017  
FXUS02 KWBC 292046  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
445 PM EDT WED JUN 29 2022  
 
VALID 12Z SAT JUL 02 2022 - 12Z WED JUL 06 2022  
   
..OVERVIEW
 
 
TODAY'S MODELS AND ENSEMBLE MEANS ARE CONSISTENT WITH THE MEAN  
PATTERN. A REX BLOCK CONFIGURATION SHOULD PERSIST THROUGH THE  
MIDDLE OF NEXT WEEK, WITH RIDGING OVER NORTHWEST CANADA AND A MEAN  
LOW ANCHORING AN EASTERN PACIFIC TROUGH. DOWNSTREAM, 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 OVER  
THE ROCKIES AND NORTHERN PLAINS. WITHIN THE PACIFIC TROUGH,  
CONSENSUS SHOWS AN INITIAL CLOSED LOW/SURROUNDING FLOW EJECTING  
INTO THE WESTERN U.S./SOUTHWEST CANADA NEXT WEEK AS UPSTREAM  
ENERGY NEAR THE ALASKA PENINSULA EARLY SATURDAY REPLACES IT. THE  
NORTHERN PLAINS RIDGE AXIS MAY RETROGRADE SOMEWHAT BY WEDNESDAY  
ONCE THIS REPLACEMENT IS COMPLETE. 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 STILL MONITORING A BROAD AREA OF LOW PRESSURE OVER THE  
WESTERN 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
 
 
GUIDANCE CONTINUES TO SHOW A NUMBER OF DETAIL UNCERTAINTIES THAT  
MAY TAKE UNTIL THE SHORT RANGE TIME FRAME TO RESOLVE, EVEN THOUGH  
AGREEMENT IS GOOD FOR THE LARGE SCALE PATTERN. MODELS/ENSEMBLE  
MEMBERS ARE STILL VARIED AND INCONSISTENT FROM RUN TO RUN FOR  
SHORTWAVE DETAILS WITHIN THE EASTERN CANADA/NORTHEASTERN U.S. MEAN  
TROUGH BEHIND A LEADING SYSTEM THAT BRINGS A FRONT INTO THE  
NORTHEAST/MID-ATLANTIC DURING THE WEEKEND. THIS MAKES IT MORE  
DIFFICULT TO MAINTAIN A STABLE FORECAST FOR SURFACE FRONT/WAVE  
DETAILS TO THE EAST OF THE ROCKIES BUT A BLEND/ENSEMBLE MEAN  
APPROACH AT LEAST MITIGATES THE PROBLEM TO SOME DEGREE. SOME  
GENERAL CLUSTERING IS DEVELOPING FOR HOW THE INITIAL UPPER  
LOW/TROUGH NEAR THE WEST COAST WILL EJECT INTO THE WESTERN  
U.S./SOUTHWESTERN CANADA EARLY NEXT WEEK AS UPSTREAM ENERGY TAKES  
ITS PLACE (BUT WITH QPF DETAILS STILL SENSITIVE TO SPECIFICS),  
WITH THE RESULTING AXIS OF THE TROUGH AS WELL AS RIDGE TO THE EAST  
LIKELY TO RETROGRADE A BIT BY NEXT WEDNESDAY. HOWEVER THERE ARE  
STILL MEANINGFUL DIFFERENCES FOR LOW-PREDICTABILITY SHORTWAVE  
IMPULSES CONTINUING ALONG THE NORTHERN TIER EARLY-MID WEEK.  
COMPARED TO PRIOR DAYS THE LATEST MODEL RUNS HAVE BACKED OFF  
SLIGHTLY FOR THE DEPICTION OF THE CURRENT WESTERN GULF FEATURE,  
HAVING THE SURFACE REFLECTION DISSIPATE WITHIN A COUPLE DAYS AND  
MAINTAINING ONLY A COMPACT MID-LEVEL IMPULSE. CURRENTLY THE 12Z  
GFS/ECMWF/UKMET SHARE SOME SIMILARITIES ALOFT WHILE THE CMC HAS  
BEEN CONSISTENTLY ILL-DEFINED. SMALL SCALE OF THIS FEATURE  
SUGGESTS LOW PREDICTABILITY FOR TRACK/STRENGTH.  
 
THE UPDATED FORECAST STARTED WITH A BLEND OF 00Z/06Z OPERATIONAL  
MODELS FOR ABOUT THE FIRST HALF OF THE PERIOD AND THEN STEADILY  
WORKED UP TO HALF TOTAL WEIGHT OF THE MEANS (06Z GEFS/00Z ECENS)  
BY DAY 7 WEDNESDAY. THIS MAINTAINED THE ESSENCE OF THE MEAN  
PATTERN AS WELL AS MOST FRONTAL/WAVE DETAILS OVER THE WEST. MODEL  
ADJUSTMENTS LED TO SOME FRONTAL/WAVE DETAIL CHANGES FARTHER EAST  
BUT LATE-PERIOD ENSEMBLE MEAN INPUT HELPED TO TEMPER CONTINUITY  
DIFFERENCES SOMEWHAT.  
   
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
 
 
MOISTURE ASSOCIATED WITH LOW PRESSURE CURRENTLY OVER THE WESTERN  
GULF MAY ENHANCE RAINFALL ACROSS PARTS OF THE LOWER MISSISSIPPI  
VALLEY AND INTO THE DEEP SOUTH. THE BEHAVIOR AND RAINFALL EFFECTS  
OF SUCH COMPACT FEATURES ARE NOTORIOUSLY DIFFICULT TO FORECAST SO  
CONFIDENCE IN DETAILS IS BELOW AVERAGE. CHECK THE LATEST PRODUCTS  
FROM THE NATIONAL HURRICANE CENTER FOR MORE INFORMATION ON THIS  
FEATURE. 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 NORTHEAST INTO THE OHIO  
VALLEY AND CENTRAL PLAINS WILL PUSH GRADUALLY EASTWARD DURING THE  
WEEKEND 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, WITH STALLING OF THE WESTERN END AND  
DECELERATION OF THE EASTERN PART OF THE FRONT ASSISTING IN THE  
POTENTIAL FOR SOME LOCALLY SIGNIFICANT TOTALS. POSSIBLE  
INTERACTION WITH SOUTHERN TIER MOISTURE IS YET ANOTHER FACTOR THAT  
WILL REQUIRE MONITORING. THIS FRONT MAY CONTINUE TO BE A FOCUS FOR  
RAINFALL INTO NEXT WEEK. 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 A PERIOD OF HEAVIER RAINFALL NEAR THE  
CANADIAN BORDER AROUND EARLY NEXT WEEK AS SOME ENERGY EJECTS FROM  
THE TROUGH. MOISTURE/CONVECTION WITH SOME POTENTIALLY HEAVY  
ACTIVITY COULD ALSO EXTEND ACROSS AT LEAST THE NORTHERN  
PLAINS/UPPER MIDWEST, AIDED BY NORTHERN TIER SURFACE FEATURES AND  
SHORTWAVES EMERGING FROM THE WEST.  
 
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 A  
STRENGTHENING UPPER LEVEL RIDGE. HIGHS AROUND 10-15F ABOVE NORMAL  
ARE POSSIBLE OVER/NEAR THE CENTRAL PLAINS, EQUATING TO  
TEMPERATURES IN THE MID 90S TO LOW 100S. SOUTHERN PLAINS LOCATIONS  
WILL SEE A SLIGHTLY HOTTER TREND AS WELL BUT WITH LESS EXTREME  
ANOMALIES. OUT WEST, BELOW NORMAL HIGHS WILL SPREAD GRADUALLY  
INLAND FROM THE WEST COAST DURING THE WEEKEND INTO EARLY NEXT WEEK  
DUE TO NEARBY UPPER TROUGHING. A FEW LOCATIONS MAY SEE HIGHS  
10-15F BELOW NORMAL AROUND SUNDAY-MONDAY. EXPECT A MODERATING  
TREND CLOSER TO NORMAL HEADING INTO MIDWEEK. IN THE EAST, A STABLE  
UPPER PATTERN OF WESTERLIES ACROSS THE NORTHEAST AND RIDGING OVER  
THE SOUTH (WITH A MEAN SURFACE FRONTAL BOUNDARY BETWEEN THE TWO)  
SHOULD KEEP BOTH DAYTIME HIGHS AND OVERNIGHT LOWS WITHIN A FEW  
DEGREES OF NORMAL THROUGH MOST OF THE PERIOD.  
 
RAUSCH/SANTORELLI  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY,  
MON-TUE, JUL 4-JUL 5.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE EASTERN  
DAKOTAS AND THE NORTHERN MINNESOTA.  
- FLOODING LIKELY ACROSS PORTIONS OF EASTERN IOWA.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN  
PLAINS INTO THE LOWER AND MID-MISSISSIPPI VALLEY, THE TENNESSEE  
VALLEY, AS WELL AS THE INTERIOR PORTION OF THE DEEP SOUTH,  
TUE-WED, JUL 5-JUL 6.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE LOWER TO MID-MISSISSIPPI  
VALLEY, MON-WED, JUL 4-JUL 6.  
 
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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