051  
FXUS21 KWNC 032005  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST JANUARY 03 2018  
 
SYNOPSIS: THE MAJOR NOR'EASTER, THAT IS FORECAST TO AFFECT THE EAST COAST PRIOR  
TO THE START OF THIS OUTLOOK PERIOD, IS LIKELY TO EXIT THE CANADIAN MARITIMES  
ON JAN 6. IN ITS WAKE, ARCTIC HIGH PRESSURE IS FORECAST TO SHIFT SOUTH FROM  
CANADA INTO THE EASTERN U.S. THIS WEEKEND. A MID-LEVEL AREA OF LOW PRESSURE IS  
EXPECTED TO ENTER THE WESTERN U.S. ON JAN 6 AND THEN PROGRESS TO THE EASTERN  
U.S. ON JAN 8. DURING THE MIDDLE PART OF NEXT WEEK, A VIGOROUS MID-LEVEL LOW IS  
EXPECTED TO MOVE INLAND INTO CALIFORNIA AND THE SOUTHWESTERN U.S. WITH IT THEN  
SHIFTING INTO THE CENTRAL U.S. EARLY IN WEEK-2. UPPER-LEVEL LOW (HIGH) PRESSURE  
IS LIKELY TO PERSIST OVER THE ALEUTIANS (MAINLAND ALASKA) DURING EARLY JANUARY.  
 
HAZARDS  
 
MUCH BELOW-NORMAL TEMPERATURES FOR THE EASTERN U.S., SAT-SUN, JAN 6-7.  
 
HIGH WINDS FOR THE NORTHEAST, SAT, JAN 6.  
 
FREEZING RAIN FOR PARTS OF THE OHIO VALLEY, CENTRAL APPALACHIANS, AND  
MID-ATLANTIC, SUN-MON, JAN 7-8.  
 
HEAVY SNOW FOR THE SIERRA MOUNTAINS, TUE-WED, JAN 9-10.  
 
HEAVY RAIN FOR PARTS OF SOUTHERN CALIFORNIA, TUE-WED, JAN 9-10.  
 
PERIODS OF HIGH WINDS FOR THE ALEUTIANS, ALASKA PENINSULA, AND PARTS OF  
SOUTHWEST MAINLAND ALASKA, SAT-TUE, JAN 6-9.  
 
PERIODS OF HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE EASTERN  
ALEUTIANS AND ALASKA PENINSULA, SAT-TUE, JAN 6-9.  
 
A MODERATE RISK OF HEAVY PRECIPITATION FROM THE CENTRAL HIGH PLAINS TO THE  
LOWER AND MIDDLE MISSISSIPPI VALLEY, THU-SAT, JAN 11-13.  
 
FROZEN PRECIPITATION FOR THE CENTRAL GREAT PLAINS, MIDDLE MISSISSIPPI VALLEY,  
AND MIDWEST, THU-SAT, JAN 11-13.  
 
A SLIGHT RISK OF HEAVY PRECIPITATION EXTENDING FROM THE SOUTHWESTERN U.S. EAST  
TO THE OHIO VALLEY, THU-SAT, JAN 11-13.  
 
A SLIGHT RISK OF HEAVY PRECIPITATION FOR THE PACIFIC NORTHWEST, MON-WED, JAN  
15-17.  
 
A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FROM THE NORTHERN GREAT PLAINS  
AND UPPER MISSISSIPPI VALLEY EAST TO NEW ENGLAND, THU-SUN, JAN 11-14.  
 
SEVERE DROUGHT ACROSS THE GREAT PLAINS, THE SOUTHWEST, THE MIDDLE AND LOWER  
MISSISSIPPI VALLEY, AND HAWAII.  
 
DETAILED SUMMARY  
 
FOR SATURDAY JANUARY 06 - WEDNESDAY JANUARY 10: THE COLDEST TEMPERATURES,  
WITHIN THIS PROLONGED PERIOD OF BELOW NORMAL TEMPERATURES, ARE EXPECTED TO  
AFFECT THE MID-ATLANTIC AND NORTHEAST THIS WEEKEND DUE TO STRONG COLD AIR  
ADVECTION IN THE WAKE OF A POWERFUL SURFACE LOW. THE GUSTY WINDS WILL LIKELY  
RESULT IN DANGEROUS WIND CHILLS, AS LOW AS 20 TO 30 BELOW ZERO, ACROSS THE  
NORTHEAST ON JAN 6. SUBZERO MINIMUM TEMPERATURES ARE EXPECTED AS FAR SOUTH AS  
THE OHIO RIVER ON JAN 6, WHILE CONDITIONS REMAIN FAVORABLE FOR A LIGHT FREEZE  
OR FROST TO AFFECT INTERIOR AREAS OF SOUTH FLORIDA THROUGH SATURDAY MORNING.  
THE COLDEST MORNING ACROSS NEW ENGLAND IS LIKELY ON SUNDAY MORNING WHEN LOW  
TEMPERATURES RANGE FROM 10 TO 20 BELOW ZERO.  
 
A SHORTWAVE TROUGH OF LOW AMPLITUDE IS EXPECTED TO PROGRESS ACROSS THE WESTERN  
U.S. ON JAN 6. ALTHOUGH SNOW IS LIKELY TO ACCOMPANY THE SHORTWAVE TROUGH ACROSS  
THE NORTHERN SIERRAS AND CENTRAL ROCKIES, HEAVY AMOUNTS ARE NOT EXPECTED GIVEN  
ITS LOW AMPLITUDE AND FAST MOVEMENT. AS THE SHORTWAVE TROUGH PROGRESSES EAST,  
PRECIPITATION IS EXPECTED TO DEVELOP ACROSS THE CENTRAL AND EASTERN U.S. DUE TO  
THE ARCTIC AIR PRECEDING THIS PRECIPITATION, THIS SETUP FAVORS FREEZING RAIN  
ACROSS PARTS OF THE OHIO VALLEY, CENTRAL APPALACHIANS, AND MID-ATLANTIC ON JAN  
7 AND 8. THE DETERMINISTIC 0Z ECMWF MODEL INDICATES THAT SHORTWAVE TROUGH  
BECOMES NEGATIVELY TITLED, INCREASING THE CHANCE OF HEAVY SNOW FROM THE UPPER  
OHIO VALLEY NORTHEAST TO NEW ENGLAND. MODELS ARE TRENDING TOWARDS A MORE  
SUPPRESSED SURFACE LOW TRACK WHICH IMPLIES AN INCREASING RISK OF MODERATE TO  
HEAVY SNOW ACROSS THE UPPER OHIO VALLEY, NORTHERN MID-ATLANTIC, AND NORTHEAST  
EARLY NEXT WEEK.  
 
MODEL SOLUTIONS ARE CONVERGING ON THE TRACK A SHORTWAVE TROUGH ENTERING  
CALIFORNIA AND THE SOUTHWESTERN U.S. NEXT WEEK, ALTHOUGH THE EXACT TIMING  
DIFFERS. THE MOST LIKELY HAZARDS WITH THIS SHORTWAVE TROUGH ARE HEAVY SNOW  
(MORE THAN A FOOT) ACROSS THE SIERRA MOUNTAINS AND HEAVY RAIN (ISOLATED AMOUNTS  
NEAR 2 INCHES) ACROSS SOUTHERN CALIFORNIA ON JAN 9 AND 10. ADDITIONAL HEAVY  
SNOW HAZARDS MAY BE POSTED FOR INLAND AREAS OF THE SOUTHWESTERN U.S. LATER THIS  
WEEK.  
 
THE UPPER-LEVEL PATTERN OVER THE NORTH PACIFIC FAVORS MULTIPLE SURFACE LOWS  
(AROUND 960-HPA) MOVING NORTH ACROSS THE ALEUTIANS TO THE WESTERN BERING SEA.  
THEREFORE, PERIODS OF HIGH WINDS (SPEEDS ABOVE 50MPH) ARE EXPECTED TO AFFECT  
THE ALEUTIANS, ALASKA PENINSULA, AND SOUTHWEST MAINLAND ALASKA THROUGH JAN 9.  
THE MOST LIKELY AREA TO EXPERIENCE HIGH WAVE HEIGHTS (POTENTIALLY IN EXCESS OF  
36 FEET) IS THE EASTERN ALEUTIANS AND ALASKA PENINSULA.  
 
FOR THURSDAY JANUARY 11 - WEDNESDAY JANUARY 17: THE ENSEMBLE MEANS ARE IN GOOD  
AGREEMENT THAT AN ANOMALOUS 500-HPA TROUGH DEVELOPS OVER THE NORTH PACIFIC,  
WHILE ABOVE NORMAL HEIGHTS AT 500-HPA BECOME PROMINENT THROUGHOUT THE LOWER 48.  
A MODERATION IN TEMPERATURES IS EXPECTED FOR THE CENTRAL AND EASTERN U.S.,  
ESPECIALLY SOUTHEASTERN AREAS, DURING MID-JANUARY AS ANOMALOUS NORTHERLY FLOW  
EASES AND 500-HPA HEIGHTS INCREASE. THIS PATTERN CHANGE IS CONSISTENT WITH THE  
ENHANCED PHASE OF THE MADDEN-JULIAN OSCILLATION (MJO) PROPAGATING EAST ACROSS  
THE INDIAN OCEAN.  
 
DESPITE THE FORECAST OF ABOVE NORMAL 500-HPA HEIGHTS DURING WEEK-2, THE  
AMPLIFIED RIDGE OVER NORTHWEST NORTH AMERICA MAY PROMOTE INTRUSIONS OF SHALLOW  
ARCTIC AIR INTO THE NORTHERN GREAT PLAINS, UPPER MISSISSIPPI VALLEY, GREAT  
LAKES, AND NEW ENGLAND. A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURE IS  
POSTED FOR THESE AREAS FROM JAN 11 TO 14, BUT THE ECMWF MODEL IS A WARMER  
SOLUTION COMPARED TO THE GEFS.  
 
THE SHORTWAVE TROUGH THAT ENTERS THE WESTERN U.S. DURING THE EARLY TO MIDDLE  
PART OF NEXT WEEK IS EXPECTED TO EMERGE ONTO THE GREAT PLAINS AT THE BEGINNING  
OF WEEK-2. A SLIGHT TO MODERATE RISK OF HEAVY PRECIPITATION (20 TO 40 PERCENT  
CHANCE OF EXCEEDING THE 85TH PERCENTILE) IS POSTED FOR AREAS ALONG THE EXPECTED  
TRACK OF THE SHORTWAVE TROUGH, FROM JAN 11 TO 13. INCREASING INFLOW FROM THE  
GULF OF MEXICO IS EXPECTED TO SUPPORT HEAVY RAIN ACROSS THE LOWER TO MIDDLE  
MISSISSIPPI VALLEY, WHILE FROZEN PRECIPITATION (SNOW, SLEET, AND/OR FREEZING  
RAIN) IS MOST LIKELY FROM THE CENTRAL HIGH PLAINS EAST TO THE MIDWEST. THE  
EVOLVING PATTERN OVER THE NORTH PACIFIC FAVORS A SLIGHT RISK OF HEAVY  
PRECIPITATION ACROSS THE PACIFIC NORTHWEST LATE IN WEEK (JAN 15-17).  
 
THE U.S. DROUGHT MONITOR, VALID ON DECEMBER 26, 2017 INDICATES A DECREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 6.97% LAST WEEK TO  
4.95% THIS WEEK. DROUGHT IMPROVEMENT RECENTLY OCCURRED ACROSS MUCH OF ARKANSAS,  
EASTERN OKLAHOMA, NORTHEAST TEXAS, AND SMALL PARTS OF LOUISIANA. DETERIORATION  
IS NOTED IN THE FLORIDA PANHANDLE AND VIRGINIA, AMONG OTHER AREAS.  
 
FORECASTER: BRAD PUGH  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page