178  
FXUS01 KWBC 230817  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
316 AM EST FRI NOV 23 2018  
 
VALID 12Z FRI NOV 23 2018 - 12Z SUN NOV 25 2018  
 
...WIDESPREAD PRECIPITATION TO IMPACT THE WESTERN U.S., WITH FLASH  
FLOODING AND DEBRIS FLOWS POSSIBLE OVER BURN SCARS...  
 
...WIDESPREAD RAIN IS EXPECTED IN THE MISSISSIPPI VALLEY ON  
FRIDAY, SPREADING TO THE EAST ON SATURDAY...  
 
...LIGHT FROZEN PRECIPITATION POSSIBLE IN THE SOUTHERN AND CENTRAL  
APPALACHIANS FRIDAY NIGHT INTO SATURDAY MORNING...  
 
...AFTER RECORD LOWS EXPECTED FOR THE NORTHEAST AND NORTHERN  
MID-ATLANTIC THIS MORNING, WILL RETURN TO NEAR NORMAL BY THE END  
OF THE WEEKEND...  
 
MULTIPLE FRONTAL SYSTEMS ALONG WITH UPPER LEVEL DISTURBANCES WILL  
MOVE ACROSS THE WESTERN U.S. OVER THE NEXT FEW DAYS. THIS WILL  
BRING AN INCREASED AMOUNT OF PRECIPITATION IN THE AREA--WITH RAIN  
IN THE LOWER ELEVATIONS AND SNOW IN THE HIGHER ELEVATIONS OF THE  
PACIFIC NORTHWEST, NORTHERN CALIFORNIA, AND ACROSS THE  
INTERMOUNTAIN WEST. ALTHOUGH THIS RAINFALL IS BENEFICIAL  
PARTICULARLY FOR NORTHERN CALIFORNIA SINCE IT HAD BEEN SO DRY,  
BURN SCARS FROM THE FIRES COULD CREATE HAZARDOUS WEATHER AND LEAD  
TO FLASH FLOODING. IN ADDITION, DEBRIS FLOWS ARE ALSO A HAZARD.  
THIS WIDESPREAD PRECIPITATION IS EXPECTED TO LAST THROUGH SATURDAY  
MORNING. FURTHERMORE, WINTER STORM WARNINGS AND WINTER WEATHER  
ADVISORIES ARE IN EFFECT FOR TODAY ACROSS THE HIGHER ELEVATIONS OF  
THE CASCADES, SIERRA NEVADA MOUNTAIN RANGE, AND ACROSS THE  
INTERMOUNTAIN WEST AS HEAVY SNOW WILL IMPACT THESE AREAS. BY  
SATURDAY EVENING AND INTO SUNDAY MORNING, PRECIPITATION WILL SHIFT  
TO PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES IN ADDITION TO THE  
NORTHERN/CENTRAL PLAINS AS THE SURFACE LOW MOVES FROM THE PLAINS  
TOWARD THE MISSISSIPPI VALLEY. THIS SYSTEM WILL BRING SNOW TO  
PORTIONS OF THE PLAINS, MIDDLE TO UPPER MISSISSIPPI VALLEY, AND  
GREAT LAKES LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK.  
 
ON FRIDAY, SHOWERS AND THUNDERSTORMS WILL DEVELOP AHEAD OF A COLD  
FRONT PUSHING ACROSS THE MISSISSIPPI VALLEY TODAY. THIS FRONT IS  
EXPECTED TO MOVE QUICKLY, THUS EXCESSIVE RAINFALL IS NOT A THREAT  
AT THIS TIME. TO THE SOUTH, A LOW PRESSURE SYSTEM DEVELOPING IN  
THE WESTERN GULF COAST WILL BRING SHOWERS AND THUNDERSTORMS TO THE  
WESTERN AND CENTRAL GULF COAST. BY SATURDAY, PRECIPITATION WILL  
INCREASE ACROSS AREAS FROM THE SOUTHEAST NORTHWARD INTO THE GREAT  
LAKES AND MID-ATLANTIC. MOST OF THIS PRECIPITATION WILL BE  
RAINFALL. HOWEVER, LIGHT SNOW AND FREEZING RAIN COULD BE POSSIBLE  
TONIGHT INTO SATURDAY MORNING--MAKING TRAVEL CONDITIONS SLICK  
TEMPORARILY. MOST OF THE PRECIPITATION WILL CLEAR OUR ACROSS THE  
SOUTHEAST AND GREAT LAKES LATE SATURDAY--WITH MODERATE RAINFALL  
CONTINUING ACROSS THE MID-ATLANTIC AND NORTHEAST OVERNIGHT INTO  
SUNDAY MORNING.  
 
AFTER LOW TEMPERATURE RECORDS EXPECTED FRIDAY MORNING ACROSS THE  
NORTHERN MID-ATLANTIC AND NORTHEAST, TEMPERATURES WILL BEGIN TO  
REBOUND SLOWLY OVER THE WEEKEND. ALTHOUGH TEMPERATURES WILL STILL  
REMAIN BELOW NORMAL THROUGH SATURDAY, BY SUNDAY HIGH TEMPERATURES  
WILL BE NEAR AVERAGE FOR THIS TIME OF YEAR. BELOW NORMAL  
TEMPERATURES OF 5 TO 15 DEGREES BELOW NORMAL ARE FORECAST FOR THE  
CENTRAL U.S. FINALLY, THE WESTERN U.S. WILL BE SLIGHTLY BELOW  
NORMAL DUE TO THE UNSETTLED WEATHER ACROSS THE REGION.  
 
REINHART/TATE  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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