788  
FXUS02 KWBC 050658  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
157 AM EST TUE MAR 5 2019  
 
VALID 12Z FRI MAR 8 2019 - 12Z TUE MAR 12 2019  
   
..WEATHER PATTERN OVERVIEW
 
 
AN ACTIVE WEATHER PATTERN IS EXPECTED DURING MUCH OF THE MEDIUM  
RANGE PERIOD AS A LARGE SCALE TROUGH ORIGINATING FROM THE PACIFIC  
AMPLIFIES OVER THE ROCKIES AND HIGH PLAINS. THIS WILL INDUCE  
SURFACE CYCLOGENESIS EAST OF THE ROCKIES AND BECOME A STRONG  
SURFACE LOW AS IT TRACKS NORTHEASTWARD. A SECOND DISTURBANCE IS  
FORECAST TO AFFECT THE WEST COAST REGION BY EARLY NEXT WEEK, AND  
THIS SHOULD ALSO LEAD TO THE DEVELOPMENT OF THE SURFACE LOW OVER  
THE SOUTHERN PLAINS BY THE END OF THE FORECAST PERIOD.  
 
   
..MODEL GUIDANCE EVALUATION AND PREFERENCES
 
 
THE MODELS AND ENSEMBLE MEANS INDICATE REASONABLE AGREEMENT ON THE  
SYNOPTIC SCALE FOR THE END OF THE WEEK, AND SLIGHTLY BETTER  
AGREEMENT COMPARED TO YESTERDAY. ONE OF THE MAIN DIFFERENCES ON  
FRIDAY IS THAT THE GFS BASED GUIDANCE INDICATE A MORE DEVELOPED  
LEAD SURFACE LOW CROSSING THE OHIO VALLEY REGION, WHEREAS THE  
CMC/ECMWF/UKMET SUPPORT MORE OF AN ELONGATED SURFACE TROUGH.  
 
THE STRONG SURFACE LOW THAT IS FORECAST TO DEVELOP ACROSS THE  
PLAINS AND THEN TRACK NORTHEASTWARD IS INDICATING REASONABLY GOOD  
AGREEMENT ON SATURDAY MORNING ACROSS EASTERN COLORADO AS LEE  
CYCLOGENESIS GETS UNDERWAY. MODEL DIFFERENCES ARE MORE APPARENT  
BY SUNDAY REGARDING THE TRACK OF THE SURFACE LOW ACROSS THE  
MIDWEST STATES AND THEN THE GREAT LAKES REGION. IN TERMS OF  
TRENDS, BOTH THE EC MEAN AND GEFS MEAN CONTINUE TO TREND STRONGER  
AND SLIGHTLY FASTER WITH THIS STORM SYSTEM, AND THE CANADIAN MEAN  
HAS TRENDED CLOSER TO THE GEFS AND EC MEANS COMPARED TO  
YESTERDAY'S RUNS. SIMILAR TO YESTERDAY, THE FV3 IS FASTER THAN  
THE MODEL CONSENSUS AND LOSES ENSEMBLE SUPPORT. THE GFS AND ITS  
ENSEMBLE MEMBERS ARE GENERALLY ON THE STRONGER SIDE OF THE  
FORECAST GUIDANCE. TAKING ALL OF THESE FACTORS INTO ACCOUNT, THE  
FORECAST WAS PRIMARILY DERIVED FROM THE 12Z ECMWF/18Z FV3 AND  
GFS/12Z CMC FOR THE FIRST TWO DAYS, AND THEN SOME OF THE ECMWF AND  
EC/NAEFS MEAN FOR THE SECOND HALF OF THE FORECAST PERIOD. THE WPC  
FORECAST IS SIMILAR TO THE PREVIOUS ONE REGARDING THE TRACK OF THE  
STORM, EXCEPT NOW IT IS FORECAST TO BE SLIGHTLY MORE INTENSE.  
 
   
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
 
 
WIDESPREAD RAIN AND THUNDERSTORMS ARE EXPECTED TO DEVELOP FROM THE  
GULF COAST TO THE OHIO VALLEY AND SOUTHERN APPALACHIANS AS A RICH  
SUPPLY OF GULF MOISTURE SURGES NORTHWARD AHEAD OF A STRONG COLD  
FRONT FROM THE SURFACE LOW. THE HEAVIEST RAINFALL IS LIKELY FROM  
EASTERN TEXAS TO TENNESSEE, WHERE A GENERAL 1 TO 3 INCHES OF RAIN  
IS LIKELY THAT MAY LEAD TO SOME FLOODING ISSUES BASED ON THE  
CURRENT FORECAST. DEPENDING ON WHERE THE SURFACE LOW TRACKS, A  
CORRIDOR OF BLIZZARD CONDITIONS WILL BE POSSIBLE ACROSS PARTS OF  
THE NORTHERN PLAINS, UPPER MIDWEST, AND WESTERN GREAT LAKES  
REGION. IT IS STILL TOO EARLY TO MENTION PRECISE LOCATIONS GIVEN  
CURRENT MODEL DIFFERENCES. ANOTHER FACET TO THIS LOW PRESSURE  
SYSTEM WILL BE THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS TO  
DEVELOP IN THE WARM SECTOR, AND THIS IS SOMETHING THAT THE STORM  
PREDICTION CENTER IS CURRENTLY MONITORING. MORE RAIN IS LIKELY  
ACROSS THE CENTRAL AND SOUTHERN PLAINS BY NEXT TUESDAY ASSOCIATED  
WITH THE NEXT STORM SYSTEM.  
 
HEAVY SNOW WILL LIKELY CONTINUE FOR ANOTHER DAY ON FRIDAY ACROSS  
THE HIGHER ELEVATIONS OF THE INTERMOUNTAIN WEST AND ROCKIES AS THE  
STRONG PACIFIC DISTURBANCE CROSSES THE REGION. TOTAL SNOWFALL  
AMOUNTS ON THE ORDER OF 1 TO 2 FEET ARE POSSIBLE ACROSS PARTS OF  
THE CENTRAL AND NORTHERN ROCKIES, BEFORE GRADUALLY ENDING EARLY  
SATURDAY.  
 
THE NORTHERN-CENTRAL PLAINS WILL LIKELY CONTINUE TO SEE BELOW  
NORMAL TEMPERATURES MOST DAYS WITH HIGHS TENDING TO BE 10-20F  
BELOW NORMAL WITH LOCALLY MORE EXTREME ANOMALIES ONE OR MORE DAYS.  
THE WEST WILL TEND TO SEE BELOW NORMAL HIGHS FOR MUCH OF THE  
PERIOD BUT MORNING LOWS SHOULD BE ABOVE NORMAL LATE THIS WEEK.  
THE SOUTHERN AND EASTERN U.S. SHOULD HAVE A BRIEF SURGE OF WARMTH  
AHEAD OF THE FRONT ASSOCIATED WITH THE PLAINS/GREAT LAKES STORM  
DURING THE WEEKEND, FOLLOWED BY A RETURN TO COOLER WEATHER.  
 
D. HAMRICK  
 
ADDITIONAL 3-7 DAY HAZARDS INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE 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  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 
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