720  
FXUS02 KWBC 171916  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
315 PM EDT FRI MAY 17 2019  
 
VALID 12Z MON MAY 20 2019 - 12Z FRI MAY 24 2019  
 
...A STORMY AND WET PATTERN FOR THE WESTERN AND CENTRAL U.S NEXT  
WEEK....  
 
   
..OVERALL WEATHER PATTERN
 
 
IT REMAINS THE CASE THAT A STORMY AND UNSETTLED WEATHER PATTERN IS  
EXPECTED ACROSS MUCH OF THE CENTRAL U.S. DURING THE MEDIUM RANGE  
PERIOD WITH A LARGE SCALE UPPER TROUGH BECOMING ESTABLISHED OVER  
THE INTERMOUNTAIN WEST AND A BUILDING UPPER LEVEL RIDGE OVER THE  
SOUTHEASTERN STATES. THREE WELL DEFINED STORM SYSTEMS ARE EXPECTED  
NEXT WEEK, WITH THE FIRST AFFECTING THE NORTHEASTERN U.S. ON  
MONDAY. THE SECOND STORM EXITS THE SNOWY ROCKIES MONDAY TO GATHER  
STRENGTH ACROSS THE PLAINS ON TUESDAY AND TRACKS TOWARDS THE GREAT  
LAKES, AND THE THIRD WELL ORGANIZED SYSTEM SLAMS INTO THE WEST  
COAST TUESDAY, DEVELOPS OVER THE INTERMOUNTAIN WEST MIDWEEK TO  
REACH THE PLAINS LATE NEXT WEEK.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 06 UTC FV3 AND 00 UTC ECMWF FORECASTS ARE WELL CLUSTERED WITH  
GEFS/ECMWF ENSEMBLE SOLUTIONS THROUGH THIS MEDIUM RANGE PERIOD,  
BOLSTERING CONFIDENCE. THE WPC MEDIUM RANGE PRODUCT SUITE WAS  
PRIMARILY DERIVED FROM A SEEMEINGLY REASONABLE COMPOSITE BLEND OF  
THESE GUIDANCE PIECES. THIS ALSO MAINTAINS GOOD WPC CONTINUITY. IN  
CONTRAST, THE 00/06 UTC GFS RUNS OFFER MORE OUTLIER SOLUTIONS  
THAT BECOME MUCH MORE PROGRESSIVE THAN THE WPC COMPOSITE FROM THE  
GULF OF ALASKA TO WESTERN CANADA AND THE NORTHWESTERN U.S.  
MID-LATER NEXT WEEK. THIS DOES NOT SEEM AS GOOD A FIT WITH THE  
OVERALL AMPLIFYING PATTERN.  
 
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
NUMEROUS SHOWERS AND THUNDERSTORMS CONTINUE TO BE IN THE FORECAST  
GOING INTO NEXT WEEK ACROSS THE CENTRAL/SOUTHERN PLAINS AND  
EXTENDING TO THE UPPER MIDWEST. MULTIPLE ROUNDS OF MCS ACTIVITY  
ARE LIKELY WITH BOTH OF THE LOW PRESSURE SYSTEMS THAT ARE PROGGED  
TO TRACK ACROSS THE PLAINS. THIS WILL HAVE THE POTENTIAL TO  
PRODUCE VERY HEAVY RAINFALL CAPABLE OF FLASH FLOODING, AND SEVERE  
WEATHER IS ALSO LIKELY FROM NORTHERN TEXAS TO THE MIDWEST BASED ON  
RECENT SPC FORECASTS. THE GREATEST CHANCE OF FLOODING WOULD BE  
FROM THE TEXAS PANHANDLE REGION TO IOWA WITH THE STRONG LOW  
PRESSURE SYSTEM FOR THE EARLY TO MIDDLE PART OF THE WEEK.  
ADDITIONAL HEAVY RAIN IS ALSO POSSIBLE FROM THE NEXT STORM SYSTEM  
TRACKING EASTWARD FROM THE INTERMOUNTAIN WEST LATER IN THE WEEK,  
ALTHOUGH DETAILS ON TIMING AND PLACEMENT ARE LESS CERTAIN.  
 
THERE WILL ALSO BE A DICHOTOMY OF TEMPERATURE ANOMALIES GIVEN THE  
AMPLIFIED FLOW PATTERN IN PLACE. TEMPERATURES ARE EXPECTED TO BE  
WELL ABOVE NORMAL ACROSS MUCH OF THE SOUTHEASTERN U.S. OWING TO  
THE STRENGTH OF THE UPPER RIDGE, AND THIS WILL ALSO SERVE TO KEEP  
RAINFALL CHANCES MINIMAL. THE OPPOSITE WILL BE THE CASE ACROSS  
MUCH OF THE WESTERN U.S. AND ALSO THE NORTHERN PLAINS THAT WILL BE  
UNDER THE INFLUENCE OF THE UPPER LEVEL TROUGH AND TO THE NORTH OF  
THE LOW TRACKS. HEAVIER LATE SEASON SNOWS ARE ALSO LIKELY FOR THE  
SIERRA NEVADA TO THE NORTHERN ROCKIES.  
 
D. HAMRICK/SCHICHTEL  
 
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  
 
HAZARDS:  
- HEAVY RAIN ACROSS PORTIONS OF THE PLAINS AND THE MISSISSIPPI  
VALLEY, MON-TUE, MAY 20-MAY 21.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN  
PLAINS, MON, MAY 20.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE  
MIDDLE MISSISSIPPI VALLEY, TUE, MAY 21.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN  
PLAINS AND THE MISSISSIPPI RIVER BASIN.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE MISSISSIPPI AND MISSOURI RIVER BASINS, AND THE  
NORTHERN ROCKIES.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN GREAT BASIN.  
- EXTREME HEAT ACROSS PORTIONS OF THE SOUTHEAST, THU-FRI, MAY  
23-MAY 24.  
- HIGH WINDS ACROSS PORTIONS OF THE SOUTHERN ROCKIES AND THE  
SOUTHERN HIGH PLAINS, MON, MAY 20.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF CALIFORNIA,  
THE CENTRAL GREAT BASIN, AND THE SOUTHWEST, MON-WED, MAY 20-MAY 22.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN  
AND CENTRAL PLAINS, MON-TUE, MAY 20-MAY 21.  
 
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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