396  
FXUS02 KWBC 152021  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
420 PM EDT WED MAY 15 2019  
 
VALID 12Z SAT MAY 18 2019 - 12Z WED MAY 22 2019  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 06 UTC GFS/FV3 AND 00 UTC ECMWF/UKMET/CANADIAN OFFER GOOD  
FORECAST CLUSTERING THIS WEEKEND. DESPITE SOME COMMON LONGER TERM  
MODEL SIMILARITIES, FORECAST CONFIDENCE NEXT WEEK REMAINS BELOW  
NORMAL DUE TO LESS THAN STELLAR CONTINUITY ISSUES. ACCORDINGLY,  
THE WPC PRODUCT SUITE PRIMARILY WAS DERIVED FROM A COMPOSITE MODEL  
SOLUTION THIS WEEKEND BEFORE QUICKLY TRANSITIONING TO MORE  
COMPATABLE 06 UTC GEFS MEAN AND 00 UTC ECMWF ENSEMBLE MEAN INTO  
EARLY NEXT WEEK AMID GROWING FORECAST SPREAD....GUIDANCE  
ASSESSMENT AND WEATHER HIGHLIGHTS/THREATS...  
   
..WEATHER HIGHLIGHTS AND HAZARDS
 
 
MODEL AND ENSEMBLE SOLUTIONS CONTINUE TO SHOW ABOVE NORMAL  
FORECAST SPREAD WITH RESPECT TO NORTHEASTERN U.S./MID-ATLANTIC  
FLOW THROUGH THIS WEEKEND AS A SERIES OF POTENT CANADIAN UPPER  
SYSTEMS PROGRESS WITHIN AN ENERGETIC NORTHERN STREAM. FAVOR A  
COMPOSITE.  
 
UPSTREAM, A DYNAMIC MID-UPPER LEVEL TROUGH WILL LIFT NORTHEASTWARD  
FROM THE SOUTHERN ROCKIES TO THE CENTRAL THEN NORTHEASTERN U.S.  
SAT-TUE. THIS SYSTEM WILL SPAWN SURFACE SYSTEM/LOW GENESIS WITH  
LEAD MOISTURE INFLOW AND INSTABILITY PROVIDING THE FOUNDATION FOR  
A THREAT OF HEAVY CONVECTION/RAINFALL AND SEVERE WEATHER AS PER  
SPC. UNDERNEATH, A GRADUALLY WEAKENING CLOSED LOW/CONVECTION WILL  
WEAKEN OVER THE EASTERN GULF OF MEXICO.  
 
THERE REMAINS A STRONG SIGNAL THAT PACIFIC FLOW WILL BRING ANOTHER  
ROUND OF STRONG HEIGHT FALLS AND WIDESPREAD PRECIPITATION/TERRAIN  
ENHANCED SNOWS TO THE WEST LATER THIS WEEKEND INTO EARLY-MID NEXT  
WEEK BEFORE EJECTING OVER THE CENTRAL U.S. FURTHER UPSTREAM, THERE  
IS A STILL UNCERTAIN GUIDANCE SIGNAL TO DEVELOP A DEEPER LOW IN  
THE EASTERN PACIFIC EARLY NEXT WEEK THAT OFFERS POTENTIAL TO REACH  
CA AND THE GREAT BASIN/SOUTHWEST AGAIN EARLY NEXT WEEK ALONG WITH  
RENEWED UNSETTLED WEATHER/PRECIPITATION.  
 
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 PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,  
CALIFORNIA, AND THE SOUTHWEST,  
SAT-SUN, MAY 18-MAY 19.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF CALIFORNIA, THE NORTHERN  
PLAINS, AND THE NORTHERN ROCKIES,  
SAT, MAY 18.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,  
THE NORTHERN ROCKIES, AND THE  
NORTHERN GREAT BASIN, SUN, MAY 19.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL ROCKIES, THE  
NORTHERN PLAINS, AND THE NORTHERN  
ROCKIES, SUN-MON, MAY 19-MAY 20.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN PLAINS, WED,  
MAY 22.  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL ROCKIES, CALIFORNIA,  
THE PACIFIC NORTHWEST, AND THE  
CENTRAL PLAINS, MON-TUE, MAY 20-MAY 21.  
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN  
PLAINS, THE GREAT LAKES, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER  
MISSISSIPPI VALLEY, THE SOUTHERN  
PLAINS, AND THE OHIO VALLEY, SAT-WED, MAY 18-MAY 22.  
- HEAVY RAIN ACROSS PORTIONS OF THE BLACK HILLS OF SOUTH DAKOTA,  
WED, MAY 22.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE UPPER MISSISSIPPI  
VALLEY, SAT, MAY 18.  
- SEVERE WEATHER ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY,  
THE LOWER MISSISSIPPI VALLEY,  
THE GREAT LAKES, THE OHIO VALLEY, AND THE TENNESSEE VALLEY, SUN,  
MAY 19.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE  
SOUTHERN PLAINS, MON, MAY 20.  
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE  
MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY, TUE,  
MAY 21.  
- FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHERN GREAT BASIN.  
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER  
MISSISSIPPI VALLEY, THE NORTHERN  
PLAINS, THE GREAT LAKES, THE NORTHERN ROCKIES, THE MIDDLE  
MISSISSIPPI VALLEY, THE UPPER MISSISSIPPI  
VALLEY, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO VALLEY.  
- FLOODING LIKELY ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE  
NORTHERN GREAT BASIN.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN,  
THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL ROCKIES,  
CALIFORNIA, THE NORTHERN GREAT  
BASIN, THE PACIFIC NORTHWEST, AND THE SOUTHWEST, SAT-WED, MAY  
18-MAY 22.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE UPPER MISSISSIPPI  
VALLEY, THE GREAT LAKES, THE NORTHERN PLAINS, AND THE NORTHERN  
ROCKIES, SAT-TUE, MAY 18-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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