559  
FXUS01 KWBC 091656  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1255 PM EDT THU AUG 09 2018  
 
VALID 00Z FRI AUG 10 2018 - 00Z SUN AUG 12 2018  
 
...UNSETTLED WET WEATHER ACROSS EASTERN & SOUTHERN TIER OF U.S.  
WITH A LINGERING HEAVY RAINFALL THREAT ACROSS THE SOUTH THROUGH  
FRIDAY...  
   
..NEAR RECORD-BREAKING HEAT LIKELY OUT WEST
 
 
...MONSOONAL MOISTURE WILL BRING AN ELEVATED HEAVY RAINFALL/FLASH  
FLOOD RISK TO PORTIONS OF THE SOUTHWEST AND SOUTHERN ROCKIES...  
 
MUCH OF THE SOUTHERN TIER OF THE U.S. WILL BE IN A WET PATTERN  
THROUGH THE END OF THE WEEK NEAR AND AHEAD OF A STALLING FRONTAL  
BOUNDARY AHEAD OF AN ELONGATED UPPER LEVEL DISTURBANCE. AS A  
SURFACE LOW LIFTS NORTHEAST THROUGH NEW ENGLAND A COLD FRONT WILL  
PASS THROUGH THE NORTHEAST WHILE THE TRAILING END SLOWS FROM THE  
MID-ATLANTIC TO THE CENTRAL/SOUTHERN PLAINS. MOISTURE STREAMING  
NORTHWARD OVER THE BOUNDARY WILL INITIATE WIDESPREAD CONVECTION  
AND LEAD TO AFTERNOONS WHICH ARE BELOW AVERAGE FOR EARLY TO MID  
AUGUST. AFTERNOON TEMPERATURES ON SUNDAY COULD LEAD TO RECORD  
COOL HIGH TEMPERATURES ACROSS NORTHWEST TEXAS NEAR WICHITA FALLS.  
AS CONVECTION POTENTIALLY REPEATS AT THE SAME LOCATION, THE RISK  
FOR FLASH FLOODING INCREASES. MONSOONAL MOISTURE ROUNDING THE  
BASE OF A STRONG UPPER LEVEL RIDGE OVER THE WESTERN U.S. WILL KEEP  
MAINLY DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS IN THE FORECAST  
ACROSS THE SOUTHWEST THROUGH THE REST OF THE WORK WEEK. HEAVY  
RAINFALL AND LOCALIZED FLASH FLOODING WILL BE POSSIBLE, ESPECIALLY  
ALONG THE FAVORED TERRAIN. WPC HAS A SLIGHT RISK FOR EXCESSIVE  
RAINFALL IN EFFECT FOR PORTIONS OF ARIZONA, NEW MEXICO, AND FROM  
NORTHEAST TEXAS TO NORTHERN ALABAMA TODAY, THEN PRIMARILY FROM  
ARIZONA TO CENTRAL TEXAS THIS WEEKEND.  
 
WITH A STRONG RIDGE ANCHORED OVER THE WEST TEMPERATURES WILL  
CONTINUE TO RISE, ESPECIALLY FOR PARTS OF THE PACIFIC NORTHWEST,  
INTERMOUNTAIN WEST AND THE NORTHERN HIGH PLAINS. HOT AND DRY  
CONDITIONS ARE EXPECTED FROM THE INTERIOR PACIFIC NORTHWEST TO  
EASTERN MONTANA. RECORD BREAKING TEMPERATURES IN THE 90S AND 100S  
IN THE AFTERNOON , WITH 60S AND 70S EXPECTED OVERNIGHT PERSIST  
THROUGH FRIDAY, WHICH ARE AS MUCH AS 10 TO 20 DEGREES ABOVE NORMAL  
FOR EARLY TO MID AUGUST. EXCESSIVE HEAT WARNINGS AND HEAT  
ADVISORIES ARE IN EFFECT ACROSS SOUTHERN CALIFORNIA, SOUTHERN  
NEVADA, AND FROM WASHINGTON AND OREGON TO MONTANA. ONGOING  
WILDFIRES COMBINED WITH THE HEAT CONTINUE TO CAUSE POOR AIR  
QUALITY ISSUES. THE HOT AND DRY CONDITIONS WILL ONLY EXACERBATE  
THE FIRE WEATHER CONCERNS OUT WEST, PARTICULARLY FOR THOSE AREAS  
ALREADY DEALING WITH WILDFIRES. THE PASSAGE OF A COLD FRONT  
SHOULD RELIEVE THE HEAT ACROSS THE PACIFIC NORTHWEST AND NORTHERN  
CONTINENTAL DIVIDE ON SATURDAY, WITH HEAT RELIEF EXPECTED FOR  
MONTANA EXPECTED ON SUNDAY.  
 
ROTH/CAMPBELL  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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