Prognostic Meteorological Discussion
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000
FXUS10 KWNH 190720
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
319 AM EDT SAT AUG 19 2017

VALID AUG 19/0000 UTC THRU AUG 22/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

00Z MODEL GUIDANCE EVALUATION ALONG WITH PREFERENCES AND FORECAST
CONFIDENCE


***COLD FRONT CROSSING THE NORTH CENTRAL U.S. THIS WEEKEND***

PREFERENCE: BLEND OF THE GFS AND ECMWF
FORECAST CONFIDENCE: AVERAGE

THE MODELS SHOW A SLOW MOVING UPPER TROUGH TRACKING EASTWARD JUST
NORTH OF THE CANADIAN BORDER, SUPPORTING A COLD FRONT THAT WILL
TRACK ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST TO NEAR LAKE
SUPERIOR SUNDAY. THE 00Z UKMET BECOMES MORE AMPLIFIED WITH THE
UPPER LEVEL TROUGH OVER LAKE SUPERIOR MON NIGHT, DEVELOPING
STRONGER LOW PRESSURE IN MI.  THE NAM CLUSTERS WELL WITH THE
GFS/ECMWF ON THE COLD FRONTAL TIMING. A BLEND OF THE NAM/
GFS/ECMWF SHOULD SUFFICE HERE GIVEN SIMILAR SOLUTIONS.

A SECONDARY CIRCULATION IS FCST TO DEVELOP IN THE CENTRAL PLAINS
SUNDAY AND MOVE NORTHEAST ALONG THE FRONT TOWARDS THE UPPER MS
VALLEY MON.  EACH MODEL SHOWS A WAVY FRONT WITH AREAS OF
CONVECTION.  THE AXIS/ORIENTATION IS SIMILAR ENOUGH TO SUGGEST A
CONSENSUS OF THE UKMET/ECMWF/GFS BE USED FOR THE FRONTAL AND WAVE
POSITIONS.

***LARGE SCALE UPPER LEVEL TROUGH OVER THE SOUTHWEST U.S. THIS
WEEKEND***

PREFERENCE: MODEL CONSENSUS
FORECAST CONFIDENCE: ABOVE AVERAGE

THE MODELS CONTINUE TO ADVERTISE A LARGE SCALE TROUGH OVER
CALIFORNIA AND THE DESERT SOUTHWEST WITH SHORTWAVE ENERGY 700-500
MB THAT MOVES NORTH ACROSS NM INTO EASTERN CO DOWNSTREAM FROM THE
SOUTHWEST TROUGH. PHASING DIFFERENCES EXIST IN THE MODEL SOLUTIONS
THAT PROVIDE MINOR DIFFERENCES. A MODEL CONSENSUS AMONG THE
NAM/GFS/ECMWF SHOULD ADDRESS DIFFERENCES IN THE FORECASTS.

***MID LEVEL TROUGH AND SURFACE COLD FRONT REACHING THE NEW
ENGLAND COAST SATURDAY NIGHT AND OFF THE COAST SUN***

PREFERENCE: MODEL CONSENSUS
FORECAST CONFIDENCE: AVERAGE

A SURFACE LOW IS FORECAST TO TRACK NORTHEASTWARD ACROSS QUEBEC
THROUGH SATURDAY, WITH A TRAILING COLD FRONT CROSSING NEW ENGLAND
SATURDAY.  GOOD AGREEMENT EXISTS AMONG THE MODELS ON THE 700-500
MB TROUGH TIMING...WITH MINOR AMPLITUDE DIFFERENCES.  GOOD
CLUSTERING SUGGESTS A BLEND OF THE GFS/ECMWF/NAM WOULD WORK WELL.

www.wpc.ncep.noaa.gov/html/model2.shtml
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

PETERSEN


$$




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