144  
FXUS02 KWBC 110649  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
148 AM EST MON FEB 11 2019  
 
VALID 12Z THU FEB 14 2019 - 12Z MON FEB 18 2019  
   
..OVERVIEW
 
 
MODELS/ENSEMBLES SHOW STRONG CONSENSUS THAT A REX BLOCK PATTERN  
ACROSS THE CENTRAL/NORTH PACIFIC, EXTENDING FROM NEAR HAWAII TO  
ALASKA, SHOULD PERSIST THROUGH THE NEXT WEEK, LEAVING THE FLOW  
REGIME ACROSS THE CONUS LARGELY UNCHANGED. TELECONNECTIONS  
RELATIVE TO THE STRONGEST 500 HA HEIGHT POSITIVE ANOMALY CENTER  
CONTINUE TO FAVOR A POSITIVELY-TILTED MEAN TROUGH NEAR THE PACIFIC  
NORTHWEST, WITH WEAK POSITIVE HEIGHT ANOMALIES FROM THE SOUTHERN  
PLAINS TO THE SOUTHEAST, AND A BROAD REGION OF MODESTLY CYCLONIC  
UPPER-LEVEL FLOW ACROSS MUCH OF THE CONUS. SHORTWAVE ENERGY  
EJECTING FROM THE NORTHEASTERN PACIFIC EVERY COUPLE DAYS WILL MOVE  
INTO THEN CROSS THE CONUS, UNDERGOING GRADUAL AMPLIFICATION IN THE  
BROAD CYCLONIC FLOW. ADDITIONALLY, A PERSISTENT AND RELATIVELY  
STRONG THERMAL GRADIENT FROM THE CENTRAL U.S. TO THE OHIO  
VALLEY/GREAT LAKES WILL SERVE TO INTENSIFY ANOTHER LOW PRESSURE  
SYSTEM BY LATER THIS WEEK.  
 
   
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
 
 
THE DEVELOPING LOW PRESSURE SYSTEM ACROSS THE CENTRAL U.S. DAYS  
3-4 (THU-FRI) REMAINS ONE OF THE MORE SIGNIFICANT CONCERNS THIS  
FORECAST PERIOD. MODEL CYCLES FROM DURING THE DAY YESTERDAY SEEMED  
TO SHOW SOME DEGREE OF IMPROVED CONSENSUS TOWARD THE IDEA OF  
LESS/SLOWER PHASING BETWEEN THE VIGOROUS PACIFIC SHORTWAVE AND  
ADDITIONAL NORTHERN STREAM ENERGY, AND A SURFACE LOW TRACK THU  
NIGHT/FRI FROM THE SOUTHERN/CENTRAL PLAINS TO THE MID-MISSISSIPPI  
VALLEY AND THE LOWER GREAT LAKES. THE 12Z ECMWF/CMC AND 18Z GFS  
WERE FAIRLY CLOSE ON THIS, AND ENSEMBLE MEMBERS SHOWED DECENT  
CLUSTERING AROUND THIS TYPE OF SOLUTION. THE WPC FORECAST DEPICTS  
A SOLUTION ALONG THESE LINES AS WELL, WHICH WAS FAIRLY CLOSE TO  
FORECAST CONTINUITY. THE ARRIVAL OF THE 00Z GFS AND UKMET THREW A  
BIT OF A FLY INTO THE OINTMENT, RETURNING TO A MUCH MORE PHASED  
SOLUTION THAT RACES THE SURFACE LOW NORTHEASTWARD FAR MORE QUICKLY  
THAN THE PREVIOUSLY MENTIONED CONSENSUS. THE AFOREMENTIONED  
OUTCOME ALSO HAS DOWNSTREAM AFFECTS BY FRI NIGHT SAT AS THE SYSTEM  
REACHES THE EASTERN U.S. WITH THE FAVORED CONSENSUS SOLUTION  
LIKELY RESULTING IN THE DEVELOPMENT OF A LOW ALONG THE  
MID-ATLANTIC COAST TRACKING NORTHWARD INTO NEW ENGLAND. A MORE  
PHASED SYSTEM EARLIER, HOWEVER, WOULD QUICKLY MOVE THE SYSTEM  
NORTH INTO CANADA BY THAT TIME. NEEDLESS TO SAY, CONFIDENCE  
REMAINS BELOW AVERAGE WITH RESPECT TO THIS SYSTEM THU-SAT, AND THE  
FORECAST IS SUBJECT TO SIGNIFICANT CHANGES.  
 
IN THE WAKE OF THE LATE WEEK LOW PRESSURE SYSTEM, MODELS HAVE AT  
LEAST COME INTO BETTER AGREEMENT ON THE NATURE OF THE FLOW ACROSS  
THE WESTERN/CENTRAL U.S. BY THE WEEKEND. THE GFS HAS BACKED OFF  
ITS PREVIOUS ATTEMPTS TO BUILD RIDGING/ANTICYCLONIC FLOW ACROSS  
THE ROCKIES/CENTRAL U.S. - NOW SHOWING A STRONGER UPPER JET  
CONTINUING TO TRANSPORT NUMEROUS AREAS OF PACIFIC SHORTWAVE ENERGY  
INLAND. A MORE SIGNIFICANT TROUGH SHOULD PUSH INTO THE WESTERN  
U.S. BY SUN-MON, AS SHOWN BY THE MAJORITY OF DETERMINISTIC  
SOLUTIONS AND ENSEMBLE MEANS. DETAIL DIFFERENCES EMERGE BY BY  
EARLY NEXT WEEK AS TO JUST HOW QUICKLY THIS AMPLIFIED TROUGH MOVES  
INLAND, LENDING TOWARD HEAVIER USE OF ENSEMBLE MEANS (ECENS AND  
GEFS) IN THE FORECAST BY DAYS 6-7.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
THE PERSISTENT UPPER TROUGH ALONG THE WEST COAST WILL PRODUCE  
MULTIPLE ROUNDS OF LOW-ELEVATION RAIN AND MOUNTAIN SNOW FROM  
CALIFORNIA TO THE PACIFIC NORTHWEST. SYSTEMS WILL ALSO SPREAD  
RAIN/SNOW EAST INTO THE INTERIOR WESTERN U.S., WITH HEAVY SNOW  
POSSIBLE AT THE HIGHER ELEVATIONS. THE LOW PRESSURE SYSTEM MOVING  
FROM THE CENTRAL U.S. TOWARD THE GREAT LAKES THU-FRI WILL LIKELY  
PRODUCE AN AREA OF WINTRY WEATHER ALONG/NORTH OF THE SURFACE LOW  
TRACK. THE EXTENT OF WINTER WEATHER AND THE DEGREE TO WHICH HEAVY  
SNOW MAY BE POSSIBLE REMAINS SOMEWHAT UNCERTAIN GIVEN THE MODEL  
DIFFERENCES DESCRIBED ABOVE. THE SAME HOLDS TRUE FOR WINTER  
WEATHER POTENTIAL IN THE NORTHEAST FRI-SAT. WHILE AT LEAST SOME  
WINTRY WEATHER IS LIKELY IN WARM ADVECTION AHEAD OF THE WARM  
FRONT, ANY POTENTIAL COASTAL LOW DEVELOPMENT WOULD ENHANCE THE  
POTENTIAL FOR HEAVIER PRECIPITATION ACROSS NEW ENGLAND, WITH THE  
BEST CHANCES FOR SIGNIFICANT SNOWS ACROSS THE INTERIOR. FARTHER  
SOUTH, THE COLD FRONT WILL LIKELY PRODUCE WIDESPREAD RAINS FROM  
THE LOWER MISSISSIPPI VALLEY TO THE EASTERN SEABOARD.  
 
WELL BELOW AVERAGE TEMPERATURES ARE EXPECTED TO PERSIST FROM THE  
INTERIOR PACIFIC NORTHWEST TO THE NORTHERN PLAINS THROUGH THE  
FORECAST PERIOD. MAX/MIN TEMPERATURES RANGING FROM 10 TO 30 DEG F  
BELOW AVERAGE WILL BE POSSIBLE THROUGH THE WEEK AND INTO THE  
WEEKEND ACROSS THESE AREAS. TEMPERATURES WILL INITIALLY BE ABOVE  
AVERAGE FROM THE SOUTHERN/CENTRAL PLAINS TO THE EASTERN SEABOARD  
THU, BUT BY LATE IN THE WEEK COLDER TEMPERATURES SHOULD SPREAD  
FARTHER SOUTH/EAST IN THE WAKE OF THE LOW PRESSURE SYSTEM, WITH  
TEMPERATURES 5 TO 15 DEG F BELOW AVERAGE ACROSS MUCH OF THE  
CENTRAL/EASTERN STATES. THE EXCEPTION WILL BE AREAS FROM THE  
SOUTHERN PLAINS TO THE SOUTHEAST WHERE TEMPERATURES WILL REMAIN  
NEAR SEASONAL NORMS EVEN INTO THE WEEKEND.  
 
RYAN  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
 

 
 
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