Prognostic Meteorological Discussion
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000 FXUS10 KWNH 260700 PMDHMD MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 300 AM EDT THU MAY 26 2016 VALID MAY 26/0000 UTC THRU MAY 29/1200 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 00Z INITIAL MODEL EVALUATION WITH PREFERENCES/CONFIDENCE LEVELS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SYSTEM MOVING FROM THE SOUTHWEST INTO THE PLAINS THU-SUN INTERACTING WITH SHORTWAVE ENERGY ACROSS THE NORTHERN PLAINS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: CONSENSUS OF THE 0Z GFS/ECMWF/UKMET...WEIGHTED TOWARDS THE ECMWF CONFIDENCE: SLIGHTLY ABOVE AVERAGE AS OF 12Z THIS MORNING WILL HAVE A SHORTWAVE NEAR THE FOUR CORNERS REGION AT THE BASE OF THE LARGE SCALE TROUGH...AND A COUPLE OTHER SHORTWAVES MEANDERING ACROSS THE NORTHERN PLAINS. THE SOUTHERN SHORTWAVE IS EXPECTED TO EJECT INTO THE ROCKIES AND PLAINS THURSDAY AND FRIDAY...EVENTUALLY INTERACTING WITH THE SLOW MOVING SHORTWAVES ACROSS THE NORTHERN PLAINS. INITIALLY MODELS ARE IN PRETTY GOOD AGREEMENT ON THE SYNOPTIC SCALE WITH THE SOUTHERN SHORTWAVE EJECTING INTO THE PLAINS. HOWEVER BY FRIDAY BEGIN TO SEE DIFFERENCES IN HOW THE VARIOUS MODELS INTERACT THIS FEATURE WITH THE ENERGY OVER THE NORTHERN PLAINS. THE 0Z GFS IS THE MOST AGGRESSIVE IN MERGING THESE WAVES INTO AN ELONGATED VORTICITY AXIS...WITH THE ECMWF KEEPING THEM MORE SEPARATE. THE 12Z ECMWF IS ALSO THE QUICKEST IN EJECTING ALL THIS ENERGY INTO CANADA. THE 12Z ECMWF IS CONSIDERABLY QUICKER THAN ITS PREVIOUS RUNS AND ALSO IS FASTER THAN ITS ENSEMBLE MEAN. THUS OVERALL THINK BOTH THE 0Z GFS AND 12Z ECMWF HAVE ISSUES IN THE HANDLING OF THESE FEATURES. THE 12Z UKMET PROBABLY REPRESENTS A GOOD CONSENSUS SOLUTION SYNOPTICALLY. WILL RECOMMEND A CONSENSUS OF THE 12Z UKMET/ECMWF AND 0Z GFS FOR THESE SYSTEMS WHICH REPRESENTS A MIDDLE GROUND SOLUTION. THE 12Z GEM ENDS UP THE SLOWEST WITH THE THE SHORTWAVE ACROSS THE PLAINS BY FRIDAY/SATURDAY...WHICH ALSO HAS IMPACTS ON ITS SURFACE FEATURES. IT LIES ALMOST OUTSIDE THE ENSEMBLE SPREAD AND IS THUS NOT RECOMMENDED AT THIS TIME. THE 0Z NAM ALSO ENDS UP A BUT SLOWER/SOUTH WITH THIS WAVE BY SATURDAY AND ALSO APPEARS TO BE AN OUTLIER. 07z UPDATE: THE 0Z ECMWF HAS STAYED CONSISTENT KEEPING THE ENERGY MORE SEPARATE ACROSS THE PLAINS ON FRIDAY....AND THE 0Z GEFS MEAN LOOKS MORE SIMILAR TO THIS ECMWF SOLUTION...ADDING SOME CONFIDENCE THAT THE GFS EVOLUTION IS LESS LIKELY AT THIS TIME. THE 0Z ECMWF DID INDEED SLOW DOWN ITS PROGRESSION OF THE WAVE INTO CANADA AS WELL ON SAT/SUN...A SCENARIO THAT ALSO SEEMS TO HAVE SUPPORT FROM THE 0Z GEFS MEAN. THE 0Z GEM HAS COME INTO MUCH BETTER AGREEMENT WITH THE CURRENT MODEL CONSENSUS...ALTHOUGH IT DOES HAVE A STRONGER CONVECTIVELY INDUCED SHORTWAVE MOVING ACROSS THE MS VALLEY FRI/SAT...A SOLUTION THAT APPEARS UNLIKELY. THE 0Z UKMET STILL LOOKS GENERALLY BETWEEN THE ECMWF/GFS SOLUTIONS...ALTHOUGH IS LIKELY A TAD TOO STRONG WITH THE SHORTWAVE ENERGY. ALL IN ALL WILL CONTINUE A GFS/ECMWF/UKMET CONSENSUS PREFERENCE...ALTHOUGH BASED ON THE 0Z GEFS WOULD LIKELY LEAN CLOSER TO THE 0Z ECMWF. ...SYSTEM MOVING FROM THE GREAT LAKES BY MAINE FRIDAY AND A SECOND ONE SAT/SUN... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL CONSENSUS CONFIDENCE: ABOVE AVERAGE MINOR DIFFERENCES EXIST WITH THE SHORTWAVE AND SURFACE FEATURE MOVING TO THE NORTH OF MAINE ON FRIDAY. IN GENERAL THE DIFFERENCES WITHIN THE GUIDANCE APPEAR TO BE WITHIN THE USUAL MARGIN OF ERROR AT THIS TIME PERIOD...THUS A MODEL BLEND SHOULD SUFFICE. ...UPPER LOW DRIFTING E OF FLORIDA CONVECTIVE LOW TRACKING N OF BAHAMAS FRI/SAT... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z ECMWF/0Z GFS CONSENSUS CONFIDENCE: AVERAGE BY 12Z SUNDAY THE 12Z ECMWF/UKMET AND 0Z GFS ARE IN VERY GOOD AGREEMENT IN THE POSITION OF THE CONVECTIVE LOW OFF THE SC COAST. HOWEVER THEY DIFFER IN HOW THEY GET IT IN THAT POSITION...WITH THE GFS/UKMET FURTHER NORTH INITIALLY THAN THE ECMWF. SEE NO REAL STRONG EVIDENCE TO PREFER ONE OVER ANOTHER AT THIS TIME...THUS WILL PREFER A CONSENSUS OF THE 12Z ECMWF AND 0Z GFS. WILL LEAN AGAINST 0Z NAM WHICH APPEARS TOO SLOW...AND THE 12Z GEM WHICH APPEARS TO QUICK AND NORTH WITH THE SYSTEM. 07Z UPDATE: WILL CONTINUE WITH A 0Z GFS/ECMWF COMPROMISE. THE 0Z GEM/UKMET/NAM CONTINUE TO SUGGEST MORE OF AN OUTLIER SET OF SOLUTIONS AT THIS TIME. ...UPPER LOW/TROUGH OVER THE NORTHWEST... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: MODEL CONSENSUS CONFIDENCE: AVERAGE AN UPPER LOW IS EXPECTED TO SET UP ACROSS THE NORTHWEST THURSDAY INTO SATURDAY. THERE IS A DECENT AMOUNT OF SPREAD WITH REGARDS TO HOW INDIVIDUAL SHORTWAVES WITHIN THE LOW/TROUGH INTERACT WITH EACH OTHER AND IMPACT THE SHAPE/ORIENTATION OF THE BROADER TROUGH. GIVEN THE MULTIPLE PIECES OF ENERGY INVOLVED...LOW CONFIDENCE EXISTS ON THE EXACT DETAILS. AND THUS SEE NO STRONG REASON TO PREFER ONE MODEL OVER ANOTHER AT THIS TIME...WITH A GENERAL COMPROMISE PREFERRED. ...SHORTWAVE ENERGY TRACKING ACROSS NORTHERN NEW ENGLAND ON SATURDAY... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: 0Z ECMWF/GEM/UKMET CONSENSUS CONFIDENCE: SLIGHTLY BELOW AVERAGE SHORTWAVE ENERGY MAY TRAVERSE THE NORTHERN PERIPHERY OF THE EAST COAST RIDGE ON SATURDAY. THE NAM/GFS ARE MORE NEUTRALLY TILTED WITH THE TROUGH ACROSS THE PLAINS...WHICH DOES NOT ALLOW THIS ENERGY TO EJECT EAST INTO NEW ENGLAND. PREFER THE MORE POSITIVELY TILTED NON NCEP MODELS WHICH ALLOW FOR THIS ENERGY TO EJECT EAST TOWARDS NEW ENGLAND. THE GEM/UKMET ARE QUICKER THAN THE ECMWF WITH THIS EVOLUTION...AND WILL PREFER A TIMING IN BETWEEN. ...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml... ...500 MB FORECASTS AT www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... CHENARD $$

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