907  
FXUS01 KWBC 072000  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
359 PM EDT TUE AUG 07 2018  
 
VALID 00Z WED AUG 08 2018 - 00Z FRI AUG 10 2018  
 
...UNSETTLED WEATHER EXPECTED TO SHIFT ACROSS THE SOUTH-CENTRAL  
AND EASTERN U.S. THROUGH MUCH OF THE WORK-WEEK...  
 
...EXCESSIVE HEAT AND AIR QUALITY CONCERNS WILL PERSIST FOR MUCH  
OF THE WESTERN U.S. AS WELL AS ACROSS THE NORTHEAST AND SOUTHEAST  
U.S....  
 
...RED FLAG WARNINGS CONTINUE ACROSS SOUTHERN CALIFORNIA AND THE  
CASCADES OF WASHINGTON...  
 
...HURRICANE JOHN WILL TRACK NORTHWEST NEAR THE BAJA CALIFORNIA  
PENINSULA...  
 
A SLOW MOVING COLD FRONT IS CURRENTLY STRETCHING FROM THE SOUTHERN  
PLAINS NORTHEAST INTO LOWE GREAT LAKES AND NORTHEAST. AS IT SLOWLY  
CONTINUES TO SHIFT EAST AND SOUTHEAST, IT WILL REMAIN THE FOCUS  
FOR SCATTERED TO WIDESPREAD SHOWERS AND THUNDERSTORMS OVER THE  
COMING DAYS, BOTH ALONG THE FRONT AND AREAS TO THE SOUTH AND EAST.  
THE TRAILING END OF THE FRONT WILL SLOW CONSIDERABLY ACROSS THE  
CENTRAL U.S. SLOW STORM MOTION ALONG THIS PORTION OF THE FRONT  
WILL INCREASE THE LIKELIHOOD OF HEAVY RAINFALL AND FLASH FLOODING  
RISK. WPC HAS THEREFORE HIGHLIGHTED A PORTION OF THE SOUTHERN AND  
CENTRAL PLAINS (INCLUDING THE LEEWARD SIDE OF THE CENTRAL AND  
SOUTHERN ROCKIES), AS WELL AS ALONG THE OHIO RIVER AND INTO THE  
MIDDLE MISSISSIPPI VALLEY AS BEING IN A SLIGHT RISK OF EXCESSIVE  
RAINFALL. THE REMAINING REGIONS ALONG THE FRONTAL BOUNDARY ARE IN  
A MARGINAL RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING.  
ADDITIONALLY, THE STORM PREDICTION CENTER HAS ALSO ISSUED A SLIGHT  
RISK FOR SEVERE STORMS FOR THE LEEWARD PORTIONS OF THE  
SOUTHERN/CENTRAL ROCKIES. A FLASH FLOOD WATCH AND SEVERE  
THUNDERSTORM WATCH ARE CURRENTLY IN PLACE FOR THE LEE SIDE OF THE  
CENTRAL AND SOUTHERN ROCKIES AS WELL. THE RISK OF EXCESSIVE  
RAINFALL WILL SLOWLY SHIFT SOUTH WITH THE FRONT EACH DAY.  
 
MEANWHILE, A RIDGE HAS SETTLED OVER THE SOUTHWEST, EXTENDING  
NORTHWARD OVER MUCH OF THE WEST, WILL KEEP HOT AND MOSTLY DRY  
CONDITIONS IN PLACE FOR THE NEXT THE FEW DAYS. THIS IS RESULTING  
IN RISING TEMPERATURES AND EXCESSIVE HEAT ACROSS MUCH OF THIS  
REGION. EXCESSIVE HEAT WARNINGS ARE IN EFFECT FOR MUCH OF THE  
SOUTHWEST AND SOUTHERN CALIFORNIA. EXCESSIVE HEAT WATCHES AND  
ADVISORIES ARE ALSO IN EFFECT FOR THE NORTHERN GREAT BASIN AND  
PORTIONS OF THE PACIFIC NORTHWEST. MANY LOCATIONS WILL OBSERVE  
DAILY MAXIMUM TEMPERATURE READING EXCEEDING 100 DEGREES. THESE HOT  
AND DRY CONDITIONS WILL MAINTAIN AN ELEVATED THREAT FOR THE SPREAD  
OF WILDFIRES. RED FLAG WARNINGS ARE CURRENTLY IN PLACE ACROSS  
SOUTHERN CALIFORNIA AS WELL AS ACROSS THE CASCADES IN WASHINGTON.  
AIR QUALITY ALERTS ALSO CONTINUE ACROSS PORTIONS OF THE SOUTHWEST,  
CALIFORNIA, AND NORTHWEST AS WILDFIRES CONTINUE TO INFUSE THE AIR  
WITH COPIOUS AMOUNTS OF SMOKE. A STEADY INCREASE IN MOISTURE IS  
EXPECTED OVER THE COMING DAYS FOR MEXICO AND THE DESERT SOUTHWEST  
AS HURRICANE JOHN TRACKS NORTH AND WEST IN THE PACIFIC OCEAN.  
SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE FOR THE SOUTHWEST BY THE  
END OF THE WEEK.  
 
ON THE EAST COAST, STRONG SOUTHERLY FLOW WILL PUMP HOT AND HUMID  
AIR INLAND. THIS WILL RESULT IN ABOVE NORMAL TEMPERATURES AND EVEN  
HIGHER HEAT INDEX VALUES AHEAD OF THE APPROACHING COLD FRONT. HEAT  
ADVISORIES AND AIR QUALITY ALERTS FOR EXCESSIVE OZONE  
CONCENTRATIONS ARE IN EFFECT ACROSS MUCH OF THE NORTHEAST AND THE  
NORTHERN EXTENT OF THE MID-ATLANTIC REGION THROUGH THIS EVENING.  
HEAT ADVISORIES HAVE ALSO BEEN ISSUED FOR PORTIONS OF THE DEEP  
SOUTH THROUGH THIS EVENING. EXPECT CONDITIONS TO BEGIN IMPROVING  
ONCE THE COLD FRONT PASSES THROUGH IN THE COMING DAYS.  
 
CAMPBELL  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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