007  
FXUS21 KWNC 022015  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST JANUARY 02 2018  
 
SYNOPSIS: AN INTENSE SURFACE LOW IS FORECAST TO EXIT NEW ENGLAND AND TRACK INTO  
THE CANADIAN MARITIMES ON JAN 5. ANOTHER STRONG AREA OF SURFACE HIGH PRESSURE  
IS FORECAST TO SHIFT SOUTH FROM CANADA INTO THE EAST-CENTRAL 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 RAPIDLY EAST TO THE CENTRAL U.S. EARLY IN WEEK-2, A MID-LEVEL  
AREA OF LOW PRESSURE IS EXPECTED TO MOVE INTO CALIFORNIA AND THE SOUTHWESTERN  
U.S. UPPER-LEVEL LOW (HIGH) PRESSURE IS LIKELY TO PERSIST OVER THE ALEUTIANS  
(MAINLAND ALASKA) DURING EARLY JANUARY.  
 
HAZARDS  
 
HEAVY SNOW ENDING ACROSS NEW ENGLAND, FRI, JAN 5.  
 
HIGH WINDS FOR THE MID-ATLANTIC AND NORTHEAST, FRI-SAT, JAN 5-6.  
 
LOCALLY HEAVY, LAKE-EFFECT SNOW DOWNWIND OF THE GREAT LAKES, FRI-SAT, JAN 5-6.  
 
MUCH BELOW-NORMAL TEMPERATURES FOR THE EASTERN AND CENTRAL U.S., FRI-SAT, JAN  
5-6.  
 
MUCH BELOW-NORMAL TEMPERATURES FOR THE MID-ATLANTIC, NORTHEAST, AND EASTERN  
GREAT LAKES, FRI-SUN, JAN 5-7.  
 
HIGH WINDS ACROSS PARTS OF WESTERN AND SOUTHWESTERN ALASKA INCLUDING KODIAK  
ISLAND, FRI-SAT, JAN 5-JAN 6.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE SOUTH COAST OF ALASKA  
AND KODIAK ISLAND, FRI, JAN 5.  
 
A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE NORTHEASTERN  
AND NORTH-CENTRAL U.S., WED-THU, JAN 10-11.  
 
A SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF CALIFORNIA AND THE  
SOUTHWESTERN U.S., WED-THU, JAN 10-11.  
 
A SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE LOWER TO MIDDLE  
MISSISSIPPI VALLEY AND OHIO VALLEY, THU-SAT, JAN 11-13.  
 
SEVERE DROUGHT ACROSS THE GREAT PLAINS, THE SOUTHWEST, THE MIDDLE AND LOWER  
MISSISSIPPI VALLEY, AND HAWAII.  
 
DETAILED SUMMARY  
 
FOR FRIDAY JANUARY 05 - TUESDAY JANUARY 09: MODEL SOLUTIONS CONTINUE TO FEATURE  
A HIGHLY ANOMALOUS 500-HPA FLOW PATTERN OVER THE EASTERN U.S. AND WESTERN  
ATLANTIC THIS WEEK. THIS FLOW PATTERN IS LIKELY TO PROMOTE A RAPIDLY  
INTENSIFYING SURFACE LOW NEAR THE EAST COAST PRIOR TO THIS PERIOD. THE  
DETERMINISTIC MODELS ARE IN GOOD AGREEMENT AT THE START OF THE OUTLOOK PERIOD  
(12Z/JAN 5) WITH A 958 TO 962-HPA LOW LOCATED OVER THE GULF OF ST LAWRENCE.  
ALTHOUGH HEAVY SNOW IS EXPECTED TO END ON JAN 5 ACROSS NEW ENGLAND, HIGH WINDS  
(GUSTS ABOVE 40MPH) ARE LIKELY TO CAUSE AREAS OF BLOWING SNOW. GUSTY WINDS,  
STRONG COLD AIR ADVECTION, AND VERY LOW WIND CHILLS (SUBZERO) ARE FORECAST TO  
EXTEND INTO THE MID-ATLANTIC ON JAN 5 AND 6.  
 
ANOTHER OUTBREAK OF ARCTIC AIR IS LIKELY TO AFFECT THE EASTERN HALF OF THE  
CONUS ON JAN 5 AND 6. SUBZERO MINIMUM TEMPERATURES ARE FORECAST TO EXTEND AS  
FAR SOUTH AS THE OHIO VALLEY ON THESE MORNINGS, WHILE THERE IS AN INCREASING  
RISK OF A LIGHT FREEZE OR FROST ACROSS INTERIOR PARTS OF SOUTH FLORIDA ON JAN 5  
AND 6. MUCH BELOW-NORMAL TEMPERATURES ARE LIKELY TO PERSIST ACROSS THE EASTERN  
U.S. THROUGH JAN 7. MINIMUM TEMPERATURES COULD FALL BELOW -20 DEGREES F ACROSS  
THE COLDEST LOCATIONS OF THE NORTHEAST ON JAN 7. THE NEXT SURGE OF STRONG COLD  
AIR ADVECTION IS EXPECTED TO RESULT IN RENEWED LAKE-EFFECT SNOW WITH LOCALLY  
HEAVY AMOUNTS (MORE THAN A FOOT) IN THE MOST PERSISTENT BANDS, ESPECIALLY ON  
JAN 5.  
 
A SHORTWAVE TROUGH OF LOW AMPLITUDE IS EXPECTED TO PROGRESS RAPIDLY EAST FROM  
THE WEST COAST ON JAN 6 TO THE MIDDLE MISSISSIPPI VALLEY BY JAN 8. 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, A BRIEF PERIOD OF FREEZING RAIN IS EXPECTED  
ACROSS PARTS OF THE OHIO VALLEY AND CENTRAL APPALACHIANS ON JAN 7 AND 8.  
ALTHOUGH NO HAZARD IS CURRENTLY POSTED, THIS WILL BE CLOSELY MONITORED IN  
SUBSEQUENT OUTLOOKS.  
 
A STRONG SURFACE LOW (SUB 950-HPA) IS FORECAST TO TRACK NORTH FROM THE WESTERN  
ALEUTIANS TO THE KAMCHATKA PENINSULA EARLY IN THE PERIOD. AT THIS TIME, THE  
MAIN CONCERN ASSOCIATED WITH THIS STORM IS HIGH WINDS ACROSS PARTS OF WESTERN  
AND SOUTHWESTERN ALASKA, INCLUDING KODIAK ISLAND, JAN 5 TO 6, AND SIGNIFICANT  
WAVE HEIGHTS FOR COASTAL PORTIONS OF THE SOUTH COAST OF ALASKA AND KODIAK  
ISLAND JAN 5. SOME AREAS MAY EXPERIENCE SUSTAINED WIND SPEEDS OF 40 KNOTS OR  
GREATER AND SIGNIFICANT WAVE HEIGHTS OF 24 FEET OR GREATER. SOME AREAS NEAR  
BRISTOL BAY AND THE KUSKOKWIM DELTA MAY BE IMPACTED BY ELEVATED SURF AND SEA  
WATER LEVELS JAN 6 AND 7 ASSOCIATED WITH THE PERSISTENT SOUTH TO SOUTHWEST  
FETCH. PARTS OF THE WESTERN ALASKA RANGE AND CHUGACH MOUNTAINS MAY ALSO SEE  
SOME HIGH GAP WINDS JAN 6 DUE TO AN EAST-WEST PRESSURE GRADIENT, ALTHOUGH WIND  
SPEEDS LOOK MARGINAL, PRECLUDING AN ADDITIONAL HAZARDOUS WIND AREA FROM BEING  
IDENTIFIED AT THIS TIME.  
 
FOR WEDNESDAY JANUARY 10 - TUESDAY JANUARY 16: A MODERATION IN TEMPERATURES IS  
EXPECTED FOR THE CENTRAL AND EASTERN U.S. DURING MID-JANUARY AS THE 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. MEANWHILE, AN AMPLIFIED 500-HPA  
TROUGH IS FORECAST TO DEVELOP OVER THE NORTHEAST PACIFIC WITH AN INCREASE IN  
ONSHORE FLOW ALONG THE WEST COAST DURING WEEK-2.  
 
PRIOR TO THIS EXPECTED PATTERN CHANGE, RESIDUAL ARCTIC AIR SUPPORTS A SLIGHT  
RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PARTS OF THE CENTRAL AND EASTERN  
U.S. THROUGH JANUARY 11. THE SLIGHT RISK AREA IS BASED ON WHERE THE GFS AND  
ECMWF ENSEMBLE MEANS HAVE THE LARGEST NEGATIVE TEMPERATURE ANOMALIES ALTHOUGH  
THESE ARE SMALLER IN MAGNITUDE COMPARED TO THE DAY 3 TO 7 PERIOD.  
 
EARLY IN WEEK-2, THE DETERMINISTIC 0Z ECMWF AND 6Z GFS MODELS INDICATE A  
VIGOROUS SHORTWAVE TROUGH ENTERING CALIFORNIA AND THE SOUTHWESTERN U.S. DESPITE  
THIS ROBUST SHORTWAVE TROUGH IN THE DETERMINISTIC MODEL SOLUTIONS, THE 6Z GFS  
ENSEMBLE MEAN HAS LESS THAN A 0.5 INCH PER 48 HOURS ACROSS THESE AREAS ON JAN  
10 AND 11. GIVEN THESE LOWER AMOUNTS, ONLY A SLIGHT RISK OF HEAVY PRECIPITATION  
IS JUSTIFIED FOR PARTS OF THE WESTERN U.S. ON JAN 10 AND 11. A MORE ACTIVE  
SOUTHERN STREAM AND PRECIPITATION TOOLS SUPPORT A SLIGHT RISK OF HEAVY  
PRECIPITATION ACROSS THE LOWER TO MIDDLE MISSISSIPPI VALLEY AND OHIO VALLEY  
FROM JAN 11 TO 13. THE NORTHERN PERIPHERY OF THIS HAZARD SHAPE MAY EXPERIENCE  
PERIODS OF SNOW AND/OR FREEZING RAIN, BUT UNCERTAINTY ON LOW-LEVEL TEMPERATURES  
PRECLUDES DESIGNATION OF ANY SPECIFIC WINTER WEATHER HAZARDS AT THIS TIME.  
 
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  
 

 
 
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