553  
FXUS02 KWBC 301601  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1100 AM EST WED JAN 30 2019  
 
VALID 12Z SAT FEB 02 2019 - 12Z WED FEB 06 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
 
 
MODEL GUIDANCE THIS MORNING HAS SHOWN CLOSER AGREEMENT REGARDING  
THE TRACK AND INTENSITY OF A COUPLE OF LOW PRESSURE SYSTEMS  
FORECAST TO DEVELOP IN THE CENTRAL PLAINS EARLY NEXT WEEK. THE  
GFS IN PARTICULAR HAS TRENDED TOWARD THE ECMWF SINCE THE 00Z RUN.  
GIVEN THE BETTER AGREEMENT SHOWN AMONG MAJOR GLOBAL MODELS THROUGH  
THE MEDIUM RANGE, A GENERAL COMPROMISE OF THE 00Z ECMWF AND 06Z  
GFS WAS USED TO GENERATE THE WPC 500MB AND SEA-LEVEL PRESSURE  
FIELDS, TREND MORE TOWARD THEIR ENSEMBLE MEANS FOR DAYS 6 AND 7.  
THE MODEL BLEND YIELDED A MORE NORTHERLY TRACK FOR THE FIRST  
CYCLONE TO MOVE ACROSS THE UPPER MIDWEST INTO THE UPPER GREAT  
LAKES ON MONDAY. ANOTHER WAVE IS FORECAST TO FORM ALONG AN ARCTIC  
FRONT OVER THE CENTRAL PLAINS ON TUESDAY. THE 06Z GFS BEGINS TO  
ACCELERATE THE TRACK OF THIS LOW TOWARD THE OHIO VALLEY NEXT  
WEDNESDAY FASTER THAN THE 00Z ECMWF, BUT IT IS WITHIN THE NORMAL  
DISCREPANCY SHOWN BETWEEN THESE TWO MODELS.  
 
   
..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.  
 
KONG/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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