206  
FXUS02 KWBC 100653  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
152 AM EST SAT FEB 10 2018  
 
VALID 12Z TUE FEB 13 2018 - 12Z SAT FEB 17 2018  
   
..WIDESPREAD PRECIPITATION EXPECTED IN THE SOUTHWEST NEXT WEEK
 
 
   
..OVERVIEW
 
 
A CLOSED LOW WILL WOBBLE OFF THE COAST OF SOUTHERN CALIFORNIA NEXT  
WEEK BEFORE PUSHING INTO THE DESERT SOUTHWEST LATE IN THE WEEK  
BRINGING WIDESPREAD RAIN AND HIGH ELEVATION SNOW TO THE REGION.  
BROAD CYCLONIC FLOW OVER MOST OF THE REST OF THE LOWER 48 WILL  
BRING IN COLDER AIR TO MONTANA IN TO THE HIGH PLAINS WHILE MOST OF  
THE COUNTRY SEES ABOVE AVERAGE TEMPERATURES.  
 
   
..GUIDANCE/UNCERTAINTY ASSESSMENT
 
 
LATEST GFS/ECMWF SOLUTIONS WERE IN GENERAL AGREEMENT WITH THEIR  
ENSEMBLE MEANS THROUGH THE PERIOD WITH THE OVERALL FLOW PATTERN.  
TIMING DIFFERENCES INCREASED BY LATER IN THE WEEK WITH THE  
WEAKENING UPPER LOW AND ALSO THE SOUTHWARD SURGE OF COOLER AIR  
FRI/SAT THROUGH THE PLAINS BUT A BLENDED SOLUTION SUFFICED GIVEN  
THE UPSTREAM DIFFERENCES OVER THE PACIFIC.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
PRECIPITATION WILL EXPAND THROUGH SOUTHERN CALIFORNIA INTO ARIZONA  
AND EVENTUALLY NEW MEXICO AFTER THE UPPER LOW NUDGES EASTWARD  
MIDWEEK. SOUTHWESTERLY FLOW WILL HELP RAISE PW VALUES TO +2 TO +4  
STANDARD DEVIATIONS WHICH SUGGESTS SOME LOCALLY HEAVY RAINFALL,  
DEPENDING ON OTHER FACTORS OF COURSE. TEMPERATURES WILL GENERALLY  
BE ABOVE AVERAGE OVERNIGHT BUT BELOW AVERAGE DURING THE DAY GIVEN  
CLOUD COVER AND PRECIPITATION.  
 
TO THE NORTH, GENERALLY BELOW AVERAGE TEMPERATURES ARE EXPECTED  
FROM MONTANA AND THE HIGH PLAINS INTO THE UPPER MIDWEST AS A  
COUPLE WEAKER SHORTWAVES GET SWEPT ALONG THE ZONAL TO  
WEST-SOUTHWEST UPPER-LEVEL FLOW FORECAST TO PERSIST OVER THE  
CENTRAL/EASTERN US. ABOVE AVERAGE TEMPERATURES ARE EXPECTED ACROSS  
MUCH OF THE EASTERN THIRD OF THE CONUS AS UPPER RIDGING MOVES INTO  
FLORIDA. 70S MAY REACH AS FAR NORTH AS CENTRAL VIRGINIA ON  
THURSDAY. COLD FRONT WILL KNOCK DOWN TEMPERATURES LATER IN THE  
WEEK, ESPECIALLY UP NORTH ALONG THE US/CANADIAN BORDER.  
 
FRACASSO  
 

 
 
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