585  
FXUS01 KWBC 181954  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
354 PM EDT TUE SEP 18 2018  
 
VALID 00Z WED SEP 19 2018 - 00Z FRI SEP 21 2018  
 
...HEAVY RAIN IS FORECAST FOR PARTS OF THE NORTHERN PLAINS TO  
MIDWEST...  
 
...FLASH FLOODING IS POSSIBLE IN THE SOUTHWEST U.S. AS MUCH ABOVE  
NORMAL MOISTURE STREAMS IN...  
 
...WARMER THAN AVERAGE TEMPERATURES ARE IN PLACE FOR THE CENTRAL  
PLAINS TO OHIO VALLEY...  
 
...CONDITIONS FAVORABLE FOR WILDFIRES ARE FORECAST FOR PARTS OF  
THE INTERMOUNTAIN WEST...  
 
OVER THE NEXT FEW DAYS, THE JET STREAM IS EXPECTED TO STRENGTHEN  
ACROSS THE NORTHERN ROCKIES AND INTO THE NORTHERN PLAINS, AS AN  
UPPER-LEVEL TROUGH SLOWLY DEVELOPS IN THE NORTHWESTERN U.S. AT THE  
SURFACE, A FRONTAL SYSTEM IS SET UP ACROSS THE INTERMOUNTAIN WEST  
THROUGH THE CENTRAL PLAINS, MIDDLE MISSISSIPPI VALLEY, OHIO  
VALLEY, AND NORTHEAST. THIS FRONT WILL NOT MOVE MUCH OVER THE NEXT  
COUPLE OF DAYS ACROSS THE CENTER OF THE COUNTRY. THIS, COMBINED  
WITH A SECONDARY FRONT MOVING THROUGH THE NORTHERN PLAINS, WILL  
HELP FORCE POSSIBLY MULTIPLE ROUNDS OF HEAVY RAINFALL ACROSS THE  
NORTHERN PLAINS AND MIDDLE TO UPPER MISSISSIPPI VALLEY. SLIGHT  
RISKS OF EXCESSIVE RAINFALL/FLASH FLOODING ARE IN EFFECT IN THOSE  
AREAS THROUGH THURSDAY. MUCH OF THIS AREA HAS BEEN ABNORMALLY WET  
RECENTLY, WHICH COULD EXACERBATE FLOODING CONCERNS. SOME  
THUNDERSTORMS COULD BE STRONG TO SEVERE, WITH THE STORM PREDICTION  
CENTER OUTLOOKS SHOWING MARGINAL RISKS OF SEVERE WEATHER. ON THE  
BACK END OF THE SECONDARY FRONT, RAIN IS EXPECTED IN THE NORTHERN  
HIGH PLAINS, WITH SOME SNOW MIXING IN IN HIGHER ELEVATIONS OF THE  
NORTHERN ROCKIES.  
 
A TROPICAL DISTURBANCE NEAR THE SOUTHERN TIP OF BAJA CALIFORNIA  
HAS SOME CHANCE OF DEVELOPMENT INTO A TROPICAL CYCLONE PER THE  
NATIONAL HURRICANE CENTER. THIS PLUS THE MUCH ABOVE AVERAGE  
MOISTURE STREAMING IN TO THE AREA WILL LEAD TO THE POTENTIAL FOR  
HEAVY RAIN ACROSS THE SOUTHWEST U.S. THROUGH THURSDAY. THE  
HEAVIEST WIDESPREAD RAINFALL TOTALS ARE EXPECTED SOUTH OF THE U.S.  
BORDER AND INTO MEXICO, BUT CONTINUE TO MONITOR THE FORECAST FOR  
CHANGES.  
 
COOLER WEATHER IS EXPECTED NORTH OF THE AFOREMENTIONED FRONTAL  
SYSTEM ACROSS THE U.S., WHILE WARM WEATHER PREVAILS TO THE SOUTH.  
HIGH TEMPERATURES IN THE 90S ARE FORECAST FOR THE CENTRAL PLAINS  
TO OHIO VALLEY AND SOUTHWARD, WHICH IS 10 TO 20 DEGREES ABOVE  
AVERAGE IN THOSE AREAS. MEANWHILE, THE NORTHERN HIGH PLAINS WILL  
SEE HIGH TEMPERATURES IN THE 50S AND 60S, 10 TO 15 DEGREES BELOW  
NORMAL FOR MID-SEPTEMBER.  
 
INCREASING WINDS IN THE INTERMOUNTAIN WEST COMBINED WITH LOW  
HUMIDITY WILL LEAD TO A WILDFIRE RISK. THE STORM PREDICTION CENTER  
HAS OUTLOOKED CRITICAL RISKS OF FIRE WEATHER IN THESE AREAS. RED  
FLAG WARNINGS ARE IN EFFECT THROUGH WEDNESDAY EVENING IN MUCH OF  
UTAH AND WYOMING.  
 
TATE  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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