155  
FXUS02 KWBC 141611  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1210 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 AND WIDESPREAD PRECIPITATION/TERRAIN  
ENHANCED SNOWS TO THE WESTERN STATES FRI INTO 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 ALONG WITH RENEWED UNSETTLED WEATHER/PRECIPITATION.  
 
MEANWHILE, MODEL AND ENSEMBLE SOLUTIONS CONTINUE TO SHOW 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 AND PREFERENCE
 
 
THE LATEST DETERMINISTIC MODELS (06 UTC GFS/FV3 AND 00 UTC  
ECMWF/UKMET/CANADIAN) SEEM TO OFFER BETTER THAN EXPECTED FORECAST  
CLUSTERING FRI INTO SUN MORNING, BUT CONFIDENCE REMAINS SOMEWHAT  
MUTED DUE TO LESS THAN STELLAR CONTINUITY ISSUES. EVEN SO, THE WPC  
PRODUCT SUITE PRIMARILY WAS DERIVED FROM A COMPOSITE MODEL  
SOLUTION DURING THIS PERIOD THAT SEEMS INCREASINGLY REASONABLE  
BEFORE QUICKLY TRANSITIONING TO THE MUCH MORE COMPATABLE ENSEMBLE  
MEANS (06 UTC GEFS/00 UTC ECMWF ENSEMBLE MEAN) INTO EARLY NEXT  
WEEK AMID GROWING FORECAST SPREAD.  
 
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  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page