Prognostic Meteorological Discussion
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000 FXUS10 KWNH 281911 PMDHMD MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 310 PM EDT THU JUL 28 2016 VALID JUL 28/1200 UTC THRU AUG 01/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... 12Z FINAL MODEL EVALUATION INCLUDING PREFERENCE AND FORECAST CONFIDENCE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TUTT ENERGY LIFTING NORTH ACROSS MS VALLEY INTO MID-ATLANTIC/NEW ENGLAND FRI INTO SAT WITH SURFACE LOW DEVELOPING IN VA/NC PIEDMONT THUR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GENERAL MODEL BLEND CONFIDENCE: ABOVE AVERAGE SYNOPTICALLY THE MODELS REMAIN IN GOOD AGREEMENT. THE 0Z GEM REMAINS THE ONLY BIG OUTLIER. UNCERTAINTY STILL EXISTS WITH THE AXIS OF HIGHEST QPF...DRIVEN IN PART BY CONVECTIVE AND MESOSCALE PROCESSES. SEE THE QPFPFD FOR MORE DETAILS ON THE QPF ASPECT OF THIS SYSTEM. 19Z UPDATE: THE 12Z GEM HAS TRENDED MORE IN LINE WITH THE REMAINDER OF THE GUIDANCE WITH REGARDS THE SHORTWAVE AND LOW TRACK. MULTIPLE WEAK SHORTWAVES OVERTOPPING SW RIDGE TO CARVE OUT A BROAD/WEAK TROF ACROSS LOWER MISSOURI RIVER VALLEY FRI AND INTO THE SOUTHERN GREAT LAKES/OH RIVER VALLEY BY SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: BLEND OF 12Z GFS/NAM/ECMWF CONFIDENCE: AVERAGE BROAD TROUGHING EXISTS AND WILL CONTINUE TO DEVELOP ACROSS THE NORTHERN PLAINS INTO THE MS RIVER VALLEY IN THE WAKE OF THE EXITING CLOSED LOW IN CANADA/TUTT CELL LIFTING NORTHEAST THROUGH NEW ENGLAND. THIS PATTERN SUPPORTS NUMEROUS CONVECTIVELY INDUCED UPSCALE GROWTH SCENARIOS...SOME WITH ADDITIVE EFFECTS...AS WAVES DROP SOUTHEAST AROUND THE PERIPHERY OF THE SOUTHWESTERN U.S. RIDGE. THE 0Z GEM/UKMET ARE STRONGER/NORTH WITH A DEVELOPING SURFACE LOW ACROSS THE GREAT LAKES...OHIO VALLEY AND MID ATLANTIC REGIONS BY THE WEEKEND. AT THIS TIME THERE IS NOT MUCH SUPPORT FOR THIS STRONGER SOLUTION. A CONSENSUS OF THE 12Z GFS/NAM AND THE 0Z ECMWF APPEARS TO REPRESENT THE MOST PROBABLE OUTCOME AT THIS TIME. 19Z UPDATE: THE 12Z GEM/UKMET REMAIN A BIT DEEPER THAN THE ECMWF AND NCEP GUIDANCE...AND ARE THUS STILL NOT PREFERRED AT THIS TIME. WHILE MINOR DIFFERENCES EXIST BETWEEN THE ECMWF/GFS/NAM...THE SOLUTIONS ARE SIMILAR ENOUGH THAT ARE ALL REASONABLE. THUS A BLEND OF THE THREE SHOULD WORK WITH THIS SYSTEM. SHORTWAVE TROF DIGGING ACROSS NORTHWEST US BY SAT ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: NON-GEM BLEND CONFIDENCE: SLIGHTLY ABOVE AVERAGE A DEVOLVING CLOSED LOW IN THE GULF OF ALASKA IS ELONGATING WITH NUMEROUS INTERNAL SHORTWAVES NOTED. AS THE OVERALL PATTERN SUPPORTS SOUTHEASTWARD TRACKING OF THE ENERGY...THE MODELS ARE IN GENERAL AGREEMENT WITH THE EVENTUAL INTERACTION OF SHORTER WAVE FEATURES CONSOLIDATING INTO TWO MORE CONCENTRIC CLOSED LOW(S) ACROSS WESTERN CANADA AND THE GULF OF ALASKA. MODELS HAVE TRENDED INTO PRETTY GOOD AGREEMENT WITH THE HANDLING OF THESE UPPER LOWS. WHILE MINOR DIFFERENCES STILL EXIST WITH THE TIMING AND DEPTH OF THE WAVES...ONLY THE 0Z GEM REALLY STANDS OUT AS AN OUTLIER AT THIS TIME. THUS A NON GEM BLEND SHOULD SUFFICE FOR THIS REGION FOR THE TIME BEING. CHENARD ...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml... ...500 MB FORECASTS AT www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... $$

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