340  
FXUS01 KWBC 080800  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EST MON JAN 08 2018  
 
VALID 12Z MON JAN 08 2018 - 12Z WED JAN 10 2018  
 
...POTENTIAL FOR MUDSLIDES AND OTHER HYDROLOGIC ISSUES ALONG THE  
CALIFORNIA COAST, ESPECIALLY WHERE BURN SCARS EXIST FROM PREVIOUS  
WILDFIRES...  
 
...WIDESPREAD THREAT FOR FREEZING RAIN EXTENDS FROM THE ATLANTA  
METRO AREA UP TO THE MID-ATLANTIC ON MONDAY...  
 
...MILDER CONDITIONS TO PREVAIL OVER MUCH OF THE COUNTRY AS ARCTIC  
AIR RETREATS...  
 
A SYSTEM CURRENTLY OUT OVER THE OPEN WATERS OF THE EAST-CENTRAL  
PACIFIC WILL CONTINUE STRENGTHENING ON ITS SOUTHEASTWARD APPROACH  
TOWARD THE SOUTHERN/CENTRAL CALIFORNIA COAST. THIS WILL COME IN  
THE FORM OF A POWERFUL CLOSED LOW WHICH IS FORECAST TO BE  
ACCOMPANIED BY A VAST PLUME OF MOISTURE EMANATING FROM THE  
SUBTROPICAL PACIFIC. HEAVY RAINFALL SHOULD SPREAD FROM NORTH TO  
SOUTH AS THE ATTENDANT COLD FRONT APPROACHES THE COAST. BASED ON  
THE LATEST FORECAST, A BROAD AREA OF 2 TO 4 INCHES OF RAIN IS  
EXPECTED FROM COASTAL NORTHERN CALIFORNIA DOWN TOWARD THE LOS  
ANGELES BASIN. LOCAL OROGRAPHICS COULD EASILY AUGMENT THESE  
AMOUNTS WHERE FAVORABLE UPSLOPE FLOW WILL INCREASE RAINFALL RATES.  
A MAJOR ISSUE WILL BE THE BURN SCAR AREAS AFTER A VERY ACTIVE FIRE  
SEASON TO CONCLUDE THE YEAR 2017. THESE REGIONS IN PARTICULAR WILL  
BE SUSCEPTIBLE TO MUDSLIDES, DEBRIS FLOWS, OR OTHER HYDROLOGIC  
ISSUES GIVEN THE HEAVY RAINFALL EXPECTED. FARTHER INLAND, THE  
PACIFIC STORM SHOULD BE MORE WINTRY IN NATURE AS 12 TO 18 INCHES  
OF SNOW IS LIKELY OVER THE SOUTHERN/CENTRAL SIERRA NEVADA RANGES.  
 
A PAIR OF DISTURBANCES SWEEPING THROUGH THE CENTRAL GULF COAST AND  
GREAT LAKES, RESPECTIVELY, WILL KEEP WIDESPREAD PRECIPITATION IN  
THE FORECAST OVER THE EASTERN THIRD OF THE COUNTRY. WHILE MODERATE  
TO LOCALLY HEAVY RAINFALL IS POSSIBLE ALONG THE CENTRAL/EASTERN  
GULF COAST, A WINTRY MIX WILL BE MORE COMMONPLACE FROM THE  
MID-SOUTH NORTHWARD. GIVEN MUCH OF THE EASTERN UNITED STATES HAS  
BEEN UNDER THE INFLUENCE OF PERSISTENT ARCTIC AIR, IT WILL BE A  
CHALLENGE TO COMPLETELY SCOUR ITS PRESENCE OUT. WITH MILD AIR  
OVERRIDING THESE SUBFREEZING SURFACES, THE RECIPE FOR FREEZING  
RAIN IS IN PLACE WITH LIGHT ICE ACCUMULATIONS EXPECTED ACROSS  
NORTHERN GEORGIA UP THROUGH THE INTERIOR CAROLINAS AND INTO THE  
CENTRAL APPALACHIANS AND MID-ATLANTIC. WHILE EXPECTED AMOUNTS  
SHOULD BE LIGHT, TRAVEL MAY BE HAZARDOUS AT TIMES, PARTICULARLY  
OVER ANY UNTREATED ROAD SURFACES. CONSEQUENTLY, WINTER WEATHER  
ADVISORIES ARE IN EFFECT OVER THESE REGIONS FOR MUCH OF MONDAY.  
 
AFTER A FRIGID START TO THE NEW YEAR, MUCH MILDER CONDITIONS ARE  
TO PREVAIL GIVEN THE STRONG INFLUENCE OF AIR MASSES WITH A  
MARITIME ORIGIN MOVING THROUGH. EXCEPT FOR THE COLD TEMPERATURES  
ON MONDAY WHERE FREEZING RAIN IS EXPECTED AS WELL AS THE  
CLOUDY/RAINY SET UP OVER CALIFORNIA, A VAST MAJORITY OF THE  
COUNTRY CAN EXPECT ABOVE AVERAGE TEMPERATURES THROUGH MID-WEEK.  
THE MOST ANOMALOUS WARMTH IS LIKELY OVER THE CENTER OF THE COUNTRY  
GIVEN DOWNSLOPING FLOW AIDING IN THE PROCESS. BY TUESDAY, HIGH  
TEMPERATURES MAY EXCEED 20 DEGREES ABOVE CLIMATOLOGY ACROSS THE  
CENTRAL/SOUTHERN HIGH PLAINS AS READINGS MOVE INTO THE UPPER 60S  
TO LOW/MID 70S.  
 
RUBIN-OSTER  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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