Prognostic Meteorological Discussion
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000
FXUS10 KWNH 030630
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
229 AM EDT FRI JUL 03 2015

VALID JUL 03/0000 UTC THRU JUL 06/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/CMC AND THE
ECMWF

...UPPER TROUGH MOVING THROUGH WESTERN/CENTRAL CANADA THROUGH SAT
AND SUN...
...COLD FRONT CROSSING THE NORTHERN PLAINS/UPPER MS VALLEY...

PREFERENCE: NON-NAM CONSENSUS
CONFIDENCE: ABOVE 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
UPPER MS VALLEY BY THE END OF THE PERIOD. THE 00Z NAM BECOMES A
SLOW OUTLIER WITH THE FRONT AFTER ABOUT 48 HOURS...AND WITH THE
OVERALL TROUGH AXIS ALOFT BY 60 HOURS. THE REMAINING MODELS ARE
WELL CLUSTERED WITH TIMING AND DEPTH...AND SO A NON-NAM CONSENSUS
WILL BE PREFERRED.


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

PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: ABOVE AVERAGE

A MID LEVEL SHORTWAVE TROUGH CURRENTLY OVER THE MID MS VALLEY WILL
ADVANCE EAST ACROSS THE OH VALLEY AND MID-ATLANTIC REGION FRI AND
SAT ALONG WITH A WAVE OF LOW PRESSURE THAT WILL BE TRAVERSING A
FRONTAL ZONE. THE WAVE SHOULD EXIT OFFSHORE THE EAST COAST BY LATE
SAT. THE 00Z CMC IS THE SLOWEST SOLUTION OF THE CURRENT MODEL
SUITE...WITH THE REMAINING MODELS REASONABLY WELL CLUSTERED WITH
TIMING AND DEPTH. A NON-CMC CONSENSUS WILL BE PREFERRED AT THIS
TIME.


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

PREFERENCE: 00Z ECMWF
CONFIDENCE: AVERAGE

THE MODELS REMAIN IN FAIRLY GOOD AGREEMENT WITH THE SHORTWAVE AND
ASSOCIATED LOW THAT TRAVERSES NORTHERN PORTIONS OF THE GREAT LAKES
AND NEW ENGLAND THIS WEEKEND. HOWEVER...THE 00Z NAM BECOMES TOO
SLOW WITH THE TROUGH EVOLUTION. THE 00Z GFS FOR ITS PART APPEARS
TO BE A JUST A TAD TOO DEEP OVER NORTHERN NEW ENGLAND...AND AS A
RESULT TRIES TO BRING THE EXITING MID-ATLANTIC SURFACE LOW IN A
LITTLE CLOSER TO THE NEW ENGLAND COAST COMPARED TO THE OTHER
MODELS. THIS LEAVES THE NON-NCEP SOLUTIONS INCLUDING THE 00Z
ECMWF/00Z CMC AND 00Z UKMET. THE 00Z ECMWF SPLITS THE TIMING
DIFFERENCE BETWEEN THE RELATIVELY SLOWER 00Z CMC AND THE GRADUALLY
MORE PROGRESSIVE 00Z UKMET...SO THE 00Z ECMWF APPEARS TO BE THE
MOST REASONABLE SOLUTION AT THIS TIME WITH THIS TROUGH.

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

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z 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 00Z UKMET
APPEARS OVERALL TO BE TOO WEAK WITH THE TROUGH. THE 00Z NAM
APPEARS TO BE HANGING ON TO TOO MUCH ENERGY FARTHER WEST OVER THE
LOWER MS VALLEY BY MON...AND ALSO HAS A NOTABLY STRONGER RIDGE
BUILDING NORTH OF THE TROUGH OVER THE OH VALLEY AND NORTHERN
MID-ATLANTIC REGION. THE STRONGER MODEL CLUSTERING INVOLVES THE
00Z GFS AND THE 00Z ECMWF...AND A BLEND OF THESE SOLUTIONS 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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