168  
FXUS01 KWBC 182001  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 PM EST TUE DEC 18 2018  
 
VALID 00Z WED DEC 19 2018 - 00Z FRI DEC 21 2018  
 
...UNSETTLED WEATHER CONTINUES IN THE WEST, WITH RAIN, SNOW, HIGH  
WINDS, AND EVEN AVALANCHES POSSIBLE...  
   
..WET WEATHER DEVELOPS ACROSS THE SOUTHERN AND EASTERN U.S.
 
 
IN THE WESTERN U.S., ACTIVE WEATHER IS ONGOING AS STRONG ONSHORE  
FLOW CONTINUES THROUGH TUESDAY NIGHT AND A FRONT MOVES THROUGH THE  
INTERMOUNTAIN WEST. PRECIPITATION WILL REMAIN RAIN ALONG THE COAST  
AND IN LOWER ELEVATIONS, AND SNOW IN THE MOUNTAINS. A MARGINAL  
RISK OF EXCESSIVE RAINFALL IS IN PLACE THROUGH TUESDAY NIGHT, WITH  
A SMALL SLIGHT RISK FOR FAR SOUTHERN OREGON AND FAR NORTHERN  
CALIFORNIA, WITH BURN SCARS PARTICULARLY THREATENED BY FLOODING.  
IN THE MOUNTAINS, HEAVY SNOW CONTINUES, ESPECIALLY FOR THE  
WASHINGTON CASCADES, WHERE AN ADDITIONAL 1 TO 2 FEET OF SNOW IS  
FORECAST. ADDITIONALLY, HIGH WIND IS A THREAT IN THE INTERMOUNTAIN  
WEST AND INTO THE NORTHERN/CENTRAL ROCKIES. AVALANCHE WARNINGS ARE  
IN EFFECT FOR PARTS OF WASHINGTON AND OREGON THROUGH TUESDAY  
EVENING. PRECIPITATION CHANCES WILL BRIEFLY LOWER ON WEDNESDAY  
BEFORE ANOTHER LOW PRESSURE SYSTEM APPROACHES ON WEDNESDAY NIGHT  
AND ANOTHER ROUND OF RAIN AND SNOW BEGINS.  
 
AS THE FIRST FRONTAL SYSTEM CURRENTLY MOVING THROUGH THE WEST  
PROPAGATES EASTWARD, RAIN AND SNOW SHOWERS WILL DEVELOP ACROSS THE  
NORTHERN PLAINS TUESDAY NIGHT AND INTO UPPER MIDWEST WEDNESDAY.  
SOME LIGHT FREEZING RAIN IS ALSO POSSIBLE. TEMPERATURE-WISE, THOSE  
AREAS WILL REMAIN MUCH ABOVE AVERAGE OVER THE NEXT FEW DAYS, WITH  
SOME RECORD HIGH MINIMUM TEMPERATURES POSSIBLE. MOST OF THE REST  
OF THE U.S. WILL REMAIN AT OR ABOVE NORMAL TOO, THOUGH COOLER  
WEATHER IS EXPECTED IN THE LOWER MISSISSIPPI VALLEY.  
 
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE EASTWARD THROUGH THE  
PLAINS, AND SURFACE LOWS WILL DEVELOP AND TRACK EASTWARD WITH IT.  
THIS WILL CAUSE INCREASING RAIN AND THUNDERSTORM CHANCES FOR THE  
SOUTHERN AND EASTERN U.S. SCATTERED SHOWERS AND STORMS ARE  
EXPECTED TO FORM IN THE SOUTHERN PLAINS TUESDAY NIGHT, MOVING INTO  
THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST ON WEDNESDAY. BY  
WEDNESDAY NIGHT AND THURSDAY, RAIN WILL SPREAD NORTH AND EAST INTO  
THE TENNESSEE AND OHIO VALLEYS AND MID-ATLANTIC. RAIN TOTALS WILL  
GENERALLY BE UNDER AN INCH, WITH LOCALLY HIGHER AMOUNTS, IN THE  
SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND TENNESSEE VALLEY.  
HOWEVER, FLORIDA AND THE COAST OF GEORGIA AND THE CAROLINAS ARE  
EXPECTING HEAVIER RAIN, SO SLIGHT RISKS OF EXCESSIVE RAINFALL ARE  
IN PLACE FOR THURSDAY. THERE IS ALSO A SLIGHT RISK OF SEVERE  
WEATHER FOR PORTIONS OF FLORIDA ON THURSDAY.  
 
TATE  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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