Prognostic Meteorological Discussion
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000 FXUS10 KWNH 301837 PMDHMD MODEL DIAGNOSTIC DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 236 PM EDT TUE JUN 30 2015 VALID JUN 30/1200 UTC THRU JUL 04/0000 UTC ...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR INGEST... FINAL 12Z MODEL EVALUATION WITH PREFERENCES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT RANGE FORECASTS. SHORTWAVE/S APPROACHING NRN PLAINS...DIVING INTO MID MS VALLEY WED/EARLY THURS AND MOVING THROUGH TN VALLEY/MID-ATL ON THURS... WHILE ADDITIONAL UPPER DYNAMICS REACH MID MS VALLEY/OH VALLEY LATE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ PREFERENCE: GFS/ECMWF THROUGH THURS/COMPROMISE FRI CONFIDENCE: AVERAGE A WELL-DEFINED SHORT WAVE TROUGH/MID-LEVEL LOW NEAR ND/ERN MT THIS EVENING WILL SHEAR-OUT DOWNSTREAM IN THE NWRLY FLOW REGIME ALOFT. THE GUIDANCE OVERALL DEPICTS THIS SCENARIO IN THE LARGE SCALE UPPER PATTERN BUT DIFFER ON THE DETAILS... WHICH WILL PLAY A SIGNIFICANT FACTOR IN QPF. THIS SPECIFIC SHORT WAVE DOES APPEAR LIKELY TO TRIGGER A POSSIBLE ORGANIZED CONVECTIVE HEAVY RAINFALL ACROSS MO INTO THE TN VALLEY/LOWER OH VALLEY THROUGH THURS AND THE GUIDANCE SHOWS THIS FOR THE MOST PART. HOWEVER BY FRI... ADDITIONAL SHORT WAVE DYNAMICS FROM BRITISH COLUMBIA WILL DIVE INTO THE BASE OF THE BROAD WEAKNESS. THE ECMWF DEEPENS THE TROUGH UPSTREAM OVER THE MID MS VALLEY BUT IS WEAKER DOWNSTREAM AND WILL ALLOW CONVECTIVE RAINS TO TAKE PLACE FROM COASTAL MID-ATL/SOUTHEAST UPSTREAM INTO THE TN VALLEY... WHILE THE STRONGER GFS SOLUTION BLENDS THE TWO TOGETHER TO FOCUS THE HEAVY RAIN OVER THE TN VALLEY/LOWER OH VALLEY INTO THE MID-ATL REGION. AT THIS MOMENT... WPC WILL RECOMMEND A BLEND OF THE GFS/ECMWF THROUGH THURS BUT A MODEL COMP ON FRI DUE TO THE SLIGHT MASS FIELD AND LARGER SMALL SCALE DETAIL DIFFERENCES. TROUGH OVER GREAT LAKES AND OH/TN VALLEYS LIFTING THROUGH NERN QUAD OF COUNTRY ON WED ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~ PREFERENCE: 12Z BLEND CONFIDENCE: ABOVE AVERAGE THE GUIDANCE FOR THE MOST PART IS IN VERY GOOD AGREEMENT WITH THE TROUGH LIFTING OUT OF THE GREAT LAKES/OH VALLEY THROUGH THE NERN CORRIDOR ON WED. THE ONE TREND WITH THE 12Z GUIDANCE IS A DEEPER TROUGH LIFTING OUT WITH A DEEPER SURFACE LOW MOVING THROUGH SERN ONTARIO INTO QUEBEC BUT THE PROGRESSION OF THE SURFACE FRONT APPEARS ON PAR. THUS WPC WILL RECOMMEND A BLEND OF THE 12Z PACKAGE ON THIS SYSTEM WITH ABOVE AVG CONFIDENCE. SHORT WAVE OVER PAC ENDING UP IN NORTHERN PLAINS/UPPER MIDWEST FRI EVENING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~ PREFERENCE: BLEND/COMPROMISE CONFIDENCE: AVERAGE THE GUIDANCE DEPICTS A SHORT WAVE OVER THE PAC ADVANCING DOWNSTREAM OVER THE WRN RIDGE AND ARRIVING INTO THE NRN PLAINS/UPPER MIDWEST ON FRI. THE GUIDANCE IS RATHER SIMILAR ON THE PROGRESSION OF THIS FEATURE BUT DIFFER ON INTENSITY AND DEPTH OF THE FEATURE ALOFT. WPC WILL RECOMMEND OF BLEND/COMPROMISE OF THE DATA AT THIS TIME. ...MODEL TREND GRAPHICS AT www.wpc.ncep.noaa.gov/html/model2.shtml... ...500 MB FORECASTS AT www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml... MUSHER $$

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