616  
FXUS01 KWBC 090759  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
259 AM EST TUE JAN 09 2018  
 
VALID 12Z TUE JAN 09 2018 - 12Z THU JAN 11 2018  
 
...HIGH RISK OF FLASH FLOODING OVER PORTIONS OF CALIFORNIA IN  
AREAS OF BURN SCARS...  
   
..MILDER CONDITIONS EXPECTED OVER MOST OF THE U.S
 
 
AS A PACIFIC FRONTAL SYSTEM MOVES INTO SOUTHERN CALIFORNIA, HEAVY  
RAINFALL WILL CONTINUE SPREADING ACROSS THE REGION. TERRAIN WILL  
ALSO AID IN INCREASING RAINFALL RATES. BURN SCARS FROM THE ACTIVE  
FIRE WEATHER SEASON WILL MAKE CONDITIONS FAVORABLE FOR FLASH  
FLOODING--IN ADDITION TO MUDSLIDES, DEBRIS FLOW, AND OTHER  
HYDROLOGIC ISSUES. BECAUSE OF THE HEAVY RAINFALL AND OTHER  
CONDITIONS IN PLACE, A HIGH RISK OF FLASH FLOODING IS POSSIBLE  
THROUGH TUESDAY NIGHT. BY WEDNESDAY, THE FRONT WILL MOVE EAST  
TOWARD THE SOUTHERN PLAINS--DIMINISHING THE RAINFALL OVER SOUTHERN  
CALIFORNIA. IN ADDITION TO THE HEAVY RAINFALL ACROSS THE AREA,  
SNOW ACROSS THE SIERRA NEVADA WILL ALSO OCCUR DURING THIS EVENT.  
 
A SEPARATE FRONTAL SYSTEM WILL ALSO APPROACH THE PACIFIC NORTHWEST  
THIS MORNING AND MOVE INLAND DURING THE DAY. ONSHORE FLOW WILL  
PROMOTE AN INCREASE IN RAINFALL ACROSS THE AREA THROUGHOUT THE DAY  
IN ADDITION TO HIGHER ELEVATION SNOW. PRECIPITATION WILL BEGIN TO  
TAPER OFF BY WEDNESDAY MORNING.THE FRONT WILL CONTINUE PUSHING  
EASTWARD ACROSS THE INTERMOUNTAIN WEST ON TUESDAY EVENING AND INTO  
WEDNESDAY MORNING. PRECIPITATION, INCLUDING HIGHER ELEVATION SNOW,  
WILL SPREAD ACROSS THE ENTIRE INTERMOUNTAIN WEST ON WEDNESDAY. BY  
THURSDAY, MOST OF THE PRECIPITATION WILL HAVE SHIFTED EAST OF THE  
ROCKIES. THERE WILL BE NO REST FOR THE WEARY, HOWEVER, AS ANOTHER  
SYSTEM APPROACHES THE PACIFIC NORTHWEST ON THURSDAY  
MORNING--GIVING WAY TO MORE PRECIPITATION ACROSS THAT AREA.  
 
TEMPERATURES ACROSS THE CENTRAL AND EASTERN U.S. WILL BE WELL  
ABOVE NORMAL THROUGH THURSDAY. HOWEVER, ANOTHER ARCTIC AIRMASS  
BEGINS TO DIVE ACROSS THE NORTHERN PLAINS BY THURSDAY--BRINGING  
VERY COLD TEMPERATURES TO THE U.S. ONCE AGAIN. THESE TEMPERATURES  
ARE EXPECTED TO SPREAD EASTWARD BEYOND THE SHORT TERM PERIOD.  
 
REINHART  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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