Prognostic Meteorological Discussion
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000
FXUS10 KWNH 040418
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1218 AM EDT SAT JUL 04 2015

VALID JUL 04/0000 UTC THRU JUL 07/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS

...UPPER TROUGH MOVING THROUGH WESTERN/CENTRAL CANADA SUN AND
MON...
...COLD FRONT CROSSING THE NORTHERN PLAINS TO THE MIDWEST/GREAT
LAKES...

PREFERENCE: BLEND OF THE 18Z GEFS MEAN AND 12Z ECENS MEAN
CONFIDENCE: AVERAGE

AN UPPER LOW AND ASSOCIATED TROUGH AXIS WILL BE CROSSING WESTERN
AND CENTRAL CANADA THROUGH THE PERIOD...WITH THE SOUTHERN PORTION
OF THE TROUGH EXPECTED TO CROSS THE NORTHERN PLAINS. THIS WILL
DRIVE A COLD FRONT EAST ACROSS THE NORTHERN PLAINS AND INTO THE
MID TO UPPER MS VALLEY AND GREAT LAKES REGION THROUGH SUN AND MON
AS A WAVE OF LOW PRESSURE DEVELOPS AND MOVES NORTHEAST ALONG THE
BOUNDARY. THE 12Z UKMET AND 12Z CMC ARE BOTH A BIT SLOWER THAN THE
MULTI-MODEL CONSENSUS WITH THE UPPER TROUGH AND CORRESPONDING COLD
FRONT EJECTING ACROSS THE NORTHERN PLAINS AND UPPER MS VALLEY. THE
12Z UKMET SURFACE WAVE DEVELOPMENT IS STRONGER THAN ANY OTHER
MODEL. THE 00Z GFS IS THE FASTEST SOLUTION WITH THE 12Z ECMWF AND
00Z NAM BOTH SPLITTING THE DIFFERENCE BETWEEN SLOWER AND FASTER
CAMPS. THE 18Z GEFS MEAN AND 12Z ECENS MEAN BOTH SUGGEST A
SOLUTION IN BETWEEN THE 00Z GFS AND 12Z ECMWF...AND SINCE THEY
CLUSTER TOGETHER QUITE WELL...A BLEND OF THE ENSEMBLE MEANS IS
PREFERRED RIGHT NOW WHICH ESSENTIALLY REPRESENTS A BLEND OF THE
00Z GFS AND 12Z ECMWF.


...SURFACE WAVE MOVING THROUGH THE OH VALLEY AND MID-ATLANTIC
THROUGH SAT...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

A MID LEVEL SHORTWAVE TROUGH AND ASSOCIATED WAVE OF LOW PRESSURE
OVER THE OH VALLEY WILL BE CROSSING THE MID-ATLANTIC REGION ON
SAT. THERE IS VERY GOOD MASS FIELD AGREEMENT SEEN AT THIS POINT
WITH THIS SYSTEM...AND SO A GENERAL MODEL COMPROMISE WILL BE
PREFERRED.


...SHORTWAVE CLIPPING THE GREAT LAKES/NORTHERN NEW ENGLAND THROUGH
SUN...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: AVERAGE

THE MODELS REMAIN IN FAIRLY GOOD AGREEMENT WITH THE SHORTWAVE
TROUGH THAT TRAVERSES NORTHERN PORTIONS OF THE GREAT LAKES AND NEW
ENGLAND THIS WEEKEND. HOWEVER...THE 00Z NAM AGAIN BECOMES TOO SLOW
WITH THE TROUGH EVOLUTION. THE REMAINING MODELS ARE SUFFICIENTLY
WELL CLUSTERED SUCH THAT A NON-NAM CONSENSUS WILL BE PREFERRED.


...UPPER TROUGH CROSSING THE GULF COAST STATES/SOUTHEAST SUN AND
MON...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: AVERAGE

SHORTWAVE ENERGY DIGGING THROUGH THE BASE 0F THE EASTERN U.S.
TROUGH WILL BEGIN TO DETACH ITSELF AND ATTEMPT TO CUT OFF OVER THE
GULF COAST STATES AND SOUTHEAST SUN INTO MON. THE 12Z UKMET
APPEARS OVERALL TO BE STILL A TAD WEAK WITH THE TROUGH. THE 00Z
NAM APPEARS TO BE A TAD TO STRONG AND ESPECIALLY EARLY IN THE
PERIOD AS TROUGHING SWINGS ACROSS THE TN VALLEY AND GULF COAST
STATES. THE 00Z GFS AND 12Z ECMWF SHOW BETTER MASS FIELD
CLUSTERING AND HAVE STRONGER ENSEMBLE SUPPORT. THE 12Z CMC ALSO
FAVORS THIS CONSENSUS...SO A BLEND OF THE GFS AND ECMWF WILL BE
PREFERRED.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

ORRISON

$$





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