541  
FXUS02 KWBC 141600  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1200 PM EDT TUE MAY 14 2019  
 
VALID 12Z FRI MAY 17 2019 - 12Z TUE MAY 21 2019  
 
   
..OVERVIEW AND WEATHER HIGHLIGHTS/THREATS
 
 
OVERALL. AMPLIFIED MEAN TROUGHING ALOFT WILL BRING A WET PERIOD TO  
A LARGE PORTION OF THE WESTERN U.S. AND PLAINS STATES DURING THE  
WEEKEND TO EARLY NEXT WEEK. MUCH OF THE WESTERN US TO THE  
NORTHERN HIGH PLAINS WILL TURN COLDER, WITH MUCH OF THE MID-LOWER  
MS VALLEY EASTWARD TURNING MORE SUMMERLIKE.  
 
GUIDANCE IS STEADILY TRENDING TOWARD RESOLVING THE LEADING STRONG  
TROUGH PROGRESSING FROM THE WEST AND ROCKIES FRI/SAT AND IN ERNEST  
OVER THE CENTRAL THEN EAST-CENTRAL STATES FROM THE WEEKEND INTO  
EARLY NEXT WEEK. THIS NEG-TILT SYSTEM WILL SPAWN SURFACE SYSTEM  
GENESIS AND OFFERS ROUNDS OF LOCALLY HEAVY CONVECTION/SEVERE  
WEATHER AS PER SPC. UNDERNEATH, A GRADUALLY WEAKENING CLOSED LOW  
IS EXPECTED TO MEANDER FROM THE NORTHERN TO EASTERN GULF OF MEXICO  
AND OFFER SOME HEAVY RAIN POTENTIAL FOR SOUTHERN FLORIDA.  
 
THERE IS SOME AGREEMENT THAT UPSTREAM FLOW WILL BRING ANOTHER  
ROUND OF STRONG HEIGHT FALLS TO THE WESTERN STATES THIS WEEKEND,  
CONTINUING INLAND EARLY WEEK ACROSS THE GREAT BASIN TO THE HIGH  
PLAINS. 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 BY  
TUESDAY 21 MAY.  
 
MODEL AND ENSEMBLE SOLUTIONS CONTINUE TO ABOVE NORMAL FORECAST  
SPREAD WITH RESPECT TO DOWNSTREAM NORTHEASTERN U.S./MID-ATLANTIC  
FLOW THROUGH THE MEDIUM RANGE PERIOD AS A SERIES OF POTENT  
CANADIAN UPPER SYSTEMS PROGRESS WITHIN AN ENERGETIC NORTHERN  
STREAM. THESE UPPER SYSTEMS AND SURFACE SYSTEM REFLECTIONS HAVE  
TRENDED STRONGER INTO THE WEEKEND. TELECONNECTIONS RELATIVE TO THE  
NEGATIVE HEIGHT ANOMALY CENTER ASSOCIATED WITH THE WEST COAST MEAN  
TROUGH THEN FAVOR MODEST CYCLONIC FLOW ALOFT INTO EARLY NEXT WEEK.  
   
..GUIDANCE ASSESSEMNT
 
 
OVERALL, THE LATEST DETERMINISTIC MODELS OFFER BETTER THAN  
EXPECTED FORECAST CLUSTERING FRI INTO SUN MORNING. THE WPC PRODUCT  
SUITE PRIMARILY WAS DERIVED FROM A COMPOSITE MODEL SOLUTION DURING  
THIS PERIOD, QUICKLY TRANSITIONING TO ENSEMBLE MEANS EARLY NEXT  
WEEK.  
 
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  
 
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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