539  
FXUS01 KWBC 172007  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
406 PM EDT TUE JUL 17 2018  
 
VALID 00Z WED JUL 18 2018 - 00Z FRI JUL 20 2018  
 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF  
THE CENTRAL PLAINS AND THE NORTHEAST STATES...  
 
...HEAVY RAIN POSSIBLE OVER PORTIONS OF ARIZONA, NORTHERN NEW  
MEXICO AND SOUTHERN COLORADO, AS WELL AS PARTS OF THE NORTHERN  
HIGH PLAINS AND THE NORTHEASTERN STATES...  
 
...HOT TEMPERATURES EXPECTED ACROSS THE SOUTHERN PLAINS AND  
SOUTHERN MISSISSIPPI VALLEY, AS WELL AS FOR THE PORTIONS OF THE  
WESTERN STATES...  
 
A LARGE FRONTAL SYSTEM CURRENTLY EXTENDS FROM NEW ENGLAND  
SOUTHWARD ACROSS THE CENTRAL APPALACHIANS AND WESTWARD THROUGH THE  
TENNESSEE VALLEY INTO THE SOUTHERN PLAINS. THE EASTERN PORTION OF  
THIS FRONT WILL CONTINUE TO SHIFT OFF SHORE INTO THE ATLANTIC  
THROUGH WEDNESDAY. MEANWHILE, THE SOUTHERN EXTENT OF THE FRONT  
WILL PUSH SOUTHWARD INTO THE SOUTHEAST THROUGH THE REMAINDER OF  
THE WEEK, WHILE A LOW PRESSURE SYSTEM DEEPENS ACROSS THE SOUTHERN  
PLAINS AND BEGINS TO TRANSITION NORTHEAST AS A WARM FRONT FOR THE  
REMAINDER OF THE WEEK. DURING THIS TIME, SHOWER AND THUNDERSTORM  
DEVELOPMENT IS EXPECTED ALONG THE EXTENT OF THE FRONTAL BOUNDARY.  
SPC HAS OUTLINED A SLIGHT CHANCE RISK FOR SEVERE THUNDERSTORM  
DEVELOPMENT ALONG THE NEW ENGLAND COAST FOR THIS AFTERNOON AND  
TONIGHT. EXCESSIVE RAIN AND FLASH FLOODING IS ALSO ONGOING IN THIS  
AREA AND WILL LIKELY CONTINUE INTO THE OVERNIGHT, BEFORE THE FRONT  
SHIFTS OFF THE COAST WEDNESDAY.  
 
MEANWHILE, UPPER LEVEL ENERGY AND A LOW PRESSURE SYSTEM OVER THE  
NORTHERN PLAINS IS ALSO RESULTING IN THE DEVELOPMENT OF STRONG  
SHOWERS AND THUNDERSTORMS. A SLIGHT CHANCE FOR BOTH EXCESSIVE RAIN  
AND SEVERE THUNDERSTORM ACTIVITY WILL REMAIN IN PLACE ACROSS  
PORTIONS OF THE CENTRAL AND NORTHERN PLAINS THROUGH TOMORROW,  
TRANSITIONING EASTWARD INTO THE MID AND UPPER MISSISSIPPI VALLEY  
BY THURSDAY. THE BEST THREAT FOR SEVERE WEATHER AND EXCESSIVE  
RAINFALL WILL BE IN THE AFTERNOON AND EVENING HOURS DURING PEAK  
DAYTIME HEATING.  
 
A STRONG PUSH OF WARM AIR FROM THE GULF OF MEXICO IS MAKING ITS  
WAY INTO THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY AHEAD OF  
THE ABOVE MENTIONED FRONTAL BOUNDARY. THIS IS LEADING TO EXCESSIVE  
HEAT AND HUMIDITY, WITH HEAT ADVISORIES IN PLACE IN PORTIONS OF  
THIS AREA THROUGH MID WEEK. OUT WEST, MUCH OF THE PACIFIC  
NORTHWEST, CALIFORNIA, AND THE WESTERN PORTION OF THE  
INTERMOUNTAIN WEST ARE EXPERIENCING VERY DRY CONDITIONS, WHICH IS  
AIDING IN BOOSTING TEMPERATURES ACROSS THIS REGION. WIND IS ALSO  
ADDING TO THE CONCERNS AS WELL. HEAT ADVISORIES, WARNINGS, AND RED  
FLAG WARNINGS ARE ALL IN EFFECT ACROSS PORTIONS OF THESE AREAS  
THROUGH AT LEAST MIDWEEK.  
 
WIX  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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