076  
FXUS02 KWBC 300637  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
137 AM EST WED JAN 30 2019  
 
VALID 12Z SAT FEB 2 2019 - 12Z WED FEB 6 2019  
   
..OVERVIEW
 
 
AFTER THE RECENT AMPLIFIED PATTERN ACROSS MUCH OF THE CONTINENTAL  
U.S. THIS WEEK, A RETURN TO A MORE QUASI-ZONAL FLOW PATTERN  
APPEARS LIKELY BY THE BEGINNING OF THE MEDIUM RANGE PERIOD THIS  
WEEKEND. THE STORM SYSTEM THAT WILL BE CROSSING THE DESERT  
SOUTHWEST LATE THIS WEEK SHOULD BE PRESENT AS AN OPEN WAVE ACROSS  
THE SOUTH-CENTRAL U.S. BY SATURDAY AS A SOUTHERN STREAM  
DISTURBANCE. THE PATTERN CHANGE CONTINUES GOING INTO THE FIRST  
PART OF NEXT WEEK AS THE LARGE SCALE PACIFIC TROUGH WORKS ITS WAY  
INLAND AND SUPPORTS SURFACE LOW DEVELOPMENT ACROSS THE GREAT  
PLAINS AND UPPER MIDWEST. THE RESPONSE TO THIS WILL LIKELY BE A  
BROAD UPPER TROUGH BECOMING ESTABLISHED OVER THE WESTERN U.S. BY  
TUESDAY WITH A WARMER WEATHER PATTERN FOR THE EASTERN U.S. BY THE  
END OF THE FORECAST PERIOD WEDNESDAY.  
 
   
..GUIDANCE EVALUATION/PREFERENCES
 
 
SIMILAR TO THE PAST COUPLE OF DAYS, THE FORECAST PERIOD BEGINS  
WITH DECENT OVERALL MODEL AGREEMENT REGARDING THE SYNOPTIC SCALE  
PATTERN, WITH THE EXCEPTION OF THE 12Z UKMET THAT HAS BEEN SLOWER  
THAN THE MODEL CONSENSUS WITH THE PACIFIC CLOSED LOW REACHING  
CALIFORNIA THIS WEEKEND. THIS ALSO HOLDS TRUE FOR THE SECOND  
PACIFIC LOW APPROACHING THE PACIFIC NORTHWEST EARLY NEXT WEEK,  
WITH THE UKMET NOTABLY FARTHER TO THE WEST. BY MONDAY, THE 12Z  
ECMWF IS INDICATING A FASTER SOLUTION THAN THE CONSENSUS WITH THE  
LOW CROSSING THE MIDWEST, AND THE CMC ON THE NORTHERN EDGE OF THE  
GUIDANCE. IT IS INTERESTING TO NOTE THAT THE 18Z GFS IS ACTUALLY  
AMONG THE SLOWEST SOLUTIONS REGARDING THIS FEATURE. THE 18Z GEFS  
MEAN/12Z EC MEAN BOTH OFFER A REASONABLE STARTING POINT FOR LOW  
PLACEMENT DURING THIS TIME. THERE WAS ENOUGH MODEL CONSENSUS  
AMONG THE DETERMINISTIC GFS/ECMWF/CMC TO USE A BLEND OF THESE  
ALONG WITH THE NBM FOR THE FIRST HALF OF THE FORECAST, AND THEN  
MAINLY EC MEAN WITH SOME GEFS MEAN FOR THE SECOND HALF OF THE  
FORECAST PERIOD.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
A MUCH MILDER WEATHER PATTERN WILL BE PREVALENT ACROSS THE  
MAJORITY OF THE CENTRAL AND EASTERN U.S. BY THIS WEEKEND WITH HIGH  
TEMPERATURES RUNNING ABOUT 10 TO 20 DEGREES ABOVE CLIMATOLOGICAL  
AVERAGES, AND MILD OVERNIGHT LOWS ACROSS THE MIDWEST AND OHIO  
VALLEY AS FLOW FROM THE GULF OF MEXICO ADVECTS HIGHER HUMIDITY  
OVER THE REGION. A COUPLE OF WELL DEFINED LOW PRESSURE SYSTEMS  
ARE EXPECTED TO TRACK ACROSS THE GREAT PLAINS AND MIDWEST OVER THE  
COURSE OF THE MEDIUM RANGE PERIOD, WITH THE POTENTIAL FOR  
SIGNIFICANT SNOW TO THE NORTHWEST OF THE SURFACE LOWS THAT DEVELOP  
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST, AND ARCTIC AIRMASSES  
WILL LIKELY SETTLE SOUTHWARD ACROSS THE DAKOTAS AND MONTANA.  
BASED ON CURRENT PROJECTIONS, THE SEVERITY OF THE COLD WILL BE  
LESS THAN THE ONGOING ARCTIC INTRUSION NOW.  
 
HEAVY RAIN AND MOUNTAIN SNOW IS EXPECTED ACROSS MUCH OF CALIFORNIA  
AND THE TERRAIN OF THE INTERMOUNTAIN WEST THIS WEEKEND AS A STRONG  
PACIFIC DISTURBANCE MOVES INLAND. SHOWERS AND STORMS ARE LIKELY  
TO DEVELOP FROM THE GULF COAST TO THE MIDWEST IN THE WARM SECTORS  
OF THE TWO SURFACE LOWS. SOME OF THIS RAINFALL MAY BE LOCALLY  
HEAVY.  
 
HAMRICK  
 
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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