Prognostic Meteorological Discussion
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FXUS10 KWNH 301714
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
114 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...

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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