931  
FXUS01 KWBC 202015  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
414 PM EDT THU SEP 20 2018  
 
VALID 00Z FRI SEP 21 2018 - 00Z SUN SEP 23 2018  
 
...SEVERE WEATHER AND A THREAT FOR FLASH FLOODING ACROSS THE UPPER  
MIDWEST TODAY...  
 
...MODERATE RISK FOR FLASH FLOODING IN PLACE OVER CENTRAL OKLAHOMA  
ON FRIDAY INTO THE OVERNIGHT HOURS...  
 
...SUBSTANTIAL TEMPERATURE CONTRAST ON THE ORDER OF 40-50 DEGREES  
F FROM THE DAKOTAS INTO THE CENTRAL U.S...  
 
...WET CONDITIONS LIKELY ACROSS SECTIONS OF WESTERN WASHINGTON UP  
INTO BRITISH COLUMBIA...  
 
SHOWERS AND THUNDERSTORMS WILL PERSIST ACROSS THE NORTH-CENTRAL  
U.S. AS A COLD FRONT DROPS SOUTH THROUGH THE NORTHERN PLAINS,  
UPPER MIDWEST AND GREAT LAKES REGION. ONGOING FLOODING WILL  
PERSIST OVER MUCH OF THE UPPER MISSISSIPPI VALLEY WITH THE  
ADDITIONAL RAINFALL- WPC HAS A SLIGHT RISK FOR EXCESSIVE RAINFALL  
IN EFFECT. THESE STORMS WILL HAVE THE POTENTIAL OF BEING SEVERE  
AND CAPABLE OF PRODUCING HEAVY RAIN. THE STORM PREDICTION CENTER  
HAS A SLIGHT AND ENHANCED RISK HIGHLIGHTED OVER MUCH OF IOWA,  
SOUTHERN MINNESOTA AND WESTERN WISCONSIN TODAY. THE RISK FOR SEVER  
WEATHER AND HEAVY RAINFALL WILL SHIFT EASTWARD ON FRIDAY,  
ENCOMPASSING PORTIONS OF THE GREAT LAKES AND NORTHEAST.  
 
STRONG GUSTY WINDS ALONG WITH MUCH COOLER TEMPERATURES CAN BE  
EXPECTED FRIDAY AND SATURDAY. RELATIVE TO CLIMATOLOGY, ANOMALIES  
WILL BE QUITE IMPRESSIVE, PARTICULARLY NORTH OF THE BOUNDARY WITH  
DEPARTURES IN THE 20 TO 25 DEGREE F RANGE. THE AIR MASS WITHIN THE  
COLD SECTOR SHOULD MODIFY A BIT BY THE FOLLOWING DAY AS HIGHS STAY  
IN THE MID TO UPPER 50S ACROSS THE NORTHERN PLAINS INTO THE UPPER  
MIDWEST.  
 
A COMPACT UPPER LOW DROPPING DOWN FROM THE GULF OF ALASKA WILL  
TAKE AIM AT THE PACIFIC NORTHWEST AND WILL USHER IN WIDESPREAD  
PRECIPITATION ACROSS WESTERN WASHINGTON UP INTO BRITISH COLUMBIA.  
THE MAJORITY OF THE PRECIPITATION WILL FOCUS AGAINST THE UPSLOPE  
TERRAIN WITH THE HIGHEST AMOUNTS EXPECTED OVER THE OLYMPIC  
MOUNTAINS.  
 
THE SOUTHERN PLAINS WILL BE IN AN ACTIVE WET PATTERN INTO THE  
WEEKEND. ENHANCED MOISTURE FROM THE REMAINS OF TROPICAL DEPRESSION  
NINETEEN-E WILL LEAD TO A HEAVY RAINFALL EVENT ACROSS THE  
SOUTH-CENTRAL U.S AS IT MERGES WITH MOISTURE FROM THE GULF OF  
MEXICO ALONG A FRONTAL BOUNDARY. THERE SHOULD BE A PARTICULAR  
FOCUS ACROSS CENTRAL OKLAHOMA WHERE A WAVY FRONTAL ZONE IS  
FORECAST TO STALL. SEVERAL INCHES OF RAIN ARE POSSIBLE ON FRIDAY  
INTO SATURDAY MORNING WHICH LED TO AN UPGRADE OF THE FLASH FLOOD  
POTENTIAL TO A MODERATE RISK WHICH INCLUDES THE CITY OF OKLAHOMA  
CITY. THE FOOTPRINT OF HEAVIER RAINFALL SHOULD SURROUND THIS  
REGION EXTENDING INTO WESTERN ARKANSAS AND SOUTHWARD ACROSS THE  
RED RIVER INTO NORTH TEXAS.  
 
CAMPBELL  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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