACROSS THE  
REGION BY TUESDAY INTO WEDNESDAY. RAINFALL MAY RETURN TO PARTS OF  
THE NORTHEAST BY NEXT TUESDAY AS WELL ASSOCIATED WITH A WEAK AREA  
OF LOW PRESSURE NEAR THE COAST.  
 
THE GREATEST CONCERN FOR TEMPERATURES DURING THE MEDIUM RANGE  
PERIOD WILL BE WITH HEAT LIKELY TO BUILD AGAIN ACROSS THE CENTRAL  
AND NORTHERN PLAINS BY EARLY NEXT WEEK IN RESPONSE TO AN UPPER  
LEVEL RIDGE. HIGHS AROUND 10 TO 15 DEGREES ABOVE NORMAL IS  
POSSIBLE FOR PARTS OF THE NORTH-CENTRAL PLAINS, EQUATING TO  
TEMPERATURES IN THE MID TO UPPER 90S. SOUTHERN PLAINS LOCATIONS  
WILL SEE SLIGHTLY HOTTER CONDITIONS AS WELL BUT WITH LESS EXTREME  
ANOMALIES. OUT WEST, BELOW NORMAL HIGHS WILL SPREAD GRADUALLY  
INLAND FROM THE WEST COAST DUE TO NEARBY UPPER TROUGHING WITH A  
FEW LOCATIONS WITH HIGHS 10-15F BELOW NORMAL AROUND SUNDAY-MONDAY.  
IN THE EAST, A LINGERING FRONTAL BOUNDARY SHOULD KEEP BOTH DAYTIME  
HIGHS AND OVERNIGHT LOWS NEAR NORMAL THROUGH MOST OF THE PERIOD.  
 
SANTORELLI/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  
 

 
 

 
 
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