440  
FXUS02 KWBC 092025  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
424 PM EDT TUE AUG 09 2022  
 
VALID 12Z FRI AUG 12 2022 - 12Z TUE AUG 16 2022  
 
...MONSOONAL MOISTURE/RAINFALL THREAT CONTINUES FOR THE SOUTHWEST  
AND INTERMOUNTAIN WEST/ROCKIES THIS WEEK, WITH SOME LOCALIZED  
HEAVY RAIN POSSIBLE FOR THE GULF COAST STATES AS WELL...  
 
...EXCESSIVE HEAT THREAT FROM THE INTERIOR NORTHWEST TO THE  
NORTH-CENTRAL PLAINS...  
 
   
..OVERVIEW
 
 
A FAIRLY STAGNANT TROUGH-RIDGE-TROUGH PATTERN IS FORECAST LATER  
THIS WEEK INTO EARLY NEXT WEEK ACROSS THE CONTIGUOUS U.S., AS  
SHORTWAVES DEEPEN AND THEN MAINTAIN A TROUGH IN THE EAST, AN UPPER  
LOW OFF THE WEST COAST LIFTS NORTHEASTWARD INTO BRITISH COLUMBIA,  
AND AN UPPER HIGH MEANDERS NEAR THE CENTRAL/SOUTHERN HIGH PLAINS.  
A COLD FRONT OR TWO APPROACHING THE GULF COAST AND STALLING WILL  
PROVIDE A FOCUS FOR MOISTURE AND RAIN/THUNDERSTORMS THERE AND  
LINGERING ACROSS MUCH OF FLORIDA INTO EARLY NEXT WEEK. MEANWHILE,  
PERSISTENT MONSOONAL MOISTURE LOOKS TO CONTINUE ACROSS THE  
SOUTHWEST AND EXPANDING INTO THE INTERMOUNTAIN WEST AND ROCKIES  
THIS WEEK INTO NEXT WEEK.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
BROAD CONSENSUS FOR AMPLIFIED PATTERNS OVER THE EAST AND WEST  
COASTS WITH AN CENTRAL U.S. RIDGE WANE TOWARD THE END OF THE  
PERIOD. A GENERAL MODEL BLEND OF DETERMINISTIC GUIDANCE WAS  
UTILIZED THROUGH DAY 4 WITH AN ENSEMBLE INTRODUCTION BY DAY 5 AND  
CONTINUING THROUGH DAY 7. ON DAY 3, THE 00Z EC/CMC/UK AND 06Z GFS  
WERE USED AS THEY AGREED ON THE OVERALL TROUGH-RIDGE-TROUGH  
PATTERN ACROSS THE LOWER 48. WE CONTINUED THIS BLEND INTO DAY 4  
WITH SOME 00Z GFS INCLUDED TO ACCOUNT FOR TIMING AND INTENSITY  
SPREAD IN THE UPPER TROUGH OVER THE PACIFIC NORTHWEST/BRITISH  
COLUMBIA. THE 00Z ECE AND 06Z GEFS WERE INCORPORATED INTO THE  
GENERAL MODEL BLEND ON DAY 5 TO ACCOUNT FOR UNCERTAINTY ASSOCIATED  
WITH AN EMBEDDED SHORTWAVE PROPAGATING THROUGH SOUTHERN CANADA AND  
THE NORTHERN PLAINS. DAY 6 WAS HEAVILY WEIGHTED TOWARD THE 00Z  
EC/ECE DUE TO REASONABLE AND RUN-TO-RUN CONSITENCY OF THE UPPER  
TROUGH OVER THE EAST COAST AND THE CENTRAL U.S. RIDGE WITH WHICH  
THE 06Z GFS/GEFS WERE A BIT MORE INCONSISTENT. THE 00Z CMC WAS A  
BIT TOO INTENSE WITH RESPECT TO AN UPPER VORT OVER SOUTHERN  
WYOMING. THE 06Z GFS/GEFS AND 00Z CMCE WERE ALSO INCORPORATED INTO  
THE BLEND, ALBEIT WITH LOWER WEIGHTING. DAY 7 WAS A BLEND OF THE  
ENSEMBLES WITH A BIT OF 00Z EC INCLUDED. THE MAIN AREA OF  
UNCERTAINTY ON DAY 7 IS IN THE DETERMINISTIC 06Z GFS, WHICH HAS AN  
ANOMALOUS CLOSED LOW CENTRERED OVER THE UPPER GREAT LAKES/MICHIGAN.  
 
   
..WEATHER/HAZARDS HIGHLIGHTS
 
 
MOISTURE STREAMING AHEAD OF A COUPLE OF COLD FRONTS MOVING INTO  
THE SOUTHEAST AND TOWARD THE GULF COAST LATE THIS WEEK WILL  
PRODUCE RAIN AND THUNDERSTORMS IN THOSE AREAS. THIS COULD CAUSE  
LOCALIZED FLOODING ISSUES SINCE STORMS SHOULD BE SLOW-MOVING AND  
MAY TRAIN OVER THE SAME AREAS. RAIN CHANCES ARE LIKELY TO CONTINUE  
ACROSS MUCH OF FLORIDA INTO EARLY NEXT WEEK AS THE FRONT STALLS.  
FARTHER NORTH, THE COLD FRONT SHOULD CLEAR OUT MOST RAINFALL FROM  
THE MID-ATLANTIC AND LIKELY THE NORTHEAST AS WELL, BUT DEPENDENT  
ON HOW CLOSE TO THE NEW ENGLAND COAST A LOW ALONG THE COLD FRONT  
SITS. SHORTWAVE IMPULSES ROUNDING THE RIDGE COULD LEAD TO RAIN AND  
STORMS ACROSS THE MIDWEST/UPPER GREAT LAKES INTO THE OHIO VALLEY  
THIS WEEKEND INTO EARLY NEXT WEEK, BUT WITH LOW CONFIDENCE ON THE  
SPECIFICS. MEANWHILE, MONSOONAL MOISTURE CONTINUES TO IMPACT THE  
SOUTHWEST INTO PARTS OF THE GREAT BASIN AND INTO THE ROCKIES WITH  
RAINFALL THROUGH THE MEDIUM RANGE PERIOD. SOME LOCALLY HEAVY  
TOTALS ARE POSSIBLE AND A SLIGHT RISK OF FLASH FLOODING HAS BEEN  
ADDED TO THE EXPERIMENTAL DAY 4 ERO.  
 
VERY WARM TO HOT TEMPERATURES AROUND 10-15F ABOVE AVERAGE, THOUGH  
NOT QUITE TO RECORD-BREAKING LEVELS, ARE FORECAST ACROSS INTERIOR  
PORTIONS OF THE NORTHWEST AND INTO THE NORTHERN/CENTRAL PLAINS  
THROUGH THE LATTER PART OF THE WEEK, AND LASTING ACROSS THE  
CENTRAL PLAINS AND PARTS OF THE MID-MISSISSIPPI VALLEY THIS  
WEEKEND INTO EARLY NEXT WEEK. A SLIGHT SOUTHERN SHIFT IS EXPECTED  
WITH TIME, LEADING TO HIGHS NEARING/REACHING 100F FORECAST EARLY  
NEXT WEEK IN THE CENTRAL/SOUTHERN PLAINS. FARTHER EAST, BELOW  
NORMAL HIGHS ARE POSSIBLE IN THE EAST-CENTRAL U.S. BEHIND THE COLD  
FRONT, WITH THE MOST PERSISTENT COOLER THAN AVERAGE WEATHER IN THE  
OHIO AND TENNESSEE VALLEYS. THE MID-ATLANTIC AND NORTHEAST SHOULD  
EXPERIENCE CLEAR AND COMFORTABLE TEMERATURES THIS WEEKEND. GIVEN  
THE RAINFALL AND CLOUDINESS OVER THE SOUTHWEST AND GREAT BASIN,  
HIGHS ARE LIKELY TO BE SEVERAL DEGREES BELOW NORMAL THERE THROUGH  
EARLY NEXT WEEK.  
 
KEBEDE/TATE  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHWEST, GREAT BASIN, AND  
CENTRAL AND SOUTHERN ROCKIES, FRI-TUE, AUG 12-AUG 16.  
- HEAVY RAIN ACROSS PORTIONS OF THE GULF COAST AND FLORIDA,  
FRI-SAT, AUG 12-AUG 13.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE NORTHERN  
PLAINS.  
- FLOODING LIKELY ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE NORTHWEST, NORTHERN  
ROCKIES, AND NORTHERN PLAINS, FRI, AUG 12.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL PLAINS AND MIDDLE  
MISSOURI VALLEY, FRI-SUN, AUG 12-AUG 14.  
- EXCESSIVE HEAT ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN  
PLAINS AND LOWER MISSISSIPPI VALLEY, SUN-TUE, AUG 14-AUG 16.  
 
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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