558  
FXUS01 KWBC 191948  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
347 PM EDT TUE JUN 19 2018  
 
VALID 00Z WED JUN 20 2018 - 00Z FRI JUN 22 2018  
 
...FLASH FLOODING AND STRONG THUNDERSTORMS EXPECTED FROM THE  
CENTRAL PLAINS EASTWARD ACROSS THE OHIO VALLEY AND INTO THE  
MID-ATLANTIC REGION...  
 
...HEAVY SHOWERS AND FLASH FLOODING CONTINUES ALONG AND NEAR THE  
TEXAS COAST...  
   
..HOT WEATHER CONTINUES ACROSS THE CAROLINAS
 
AND GRADUALLY  
BUILDS AGAIN OVER THE SOUTHWESTERN U.S...  
 
A SLOW-MOVING FRONTAL SYSTEM EXTENDING FROM THE CENTRAL PLAINS  
EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY, OHIO VALLEY, AND  
MID-ATLANTIC STATES WILL REMAIN A FOCUS FOR MULTIPLE ROUNDS OF  
SHOWERS AND THUNDERSTORMS THROUGH THURSDAY. WITH A VERY WARM AND  
HUMID AIR MASS ALIGNED WITH THE FRONT, SOME OF THE STORMS COULD BE  
SEVERE, AS WELL AS PRODUCE LOCALIZED EXCESSIVE RAINFALL AND FLASH  
FLOODING. DURING TUESDAY NIGHT AND WEDNESDAY, AN UPPER LEVEL  
DISTURBANCE MOVING OUT OF THE ROCKIES WILL HELP BRING THE BEST  
CHANCE OF WIDESPREAD RAINFALL TO THE PLAINS AND MIDDLE MISSISSIPPI  
VALLEY. AS THIS DISTURBANCE PUSHES EASTWARD ON THURSDAY, THE HIGH  
PLAINS WILL BEGIN TO DRY OUT, BUT WIDESPREAD SHOWERS/THUNDERSTORMS  
WILL CONTINUE OVER THE MISSISSIPPI VALLEY AND EXTEND EASTWARD  
ALONG THE FRONT THROUGH THE OHIO VALLEY AND CENTRAL APPALACHIANS.  
 
SOUTH OF THIS FRONT, DEEP TROPICAL MOISTURE AND A TROUGH OF LOW  
PRESSURE EXTENDING FROM A LOW IN SOUTHERN TEXAS WILL CONTINUE THE  
THREAT FOR WIDESPREAD HEAVY RAINFALL ACROSS EASTERN AND  
SOUTHEASTERN TEXAS THROUGH WEDNESDAY. FLASH FLOOD WATCHES ARE  
POSTED ACROSS THIS REGION GIVEN THE HIGH MOISTURE VALUES IN PLACE  
AND HEAVY RAINS THAT FELL ON MONDAY. DURING THURSDAY, THE MOST  
ORGANIZED ACTIVITY OF SHOWERS AND THUNDERSTORMS WILL TEND TO BE  
DRAWN NORTH AND EASTWARD INTO THE LOWER MISSISSIPPI VALLEY AHEAD  
OF A SLOW-MOVING COLD FRONT, THOUGH A WEAK UPPER LEVEL DISTURBANCE  
WILL MAINTAIN THE THREAT HEAVY, SLOW-MOVING STORMS AND LOCALIZED  
FLOODING ACROSS EASTERN TEXAS.  
 
FARTHER EAST OVER THE CAROLINAS, THE HEAT WAVE WILL CONTINUE, WITH  
HIGHS RANGING INTO THE MID-UPPER 90S THROUGH THURSDAY. AS A  
RESULT, HEAT ADVISORIES REMAIN IN EFFECT FOR EASTERN SECTIONS OF  
NORTH AND SOUTH CAROLINA. HOT WEATHER WILL BEGIN TO ABATE OVER  
SOUTHERN VIRGINIA AND SECTIONS OF THE MIDDLE MISSISSIPPI VALLEY AS  
CLOUDS AND THE CHANCE FOR RAIN INCREASES IN ASSOCIATION WITH THE  
AFOREMENTIONED SLOW-MOVING FRONTAL BOUNDARY.  
 
ACROSS THE WESTERN U.S., DRY AND VERY WARM CONDITIONS WILL PERSIST  
THROUGH WEDNESDAY OVER THE PACIFIC NORTHWEST; HOWEVER, AN UPPER  
LEVEL TROUGH MOVING IN FROM THE PACIFIC WILL BRING CLOUDS AND  
COOLER CONDITIONS BY THURSDAY. OVER THE SOUTHWEST, A BUILDING  
UPPER RIDGE WILL BRING INCREASINGLY HOT CONDITIONS TO THE REGION  
THROUGH THE END OF THE WEEK. EXCESSIVE HEAT WARNINGS ARE POSTED  
FROM SECTIONS OF SOUTHEASTERN CALIFORNIA, SOUTHERN NEVADA AND  
SOUTHERN ARIZONA.  
 
OVER THE NORTHERN TIER OF STATES, PERSISTENT CLOUDS AND SHOWERS  
OVER THE NORTHERN INTERMOUNTAIN REGION/ROCKIES AND HIGH PLAINS  
WILL BRIEFLY ABATE ON WEDNESDAY AS HIGH PRESSURE BUILDS IN. BY  
THURSDAY, HOWEVER, THE UPPER TROUGH THAT BRINGS COOLER  
TEMPERATURES TO THE PACIFIC NORTHWEST WILL MOVE INLAND AND  
POTENTIALLY TRIGGER ANOTHER ROUND OF RAINFALL FOR THE REGION.  
MOSTLY DRY CONDITIONS ARE EXPECTED FROM THE UPPER MISSISSIPPI  
VALLEY EASTWARD ACROSS THE NORTHEAST. A WEAKENING COLD FRONT MAY  
BRING SCATTERED SHOWERS OR THUNDERSHOWERS TO NEW ENGLAND WEDNESDAY  
AFTERNOON, BUT RAINFALL AMOUNTS SHOULD BE LIGHT.  
 
KLEIN  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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