491  
FXUS21 KWNC 060600  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST FEBRUARY 05 2018  
 
SYNOPSIS: A COLD FRONT IS FORECAST TO MOVE FROM THE NORTHERN GREAT PLAINS TO  
THE SOUTHEAST BY EARLY NEXT NEXT, WITH COLD AIR MOVING SOUTHWARD BEHIND IT. AN  
UPPER-LEVEL LOW-PRESSURE SYSTEM IS FORECAST TO MOVE OVER THE SOUTHWEST AND  
SOUTHERN PLAINS, BEFORE INTERACTING WITH THE FRONT, OVER THE SOUTHEAST. DURING  
THE LATTER PORTION OF THE OUTLOOK PERIOD, COOL CONDITIONS ARE LIKELY TO  
CONTINUE OVER THE CENTRAL PORTIONS OF THE CONTIGUOUS 48 STATES, WITH THE  
POTENTIAL FOR ACTIVE WEATHER TO REMAIN OVER THE SOUTHEAST. FOR ALASKA, A  
LOW-PRESSURE SYSTEM IS FORECAST TO IMPACT SOUTHWEST ALASKA. DURING WEEK-2, AN  
ACTIVE PATTERN IS LIKELY TO PUSH MOISTURE INTO CENTRAL ALASKA.  
 
HAZARDS  
 
HEAVY RAIN FROM THE GULF COAST TO THE MID-ATLANTIC AND NORTHEAST, SAT-SUN, FEB  
10-FEB 11.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES, THU, FEB 8.  
 
HEAVY SNOW ACROSS PORTIONS OF NEW ENGLAND, SUN, FEB 11.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN AND CENTRAL  
PLAINS, THE NORTHERN ROCKIES, THE UPPER AND MIDDLE MISSISSIPPI VALLEYS, AND THE  
GREAT LAKES, THU-SAT, FEB 8-FEB 10.  
 
HIGH WINDS ACROSS PORTIONS OF SOUTHWEST ALASKA AND THE ALEUTIANS, FRI-SAT, FEB  
9-FEB 10.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND  
IDAHO.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE CENTRAL ROCKIES, THE LOWER MISSISSIPPI VALLEY, THE NORTHERN PLAINS,  
THE GREAT LAKES, THE NORTHERN ROCKIES, THE SOUTHERN ROCKIES, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE  
OHIO VALLEY, TUE-THU, FEB 13-FEB 15.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI VALLEY, AND THE  
NORTHERN PLAINS, TUE-WED, FEB 13-FEB 14.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN APPALACHIANS, AND THE TENNESSEE VALLEY,  
TUE-WED, FEB 13-FEB 14.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF MAINLAND ALASKA, TUE-WED,  
FEB 13-FEB 14.  
 
SEVERE DROUGHT ACROSS PARTS OF CALIFORNIA, THE CENTRAL AND SOUTHERN  
INTERMOUNTAIN REGION, THE CENTRAL AND SOUTHERN ROCKIES, THE GREAT PLAINS, THE  
MIDDLE AND LOWER MISSISSIPPI VALLEY, THE SOUTHEAST, AND THE MID-ATLANTIC.  
 
DETAILED SUMMARY  
 
FOR THURSDAY FEBRUARY 08 - MONDAY FEBRUARY 12: A COLD FRONT IS FORECAST TO MOVE  
FROM THE NORTHERN GREAT PLAINS TO THE SOUTHEAST, WITH HIGH PRESSURE BUILDING IN  
BEHIND THE FRONT. OVER THE NORTHERN AND CENTRAL PLAINS, EASTWARD TO THE UPPER  
GREAT LAKES, TEMPERATURES ARE FORECAST TO BE 20-30 DEG F BELOW NORMAL BEHIND  
THE FRONT. AS THE COLD AIR SPILLS SOUTHWARD, SOME FROSTS AND FREEZES ARE LIKELY  
AS FAR SOUTH AS WEST-CENTRAL TEXAS. TEMPERATURES ARE LIKELY TO MODERATE THROUGH  
THE FIRST WEEK, BUT SHOULD REMAIN WELL BELOW NORMAL THROUGH FEB 10.  
 
UPSLOPE FLOW ON THE WESTERN FLANK OF THE HIGH PRESSURE COULD RESULT IN MODERATE  
TO HEAVY SNOWS (6 INCHES IN 24 HOURS) FROM MONTANA, WYOMING, AND POTENTIALLY AS  
FAR SOUTH AS COLORADO. AS THE COLD FRONT SLIDES SOUTHWARD OVER THE PLAINS, SOME  
SNOWS ARE LIKELY TO SPREAD TO THE MIDWEST ON FEB 9. WINDS APPROACHING HIGH  
WINDS THRESHOLDS ARE POSSIBLE OVER THE CENTRAL AND SOUTHERN HIGH PLAINS AS THE  
HIGH PRESSURE BUILDS SOUTHWARD.  
 
BY FEB 10 AND 11, THE COLD FRONT IS LIKELY TO BE OVER THE SOUTHEAST, AND AN  
UPPER-LEVEL TROUGH IS FORECAST TO MOVE OVER THE SOUTHERN GREAT PLAINS.  
INTERACTIONS WITH THE TROUGH AND THE FRONT ARE LIKELY TO RESULT OF HEAVY RAINS  
FROM LOUISIANA TO THE SOUTHERN PORTIONS OF NEW ENGLAND. THE HEAVIEST RAINS ARE  
LIKELY FROM THE CENTRAL GULF COAST TO THE CAROLINAS, WITH PRECIPITATION AMOUNTS  
APPROACHING 2 INCHES OVER THE SOUTHERN APPALACHIANS. SOME HEAVIER SNOWS (4  
INCHES OR MORE) ARE FORECAST OVER MAINE DURING FEB 11, AS THE MOISTURE STREAMS  
NORTHWARD.  
 
WITH THE UPPER-LEVEL TROUGH MOVING OVER THE SOUTHWEST AND SOUTHERN PLAINS, SOME  
WINDS COULD MIX DOWN OVER NEW MEXICO AND TEXAS, INCREASING THE RISK FOR  
CRITICAL FIRE WEATHER CONDITIONS. FURTHER WEST, OVER NEVADA AND CALIFORNIA,  
STRONG WINDS ARE POSSIBLE SATURDAY AND SUNDAY, ESPECIALLY IN AREAS WITH LOCAL  
TERRAIN FUNNELING.  
 
LOW-PRESSURE APPROACHING ALASKA FROM THE WEST IS LIKELY TO BRING HIGH WINDS TO  
SOUTHWEST ALASKA DURING FEB 9-10. WIND SPEEDS ARE FORECAST TO APPROACH 45 KNOTS  
ON THE SOUTHERN COASTS OF THE ALEUTIANS, KODIAK ISLAND, AND THEN ALASKA  
PENINSULA. WAVE HEIGHTS ARE EXPECTED TO REMAIN BELOW HAZARDOUS THRESHOLDS.  
 
FOR TUESDAY FEBRUARY 13 - MONDAY FEBRUARY 19: THE MODEL OUTPUT FOR WEEK-2  
EXHIBIT A GOOD AMOUNT OF DISAGREEMENT. CALIBRATED OUTPUT FROM THE GEFS AND  
ECMWF AGREE THAT ACTIVE PATTERN IS LIKELY FOR WESTERN AND CENTRAL ALASKA, WITH  
A PERSISTENT WESTERLY FLOW, SO A SLIGHT RISK OF HEAVY PRECIPITATION IS  
INDICATED FOR FEB 13 AND 14. A LESS COHERENT SIGNAL IS PRESENT OVER THE  
SOUTHEAST, WHERE THE MODELS INDICATE AN INCREASED RISK OF MORE THAN 1 INCH,  
WITH THE ECMWF OUTPUT HIGHLIGHTING AN ENHANCED RISK OF MORE THAN 1.5 INCHES  
DURING THE EARLY PORTIONS OF WEEK-2.  
 
GEFS OUTPUT OVER THE CENTRAL CONUS IS SIGNIFICANTLY COLDER THAN ECMWF OUTPUT.  
THE SLIGHT AND MODERATE RISKS INDICATED ON THE MAPS REFLECT PROBABILITIES FOR  
MUCH BELOW NORMAL MINIMUM TEMPERATURES THAT ARE LOWER THAN INDICATED BY THE  
GEFS, AS THE ECWMF OUTPUT IS NOT AS COLD. THE MOST LIKELY AREA FOR MUCH BELOW  
NORMAL MINIMUM TEMPERATURES IS OVER THE NORTHERN PLAINS, FROM MONTANA TO IOWA,  
WHERE THE MODELS AGREE.  
 
THE U.S. DROUGHT MONITOR, VALID ON JANUARY 30, 2018 INDICATES A SUBSTANTIAL  
INCREASE IN THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 13.60%  
LAST WEEK TO 17.21% THIS WEEK. DRYNESS AND DROUGHT HAVE INCREASED IN SPATIAL  
COVERAGE AND/OR INTENSIFIED OVER PORTIONS OF CALIFORNIA AND THE SOUTHWEST THIS  
WEEK. SOME DETERIORATION IN CONDITIONS IS ALSO NOTED OVER THE SOUTHERN PLAINS.  
 
FORECASTER: MATTHEW ROSENCRANS  
 

 
 
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