366  
FXUS02 KWBC 061337  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
836 AM EST TUE FEB 06 2018  
 
VALID 12Z FRI FEB 09 2018 - 12Z TUE FEB 13 2018  
 
OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENT  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
WHILE FORECAST INTRIGUE CONTINUES IN REGARDS TO DETAILS, THE  
GUIDANCE BROADLY AGREES WITH A POSITIVELY TILTED UPPER TROUGH  
EXTENDING FROM THE MID-LEVEL REFLECTION OF THE POLAR VORTEX INTO  
THE SOUTHWEST, BETWEEN PERSISTENT RIDGES ANCHORED OVER THE EAST  
PACIFIC AND OVER/EAST OF THE BAHAMAS. PREFERENCES REMAIN NEAR THE  
MIDDLE OF THE ENVELOPE AMONG OPERATIONAL SOLUTIONS EARLY WITH A  
TREND TOWARD AN ENSEMBLE MEAN AVERAGE LATER IN THE PERIOD TO  
ACCOUNT FOR UNCERTAINTY INHERENT AT DAYS 6 AND 7. TELECONNECTIONS  
RELATIVE TO THE MEAN PATTERN SHOW THE STRONGEST SIGNALS FOR ONE OR  
MORE EPISODES OF SIGNIFICANT PRECIP FROM THE GULF COAST REGION  
NORTHEASTWARD WITHIN THE AREA OF MID TO UPPER-LEVEL SOUTHWESTERLY  
FLOW AND BELOW NORMAL TEMPS OVER THE CENTRAL U.S. CAUSED BY A  
COUPLE FRONTAL INCURSIONS THIS PERIOD.  
 
WEATHER HIGHLIGHTS/THREATS  
~~~~~~~~~~~~~~~~~~~~~~~~~~  
THE WEST WILL LIKELY SEE A COOLING TREND AFTER DECENT COVERAGE OF  
PLUS 10-20F ANOMALIES LATE THIS WEEK. THE EXTENT OF THIS COOLING  
TREND WILL DEPEND ON DETAILS ALOFT BUT ANOMALIES SHOULD DECLINE AT  
LEAST TO SINGLE-DIGIT POSITIVE VALUES. THE NORTHERN INTO CENTRAL  
ROCKIES WILL SEE A PERIOD OF SNOW WITH ONE OR MORE AREAS OF SNOW  
EXTENDING ACROSS PARTS OF THE NORTHERN U.S. INTO NEW ENGLAND.  
UNCERTAINTY IN THE PRECIPITATION INTENSITY ACROSS THE  
INTERMOUNTAIN WEST IS CAUSED BY MID-LEVEL DIFFERENCES AMONGST THE  
GUIDANCE, WITH UT/AZ MOST LIKELY TO SEE SOME PRECIP IN THE EVENT  
OF A MODERATELY DEEP UPPER TROUGH/POSSIBLE CLOSED LOW. UPSTREAM  
ENERGY SHOULD BRING AN EPISODE OF MOSTLY LIGHT PRECIP TO THE  
NORTHWEST DURING THE LATTER HALF OF THE PERIOD.  
 
MUCH OF THE PLAINS SHOULD SEE BELOW NORMAL TEMPS DURING THE PERIOD  
ALBEIT WITH A MODERATING TREND FOR MON-TUE BEFORE THE NEXT FRONTAL  
INTRUSION. SOME AREAS OVER THE NORTHERN-CENTRAL PLAINS MAY SEE  
TEMPS AS MUCH AS 20-30F BELOW NORMAL ON FRI-SAT.  
 
GUIDANCE INDICATES LOCALLY HEAVY RAINFALL POTENTIAL FROM THE GULF  
COAST REGION INTO THE TN VALLEY/SOUTHERN APPALACHIANS/SOUTHERN MID  
ATLANTIC. EXPECT THE MOST FAVORED PERIOD OF FOCUSED ACTIVITY TO  
BE FROM FRIDAY NIGHT INTO THIS WEEKEND BUT SOME MOISTURE MAY  
LINGER INTO NEXT WEEK. GULF INFLOW, SHORTWAVE IMPULSES WITHIN  
SOUTHWESTERLY FLOW ALOFT, INSTABILITY NEAR THE GULF COAST, AND AT  
TIMES SLOW MOVEMENT OF THE FOCUSING FRONTAL BOUNDARY WILL BE AMONG  
THE INGREDIENTS THAT WOULD ENHANCE RAINFALL. ANTICIPATE A PERIOD  
OF VERY WARM MIN TEMPS OVER THE SOUTHEAST THIRD OF THE U.S. WITH  
SOME PLUS 10-20F ANOMALIES.  
 
FARTHER NORTH, UNCERTAINTY IN THE SPECIFICS OF FLOW AT THE SURFACE  
AND ALOFT LEAD TO FAIRLY LOW CONFIDENCE IN DETERMINING HOW MUCH  
INTERACTION WILL OCCUR BETWEEN THE NORTHERN PERIPHERY OF THE GULF  
TO MID ATLANTIC MOISTURE SHIELD AND SUFFICIENTLY COLD TEMPS THAT  
WOULD SUPPORT WINTRY PRECIPITATION TYPES.  
 
ROTH/RAUSCH  

 
 
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