279  
FXUS02 KWBC 282029  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
429 PM EDT TUE JUN 28 2022  
 
VALID 12Z FRI JUL 01 2022 - 12Z TUE JUL 05 2022  
   
..OVERVIEW
 
 
GUIDANCE AGREES FAIRLY WELL ON THE LARGE SCALE PATTERN, FEATURING  
A REX BLOCK CONFIGURATION CENTERED NEAR 130-135W LONGITUDE  
(RIDGING OVER NORTHWEST CANADA AND AN UPPER LOW ANCHORING A MEAN  
TROUGH OFF THE WEST COAST), A BROAD MEAN TROUGH OVER EASTERN  
CANADA AND EXTENDING INTO THE NORTHEASTERN U.S., AND SOUTHERN TIER  
U.S. RIDGING WHOSE NORTHWESTWARD EXTENSION DRIFTS FROM THE ROCKIES  
INTO THE 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 AND BEYOND  
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
 
 
ALTHOUGH THE MODELS AND ENSEMBLE MEANS DISPLAY GOOD CONSENSUS ON  
THE OVERALL PATTERN, INDIVIDUAL MODELS/SEQUENTIAL RUNS SHOW  
SIGNIFICANT SPREAD AND VARIABILITY WITH EMBEDDED FEATURES THAT  
WILL AFFECT SENSIBLE WEATHER OVER SOME AREAS. THESE INCLUDE  
INDIVIDUAL SHORTWAVES WITHIN THE CANADIAN TROUGH WHOSE INFLUENCE  
EXTENDS INTO THE NORTHEASTERN QUADRANT OF THE LOWER 48 (AFFECTING  
FRONTAL POSITION TO THE EAST OF THE ROCKIES) AND DETAILS OF THE  
UPPER TROUGH NEAR THE WEST COAST (WITH EFFECTS ON THE LEADING  
FRONT/S AND WAVES). THE SMALL SCALE OF THE NORTHWESTERN GULF  
FEATURE LEADS TO LOW PREDICTABILITY FOR IT BY LATE THIS WEEK.  
 
FOR THE TROUGH NEAR THE WEST COAST, CONSENSUS GENERALLY SHOWS  
GRADUAL DEEPENING/SHARPENING FROM LATE THIS WEEK INTO THE WEEKEND.  
THEN THE DETAILS BECOME SOMEWHAT MORE UNCERTAIN AS SOME OF THIS  
ENERGY EJECTS WHILE UPSTREAM ENERGY DROPS INTO THE WESTERN SIDE OF  
THE MEAN TROUGH. WITHIN THE CANADIAN INTO NORTHEASTERN U.S.  
TROUGH, THERE IS GOOD INITIAL AGREEMENT THAT A STRONG SYSTEM NEAR  
SOUTHERN HUDSON BAY WILL ANCHOR A FRONT THAT SHOULD REACH THE EAST  
COAST BY SUNDAY, LIKELY STALLING FROM THE MID-ATLANTIC INTO THE  
PLAINS. WITH TIME THE MODELS BECOME INCREASINGLY DIVERSE AND  
INCONSISTENT WITH TRAILING SHORTWAVES, LEADING TO INCREASING  
DIFFERENCES FOR POSITION OF THE AFOREMENTIONED LEADING FRONT AND  
ANY FRONTS/WAVES THAT MAY REACH THE NORTHERN TIER FROM CANADA.  
WESTERN TROUGH DETAILS ALSO COME INTO PLAY OVER THE CENTRAL U.S.  
BY LATE IN THE PERIOD AS WELL. OVER THE PAST COUPLE DAYS THE  
ENSEMBLE MEANS HAVE BEEN MORE CONSISTENT WITH THE SURFACE PATTERN  
TO THE EAST OF THE ROCKIES LATE IN THE PERIOD, FAVORING MEANINGFUL  
INCORPORATION INTO THE FORECAST BY THAT TIME. REGARDING THE  
NORTHWESTERN GULF FEATURE, MOST GUIDANCE SUGGESTS THE SURFACE  
REFLECTION MAY LOSE DEFINITION BY THE START OF THE FORECAST PERIOD  
EARLY FRIDAY. THERE MAY STILL BE A REFLECTION ALOFT BUT AGREEMENT  
IS POOR FOR HOW LONG IT WILL PERSIST AND EXACTLY WHERE IT WILL  
TRACK.  
 
BASED ON THE LATEST ARRAY OF GUIDANCE, THE UPDATED FORECAST  
STARTED WITH A 00Z/06Z OPERATIONAL MODEL BLEND OF THE  
ECMWF/GFS/CMC/UKMET IN ORDER FROM MOST TO LEAST WEIGHT FOR THE  
FIRST HALF OF THE PERIOD. CONTINUITY AND DIVERGING MODEL DETAILS  
FAVORED INCORPORATING HALF TOTAL WEIGHT OF THE 06Z GEFS/00Z ECMWF  
MEANS BY DAY 7 TUESDAY.  
   
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
 
 
A LINGERING FRONT ALONG THE SOUTHEASTERN COAST LATE THIS WEEK WILL  
LIKELY PROMOTE THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS  
AND STORMS. EVEN WITH THIS FRONT DEPARTING/DISSIPATING AFTER  
FRIDAY, THE AREA MAY STILL SEE SOME ACTIVITY CONTINUE INTO THE  
WEEKEND DEPENDING ON SPECIFICS OF IMPULSES ALOFT. MEANWHILE, CHECK  
THE LATEST NATIONAL HURRICANE CENTER PRODUCTS FOR LATEST  
INFORMATION REGARDING THE FEATURE OVER THE NORTHWESTERN GULF OF  
MEXICO. ASSOCIATED MOISTURE MAY ENHANCE RAINFALL ACROSS PORTIONS  
OF TEXAS AND PERHAPS OTHER AREAS, DEPENDING ON PERSISTENCE AND  
PATH OF A POSSIBLE UPPER LEVEL REFLECTION. THE SMALL SCALE OF THIS  
FEATURE AND SIGNIFICANT GUIDANCE DIFFERENCES LEAD TO LOW  
CONFIDENCE IN SPECIFICS AT THIS TIME. FARTHER NORTH, A FRONT  
INITIALLY ORIENTED FROM THE GREAT LAKES INTO THE CENTRAL PLAINS  
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 TROUGH NEAR THE WEST COAST.  
THIS WEST COAST TROUGH MAY PRODUCE PERIODS OF RAINFALL OVER PARTS  
OF THE NORTHWEST. 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.  
 
EXPECT A BAND OF TEMPERATURES UP TO 10-15F ABOVE NORMAL AHEAD OF  
THE FRONT CROSSING THE CENTRAL GREAT LAKES ON FRIDAY, WITH HIGHEST  
READINGS VERSUS NORMAL FROM THE EASTERN GREAT LAKES INTO NEW  
ENGLAND. ARRIVAL/PERSISTENCE OF THE FRONT NEAR THE EAST COAST  
THEREAFTER WILL TEND TO KEEP EASTERN U.S. TEMPERATURES NEAR NORMAL  
FOR HIGHS AND A LITTLE ABOVE NORMAL FOR LOWS. HEAT IS LIKELY TO  
BUILD AGAIN ACROSS THE CENTRAL AND NORTHERN PLAINS BY NEXT  
MONDAY-TUESDAY IN RESPONSE TO THE BUILDING UPPER RIDGE, WITH  
NORTH-CENTRAL AREAS SEEING HIGHS UP TO 10-15F ABOVE NORMAL.  
SOUTHERN PLAINS LOCATIONS WILL SEE SLIGHTLY HOTTER CONDITIONS AS  
WELL BUT WITH LESS EXTREME ANOMALIES. FINALLY, BELOW NORMAL HIGHS  
WILL SPREAD GRADUALLY INLAND FROM THE WEST COAST DUE TO NEARBY  
UPPER TROUGHING. THERE COULD BE A FEW LOCATIONS WITH HIGHS 10-15F  
BELOW NORMAL AROUND SUNDAY-MONDAY.  
 
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 PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE LOWER MISSISSIPPI VALLEY, AND THE SOUTHERN  
PLAINS, FRI-SAT, JUL 1-JUL 2.  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN ROCKIES AND THE  
SOUTHWEST, FRI-MON, JUL 1-JUL 4.  
- HEAVY RAIN ACROSS PORTIONS OF THE GREAT LAKES, THE UPPER  
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, TUE, JUL 5.  
- HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC, THE LOWER  
MISSISSIPPI VALLEY, AND THE TENNESSEE VALLEY, SUN-MON, JUL 3-JUL 4.  
- HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC AND THE  
NORTHEAST, SAT, JUL 2.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE UPPER  
MISSISSIPPI VALLEY AND THE NORTHERN PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN GREAT BASIN.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN PLAINS, THE MIDDLE MISSISSIPPI  
VALLEY, THE UPPER MISSISSIPPI VALLEY, AND THE SOUTHERN PLAINS,  
MON-TUE, JUL 4-JUL 5.  
- HEAVY RAIN ACROSS PORTIONS OF MAINLAND ALASKA, FRI-SAT, JUL  
1-JUL 2.  
- MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF MAINLAND  
ALASKA, FRI-MON, JUL 1-JUL 4.  
 
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